The World Organisation for Animal Health (OIE) is an international organization that establishes a single OIE list of notifiable terrestrial and aquatic animals diseases. These diseases are classified as specific hazards and given the same degree of importance in the international trade. The following are the general status of OIE-listed crustacean diseases in Thailand which made an impact on the aquaculture of Pacific White Shrimp (Penaeus vannamei).
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).
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 literatures 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 under study (Biosecurity Australia, 2009).
Infectious hypodermal and haematopoietic necrosis virus (IHHNV)
IHHNV is widespread in cultured Penaeus monodon and Penaeus vannamei in Thailand. It causes 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 lack of scientific evidences, 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 on-line 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)
- Biosecurity Australia. 2009. Generic Import Risk Analysis for Prawns and Prawn Products. Biosecurity Australia, Canberra, Australia.
- 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. (http://www.fao.org/docrep/005/y3610e/y3610E17.htm)
- 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 (https://www.ncbi.nlm.nih.gov/pubmed/16408834)
- Department of Livestock Development. 2012. Animal Health In Thailand 2011, Bangkok, Thailand, pp 22 and 27. (http://cdn.aphca.org/dmdocuments/PAP_12_Thailand%20Animal%20Health%202011_DLD.pdf)
- Kasornchandra, J., Kongkumnerd, J., & Komvilai, C. 2013. Status of EMS/AHPNS in Thailand. Network of Aquaculture Centres in Asia-Pacific (NACA) (https://enaca.org/publications/health/ahpns-terminal-workshop/Presentation%2013_KASORNCHANDRA_Status%20in%20Thailand.pdf)
- Limsuwan, C. & Chuchira, N. 2009. Histopathological Study of Necrotizing Hepatopancreatitis (NHP) infection in Litopenaeus vannamei in Thailand. Faculty of Fisheries, Kasetsart University (http://www.thailandshrimp.org/data/research_data/year45)
- Lumsiwan, C.& Chuchird, N. 2007. Taura Syndrome Virus Disease in Farm-Reared Penaeus monodon in Thailand. Kasetsart University, Department of Fishery Biology, pp 320. (http://kasetsartjournal.ku.ac.th/kuj_files/2008/A0804171223407330.pdf)
- 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 (https://www.ncbi.nlm.nih.gov/pubmed/15819424)
- OIE (World Organization for Animal Health). 2009. Manual of Diagnostic Tests for Aquatic Animals, pp 133.
- OIE (World Organization for Animal Health). 2017. Manual of Diagnostic Tests for Aquatic Animals.
- Quarterly Aquatic animal Disease Report (Asia and Pacific Region). January – March 2017. Published July 2017.
- 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 (https://www.ncbi.nlm.nih.gov/pubmed/21813002)
- 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. (https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2761.2009.01135.x)
- 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. (https://www.researchgate.net/publication/249647139_The_microsporidian_Enterocytozoon_hepatopenaei_is_not_the_cause_of_white_feces_syndrome_in_whiteleg_shrimp_Penaeus_Litopenaeus_vannamei)
- Tangtrongpiros, J. 2006. Emerging aquatic animal diseases in Thailand. Chulalongkorn University, Faculty of Veterinary Science (http://www.vet.chula.ac.th/vet2014/Ebook/ebook/azwmp2006/G04.pdf)
- Thitamadee, S. et al. 2015. Review of current disease threats for cultivated penaeid shrimp in Asia. Aquaculture, pp 70.
- Tookwinas, S., Chiyakum, K., & Somsueb, S. 2005. Aquaculture of White Shrimp Penaeus vannamei in Thailand. Department of Fisheries, Bangkok, Thailand.
- Yan, W. 2016. A Hope for Thailand’s Shrimp Farms. Hakai Magazine (https://www.hakaimagazine.com/news/hope-thailands-shrimp-farms/)
- 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 (https://www.ncbi.nlm.nih.gov/pubmed/16724570)