Import Risk Analysis: Live Pacific White Shrimp (Penaeus vannamei) transported from Thailand to the Philippines for Aquaculture


Acute hepatopancreatic necrosis disease

Outbreaks of acute hepatopancreatic necrosis disease (AHPND) of shrimp began in China in 2009 and spread sequentially to Vietnam (2010),  Malaysia (2011), Thailand (2012), and Mexico (Thitamadee et al., 2015). Species susceptible to AHPND include giant tiger prawn (Penaeus monodon) and whiteleg shrimp (P. vannamei) (OIE, 2017).

A disease similar to EMS/AHPNS was first reported in shrimp farm located in the eastern Gulf of Thailand in late 2011. It was claimed that those farms used the same stock of PLs. In early 2012 (January-April) EMS/AHPNS was reported in the east coast (Gulf of Thailand): Rayong, Chantaburi, Trad, and Chachoengsao provinces (Kasornchandra et al., 2013).

Shrimp pathologist Donald Lightner identified the cause of the deaths: an infection by the bacterium Vibrio parahaemolyticus. The disease first emerged in southern China in 2010 and moved through Vietnam and Malaysia before it reached Thailand (Yan, 2016).

Aphanomyces astaci (Crayfish plague)

To date, only crayfish species and Chinese mitten crab (Eriocheir sinensis) are known to be susceptible to infection by Aphanomyces astaci (OIE, 2017). For this reason alone, this OIE-listed crustacean disease shall be of negligible importance to the risk analysis for the importation of P. vannamei into the Philippines.

Hepatobacter penaei (necrotizing hepatopancreatitis)

Most occurrences have been reported from the Western Hemispheres (affected countries include Belize, Brazil, Colombia, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Panama, Peru, United States of America, and Venezuela (OIE, 2017). But some literature indicates that necrotizing hepatopancreatitis has been detected from farmed L. vannamei in Thailand and Indonesia as well (Biosecurity Australia, 2009). In Thailand, gross signs of NHP infection in farm-reared L. vannamei from Krabi and Phangnga province of Thailand between November 2005 – August 2006 (Limsuwan & Chuchira, 2009; Tangtrongpiros, 2006).

Currently, necrotizing hepatopancreatitis is listed by the OIE as an understudy (Biosecurity Australia, 2009).

Infectious hypodermal and haematopoietic necrosis virus (IHHNV)

IHHNV is widespread in cultured Penaeus monodon and Penaeus vannamei in Thailand. It causes the runt-deformity syndrome that is characterized by physical abnormalities and stunted growth in P. vannamei, but causes no apparent disease in P. monodon (Chayaburakul et al., 2005). An investigation into IHHNV in prawn aquaculture in Thailand found similar levels of IHHNV in P. monodon and P. vannamei tissues. However, IHHNV is reported to be well tolerated in farmed P. monodon (Biosecurity Australia, 2009).

Genetic similarity also suggests IHHNV was introduced into Taiwan from Thailand potentially via trade in live or frozen prawns (Biosecurity Australia, 2009).

Infectious myonecrosis virus (IMNV)

Some publications state that infection with IMNV has been reported to occur in Thailand. Such publications include Biosecurity Australia’s Generic Import Risk Analysis Report for Prawns and Prawn Products (2009) and OIE’s Manual of Diagnostic Tests for Aquatic Animals (2009). But due to the lack of scientific evidence, more recent publications declared that IMNV infection is considered absent in Thailand and that previous positive reports of IMNV occurrence in Thailand are incorrect. To date, Indonesia is the only Asian country known to have tested positive for IMNV (Thitamadee et al., 2015; Senapin et al., 2011). This error has now been corrected in the latest current online version of the OIE’s Manual of Diagnostic Tests for Aquatic Animals (Senapin et al., 2011).

International spread of IMNV is considered to have occurred via the unrestricted movement of live prawns (Biosecurity Australia, 2009).

Macrobrachium rosenbergii nodavirus (white tail disease)

The first detection of White Tail Disease infection in Thailand was first reported in 2006 (Yoganandhan et al., 2006). It has been detected through targeted surveillance (Department of Livestock Development, 2012). The disease is also known to occur in French West indies, later in China (People’s Republic of), India, and Chinese Taipei (OIE, 2009).

Taura syndrome virus

Thailand’s Department of Livestock Development publicized that Taura Syndrome is locally present in Thailand and it has been last detected via targeted surveillance. The first outbreak was reported early in 2003 (Nielsen et al., 2005). Thailand’s TSV infection was due to the introduction of P. vannamei shrimp stocks illegally imported to the country from March 2002 – February 2003(Lumsiwan & Chuchird, 2007; Tookwinas et al., 2005).

White spot syndrome virus (WSSV)

When outbreaks first appeared, they were all associated with extremely severe production and economic losses, and the virus appeared to be highly pathogenic. If shrimp were exposed to enough of the virus, they would die, regardless of the environmental conditions. Losses due to WSSV alone were estimated at US $600 million in Thailand in 1997 and at over US $2 billiion throughout Asia in the same year, Now, however, infections appear to cause severe losses only if the shrimp are also suffering from poor environmental conditions in the ponds. It is still not clear if this change has been due to an alteration in the virus, the host, or to other factors, including the implementation of better management practices by the farmers. The direct economic impact of the virus appears to have decreased (Chanratchakool & Phillips, 2002).

Yellow head virus genotype 1

YHV-type 1 has been only YHV type known to cause continual, severe disease outbreaks in both P. vannamei and P. monodon, and then only in Thailand (Thimatadee et al., 2015). YHV is widespread in Asia and was first reported in Thailand in the early 1900s. Mortalities due to the disease in Thailand were initially serious and widespread. However, high-level mortality of shrimp attributed to the disease declined within 1.5 years (Biosecurity Australia, 2009). In one study, detailed sequence analysis from shrimp in 20 study farms rearing P. vannamei in the central part of Thailand revealed the presence of YHV Type 1b and the absence of YHV Type1a which is the original YHV type reported from Thailand (Senapin et al., 2010)

Table 1. Status of OIE-listed Crustacean Diseases in Thailand, 2018

Disease Status Hazard/Non-hazard
Acute hepatopancreatic necrosis disease positive hazard
Aphanomyces astaci (Crayfish plague) negative non-hazard
Hepatobacter penaei (necrostising hepatopancreatitis) positive hazard
Infectious hypodermal and haematopoietic necrosis virus positive hazard
Infectious myonecrosis virus negative non-hazard
Macrobrachium rosenbergii nodavirus positive hazard
Taura syndrome virus positive hazard
White spot syndrome virus positive hazard
Yellow head virus genotype 1 positive hazard


Importation of aquatic animals for aquaculture from a country, zone or compartment declared free from infection with the pathogen/disease

If the country, zone or compartment has been declared free from infection with the pathogen/disease, the Competent Authority of the importing country should require that the consignment is accompanied by an international aquatic animal health certificate issued by the Competent Authority of the exporting country or a certifying official approved by the importing country. The international aquatic animal health certificate should state that the place of production of the aquatic animals is a country, zone or compartment declared free from infection with the pathogen/disease.

Importation of aquatic animals for aquaculture from a country, zone or compartment not declared free from infection with the pathogen/disease

  1. If the intention is to grow out and harvest the imported aquatic animals, consider applying the following:
    1. The direct delivery to and lifelong holding of the imported commodity in a quarantine facility; and
    2. The treatment of transport water, equipment, effluent, and waste materials to inactivate the pathogen in accordance with Chapter 4.3., 4.7., and 5.5. of the Aquatic Animal Health Code 20th Edition.
  2. If the intention is to establish a new stock for aquaculture, consider applying the following.
    1. In the exporting country:
      1. Identify potential source populations and evaluate their aquatic animal health records;
      2. Test source populations in accordance with Chapter 1.4 of the Aquatic Animal Health Code 20th Edition and select a founder population (F-0) of aquatic animals with a high health status for the pathogen.
    1. In the importing country:
      1. Import the F-0 population into a quarantine facility
      2. Test the F-0 population for the pathogen in accordance with Chapter 1.4 of the Aquatic Animal Health Code 20th Edition to determine their suitability as broodstock;
      3. Produce a first generation (F-1) population in quarantine;
      4. Culture F-1 population in quarantine under conditions that are conducive to the clinical expression of the pathogen (as described in Chapter 2.2.1 of the Aquatic Manual) and test for the pathogen in accordance with Chapter 1.4
      5. If the pathogen is not detected in the F-1 population, it may be defined as free from the pathogen and may be released from quarantine;
      6. If the pathogen is detected in the F-1 population, the commodity should not be released from quarantine and should be killed and disposed of in a biosecure manner.



Hepatopancreatic Microsporidiosis caused by Enterocytozoon hepatopenaei (HPM-EHP)

Shrimp farms in Southeast Asia have been affected by the microsporidian parasite, Enterocytozoon hepatopenaei (EHP) in P. vannamei culture (Kmmari et al., 2018). The parasite was first reported from Penaeus monodon in Thailand and was later found to infect cultured P. vannamei (Kmmari et al., 2018; Songsangjinda & Polchana, 2016). EHP infection of P. vannamei was revealed by in situ hybridization assays (Flegel, 2012; Tangprasittipap, 2012). Though EHP is not associated with mortality of shrimps, it will cause growth retardation in P. vannamei and P. monodon (Kmmari et al., 2018).

Viral covert mortality disease (VCMD) of shrimps

According to the Quarterly Aquatic Animal Disease Report (Asia and Pacific Region) from January to March 2017, Viral Covert Mortality Disease (VCMD) of shrimps is known to occur in Thailand but has been not reported.

Spiroplasma eriocheiris infection

Identified in 2011, Spiroplasma eriocheiris is a novel causative pathogen of tremor disease (TD) of freshwater Chinese mitten crab, Eriocheir sinensis (Wang, 2011). To date,  there is no report of S. eriocheiris infection to shrimps.

Iridovirus in crayfish

For the import risk analysis of Pacific White Shrimp (Penaeus vannamei), it is of negligible concern.



Abdominal segment deformity disease (ASDD)

From 2004 – 2006, shrimp farmers in Thailand, Malaysia and Indonesia have complained of cultured whiteleg shrimp Penaeus vannamei that grow and survive normally but have ASDD. This is characterized by abdominal segments that are enlarged or twisted laterally and/or dorso-ventrally, sometimes accompanied by opaque muscles. It has been found that ASDD in P. vannamei may be caused by a new virus that primarily invades neural tissue and results in neuromuscular dysfuntion and abnormal morphology (Sakaew et al., 2008).

Hepatopancreatic parvovirus (HPV)

HPV infection is frequently observed in dual infections with MBV in Thailand. Anecdotal information by farmers in Thailand reported that 20% of the production profit was lost in one season due to stunted prawns possibly associated with dual infection involving HPV (Biosecurity Australia, 2009).



  1. Biosecurity Australia. 2009. Generic Import Risk Analysis for Prawns and Prawn Products. Biosecurity Australia, Canberra, Australia.
  2. Chanratchakool, P. & Phillips, M.J. 2002. Social and economic impacts and management of shrimp disease among small-scale farmers in Thailand and Vietnam. Food and Agriculture Organization of the United Nations. (
  3. Chayaburakul, K., Lightner, D.V., Sriurairattana S., Nelson K.T., & Withyachumnamkul B. 2005. Different responses to infectious hypodermal and hematopoietic necrosis virus (IHHNV) in Penaeus monodon and Penaeus vannamei. National Center for Biotechnology Information, U.S. National Library of Medicine (
  4. Department of Livestock Development. 2012. Animal Health In Thailand 2011, Bangkok, Thailand, pp 22 and 27. (
  5. Flegel, T.W. 2012. Historic emergence, impact and current status of shrimp pathogens in Asia. Journal of Invertebrate Pathology. (
  6. Kasornchandra, J., Kongkumnerd, J., & Komvilai, C. 2013. Status of EMS/AHPNS in Thailand. Network of Aquaculture Centres in Asia-Pacific (NACA) (
  7. Kmmari, S., Rathlavath, S., Pillai, D., & Rajesh, G. 2018. Hepatopancreatic Microsporidiasis (HPM) in Shrimp Culture: A Review. International Journal of Current Microbiology and Applied Sciences, pp 3209. (,%20et%20al.pdf)
  8. Limsuwan, C. & Chuchira, N. 2009. Histopathological Study of Necrotizing Hepatopancreatitis (NHP) infection in Litopenaeus vannamei in Thailand. Faculty of Fisheries, Kasetsart University (
  9. Lumsiwan, C.& Chuchird, N. 2007. Taura Syndrome Virus Disease in Farm-Reared Penaeus monodon in Thailand. Kasetsart University, Department of Fishery Biology, pp 320. (
  10. Nielsen, L., Sang-oum, W., Cheevadhanarak, S., & Flegel, T.W. 2005. Taura Syndrome Virus (TSV) in Thailand and its relationship to TSV in China and the Americas. National Center for Biotechnology Information, U.S. National Library of Medicine (
  11. OIE (World Organization for Animal Health). 2009. Manual of Diagnostic Tests for Aquatic Animals, pp 133.
  12. OIE (World Organization for Animal Health). 2017. Manual of Diagnostic Tests for Aquatic Animals.
  1. Quarterly Aquatic animal Disease Report (Asia and Pacific Region). January – March 2017. Published July 2017.
  1. Senapin, S., Phiwsaiya, K., Gangnonngiw, W., & Flegel, T.W. 2011. False rumours of disease outbreaks caused by infectious myonecrosis virus (IMNV) in the whiteleg shrimp in Asia. National Center for Biotechnology Information, U.S. National Library of Medicine (
  2. Senapin, S., Thaowbut, Y., Gangnonngiw, W., Chuchird, N., Sriurairatana, S., & Flegel, T.W. 2010. Impact of Yellow Head Virus outbreaks in the Whiteleg Shrimp, Penaeus vannamei (Boone), in Thailand. Journal of Fish Diseases, Volume 33, Issue 5. (
  3. Songsangjinda, P. & Polchana, J. 2016. Current status and impact of early mortality syndrome (EMS)/acute hepatopancreatic necrosis disease (AHPND) and hepatopancreatic microsporidiosis (HPM) outbreaks on Thailand’s Shrimp Farming. Southeast Asian Fisheries Development Center (SEAFDEC) Institutional Repository, pp 83. (
  4. Tangprasittipap, A., Srisala, J., Chouwdee, S., Somboon, M., Chuchird, N., Limsuwan, C., Srisuvan, T., Flegel, T.W., Sritunyalucksana, K. 2013. The microsporidian Enterocytozoon hepatopenaei is not the cause of white feces syndrome in whiteleg shrimp Penaeus (Litopenaeus) vannamei. BMC Veterinary Research, pp 1. (
  5. Tangtrongpiros, J. 2006. Emerging aquatic animal diseases in Thailand. Chulalongkorn University, Faculty of Veterinary Science (
  6. Thitamadee, S. et al. 2015. Review of current disease threats for cultivated penaeid shrimp in Asia. Aquaculture, pp 70.
  7. Tookwinas, S., Chiyakum, K., & Somsueb, S. 2005. Aquaculture of White Shrimp Penaeus vannamei in Thailand. Department of Fisheries, Bangkok, Thailand.
  8. Wang, W., Gu, W., Gasparich, G., Bi, K., Ou, J., Meng, Q., Liang, T., Feng, Q., Zhang, J., & Zhang, Y. 2011. Spiroplasma eriocheiris nov., associated with mortality in the Chinese mitten crab, Eriocheir sinensis. International Journal of Systematic and Evolutionary Microbiology, pp 1. (
  9. Yan, W. 2016. A Hope for Thailand’s Shrimp Farms. Hakai Magazine (
  10. Yoganandhan, K., Leartvibhas, M., Sriwongpuk, S., & Limsuwan, C. 2006. White Tail Disease of the giant freshwater Macrobrachium rosenbergii in Thailand. National Center for Biotechnology Information, U.S. National Library of Medicine (
  11. Sakaew, W., Pratoomthai, B., Anantasomboon, G., Asuvapongpatana, S., Sriurairattanam, S., Withyachumnarnkul. B. 2008. Abdominal segment deformity disease (ASDD) of the whiteleg shrimp Penaeus vannemei reared in Thailand. Aquaculture, Volume 284, Issues 1-4, pp 46 – 52.

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