EMS and EHP Threatened Shrimp Industry in Asia Countries

EMS and EHP Threatened Shrimp Industry in Asia Countries

Shrimp is an important commodity in international trade accounting for 15 % in terms of value of internationally traded seafood products which reached $102.00 billion in 2008. Aquaculture contributes to over 50 % of global shrimp production. [1] However, the economic impact that parasites and bacterial, fungal and viral diseases have on the shrimp industry is highly significant for the many countries that rely heavily on this industry.

Two non-viral diseases that are currently threatening Asia countries are:

  • Acute Hepatopancreatic Necrosis Disease (AHPND), also known as Early Mortality Syndrome (EMS) – bacterial infection
  • Hepatopancreatic microsporidiosis caused by Enterocytozoon hepatopenaei (EHP) - fungal infection

AHPND (EMS)

Acute hepatopancreatic necrosis disease (AHPND), also called early mortality syndrome (EMS), is a recently emergent shrimp bacterial disease that has resulted in substantial economic losses in countries such as China, Thailand, Vietnam and Malaysia. AHPND was originated in China since 2009. AHPND originated in China in about 2009 and was officially reported in the People’s Republic of China and Vietnam in 2010, in Malaysia in 2011, in Thailand in 2012 and in Mexico in 2013 – with the worst affected country being Thailand [2].

AHPND can occur in the first 30 days after stocking shrimp into ‘grow-out’ ponds. The disease is caused by a bacterium that colonizes the shrimp gastrointestinal tract and produces a toxin that causes tissue destruction and dysfunction of the hepatopancreas, the shrimp digestive organ. The affected shrimp species are L. vannamei, P. monodon and P. chinensis [2]. The mortality rate is up to 90% within 30 days[3] .

The transportation of live feeds including polychaete worms fed to broodstock shrimp is thought to have resulted in the spread of AHPND across the Asia region [4].

Prevention, control and mitigation measures include improved biosecurity at the farm, zone, national, and regional levels, zonal management of production units, disease risk assessments and development and implementation of aquatic veterinary health plans.

EHP

Hepatopancreatic microsporidiosis was first detected in P. monodon in Thailand in 2004 and then later in Vietnam With it now being reported in China and Malaysia, the infection is also reported as being an increasing problem in India [2].

What is known so far is that EHP infects only the tubule epithelial cells of the hepatopancreas of the shrimp. The spores are very small (1.1 × 0.60–0.07μm) and have a polar filament with 4–5 coils [4]. EHP was reported as being found in the shrimp hepatopancreas tubule epithelial cells as well as the hepatopancreas.

ShrimpCheck EMS and EHP PCR Kits

Creating a need to reduce risk through the establishment of effective means to control and monitor this parasite due to EHP and EMS infections in farmed shrimp populations are likely to be happened continuously. In this regard, the use of specific and sensitive molecular methods for the detection of EHP/EMS in shrimp, live feeds, and the pond environments will likely prove to be very important. EHP or EMS-infected shrimp cannot be determined by simple visual inspection; there are no obvious clinical signs of infection.

Diagnostic protocols, based on PCR developed in Speedy Assay ShrimpCheck EMS Nested PCR Kit and Shrimp EHP PCR Kit have proven to be both specific and sensitive, thus providing valuable tools for routine diagnosis and monitoring of shrimp stocks, pond environments and aquaculture commodities.

References

  1. Karunasagar I. and Ababouch L. (2012) Shrimp Viral Diseases, Import Risk Assessment and International Trade, Indian J Virol; 23(2): 141-148
  2. The Challenge of Shrimp Diseases in Asia, The Fish Site, 9 May 2016. Date Accessed: 25 Oct 2016.
  3. Necrotising hepatopancreatitis. Date Accessed: Oct 26, 2016
  4. The Challenge of Shrimp Diseases in Asia, Technical Centre of Auaculture, Date Accessed: Oct 26, 2016