John Williamson addressed the challenges in maintaining animal health and productivity through functional nutrition.

Central to these strategies is gut health, which is the foundation of shrimp performance. The assertion is that a healthy gut supports better digestion, stronger immunity and resilience to stress. Increasing concerns on antimicrobial resistance and consumer demand for residue free seafood are limiting the use of antibiotics. This has accelerated the development of non-antimicrobial and sustainable health solutions.

During TARS 2025, on shrimp aquaculture, John Williamson, Business Development Director, Auranta, Ireland, discussed functional nutrition strategies to mitigate major diseases and outlined results from laboratory and field trials. Auranta is an Irish biotech startup focused on natural, science‑backed solutions for animal health, especially gut health, immunity and antimicrobial reduction. It originated as a spin‑off from NovaUCD, the University College Dublin innovation hub. “It is important to understand the enemy and then develop solutions,” said John. “Understanding the value proposition is critical. Targeted use is important such as during a WSSV outbreak.”

Various pathogens such as Vibrio, white spot syndrome virus (WSSV) and Enterocytozoon hepatopenaei (EHP) are disrupting production cycles and constraining profitability. At Auranta, shrimp primary gut and hepatopancreas cells have been isolated to study infection mechanisms and cellular responses. Combined with in vivo infection studies, this work has been documented in seven peer reviewed papers covering Vibrio, translucent post larvae disease (TPD), EHP, WSSV and gregarines (Nematopsis), the latter prevalent in Ecuador.

On the use of functional feeds, John Williamson said, “I think what we should focus on is value and cost per kg shrimp produced as opposed to cost per kg of feed or of the functional additive itself.” 

Managing Vibrio and TPD
TPD is caused by Vibrio parahaemolyticus strains carrying multiple plasmid-borne toxin genes. Key among these are VHVP-1 and VHVP-2, a two-component toxin system where VHVP-1 supports attachment to the shrimp epithelial cell whilst VHVP-2 executes toxic effects inside shrimp cells (Williamson, 2025).

TPD can cause more than 90% mortality within 24–48 hours in PL 2–4 shrimp if left unchecked. Research using shrimp cell models showed that a natural antimicrobial blend based on an organic acid/phytogenic blend can silence key virulence genes, including VHVP toxins and PirA. Downregulation of HCP1 and HCP2 reduces bacterial adhesion and cytotoxicity across different salinities and strains (Asian and Latin America). In a Vibrio TPD challenge trial, untreated shrimp showed mortality around 91%, while the inclusion of natural antimicrobial blend reduced mortality to below 6%.

Efficacy to overcome WSSV and EHP
John demonstrated how the organic acid/phytogenics blend modulated immune oxidative pathways exploited by the virus. Downregulation of genes such as beta-1,3-glucan binding protein reduced hyperinflammation and cell death. Increased mucin gene expression (Mucin 1 and Mucin 2) improved mucus production and antioxidant activity further reduced oxidative stress. In vivo trials demonstrated significant reductions in viral copy numbers and mortality (from 96% in controls to 7% in treated shrimp).

Field trials in Thailand and Ecuador showed reduced white faeces and WSSV prevalence. In a farm in Thailand, WSSV prevalence decreased from over 30% in 2021 to 3% in 2022, which remained between 3–10% throughout 2024. Growth performance and feed conversion ratio (FCR) were maintained in Ecuador. In the Thai farm with 200 ponds, the organic acid blend was added directly into feeds at 5kg/tonne by the feed mill and fed to shrimp all year round. This farm has been successful in overcoming WSSV whilst others in the area encountered disease.

In a field trial in India, the blend was effective against EHP by attacking the parasite’s infection process and bolstering host cell defences. Inclusion of the product during an ongoing EHP infection restored linear growth performance (Figure 2). The effect was a significant reduction in EHP copy numbers.

John concluded that undoubtedly, functional nutrition is a critical pillar of health management. However, further research is needed to define nutritional thresholds and identify novel functional ingredients. Clear documentation of performance, cost and ROI is essential to drive adoption by producers. “Often, functional ingredients seem to be expensive. I think what we should focus on is value and cost per kg shrimp produced as opposed to cost per kg of feed or of the functional additive itself. The application strategy is also crucial, necessitating close collaboration between feed manufacturers and farmers.”

Reference
Williamson, J., 2025. Natural antimicrobials in shrimp aquaculture: Broad-Spectrum protection against WSSV, EHP and TPD. September/October 2025, pp 32-34. https://issues.aquaasiapac.com/view/879690187/34/

The rising concern of TPD regionally
A panel led Dr Kallaya Sritunyalucksana-Dangtip, BIOTEC/NSTDA, Thailand, with invited industry players noted that while some countries reported no official detection, anecdotal evidence from farmers suggested otherwise. Private laboratory testing in Vietnam confirmed TPD cases. Malaysia has already implemented stricter biosecurity measures, requiring imported broodstock to be certified free of TPD. Thailand has formed a task force for regular surveillance. Panellists stressed that cross-border movement of post larvae and broodstock presents significant risk making coordinated enforcement essential.

Members also cautioned against the misinformation on how to prevent or manage TPD. Practices such as indiscriminate antibiotic baths for post larvae may risk long term consequences, including antimicrobial resistance. The importance of infrastructure and regulation was highlighted. Proper farm design, water treatment systems and reservoir capacity can reduce disease pressure. Meanwhile, stricter oversight of cross-border livestock transfers is essential to prevent pathogen spread.

The promise and skepticism of functional feeds
One of the central themes of the discussion was functional nutrition. In Thailand, with increasing pressure to reduce antibiotic use and move toward antibiotic-free production, functional ingredients could serve as alternatives. Yet, cost remains a barrier. Without clear field data demonstrating consistent performance improvements and links to profitability, feed mills and farmers remain hesitant to fully embrace functional formulations.

John provided a useful benchmark with salmon farming, where functional nutrition is widely adopted during stress periods, such as seawater transfer and has been linked to measurable performance gains. The shrimp sector may learn from this model. In Ecuador, farmers use functional feeds throughout the production cycle as part of a broader strategy to manage the disease. In Asia, premium functional feeds priced significantly higher than standard diets have struggled to gain widespread adoption. Lower cost formulations with select additives like organic acids or beta glucans are more acceptable, but farmers remain cautious due to their high expectations.

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Dragoș Mircea discussed his battle with TPD at his two farms in Vietnam and the lessons learnt

In early 2025, translucent post larvae disease (TPD) became a major issue in Vietnam. At TARS 2025, held in August, Dragoș Mircea, CEO of Good Tôm (a shrimp farming startup), discussed his experience tackling TPD at his two shrimp farms and shared relevant field data and insights gained from managing this disease.

Good Tôm (Good Shrimp) operates a 2ha research farm and a 10ha production farm in Bac Lieu, Mekong Delta. The farms use intensive, circular, HDPE-lined ponds (350–1000m³), with biosecurity fencing, automated feeding and waste removal, together with data-based, precise protocols. He runs 3–4 annual cycles targeting size 30-40/50 per kg. Stocking density is typically 200 PL/m² during grow-out. The aim is an antibiotic-free, profitable and sustainable farming, adjusting stocking density as needed to ensure that carrying capacity is not exceeded. 

“We had some great, very profitable crops, with shrimp sizes 27-40/kg and 70-83% survival rates. We also had EHP outbreaks, producing size 80-100/kg, and some crops with 50-60% survival rates. TPD was a different experience,”  said Dragoș Mircea.

Three TPD outbreaks
Both farms encountered TPD outbreaks. The first occurred in December 2024, the second in February 2025, and both were in Farm 1. The third case was in May 2025 in Farm 2. In two outbreaks, he linked the source to hatcheries and for one of them, a water borne source. Mortality was high, usually well over 50%, but not precisely measured until harvest. TPD diagnosis was confirmed by PCR.

Case one

“In the beginning, my technicians reported unusual observations. The shrimp exhibited pallor, mortality began at DOC6, transparency increased, and the gut was no longer visible. Despite interventions, mortalities could not be contained,” stated Dragoș. Mortality rates rose sharply, with estimated losses exceeding 50% within several days (Figure 1). In ponds 2 and 3, mortality persisted through DOC75 and remained unmitigated. By DOC110, survival was recorded at 33%, with FCR of 1.75. In pond 1, significant mortality continued for an additional 20 days before stabilising. Although these ponds showed improved survival, managing them remained highly challenging, said Dragoș. 

An outlier

This is pond 4 where shrimp showed sharp mortality(~75%) until DOC 25-30 at the nursery phase, but as they were transferred to grow-out ponds, it was an easy cycle with survival at 85-90%, resulting in strong economic outcomes. “In the prolonged nursery phase which began with PL12, the shrimp recovered somewhat, and mortality stabilised. Shrimp grew to size 27/kg. How did we do this? To reduce Vibrio parahaemolyticus in the gut and water, we used water disinfectants, feed probiotics, organic acids and phytogenics, along with extended probiotic and carbon use in the grow-out pond before transfer from the nursery. I was hoping that V. parahaemolyticus TPD will reduce below its lethal threshold and/or evolve into a no nor less deadly strain. 

Dragoș explained, “This gave us the confidence to keep the crop. We continued as usual, distributing the shrimp among the available grow-out ponds. As a result, the density was lower than our typical practice—60–80/m3at harvest, instead of the usual 150+ PL/m3. We had three ponds with TPD shrimp, which we harvested at around DOC 110–115.The shrimp sold for a premium of USD 6-7/kg, partly because it was Chinese New Year (Tet in Vietnam) when prices were high, and because supply was low due to many farms facing TPD.”

Case two

A hatchery-linked outbreak with high TPD levels (confirmed by plating and PCR) caused ongoing mortality for 45 days. The post-larvae came from a different hatchery. The crop was terminated, as the same intervention from case 1 was in effective. Mortality decreased after 15 days but persisted until the crop was abandoned at DOC 45 with shrimp size~300/kg.

Case three

This was likely a waterborne outbreak in a single pond. The same batch of post-larvae was stocked in several ponds but only one pond had a TPD outbreak. “We believe that shrimp contracted TPD from poorly disinfected pond water. Economic performance was acceptable, as the shrimp recovered relatively fast in this instance. ”Early intervention, strong disinfection and biosecurity containment prevented the spread. Survival was 50-60%post challenge. The cycle finished with a survival rate of35%, size 40 CAL, in 95 days.

Lessons to manage TPDTPD is among the most severe diseases affecting shrimp farming. Drawing from his experience with TPD, Dragoș categorised key lessons into methods for prevention and containment:

• Preventing TPD requires sourcing post-larvae from reputable hatcheries and verifying their quality. This isthe most important step.
• It is prudent to always assume water sources may be contaminated with TPD and to implement effective water treatment protocols. For instance, high pH level scan reduce chlorine’s efficacy. In Vietnam, it is advisable to presume TPD is present in nearby canals and to apply the required dose of disinfectant before stocking.
• The use of nursery ponds will limit the spread of TPD within the farm. This will also minimise economic losses as smaller volumes of water will be compromised.
• Implementing biosecurity measures has proven effective in limiting the spread of TPD, as demonstrated in case 3

Dragoș added, “While this may not be the ideal solution, farmers who choose to retain TPD-infected shrimp may consider approaches aimed at strengthening shrimp health, reducing horizontal transmission, and optimising gut health.” These are outlined in the table below

The message was “We noticed that the outcome was mixed, despite using the same protocols. It was an unpredictable disease and we suspected we were dealing with different strains of TPD.

”Post note by Dragoș. As an update on TPD since TARS2025 – outbreaks have decreased significantly, I have not heard of it much in the South of Vietnam this season. Probably hatcheries figured out a way to prevent it, and the consensus has always been that it came from them.

The diagnostics gap: Early detection of pathogens

“There is the financial toll of disease across board,” said Kit Yong, Founder of Forte Biotech, as he highlighted the harsh economic realities faced by aquaculture farmers across Southeast Asia in a presentation at TARS 2025on shrimp aquaculture, in August 2025. “When disease strikes, farmers lose their harvest and income while feedmills and dealers risk losing receivables tied up in ponds for one to three months. Furthermore, credit chains are disrupted, straining cash flow across the value chain.”

“Time is the most critical factor in disease management. Early detection, that is within the first 24 hours of infection, can significantly reduce financial losses. With timely diagnostics, farmers can conduct emergency harvesting, remove infected stocks early, save feed, labour and medication costs and prevent wider spread to neighbouring farms.

“The startup, Forte Biotech has been piloting on-site diagnostic tools with farmers across Southeast Asia and reports detecting white spot outbreaks up to seven days before visible symptoms appear. This early warning window allows farmers and their partners to take preventive action rather than reacting to catastrophic losses.

The company offers customisable, on-site diagnostic tools, white label partnerships, subscription models and AI driven advisory support to help farmers interpretresults and optimise treatment timing. Its TPD assay was ready for use recently. It runs on the RAPID devices with the same simple workflow: extract, load and get quantitative results in one hour on site. “We have since then, tested this with TPD isolates in Vietnam,” added Kit

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 In India, running mortality syndrome (RMS) has recently intensified, leading to ongoing losses and frequent crop failures. Farmers often cannot sustain crops beyond 70–75 days. RMS is typically associated with white muscle and pinkish discolouration. Along with white faeces disease (WFD) and the age-old WSSV, these conditions contribute to chronic production losses.

In August, the Prawn Farmers Federation of India (PFFI) launched the pilot phase of a historic farmer-led targeted disease investigation program at Velankanni in Tamil Nadu. This initiative brings together farmers, scientists from the Central Institute of Brackishwater Aquaculture (ICAR–CIBA) and the Rajiv Gandhi Centre for  Aquaculture (RGCA–MPEDA), industry supporters, and international experts from the University of Arizona, including Professor Arun K. Dhar and his team.

The program aimed to tackle the persistent disease related mortalities and crop failures that continue to threaten Indian shrimp farming.

Balasubramaniam V, General Secretary of the Prawn Farmers Federation of India (PFFI), said,

“We desperately needed to understand the disease and to figure a way out of this terrible situation. For the first time, farmers and scientists are working hand in hand under a structured framework, using each other’s strengths. PFFI will be the coordinator for field visits, farmer data and sample collection, while the researchers focus on the disease investigation in the laboratories. I am privileged to initiate and coordinate this effort, with overwhelming support from the industry and farming communities across the country.”

Technical and marketing teams from feed and input suppliers are coordinating with farmers and project field coordinators to regularly visit farms and collect data and samples, especially during disease outbreaks. Activities follow a structured and coordinated program.

The inaugural session brought together more than 150 farmers, industry stakeholders from across the country, and key government bodies. For the first time, eight national organisations are working under one umbrella. These are: 
• PFFI – Prawn Farmers Federation of India – Lead farmer
organisation driving the program.
• ICAR–CIBA – Central Institute of Brackishwater
Aquaculture – National aquaculture research institution
& key investigator.
• MPEDA–RGCA – Rajiv Gandhi Centre for Aquaculture
– National aquaculture research & demonstration
centre under MPEDA; key investigator.
• NFDB – National Fisheries Development Board (funding
agency).
• CAA – Coastal Aquaculture Authority (regulatory
agency).
• AISHA – All India Shrimp Hatchery Association.
• SAP – Society of Aquaculture Professionals.
• SEAI – Seafood Exporters Association of India.

The pilot phase focuses on two commonly reported but insufficiently studied conditions: rapid mortalities associated with white muscle, and chronic production challenges linked to white faeces. Over the next two years, the study will combine: a case–control epidemiological survey to identify risk factors, continuous farm-level monitoring and field investigations, and laboratory-based challenge trials to assess suspected causative agents and triggering conditions. 

Update: Program now moves into the next phase during the upcoming crop cycle

In February, Balasubramaniam V, updated on activities. 
“Over the past few months, a considerable amount of work has been taking place quietly in the field and at the laboratories, and we felt it was the right time to share the latest developments with all of you who have been supporting this initiative.”

Since the recruitment of our first research associate, Mary Divya, the laboratory work  at ICAR–CIBA has been progressing steadily. Live samples collected from farms in Nagapattinam and sent by our field technical team have been undergoing continuous screening and analysis.

Last week, a joint scientific review meeting was held at the RGCA headquarters in Sirkazhi, bringing together investigators from ICAR–CIBA, RGCA and PFFI. The meeting was attended by Dr. Kuldeep Lal, Director of CIBA, and Dr. Anup Mandal, Project Director of RGCA, along with the investigation team.

The preliminary investigations by both CIBA and RGCA indicate the possible involvement of a pathogen in the disease situation being investigated. Further validation work will continue before firm conclusions are drawn.

The program now moves into the next phase during the upcoming crop cycle, where selected farms will be closely monitored through the crop, additional field sampling will continue, and case–control studies will be carried out to better understand the factors associated with the disease occurrence.

“We remain deeply grateful to all our corporate supporters, Scientific committee members and well-wishers who have stood with farmers and scientists in making this farmer-led investigation possible.”

Science without borders. Solutions for farmers.
Led and coordinated by the Prawn Farmers Federation of India (PFFI).

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Enterocytozoon hepatopenaei remains a silent yet pervasive threat to shrimp aquaculture worldwide. Now, a new breakthrough brings unprecedented speed and insights to manage its risk

Silent but pervasive threat to shrimp aquaculture
White faeces disease (WFD) has emerged as a significant threat to shrimp aquaculture, characterised by floating white faecal strings and pale midguts in affected animals. One of the causative agents of WFD is Enterocytozoon hepatopenaei (EHP), a microsporidian parasite responsible for hepatopancreatic microsporidiosis (HPM). First identified in Thailand in 2004, EHP has rapidly spread across major shrimp-producing regions in Southeast Asia and Latin America.

Although EHP infections rarely result in acute mortality, their chronic impact on shrimp health and farm productivity is profound. Infected shrimp exhibit poor growth performance and reduced feed conversion efficiency. This leads to uneven size distribution, extended production cycles, and diminished harvest value. The economic losses caused by EHP alone were estimated to be USD~560 million in India (2018-2019) and USD~230 million in Thailand (2018). As the pathogen continues to spread, its management has become a focal point for the industry to sustain the viability of shrimp farming operations.

“Symptoms are often absent or mild in early stages, infections frequently go unnoticed until performance losses become apparent.”

Persistent and tiny spores

The biological characteristics of EHP add to its threat. Its oval spores, measuring approximately 1.1–1.7μm X 0.7–1.0μm, can persist in pond water, sludge, and organic matter even under harsh environmental conditions. Once a shrimp is infected, (im)mature spores multiply in the hepatopancreas and are shed via faeces, rapidly seeding the pond environment and contributing to pond-wide transmission. Compounding the challenge is EHP’s subclinical progression; symptoms are often absent or mild in early stages, which means infections frequently go unnoticed until performance losses become apparent.

A new early-warning tool:

EHP indicator

Recent studies suggest that environmental EHP levels in pond water and sediment are linked to infection levels in shrimp. Active outbreaks showed spore loads ranging from as little as 101–103 DNA copies/mL of pond water. This underscores the potential of pond water monitoring as an early-warning system.

By tracking the mature spore concentrations released via the faeces, over time, farmers can detect rising infection pressure before clinical symptoms appear. However, this proactive approach depends on highly sensitive, rapid and cost-effective tools capable of detecting mature EHP spores in complex pond environments.

As ingestion of mature EHP spores forms the main risk factor for infection, measurements of this specific phenotype of EHP, are a crucial piece of information to enable its effective management. Here, we describe the development and application of a new EHP mature spore indicator for rearing environments of hatchery and farm environments in Vietnam and Thailand.

Capturing information on single EHP spore

At the core of the EHP Indicator is KYTOS’ proprietary single-cell analysis platform (Figure 1), which merges advanced microbiological profiling with machine learning to create predictive indicators. The process begins with the analysis of purified reference material from infected Penaeus vannamei, which is then analysed on the KYTOS platform to capture information on every single EHP spore particle.

Proprietary machine-learning workflows are then used to fine-tune models capable of detecting these mature EHP spores in the presence of naturally occurring microbiota from shrimp ponds and hatcheries. In our case, this training data comprised more than 600 million single-cell data points from shrimp ponds (water, gut and hepatopancreas) and yielded highly robust model accuracy (99.5 %) and overall performance (Table 1).

Rapid insights for farmers
The beauty of this approach is that through a simplesoftware update, these predictions can be made available to all customer data analysed by the Kytos platform. The EHP Indicator quantifies mature spore loads and embeds them within a predictive framework, enabling farmers to detect infection pressure before visible symptoms arise. By providing early warning, it empowers shrimp producers to make informed management decisions, from strengthening biosecurity and adjusting feeding strategies to applying targeted pond interventions.

Delivered through the Kytos platform, the dedicated EHP dashboard transforms complex microbiome data into clear, actionable insights: spore density trends are visualised in real time, benchmarked against an extensive country-specific database and contextualised to distinguish background levels from critical infection thresholds (Figure 2). A continuous monitoring of pond water and shrimp tissue allows producers to detect deviations from baseline microbial conditions, anticipating outbreak risks with time to intervene.

This data-driven approach shifts disease management from reactive treatment to proactive prevention, resulting in improving crop outcomes, reducing economic losses, and enhancing sustainability. Integrated into a broader microbiome analysis service, the EHP Indicator is complemented by more than 25 additional indicators spanning bacterial, algal, and fungal groups, providing a comprehensive view of pond health.

Each sample can be analysed in under one minute, delivering all indicators – including EHP risk markers – with rapid turnaround, automated updates, and seamless digital access. Its strength lies in detecting mature spores rather than residual DNA, leveraging single-cell analysis and AI-powered models trained on over 100,000 aquaculture samples, and validated across thousands of real-world shrimp datasets. Robust to pond variation, geographic diversity, and farming practices, the EHP Indicator delivers accuracy, scalability, and real-time feedback, turning microbiome data into practical tools to achieve more profitable shrimp farming.

Cross-country differences in spore loads
Using this new model, EHP mature spore predictions were made on data of farms in our early-testing program to evaluate differences across geographical and market segments (Figure 3).

In Thailand, aggregated data indicated considerably higher EHP levels in exchange water than in rearing water, suggesting that incoming water may serve as an important contamination source. In contrast, Vietnamese farms exhibited much lower EHP densities in exchange water, likely reflecting the widespread application of stronger disinfection and water-treatment protocols. Nevertheless, EHP concentrations increased sharply in rearing water, pointing to internal amplification during culture despite clean water inputs.

At the production stage level, hatchery samples from Vietnam tended to show higher EHP spore densities than those from Thailand, potentially contributing to the elevated loads later observed in farm systems. These patterns underscore the critical link between hatchery biosecurity, post larvae (PL) quality, and the downstream risk of EHP outbreaks in grow-out ponds. Identifying the points at which contamination is most likely to occur provides a basis for targeted preventive measures that safeguard shrimp health and improve production performance.

EHP changes with seasons
Seasonal patterns in EHP spore densities revealed clear geographical differences between Thailand and Vietnam (Figure 4). In both countries, EHP levels fluctuated across dry and rainy seasons, reflecting the influence of environmental conditions and management practices on microbial risks in shrimp ponds. Thailand displayed more stable yet persistent EHP signals throughout the year, whereas Vietnam showed greater volatility during the dry season. These trends highlight the interaction between seasonality and water management in shaping pathogen pressure.

To capture these dynamics more effectively, the Kytos team updates its microbial monitoring database continuously. This growing dataset enables the identification of emerging trends, local risk periods, and region-specific responses to management practices.

By collaborating closely with industry stakeholders, Kytos translates microbial insights into practical recommendations that support early detection and farm management. Continuous monitoring not only reveals how EHP behaves across seasons but also empowers producers to make informed, data-driven decisions that enhance shrimp health, improve production outcomes, and build long-term resilience.

Acknowledgments
The development of the EHP Indicator is the result of the collective efforts of KYTOS teams in Belgium, Thailand, and Vietnam, whose dedication and creativity were instrumental in bringing this innovation to fruition (Ruben Props, Bui Ngoc Minh Ngan, Doan Dang Quynh, Hoang Truc Linh, Waraporn Tongyos and Tita). This work was supported by the Flanders International Climate Action Programme (FICAP) through the project “Sustainable Water Management for Aquaculture in Southeast Asia through Innovative Microbial Management” (IKF 23/059).

This article was first published in Aqua Culture Asia Pacific November/December p37-39.  https://issues.aquaasiapac.com/view/717436716/38/#zoom=true

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A deeper analysis shows that the impact on costs goes beyond increases in feeding the shrimp.

Shrimp aquaculture has been a pillar of economic growth in several Asian countries, yet beneath the surface lurks a formidable threat, Enterocytozoon hepatopenaei (EHP). Unlike pathogens that cause visible mass mortalities, EHP operates quietly, gradually undermining farm profitability through less obvious but significant impacts on shrimp growth and yield.

The nature of EHP and its impact
EHP is a microsporidian parasite that targets the shrimp hepatopancreas, a key organ responsible for digestion and nutrient absorption. Rather than causing immediate death, EHP infections primarily result in stunted growth and large size variations at harvest. These translate directly into economic losses, as farmers deliver smaller shrimp, often missing premium market opportunities.

Economic consequences
The chronic presence of EHP leads to several detrimental outcomes for shrimp farmers, which include:
• Extended crop cycles which increase feed and labour costs.
• Higher feed conversion ratios (FCRs), demanding more input per cycle of shrimp production.
• Uneven shrimp size and shrimp not reaching target market size complicate marketing and reduce overall sales value.
• Additional investments in diagnostics, feed supplements, and pond management further strain financial resources

Quantitative assessments, particularly from major production zones, such as Andhra Pradesh, reveal economic losses due to EHP which may exceed 20-30% of typical profit margins. This scale of loss sums up to hundreds of millions of rupees annually, threatening both individual farm viability and resilience within the broader industry.

Enhanced management strategies for controlling EHP
Effectively managing EHP requires a comprehensive approach that integrates preventive, regular monitoring, and remedial measures tailored to the unique challenges this pathogen presents. Since EHP is a chronic resilient parasite that rarely causes acute mortality, early detection and proactive management are crucial to minimise economic losses.

Pond preparation and biosecurity
Steps taken to ensure proper pond preparation and biosecurity include:
• Thorough elimination of residual pathogens and minimising infection risks during pond preparation.
• Complete drying and sun exposure during pond dry-out periods to help reduce pathogen load in the sediment.
• Application of lime and appropriate disinfectants to neutralise spores and improve pond water quality.
• Use of biosecurity protocols such as restricting farm access, controlling equipment sharing, and adopting other inputs to minimise contamination risks.
• Management of water source like using filtered or treated water to reduce introduction of EHP spores and other pathogens.

Regular health monitoring and early diagnosis
EHP Infections often remain undetected until harvest, hence, routine monitoring is indispensable. Measures taken include:
• Visual assessments for growth reduction and uneven size distribution, which serve as initial warning signs.
• Scheduled sampling of shrimp hepatopancreas tissues for microscopic observation (wet mount) and molecular testing (PCR/RTPCR) helps in early detection. (Table 1).

Nutritional and functional feed interventions
Nutritional intervention is increasingly recognised as a key component in managing EHP and reducing its economic impact on shrimp farming. Functional feeds not only fulfil the nutritional requirements of shrimp but also deliver bioactive compounds that modulate immunity, enhance gut health, and improve resilience against pathogens.

Recent advances have demonstrated the potential of targeted feed formulations such as Nutriva Plus (Growel, India), which incorporates bioactive ingredients designed to reduce pathogen pressure and improve host defence mechanisms. The functional components of this feed operate through multiple mechanisms, which include:
• Strengthening of intestinal integrity reduces the adverse effects of pathogen-derived toxins.
• Immune system modulation helps to maintain shrimp in a heightened state of readiness against infection.
• Direct antimicrobial action, with certain compounds capable of inactivating or disabling pathogens.
• Improved feed intake and nutrient utilisation, ensuring effective delivery of health-supportive compounds.

When integrated with husbandry measures such as water quality management, stocking density based on carrying capacity of the pond, and strict biosecurity protocols, functional feeds like Nutriva Plus represent a practical approach to mitigating EHP-related losses.

Water quality management
The shrimp pond with ideal water quality parameters (Table 2) and regular applications of water and soil probiotics, for bioremediation will minimise stress and pathogen proliferation.

Managing EHP outbreaks in Andhra Pradesh
Recent times have seen shrimp farmers across key districts of Andhra Pradesh grappling with escalating challenges from EHP infections, resulting in significant production decline and economic losses.

Mapping the impact
We conducted a comprehensive questionnaire-based survey over the past year across Krishna, East Godavari, and West Godavari districts—major shrimp farming regions of Andhra Pradesh. The survey covered more than 145 shrimp farms, including both healthy and EHP-affected farms, each operating under the region’s standard 2–4 crop annual cycle. The study relied on the Growel 360° app to capture and organize all pond-level data.

EHP infection status
Of the 145 farms surveyed, 93 (64%) showed signs of EHP infections during the year. Only 52 farms (36%) remained unaffected, suggesting either successful implementation of preventive measures or just limited exposure to microsporidium. The high infection rate underscores the urgent need for coordinated disease management and biosecurity protocols across the region.

Categorising severity of infection
Based on field observations, EHP-affected ponds were classified into three categories:

• Healthy shrimp: No visible signs of infection, optimal growth, and feed conversion.
• Moderate EHP: Shrimp showed signs of stunted growth, moderate size variation and reduced feed efficiency.
• Severe EHP: Severe growth retardation, high mortality, high size variation and significant economic loss.

Distinct impacts of EHP on production costs

In farms affected by EHP, pond preparation has become more intensive and costly. Activities such as tillage and soil preparation with tractors, bleaching, and liming critical for disinfection, are now performed more rigorously to eliminate residual spores and prevent reinfection.

Our study revealed a 15% to 28% increase in pond preparation costs depending on the severity of EHP in infected ponds compared to healthy ones. This escalation is driven by the need for enhanced cleaning protocols between crop cycles, often requiring additional labour and materials.

More rigorous diagnostic approach for EHP detection

To assess the presence of EHP, a structured diagnostic
protocol was followed:
• Preliminary observations: Field technicians examined shrimp for visual signs of EHP, including growth retardation, pale hepatopancreas, white faeces, and poor feed conversion.
• Wet mount microscopy: Suspected samples were screened under a wet mount to detect microsporidian spores in hepatopancreatic tissue.
• Confirmation with RT-PCR: Molecular confirmation was performed using reverse transcriptase polymerase chain reaction (RT-PCR), ensuring high sensitivity and specificity in detecting EHP DNA.

Using a classification of pond health status based on RT-PCR results and cycle threshold (CT), ponds were categorised into three health status groups.
• Healthy pond: No detectable EHP infection.
• Moderately infected ponds: CT > 25
• Highly infected ponds: CT < 25

This classification enabled targeted analysis of production costs and disease impact across varying infection levels.

Comparison of economic losses
This was studied with direct costs between the non- EHP-infected farms and EHP-infected ponds, as shown in Table 4. We also analysed the impact on costs, ranking them as in Table 5.

Conclusion
In this article, we demonstrate the cost impact per kg shrimp with EHP infections and its subsequent influence on WFD incidences. In moderately and severely infected ponds, the cycle is not profitable with harvests of size 100/kg. The cycle is profitable when the cycle continues to harvest size of 60/kg, aided by higher selling prices. Effective EHP control benefits farmers reducing cost of production thus increasing the profit margins for farmers.

Shrimp culture practices require the adoption of effective methods for pond preparation and biosecurity, regular health monitoring, early disease diagnosis, nutritional and functional feed interventions as well as water quality management.

This article was first published in Aqua Culture Asia Pacific November/December p40–43.  https://issues.aquaasiapac.com/view/717436716/42/

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Pushing the boundaries of current knowledge in managing outbreaks in marine fish and the uptake of vaccination for tilapia against bacterial diseases.

Industry’s growth and productivity are constantly constrained by current bacterial and viral diseases as well as parasite infestation. Additionally, the aquaculture industry is saddled with emerging pathogens. Preceded by presentations on managing diseases in marine fish and tilapia, and developing next generation biotech solutions, the panel on disease mitigation and innovations at TARS 2024 deliberated on how the industry can adopt present- day solutions to overcome these problems. Aside from presenters mentioned below, panel members were Jessica Kaye Turner, Assistant Managing Director, Nam Sai Farms Co Ltd, Thailand, and Dr Ei Lin Ooi, Regional Manager, Aquaculture Asia-Pacific, Adisseo Asia Pacific, Singapore. Dr Jarin Sawanboonchun, Aquaculture Nutrition and Feed Specialist, Thailand, was the moderator.

A science and an art in disease management

Dr Susan Gibson-Kueh, Associate Professor (Aquatic Animal Health), Tropical Futures Institute, James Cook University, Singapore, presented on “Diseases in Tropical Finfish Aquaculture: Busting Myths, Pushing Borders”. Farms experiencing disease outbreaks are often after a quick cure. However, there is seldom a secret remedy. Farmers need to focus on early detection and intervention.

She emphasised that disease management in aquaculture is both a science and an art. “Science because effective disease control should be based on facts from accurate diagnosis. Using information to manage disease is an art based on experience and a good grasp of the disease process in fish in the aquatic environment. The current thinking on pathobiome is that maintaining the diversity of bacteria in the gut and water through optimal nutrition and husbandry practices can be more effective than trying to eliminate a single pathogen.”

Scale drop disease

Scale drop disease (SDD) in Asian seabass Lates calcarifer is characterised by skin and scale loss, multifocal tissue deaths, and splenic infarcts. The disease spreads in the population, with clinical disease seen in older fish (>200-300g, Figure 1). “The loss of extensive areas of skin results in fish dying from dehydration in seawater. Bringing fish species tolerant to lower salinity to freshwater or lowering salinity to 15‰ to control the dehydration reduces mortality rate. But this is not easy as some farms do not have access to large volumes of freshwater.” She added that any pathogens that damage skin will cause dehydration in fish in seawater. SDD also causes severe inflammation and blockage of blood supply. “The spleen is an important immune organ in fighting diseases. Loss of the spleen means that fish becomes more susceptible to infection by bacteria commonly present in the water. Fish with SDD may die from dehydration or secondary bacterial infection. Vaccination can prevent fish from succumbing to bacterial infections.” Gibson-Kueh’s message was, “To know not only the pathogens but also understand how they affect and why they kill the fish.”

Big belly

This is a chronic, granulomatous bacterial enteritis and peritonitis, first reported in 3-4 week old seabass. “The on-going inflammation progresses to gut perforation and severe inflammation in the abdominal cavity. Fish die because in seawater the gut plays a key role in water absorption to counter dehydration. Moving the fish to freshwater will reduce losses,” said Gibson-Kueh.

Parasites

Parasite control can be quite a struggle, especially when the life cycle of parasites is never broken. It is not just a matter of treating with the right chemicals, but treatment frequency must target susceptible parasite stages and break the life cycle. Eggs are very resistant to chemicals. It is critical to monitor the effectiveness of treatment which can vary with temperature and salinity.

“One of the reasons that some tropical fish farms struggle with parasite control is because they do not coordinate treatment of the whole farm or site due to limited manpower. Re-infection by hatching eggs or cysts needs to be considered to effectively treat parasites. In Norway, for sea lice, there is a very coordinated strategy to treat the entire site all at once.” Gibson-Kueh added that what is needed are efficacious oral medications to allow farms to treat the whole farm at any one time.

Effective treatment strategies depend on knowing the duration of each parasite stage to determine the frequency of treatment. More research is needed on parasite life cycle studies.

Monitoring and biosecurity

Keeping farms disease-free can be expensive. Representative fish samples and test selections are important in disease diagnosis. Gibson-Kueh cited a case where a farmer suspected viral disease on fish. She said, clinical recently transferred to grow-out tanks. signs generally appear more than 2-3 weeks after viral infections, and based on the face lesions it is more likely that cannibalism and recent transfer stress are responsible for poor health in these fish.

“We need to find the reasons why fish succumb to infections. Sometimes, bacteria in the water do not cause diseases at all; at other times they do. Proper diagnosis is necessary to guide disease management as there is no one-size-fits-all solution. Understanding the progression of specific diseases is important in effective management.”

Dr Roberto Cascione, Key Account Manager Asia & Middle East, Virbac Asia Pacific, Thailand, discussed “Tilapia Disease Pathogen Mapping: Challenges, Trigger Points and Possible Solutions”. He started with a pathogen mapping for tilapia in Southeast Asia, developed after years of epidemiological observations.

“Overall, we see that Streptococcus agalactiae serotypes Ia, III, Ib have spread all over farming areas in the last 10 years, evolving into a multivalent serotype scenario in Asia as well as in Africa and Latin America. For decades, the Philippines and Indonesia were decidedly monovalent with type Ib only. Today, S. agalactiae serotype Ia and Ib are infecting tilapia with Streptococcus iniae in Calabarzon in the Philippines. In Indonesia, there is S. agalactiae Ia, III and Ib in Java and Sumatra.”

“In Thailand, there is the prevalence of specific serotypes of S. agalactiae with tilapia lake virus (TILV) in various districts in Khon Kean, Nong Kai, Petchaburi, Samut Prakan, and with Francisella noatunensis in Uttaradit. In Malaysia, S. agalactiae (Ia, III) are found together with TILV and spleen and kidney necrosis virus (ISKNV).”

Tilapia lake virus (TiLV) was a challenge 10 years ago, affecting especially at the hatchery and nursery stages. In red tilapia the infection is at varying pathogenicity and virulence. It is a serious limiting factor in the fry of black tilapia in Malaysia. These pathogens affect different stages of production.

Cascione said, “It is now clear that we often observe multiple infection scenarios in tilapia farming, an outbreak can include 1-3 pathogens at one time. Finding the pathogens is only the first step of the diagnostic process, because the simple detection does not give us the answer. We need to analyse farming history and seasonal changes, weather, temperature, and clinical signs together.”

Trigger factors
Cascione attributed the spread of these diseases to the global market and globalisation of diseases. There is the influence of climate change, fish movement, biosecurity lapses and production increases. “Tilapia has shown the fastest growth rates at 8.7% in the last 12 years. Farmers increase stocking density to produce more fish. We also note that vaccinated fish have shown a significant (30% average) better survival rate during outbreak seasons and at final recovery.”

New pathogens
The list is led by Francisella noatunensis, which is becoming more aggressive, especially in Indonesia, when water temperature drops below 25°C. ISKNV affects early or nursery stages. Edwardsiella ictaluri in north Vietnam does not allow farming in November to February as mortality is too high. ISKNV is an iridovirus affecting early stages. Indonesia, Malaysia and Vietnam are heavily affected by this virus with serious impacts on production. Parvovirus was recently reported by Dr Win Surachetpong, Kasetsart University in Thailand. It was detected in China and is lethal when associated with other disease such as TiLV.

Solutions
Vaccination helps to reduce mortality costs and harmonise the growth and predictability of crops. The limit, though, is the absence of multiple vaccines to overcome the current multiple pathogen situation. “However, Asia can learn from Brazil which has a massive growth rate at 8.3% which is related to a vaccination rate of 35%. In comparison, the vaccination rate is 1% in Southeast Asia and there are only three companies with vaccination programs: Manit Farms in Thailand, Regal Springs in Indonesia, and Trapia in Malaysia. In Colombia, there was a national vaccination program because of a large outbreak of S. agalactiae.”

Vaccination plays a key role in farming with differences in mortality rate with vaccinated and non-vaccinated fish. Other solutions include the Thai model of low-density and large surface farming, stocking in 3x3m or 6x6m cages, 2,000 to 6,000 fish. Recirculating aquaculture systems (RAS) and biofloc technology are options to overcome weather woes.

Cascione concluded, “Disease patterns are becoming unpredictable. We need regulatory changes to permit an open market for autogenous vaccines or simplify the accessibility to commercial vaccines. We need improved genetics on disease resistance and fish quality. There is no solution for all, but each system can find its own solution compatible with its needs.”

-Interestingly, Turner shared her experience at Nam Sai Farms, where the philosophy is to let nature play a key role. “What we did was allow our broodstock to faced diseases and develop natural immunity. We also let natural selection take its course—weak fish do not survive, while the stronger ones continue to thrive. In 1998, we lost 50% of the stock when a Streptococcus outbreak broke out. Resistant genes were passed to subsequent stocks, such that today mortality is less than 5% in summer.” Nam Sai now supplies disease resistant fry to farmers.

Next generation biotech solutions
Teora Pte Ltd, Singapore is a startup involved in developing next generation biotech solutions for disease management. CEO Dr Rishita Changede gave information on what it has in terms of solutions. “The current vaccines; primarily whole inactivated bacteria; if applied as orally can increase risk of disease. Viral vaccines are few, as they require specialised cell lines to produce. Injection vaccines may not be scalable for non-high margin species.”

The question is how to bring safe solutions from the human pharmaceutical industry to manage fish disease in Asia. “It is possible to create vaccines for bacterial and viruses. What we do is just use nanopeptides – a small portion, enough to trigger the immune system and anti-viral solutions to curb viral spread. Delivery is oral via top coating at the feed mill or farm. This allows us to protect against multiple different strains at the same time and give boosters.”

Trials were conducted against S. iniae and against SDD in Asian seabass at Thai Union and Asian Institute of Technology (AIT) in Thailand. These showed high survival rates and no adverse effects on production parameters such as weight gain and average daily growth. Rishita also introduced the SOLAQ platform where together with industry, the company can develop preventive biotech solutions against specific virus, parasites, and bacteria. “This can be the way forward to manage the multiple pathogens affecting fish.”

Ooi ended the conversation with, “We could be always chasing pathogens. Therefore, early detection or even good husbandry are key. Vaccination is very specific. Since we cannot foresee diseases coming, prevention and strengthening immunity will help.”

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Shrimp farming in Asia is confronted with significant challenges due to disease outbreaks, particularly white faeces syndrome (WFS)

Shrimp farming faces significant challenges due to frequent disease outbreaks that undermine profitability. One particularly severe shrimp disease is white faeces syndrome (WFS), a gastrointestinal disorder commonly reported in Asia. WFS is characterised by a white discolouration in the shrimp gut and the appearance of floating white faecal strings in pond water.

Studies indicate that the co-infection of pathogenic Enterocytozoon hepatopenaei (EHP) and Vibrio spp. is necessary to induce WFS in shrimp (Aranguren Caro et al., 2021). EHP acts as a primary pathogen, intensifying the impact of opportunistic bacteria such as Vibrio spp., resulting in WFS. Shrimp infected by WFS exhibit retarded growth, significant size variation, elevated feed conversion ratios, and, in severe cases, increased mortality. These issues collectively heighten production costs and pose substantial economic risks for shrimp farmers.

Addressing WFS requires improved pond management strategies along with health management strategies via feed. The latter involves using health-promoting additives to maintain shrimp immunocompetence. Sanacore® GM (Adisseo) is a phytobiotic-based additive with broad- spectrum health-promoting effects. It regulates pathogenic bacteria and parasites while enhancing non-specific immune responses to mitigate the severity of infections on multiple levels.

Combating EHP-WFS through an optimal application strategy

This report presents a detailed evaluation of Sanacore® GM’s efficacy on white shrimp, Penaeus vannamei, co-challenged with EHP and Vibrio spp. The trial was conducted in collaboration with ShrimpVet Laboratory, Vietnam. The application strategy was based on a continuous preventive dose of the additive, boosted with a corrective dose when disease symptoms arise.

Two experimental groups, control and treatment, were established. The treatment group received a preventive dose (0.3%) of the additive during the pre-challenge phase (14 days), and the preventive dose was boosted with a corrective dose of 0.5% during the disease challenge period of 10 days (Figure 1). The treatment group returned to the preventive dose during the post- challenge period (35 days). During the challenge phase, EHP-infected shrimp were used as inoculant donors and cohabited with the experimental shrimp for 7 days. After cohabitation, inoculum donor shrimp were removed, and the recipient shrimp were subsequently challenged with Vibrio spp. via the per os method.

The evaluation of the efficacy of this phytobiotic-based functional additive was carried out at two time points. The first at 7 days post-challenge (dpc) at the early infection stage. The second was at 35 dpc at the end of the infection. During early infection, size variation was monitored as the typical syndrome caused by EHP, resulting from metabolic and immune impairment (Zhang et al., 2023). Mortality was assessed at the end stage, where the combined effects of EHP and Vibrio severely damaged the digestive system, leading to high mortality.

Mitigating the severity of WFS by reducing EHP replication and enhancing shrimp immunity

The EHP load in the hepatopancreas is a key indicator of the severity of EHP-WFS infection. Sanacore® GM showed remarkable efficacy in inhibiting EHP replication, reducing its load by 97.5% and 39.6% at the early and late infection stages, respectively(Figure 2A). Such reduction indicates that the additive effectively curbs EHP replication from the outset, thereby attenuating disease progression and offering shrimp protection against EHP.

Haemocytes are central components of the shrimp immune system, involved in pathogen-removal mechanisms such as phagocytosis and encapsulation, as well as in humoral responses such as the release of prophenoloxidase (proPO) or antimicrobial peptides. Recent studies have shown that EHP-WFS infection alters the innate defence immune mechanism, specifically reducing total haemocyte counts (THC), as well as catalase and lysozyme activities (Subash et al., 2022 & 2023).

Enhanced immunocompetence

In the present study, THC levels increased by 23.5% and 14.6% at both early and late stages of infection, respectively, indicating enhanced immunocompetence (Figure 2B). These results suggest the activation of haemocyte proliferation and effective antimicrobial activity against EHP-WFS infection.

Reduced size variation

The use of the phytobiotic-based functional additive resulted in benefits in terms of performance parameters. At the early infection stage, supplementation reduced size variation by 17%. Additionally, average daily gain was improved by 8% and FCR by 1.6%. Notably, after 35 days of infection, the survival rate of shrimp in the treatment group increased by 17%. These improvements clearly demonstrate the additive’s efficacy in promoting growth and resistance to EHP-WFS infection.

Conclusion

The present study demonstrated a feed-health management strategy to effectively support shrimp growth and survival in WFS infected shrimp, caused by the co-infection of EHP and Vibrio spp. The preventive supplementation of this phytobiotic-based functional additive Sanacore® GM supports non-specific immunity and provides broad spectrum activity, which are crucial during the early and more susceptible stages of the grow-out period. When disease pressure increases and symptoms appear, boosting feed with a corrective dose of the additive mitigates pathogens proliferation. Sanacore® GM provides feed mills and shrimp farmers with a tool to reduce the impact of disease outbreaks and improve farm profitability by reducing losses associated with WFS.

References
Aranguren Caro, L. F., Mai, H. N., Cruz-Florez, R., Marcos,
F. L. A., Alenton, R. R. R., & Dhar, A. K. (2021). Experimental reproduction of White Feces Syndrome in whiteleg shrimp, Penaeus vannamei. PloS one, 16(12), e0261289. https://doi. org/10.1371/journal.pone.0261289

Chen, I., Mamora M., Isern-Subich, M. M., & Nuez-Ortín W.
G. (2023). Efficacy of a phytobiotic-based additive to reduce the severity of EHP-WFS outbreaks in field conditions. AQUA Culture Asia Pacific, May/June, P31- 33. bit.ly/3BO1ZDc Subash, P., Chrisolite, B., Sivasankar, P., George, M. R., Amirtharaj, K. V., Padmavathy, P., … & Mageshkumar, P. (2023). White feces syndrome in Penaeus vannamei is potentially an Enterocytozoon hepatopenaei (EHP) associated pathobiome origin of Vibrio spp. Journal of Invertebrate Pathology, 198, 107932. DOI: 10.1016/j.jip.2023.107932

Subash, P., Uma, A., & Ahilan, B. (2022). Early responses in Penaeus vannamei during experimental infection with Enterocytozoon hepatopenaei (EHP) spores by injection and oral routes. Journal of Invertebrate Pathology, 190, 107740. https:// doi.org/10.1016/j.jip.2022.107740

Zhang, L., Zhang, S., Qiao, Y., Cao, X., Cheng, J., Meng, Q., & Shen, H. (2023). Dynamic Interplay of Metabolic and Transcriptional Responses in Shrimp during Early and Late Infection Stages of Enterocytozoon hepatopenaei (EHP). International Journal of Molecular Sciences, 24(23), 16738. https://doi.org/10.3390/ijms242316738

I-Tung Chen, PhD, is Project Research Manager Aquaculture Health, Adisseo.
Email: i-tung.chen@adisseo.com

Maria Mercè Isern-Subich, DVM, is Global Product Manager Health Aquaculture, Adisseo.

Waldo G. Nuez-Ortín, DVM, PhD, is Global R&D Manager Aquaculture, Adisseo.

Khin Thiri Khit, R&D Specialist, ShrimpVet Laboratory, Vietnam

Phuc Hoang, Managing Director, ShrimpVet Laboratory, Vietnam

Loc Tran, Founder & Director, ShrimpVet Laboratory, Vietnam

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In what could revolutionise the USD 45 billion global shrimp farming industry, US based Dalan Animal Health has announced a groundbreaking achievement: successful proof of concept trials with their vaccine indicating the protection of shrimp against common and devastating diseases. The company, already known for creating the world’s first honeybee vaccine, has successfully applied its innovative maternal immune priming technology to aquaculture, potentially transforming how the industry approaches disease prevention in shrimp farms across Asia-Pacific and beyond.

From bees to shrimp: Cross-species innovation
Dalan’s journey into shrimp health began with bees. In January 2023, the company received conditional approval from the USDA for the world’s first honeybee vaccine against American foulbrood, a bacterial disease that has plagued beekeepers worldwide.

The technology behind this innovation – maternal immune priming – has proven surprisingly adaptable across species boundaries. This biological mechanism allows a mother to pass immunity to her offspring after exposure to disease-causing pathogens, creating a natural vaccination effect that works even in invertebrates previously thought incapable of such immune responses.

Dalan Animal Health CEO Dr Annette Kleiser explained,

“The same fundamental biological principle that works in bees also functions in shrimp. This cross-species application demonstrates the versatility of our platform and opens new possibilities for sustainable disease prevention across aquaculture.”

Addressing critical industry challenges
The timing of this breakthrough could not be more critical for Asia-Pacific’s shrimp industry, which has long struggled with devastating disease outbreaks. Early mortality syndrome (EMS), white spot syndrome virus (WSSV), and various vibrio bacterial infections continue to cause billions in annual losses while limiting the industry’s growth potential.

Kleiser added,

“Dalan’s vaccine technology offers a fundamentally different approach by stimulating the shrimp’s own immune system to resist infection, potentially reducing or eliminating the need for antibiotics while providing more consistent protection against multiple pathogens.”

Field trial success
Dalan’s initial field trials have demonstrated promising results. Shrimp exposed to the company’s vaccine technology showed significantly higher survival rates when challenged with common pathogens compared to unvaccinated control groups.

The company has focused its initial efforts on WSSV and vibrio bacteria – two of the most economically damaging pathogens in shrimp farming. These early successes suggest the platform could eventually address a broader spectrum of diseases that currently limit production efficiency.

Commercialisation timeline
Dalan is working toward commercial availability of its shrimp vaccine technology within the next 18-24 months, following completion of expanded field trials and regulatory approvals. The company has opened discussions with several major shrimp producers in Asia to accelerate testing and adaptation of the technology to regional production systems.

Initial deployment will likely focus on hatcheries and breeding centers, where the maternal immune priming can be most efficiently implemented before broodstock distribution to farms. This approach allows for centralised application while providing protection throughout the production cycle.

Industry implications
For Asia-Pacific’s shrimp industry, which accounts for approximately 80% of global production, the implications of effective vaccination could be transformative. Beyond the immediate benefits of reduced mortality and improved production efficiency, the technology could enable:

• Reduced antibiotic use, improving both environmental sustainability and market access
• More predictable harvests, stabilising supply chains and pricing
• Higher stocking densities with lower disease risk
• Expansion of production into areas previously limited by disease pressure

This article was first published in May/June 2025 

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Forte Biotech is committed to empowering shrimp farmers with rapid, accurate, and affordable disease diagnostics. The RAPID test kits offer point-of-care detection for major shrimp diseases like EHP, WSSV, and AHPND, enabling proactive farm management without the delay and cost of conventional lab testing.

Its  mission is simple: to make early disease detection accessible to everyone, from smallholder farmers to large-scale operations.

“In this industry, time is everything. Just a few days can mean the difference between saving a harvest or losing everything. Thatâ€s why early detection is no longer a luxury—itâ€s the standard,” said Kit Yong, Founder at Forte Biotech. 

“Our partners in Indonesia used RAPID test kits as part of their routine surveillance. The kits detected signs of WSSV and AHPND a full ten days before confirmation by PCR. That early warning gave the team a critical window to intervene, potentially saving entire ponds from devastating losses.”

But the benefits of early detection go far beyond saving lives. Monitoring diseases proactively helps farms reduce waste, improve efficiency, and grow stronger, healthier shrimp.

“In Vietnam, farmer Phuoc transformed his operation by switching from routine disinfection and broad-spectrum antibiotic use to a targeted, data-driven strategy using RAPID. His disinfection cycles dropped from 36 to just 5, and his monitoring costs fell by over 80%. With healthier ponds, his shrimp grew faster and bigger—from 30 shrimp/kg to 20 shrimp/kg—doubling his yield and boosting profits. He now reports a 180x return on investment, a powerful testament to how accessible diagnostics can reshape farm economics,” added Michael Nguyen, Co-founder. 

Meanwhile in the Philippines, Forte Biotech’s ongoing collaboration with Negros COOP, a major shrimp cooperative, is further validating the performance of its kits. In a comparative study against another on-site diagnostic test kit across three months, RAPID demonstrated a 100% match rate so far for all three major pathogens.

“These results reinforce what we see in the field: that affordable diagnostics can be both accessible and reliable, ” added Yong. “All of these stories point to one thing: when farms have the right tools to act early, they gain more control over  farm, harvest, and ultimately the bottom line.”

Experiences at VietShrimp 2025
Participating in VietShrimp 2025 was a major highlight for Forte Biotech’s team this year. More than just a trade show, the event felt like a celebration of innovation, community, and shared progress in aquaculture. The team was grateful for the opportunity to reconnect with long-time partners and clients from Vietnam and beyond, while also meeting many new faces—ranging from smallholder farmers to representatives of international companies and institutions.

Forte Biotech is proud to be part of this movement. And as it continue expanding across Southeast Asia and beyond, it is committed to walking alongside farmers—bringing better tools, better insights, and better outcomes to shrimp farms everywhere.

“Lets build a smarter, safer, and more successful future for aquaculture together,” said Nguyen and Yong. 

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Molecular testing is essential for accurate identification of the specific cause combined with stringent biosecurity measures

By Andrew Shinn, Ratchakorn Wongwaradechkul, Jorge Piazza, Bruno Decock, Thomas Raynaud, Alfredo Medina and Emmy Léger

Understanding Vibrio infections in shrimp production

Infections associated with Vibrio species pose significant challenges in commercial shrimp operations. If unmanaged, these bacteria can establish populations in water, sediment, or biofilms within farm systems, leading to infections and high mortality rates.

In shrimp hatcheries, Vibrio species can infiltrate or proliferate through multiple routes. These include introduction via broodstock, infected shrimp nauplii, contamination through water sources, and transmission from microalgae, live feeds, or water and air pipelines. Moreover, they can be transported on personnel equipment, on skin, or dispersed through aerosols (Shinn et al., subm.).

What is Translucent Post Larvae Disease?

Translucent Post Larvae Disease (TPD), also known as Highly Lethal Vibrio Disease (HLVD), is a severe condition that has impacted shrimp post larvae production in China and Vietnam since 2020.

The disease is primarily caused by a strain of Vibrio parahaemolyticus, though a Baishivirus has also been implicated in some cases. The V. parahaemolyticus strain associated with TPD produces a toxin that disrupts the hepatopancreas, affecting nutrition and leading to rapid mortality, especially in smaller shrimp.

Visually, affected post larvae (PL), particularly at stages 2-4, exhibit distinct symptoms such as an empty gut and a colourless, translucent hepatopancreas, leading to diminished activity and sluggish movements. Mortality occurs rapidly, typically within a few hours of infection, with rates reaching as high as 80-100% within 24-48 hours, often occurring 3-5 days post-stocking.

Since other pathogens can cause similar visual symptoms in shrimp, accurate diagnosis requires proper testing rather than relying solely on the visible symptoms.

TPD infected post larvae at stages 2-4 show empty gut and a colourless, translucent hepatopancreas. Mortality occurs typically within a few hours of infection. Photo credit: Xu Tao

The role of Vibrio parahaemolyticus in TPD

Most cases of TPD are caused by V. parahaemolyticus strains that carry an aerolysin gene, which produces a toxin leading to cellular damage in the hepatopancreas and resulting in death. Another shrimp disease, acute hepatopancreatic necrosis disease (AHPND), is also caused by V. parahaemolyticus, but these strains carry a different toxin gene. Although both toxin genes cause similar damage to the hepatopancreas and lead to comparable outcomes, molecular testing is essential for accurate identification of the specific cause.

How to test for TPD and AHPND

Visual inspections alone are insufficient for diagnosing TPD or AHPND. Accurate diagnosis requires laboratory testing. To do this, collect a targeted sample of PL (i.e., those exhibiting pale and moribund characteristics, approximately 30-50 individuals). Rinse the PL with sterile distilled water and then fix them in 95-99% molecular-grade ethanol.

Laboratory tests can then identify the different toxin producing genes produced by Vibrio species. Simultaneously, request that the samples are tested for the presence of plasmid genes pirAB producing the toxins responsible for AHPND, utilising the AP4 nested PCR method developed by Dangtip et al. (2015) and for TPD using primers for the ldh gene, which produces the thermolabile hemolysin toxin (Vicente et al., 2020; Zou et al., 2020). If both tests are negative, request that samples are tested for the Baishivirus, using primers as specified by Xu et al. (2023).

Parallel assessment of microbiology results is essential. If all three PCR test results are negative, then look to other potential bacterial pathogens that might result in PL that are translucent in appearance.

Why test

Regular testing is crucial for identifying early-stage infections and preventing their establishment and spread. It raises awareness of the local risks of infection. Testing can offer valuable insights into disease dynamics and potential introduction routes. It facilitates timely interventions and enables the revision of biosecurity protocols to reduce the likelihood of future introductions and outbreaks, thereby minimising economic losses.

“Vibrios pose a serious threat to shrimp production, but strict biosecurity measures and regular surveillance can effectively manage these risks.”

Managing TPD outbreaks

If TPD is detected, take immediate action:

• Isolate infected shrimp and quarantine the affected areas.
• Conduct tests to confirm the disease.
• Assess the risk to other shrimp batches and the overall farm operations.
• Cull infected stock to prevent further spread.
• Strengthen biosecurity measures, including monitoring visitors and disinfecting equipment and water systems.
• Increase surveillance to monitor the situation and prevent future outbreaks.

Other Vibrio infections affecting shrimp

Besides TPD, other Vibrio infections can also cause shrimp to appear translucent. For example, some strains of V. parahaemolyticus carrying a different toxin gene are
responsible for AHPND, also known as early mortality syndrome, which can result in sudden and severe mortality. Additionally, other Vibrio species, such as V.
alginolyticus and V. harveyi, can cause systemic infections leading to septic  hepatopancreatic necrosis (SHPN).

Need for Vibrio vigilance and tight biosecurity

The rapid and severe onset of Vibrio-induced mortalities in penaeid shrimp hatcheries, transitioning from a state of apparent health to moribundity and death within mere hours, underscores the critical need for stringent biosecurity measures and vigilant surveillance protocols.

Recognising the risks associated with Vibrio infections is paramount from a biosecurity standpoint, necessitating proactive measures to prevent and mitigate potential outbreaks. Establishing robust control and management procedures are essential to effectively manage these risks. Surveillance emerges as a crucial practice for early detection and containment of infections, ensuring swift intervention when necessary.

Best practices for biosecurity in shrimp hatcheries:

1. Disinfect water and equipment using ozone, UV light, or hypochlorite.
2. Conduct comprehensive and regular cleaning of the entire production system, including pipework, air lines, and air delivery systems, to remove biofilms and
   surfaces where Vibrio can establish.
3. Use separate, biosecure water systems to minimise contamination risks.
4. Add probiotics to the water to enhance shrimp health and reduce harmful bacteria. Isolate broodstock in clean conditions and provide biosecure diets to maintain their health.

Managing Vibrio at every stage of shrimp production

• Vibrio infections can occur at any stage of shrimp farming, from broodstock to grow-out ponds.
• Implementing proper disinfection, maintaining strict hygiene, and
  adding probiotics to feed and water are essential for reducing infection risks.
• Hatcheries: Ensure biosecure water systems and conduct regular facility cleanings.
• Live feeds: Source live feeds from biosecure providers to prevent introducing Vibrio.
• Pond preparation: Disinfect ponds, use clean water, and avoid transferring contaminated water.
• Grow-out ponds: Monitor stocking densities and manage wastes effectively to minimise the risk of Vibrio outbreaks.

Remember!

Vibrio bacteria pose a serious threat to shrimp production, but strict biosecurity measures and regular surveillance can effectively manage these risks. Early detection is crucial for minimising the impact of Vibrio-related diseases, improving shrimp survival, and ensuring the sustainability of shrimp farming operations. Isolate broodstock in clean conditions and provide biosecure diets to maintain their health.

References are available on request. The article was published in issue November/December 2024 AQUA Culture Asia Pacific

Authors are with INVE Aquaculture

• Andrew Shinn is Global Technical Expert (Health).
• Ratchakorn Wongwaradechkul is an aquatic veterinarian, Regional Technical
  Support Asia.
• Jorge Piazza is Strategic Marketing Manager
• Bruno Decock is Business Development Manager
• Thomas Raynaud is Product Manager
• Alfredo Medina is Global Technical Expert Shrimp Hatchery
• Emmy Léger is Customer Success Director.

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