Research shows POC tests only detect high-level infection of WSSV – but there’s a better solution for shrimp farmers   

In 2019, Australia’s CSIRO undertook a scientific investigation into the effectiveness of shrimp point of care test kits in detecting white spot syndrome virus (WSSV). At the time of the study, point of care tests had become a go-to method of disease detection for farmers, a situation that persists to this day. But, with the CSIRO’s recent presentation of their findings at ProAqua Symposium, it’s time for an urgent reassessment of testing practices.   

(Image above: the author, Dr. Melony Sellars, working in the laboratory.) 

White spot virus demands best practice controls   

WSSV continues to persist as one of the global shrimp industry’s most economically impactful pathogens. In 2016, severe outbreaks of WSSV in Queensland, Australia, snapped WSSV to the forefront of the national shrimp industry’s attention. With the WSSV emergency response destroying farm populations and costing producers millions of dollars, farmers urgently needed a way to monitor their animals for early-stage WSSV infection.   

Global uptake of POC test kits, including for WSSV, had become second nature in the shrimp industry, being used for various purposes, including early-stage WSSV detection. With WSSV devastation at their doorstep in 2016, the Australian Industry requested access to such kits, which first required Government approval.    

In 2019, at the request of a battered shrimp industry, the CSIRO commenced a laboratory-based evaluation of WSSV tests to determine the efficacy and fitness for purpose of POC test kits compared to laboratory PCR Testing.   

CSIRO examines WSSV POC testing   

Commencing in 2019, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) collaborated with shrimp industry stakeholders on a comprehensive study of WSSV testing methods. The study report – Evaluation of point of care (POC) tests for White Spot Syndrome Virus (WSSV) – compares commercially available tests designed to detect WSSV on commercial shrimp farms with laboratory-run PCR WSSV tests.  

The CSIRO’s research compares and assesses five WSSV tests, comprising three rapid antigen-style and two PCR-based tests. After exhaustive testing, the study clearly shows that rapid antigen POC test kits yield inferior limits of detection when compared with PCR laboratory testing. The research group found that rapid antigen-style POC tests were a sub-optimal defense against WSSV because “POC tests had lower sensitivity than validated laboratory reference WSSV qPCR tests.”   

The lack of sensitivity of rapid antigen POC testing is such that it actually creates a false sense of security for farmers. The CSIRO study’s findings are crucially significant for the global industry because the current expectation among farmers is that POC tests can detect WSSV in the early stages of infection, providing early warning of disease. However, CSIRO’s study identifies vital issues with rapid antigen POC testing kits, which means that they are not, in fact, a solution for WSSV early warning and prevention.   

The dangerous flaw revealed by CSIRO’s POC testing study   

CSIRO’s study reveals substantial issues with POC test kits as a means to prevent WSSV outbreaks. Among the problems with POC kits, CSIRO emphasizes the gap between user expectations and actual test kit sensitivity in the field.    

Farmer’s confidence in POC test kits is supported by the perception that they can detect WSSV early enough to prevent large-scale stock losses. However, CSIRO’s research reveals that the studies used to prove POC kit capability were conducted in laboratory conditions, where the infection speed and transmission pathways did not reflect the reality on farms. A careful reading of manufacturers’ guidelines on some kits also reveals that validation occurs on synthetic templates, providing unrealistic guidelines for real-world use on shrimp samples.  

The CSIRO team writes in the report that “in existing literature, all POC tests were reported to be able to detect WSSV in the early stages of infection.” However, they continue, “the live prawn experiments conducted in this study demonstrate that white spot disease progresses much faster when prawns are injected with WSSV compared to when they are cohabitated with WSSV infected cohorts. Thus, the predicted timeframe from WSSV exposure to WSSV detection by POC testing in the field may be over-estimated…”    

(Image above: shrimp infected with WSSV.)

This finding underlines the crucial problem with POC tests as a means of WSSV control. The virus develops more rapidly in shrimp that are deliberately infected for the purposes of POC test kit validation. However, when used in commercial settings, where disease develops more slowly in individual animals, POC test kits fail to find the virus early enough to prevent infection from spreading throughout farm populations. This fatal flaw in POC kit sensitivity means that if farmers continue to use them for WSSV detection, they will miss the virus in its early stages, leading to continued disease outbreaks.       

Protecting against WSSV requires a strategic change   

WSSV is now endemic worldwide, so vigilant preventative monitoring with fit-for-purpose testing technology is essential. WSSV can destroy entire shrimp farm populations in mere days, underlining the need for an effective early detection regime.     

One of the key findings of CSIRO’s recent study is that when it comes to reliable testing for WSSV, current POC test kits cannot match the sensitivity and accuracy of validated laboratory-based PCR testing.     

“For all 3 WSSV strains assessed, the laboratory reference qPCRs were 10-fold more sensitive than the most sensitive POC test,” the CSIRO study found. Indeed, PCR tests are 100-fold more sensitive than one of the most commonly used POC test kits on the market. CSIRO states in their findings that for “For weak positive samples,” – typical of early stage WSSV infection – sensitivity of POC tests is inadequate, “with only 56% – 78% of replicate weak positive samples testing positive, in contrast to the 100% concordance demonstrated by the laboratory reference qPCRs.”    

(Image above: laboratory pathogen testing for WSSV is more accurate and reliable than conventional POC kits.) 

For farmers, the conclusion to be drawn from CSIRO’s research is emphatically clear: to avoid destructive outbreaks of WSSV, the shrimp industry urgently needs to pivot toward using lab-based PCR tests for routine testing instead of relying on rapid antigen POC kits. Notably, such lab-based PCR tests must also be properly validated by the laboratory personnel, with all assays varying in performance based on equipment, chemistry, people, and operating conditions.   

With turnaround times on laboratory testing as short as twenty-four hours, any concerns about immediacy can be set aside. Performing a POC test on-site gives the false security of quick results, but the reality is that due to their lack of sensitivity, POC tests miss disease in its early stages when a lab test would detect it.    

The research takeaways for farmers  

The CSIRO report clearly shows that lab-based PCR tests are more sensitive and reliable than the currently ubiquitous POC kits. It should also be noted that such lab-based PCR tests must be properly validated in any given laboratory to ensure optimal performance and that validation is an ongoing requirement, not a one-off event.  

The early warning aspect of lab-based PCR testing delivers a vital advantage to farmers since knowing about WSSV infection on their farm a few days early can prevent catastrophic stock losses.     

When disease outbreaks can decimate shrimp farms in mere days, and millions of dollars are on the line, CSIRO’s research sends a strong signal to the shrimp industry to stop relying on POC kits. Lab-based PCR testing, with its superior sensitivity and reliability, is the only way to effectively manage the threat of WSSV.   

Shrimp MultiPath2.0 provides reliable, fast WSSV detection 

Genics Shrimp MultiPath2.0™ is a lab-based PCR test that sets the industry standard for reliable, rapid shrimp pathogen detection.  

Unlike conventional test kits, Shrimp MultiPath2.0 detects 18 common shrimp pathogens with a single test, including WSSV.  

Acting as an early warning system, Shrimp MultiPath2.0 alerts farmers to the presence of pathogens weeks before any visible symptoms appear. This proactive approach is invaluable in preventing costly stock losses and maintaining the health of the aquaculture environment.  

With CSIRO research clearly showing the inadequacy of conventional POC test kits, Shrimp MultiPath2.0 is the best solution for producers who want cutting-edge protection against WSSV. 

Protect your shrimp from WSSV  

Discover the advantages of Shrimp MultiPath2.0 and book a free consultation: click here

About the author 

Dr. Melony Sellars has 20 years of experience in Aquaculture, with an in-depth background in shrimp aquaculture. She has extensive expertise in the application of novel biotech solutions for industry, genetics, and breeding programs. Dr. Sellars is the CEO and Managing Director of Genics, the leading provider of shrimp health and pathogen management technology.  

The Shrimp MultiPath2.0 advantage: A quantum leap forward in very early pathogen detection 

The Genics team spends a lot of time on shrimp farms, listening to the challenges producers face, and we’re constantly looking for ways to enhance our services to meet the needs of farmers. Disease control is a high priority, along with an urgent demand for testing solutions that are both effective and affordable. 

Genics is proud to announce the release of Shrimp MultiPath2.0, which brings game-changing capabilities to shrimp pathogen detection. Identifying 18 shrimp pathogens with a single test, this latest edition of our testing technology redefines industry standards, giving farmers cost-effective and comprehensive protection for their animals. 

Comprehensive pathogen detection 

One of the standout features of Shrimp MultiPath2.0 is its unique capacity to detect 18 common shrimp pathogens with a single test: WSSV, AHPND pirA/AHPND pirB, EHP, GAV YHV2, IHHNV, IMNV, YHV 1, YHV 7, HPV HDV, MBV, LSNV, MoV, TSV, NHP, DIV1, PvNV, CmNV and MrNV. 

Unlike conventional kits and services that look for only one pathogen per sample, Shrimp MultiPath2.0 allows farmers to detect every prominent disease threat with a single highly accurate test. Shrimp MultiPath2.0 also detects and differentiates between genetic subvariants of major pathogens, delivering optimal protection. 

When it comes to a species like shrimp where there are multiple pathogens at any given time causing production impacts, Genics Shrimp MultiPath2.0 is the solution of choice, defining multi-factorial production risks at hand. 

Fast and reliable results 

When it comes to disease protection in aquaculture, time is of the essence. Genics sets the industry standard for sample shipping, with a 1-to-5-day farm-to-lab data delivery window worldwide, including shipping and processing time at the lab.  

Once clients’ samples arrive at the Genics lab, Shrimp MultiPath2.0 delivers accurate, verified test results within 48 hours. This rapid global response time empowers farmers to take prompt action based on accurate data they can trust, minimizing the risk of disease outbreaks and potential stock losses. 

Shrimp MultiPath2.0 sample collection systems are easy to use on the farm, and Genics goes the extra mile with real-time GPS sample tracking. This exclusive service for Genics key clients provides peace of mind to farmers, knowing that their samples are securely tracked from the farm to the laboratory every minute of the day. 

Farmers’ early warning system against disease 

Genics Shrimp MultiPath2.0 acts as an early warning system, alerting farmers to the presence of pathogens weeks before any visible signs of illness appear in their animals. This proactive approach is invaluable in preventing costly stock losses and maintaining the health of the aquaculture environment. 

In the case of infectious hypodermal and hematopoietic necrosis virus (IHHNV), Shrimp MultiPath2.0 can significantly increase farm gate value by up to US$52,000.00 per hectare. For devastating pathogens like white spot syndrome virus (WSSV) and IMNV, Shrimp MultiPath2.0 has the potential to save entire harvests, sparing farmers from substantial financial setbacks.*  

Cost-effective, precise testing 

Shrimp MultiPath2.0 detects a broad spectrum of pathogens, focusing on the most economically damaging. This comprehensive, targeted approach enables farmers to defend against the most critical disease threats efficiently. 

Moreover, precision is a cornerstone of Genics’ testing methodology. Shrimp MultiPath2.0 includes control tests that validate the integrity of DNA and RNA in every sample, setting the bar higher than industry standards. This precision is particularly crucial for shrimp, which contain PCR inhibitors like chitin.  

Verified and secure data 

Genics prioritizes the security and integrity of test data by encrypting and delivering it directly to clients for exclusive use. This commitment to data security ensures confidentiality and has fostered a trusting relationship between Genics and its clients. 

The new standard for shrimp disease control  

With recent research clearly showing the inadequacy of POC test kits, which are still widely used in the industry, Genics is committed to providing a better alternative for farmers that is not only effective but also less expensive than conventional testing.  

Shrimp MultiPath2.0 is a genuine innovation in shrimp pathogen detection, addressing the industry’s need for a comprehensive, fast, and accurate testing solution. With its ability to detect a wide range of pathogens, deliver swift results, and provide secure, verified quantitative data, Shrimp MultiPath2.0 sets a new standard for certainty and safety. 

Want to know more about Shrimp MultiPath2.0?  

Get all the information you need and book a free consultation here.

*Source: Sellars, M.J., Cowley, J.A., Musson, D., Rao, M., Menzies, M., Coman, G.J., Murphy, M. 2019; Reduced growth performance of Black Tiger shrimp (Penaeus monodon) infected with infectious hypodermal and hematopoietic necrosis virus.  Aquaculture 488: 160-166.