Proceedings of the ASEAN Regional Technical Consultation on EMS/AHPND and Other Transboundary Diseases for Improved Aquatic Animal Health in Southeast Asia
This publication presents the outputs of the Regional Technical Consultation on EMS/AHPND and other Transboundary Diseases. The information and experiences compiled in this publication will help us face disease problems or health management issues in the future. Farmers from countries who have not experienced these diseases will surely learn from those that have developed strategies or technologies for early disease detection, prevention and management.
We expect that the outputs of this Consultation will help guide the ASEAN Member States, regional organizations and other partners in the region in drawing up country-specific and regional policies that would avert impending epidemics that could affect the region’s fishery sector.
Excerpt from Foreword by Felix G. Ayson, D.Sc.
Former Chief, SEAFDEC/AQD
We gratefully acknowledge the Government of Japan through the Japan-ASEAN Integrated Fund, administered by the ASEAN Secretariat, for the main financial support. We also thank the Philippine Bureau of Fisheries and Aquatic Resources for co-organizing the meeting and for the in-kind contributions. Special thanks are also due to all meeting participants, particularly the Member Country representatives and the Panel of Experts for their invaluable contributions to the meeting.
The editors would like to thank the members of SEAFDEC/AQD’s Publications Review Committee for reviewing the Proceedings prior to its publication. Thanks are also due to the Development Communication Section of the Training and Information Division of SEAFDEC/AQD, led by Mr. Rex Dianala, for copy-editing and layout. And lastly, to Mr. Isidro Tendencia for the design and concept of the cover.
- PHOTO OF PARTICIPANTS
- POLICY RECOMMENDATIONS
Latest Research on Acute Hepatopancreatic Necrosis Disease (AHPND) of Penaeid Shrimps
Ikuo Hirono, Sasiwipa Tinwongger, Yuki Nochiri, and Hidehiro Kondo
OIE Initiatives on Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Aquatic Animal Diseases in Asia
Acute Hepatopancreatic Necrosis Disease (AHPND) of Penaeid Shrimps: Global Perspective
Melba G. Bondad-Reantaso
Regional Response on AHPND and Other Emerging Shrimp Diseases in the Asia-Pacific
Eduardo M. Leaño
- Latest Research on Acute Hepatopancreatic Necrosis Disease (AHPND) of Penaeid Shrimps
Current Status of Shrimp Farming and Diseases in Cambodia
Ouch Lang and Mey Sothea
Current Status of Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Transboundary Diseases of Farmed Shrimps in Indonesia
Mukti Sri Hastuti and Desrina
Important Diseases and Practical Control Measures in Shrimp Culture in Japan
Kei Yuasa, Toru Mekata, and Jun Sato
- Lao PDR
Status of Aquatic Animal Health Activities in Lao PDR
Vonsamay Dalasaen and Bouakeo Vong Amnath
Current Status of Acute Hepatopancreatic Necrosis Disease (AHPND) of Farmed Shrimp in Malaysia
Kua Beng Chu, Ahmad IAR, Siti Zahrah A, Irene J, Norazila J, Nik Haiha NY, Fadzilah Y, Mohammed M, Siti Rokhaiya B, M Omar and Teoh TP
Status of Shrimp Health Management in Myanmar
Saw Lah Paw Wah and Maw Maw Than
Status of Acute Hepatopancreatic Necrosis Disease (AHPND) of Cultured Shrimps in the Philippines
Maria Abegail G. Apostol-Albaladejo
Status of Transboundary Diseases of Penaeid Shrimps in Singapore
Wong Yelin and Jiang Junhui
Current Status and Impact of Early Mortality Syndrome (EMS)/ Acute Hepatopancreatic Necrosis Disease (AHPND) and Hepatopancreatic Microsporidiosis (HPM) Outbreaks in Thailand’s Shrimp Farming
Putth Songsangjinda and Jaree Polchana
- Viet Nam
Status of Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Emerging Diseases of Penaeid Shrimps in Viet Nam
Nguyen The Thien, Nguyen Thi Lan Huong, Vo Dinh Chuong, Nguyen Thi Viet Nga, Pham Hong Quang, Bui Thi Viet Hang, and Nguyen Van Long
Conference paper- In RV Pakingking Jr., EGT de Jesus-Ayson & BO Acosta (Eds.), Addressing Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Transboundary Diseases for Improved Aquatic … Diseases for Improved Aquatic Animal Health in Southeast Asia, 22-24 February 2016, Makati City, Philippines, 2016 - Aquaculture Department, Southeast Asian Fisheries Development CenterTransboundary aquatic animal diseases are among the major concerns for establishing biosecurity measures and strengthening of aquatic animal health (AAH) management capacity (including emergency preparedness) in the region. In aquaculture, biosecurity and AAH management entails protection of fish or shellfish from infectious agents (viral, bacterial, fungal or parasitic) as well as prevention of disease spread from one area to another. Several transboundary aquatic animal diseases have swept the region over the past 25 years causing massive economic and social losses. These include spread and outbreaks of epizootic ulcerative syndrome (EUS) in freshwater fish, viral nervous necrosis (VNN) in marine fish, viral haemorrhagic septicaemia (VHS) in marine and freshwater fish, and several viral diseases in shrimps (e.g. white spot disease [WSD], infectious haematopoietic necrosis [IHHN]). The spread of these transboundary diseases clearly demonstrates the vulnerability of the aquaculture industry to disease emergence where impacts have been aggravated by the lack of effective preparedness and response when diseases emerge. Recently, outbreaks of acute hepatopancreatic necrosis disease (AHPND), popularly known as early mortality syndrome (EMS), among cultured shrimps were reported in China and Viet Nam (2010), Malaysia (2011), Thailand (2012), Mexico (2013) and the Philippines (2014). There have been reports of its spread in South American countries but limited report is available in this regard. This disease caused significant losses in the production of Penaeus monodon and P. vannamei in the affected countries. NACA s regional response to this disease during its initial outbreak in Viet Nam, Thailand and Malaysia signified that improved control on transboundary diseases and emergency preparedness are still needed in the region. In collaboration with international organizations (OIE, FAO), NACA has implemented awareness programs, efficient information dissemination, and emergency regional expert consultation to address this disease problem. OIE and FAO also deployed experts to assess the disease and identify the pathogen involved. All of these efforts, together with subsequent studies on prevention and disease management, have paved the way in preventing further spread of this disease to other shrimp-producing countries so far. However, the risk is still very high that this disease will spread, as transboundary movement of live shrimps within and outside the region is inevitable. In addition, other emerging diseases are now affecting production of major cultured shrimps in the region. These include hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) with confirmed reports from China, Viet Nam, Thailand, Malaysia and Indonesia (unconfirmed reports from India), and viral covert mortality disease (VCMD) which was reported to be affecting cultured shrimps in China. By and large, outbreaks of damaging aquatic animal diseases are likely to continue and the potential consequences are likely to increase with the expansion (intensification) of aquaculture systems and introduction of new species for culture. Consequently, the risks associated with emerging and transboundary diseases are shared - shared water bodies and epidemiological links through trade (especially live movement) - thus, a collaborative approach in dealing with these diseases is therefore warranted and necessary.
Conference paper- In RV Pakingking Jr., EGT de Jesus-Ayson & BO Acosta (Eds.), Addressing Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Transboundary Diseases for Improved Aquatic … Diseases for Improved Aquatic Animal Health in Southeast Asia, 22-24 February 2016, Makati City, Philippines, 2016 - Aquaculture Department, Southeast Asian Fisheries Development CenterLao PDR s National Strategy for Fisheries stipulates the expected outcomes, work plan, and framework aimed at attaining the implementation of current plans and long-term projects up to 2020. Government estimates percent per capita consumption of aquatic animals and aquatic animal products at 15 kg per annum, i.e. accounting for about 40% of the animal protein intake, and targets to increase its per capita availability of fish to 23 kg by the year 2020. Lao PDR does not have areas for shrimp culture but researches on the migration pattern and reproductive biology of indigenous shrimp species found in the rivers have been undertaken. Inspection of documents for import, transit and export of live aquatic animals at international checkpoints before entry into Lao PDR has been likewise implemented. With regard to importation, permission of import-export (final destination and origin country), certificate of pedigree, and certificate of sanitary quality are being required. In addition, disease-free status (especially those notifiable to the World Organization of Animal Health [OIE]) of imported shrimps and other aquatic organisms is mandatory at international checkpoints before entry into Lao PDR. For shipments suspected to harbor diseases, samples are sent for analysis at the Namxouang Aquaculture Development Center (NADC), Department of Livestock and Fisheries, Ministry of Agriculture and Forestry, Vientiane, Lao PDR.
Conference paper- In RV Pakingking Jr., EGT de Jesus-Ayson & BO Acosta (Eds.), Addressing Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Transboundary Diseases for Improved Aquatic … Diseases for Improved Aquatic Animal Health in Southeast Asia, 22-24 February 2016, Makati City, Philippines, 2016 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe Organization for Economic Cooperation and Development (OECD) and the Food and Agriculture Organization (FAO) of the United Nations Agricultural Outlook 2015-2024 reported that fisheries production worldwide is projected to expand by 19% between the 2012-14 base period and 2024, to reach 191 million metric tons (MT) and the main driver of this increase will be aquaculture, which is expected to reach 96 million MT by 2024, 38% higher than the base period (average 2012-14) level. Among the 7 key uncertainties that affect gains in productivity, the potential of animal disease outbreaks to affect aquaculture production and subsequently domestic and international markets are once again highlighted, although for the first time in this outlook. Another milestone document, the Blue frontiers: managing the environmental costs of aquaculture identified a number of fish health issues, including increased risk of the spread of pathogens and diseases with intensification, through increased movement of aquatic animals, inter-regional trade and introduction of new species and new strains, and through the use of trash fish or live feed; concerns on residues and development of drug resistant pathogens brought about by the abuse on the use antimicrobials and other veterinary drugs; limited availability of vaccines; environmental stressors that compromise the immune system; difficulties faced by developing countries in implementing international standards; and the need for legislation, enforcement and capacity building. The issues identified then and now are almost the same. Addressing animal health issues in aquaculture is very challenging because the sector is highly complex (with a wide range of diversity in terms of species, systems, practices and environment, each presenting different risks), its fluid environment, and the transboundary nature where fish is considered as one of the most traded commodity, aquatic animals require more attention in order to monitor their health: they are not visible except in tank holding conditions; they live in a complex and dynamic environment and feed consumption and mortalities are hidden under water. This paper looks at the status of a newly emerging disease of cultured shrimp, acute hepatopancreatic necrosis disease (AHPND), which has been recognized as the most important non-viral disease threat to cultured shrimp. In particular, this paper presents the highlights of the International Technical Seminar/Workshop: EMS/AHPND: Government, Scientist and Farmer Responses held from 22-24 June 2015 in Panama City, Panama, which was organized under the auspices of an FAO inter-regional project TCP/INT/3502: Reducing and Managing the Risks of AHPND of Cultured Shrimp, being participated by 11 countries, namely: Colombia, Ecuador, Guatemala, Honduras, Mexico, Panama and Peru from Latin America and the Caribbean (LAC) region and India, Iran, the Philippines and Sri Lanka from the Asian region. The Panama EMS/AHPND June 2015 event aimed to provide a platform to improve the understanding of the disease through the lens of governments, scientists and producers and collectively generate practical management and control measures. More than 100 stakeholders from 21 countries representing the government, academe and producer sectors participated in the event. The highlights contain the latest available information at that time (June 2015) about AHPND including the current state of knowledge about the causative agent, the host and geographical distribution, detection methods, risk factors, management and actions of regional and international organizations.
Conference paperThe farming of penaeid shrimps in Cambodia began in 1989 and has significantly expanded since 1991. Shrimp cultivation has been carried out in the four coastal provinces, i.e. Kampot, Kep, Preah Sihanouk Ville, and Koh Kong. Black tiger shrimp (Penaeus monodon) and whiteleg shrimp (P. vannamei) are the main species being cultured extensively and intensively in brackishwater ponds in Kampot, Kep, and Preah Sihanouk Ville, and Koh Kong, respectively. Extensive shrimp ponds were constructed close to the mangrove areas with some containing mangroves within the pond and stocking density ranging from 5,000 to 20,000 postlarvae/ha. However, the productivity remains low at >100 kg/ ha/ year. On the contrary, intensive culture has a stocking density ranging from 300,000 to 500,000 postlarvae/ha. While high cost of investment for farm establishment, pond construction and farm operation are required, productions of newly established farms have reached 7 to 8 metric tons (MT) /ha per crop. The occurrence of white spot disease, monodon baculovirus disease, and yellow head disease was first reported in 1999 among cultured P. monodon in Koh Kong province causing a number of farmers to stop the intensive cultivation of black tiger shrimp. To date, only a small proportion of shrimp farmers have ventured into extensive shrimp farming with approximately 10 ha of shrimp areas currently in operation. To mitigate the negative impacts of shrimp diseases and promote the expansion of the shrimp industry in Cambodia, development of a national reporting system for aquatic animal diseases; capacity building for detection, monitoring and disease surveillance; creation of National Guidelines On Good Shrimp Aquaculture Practices; establishment of subresearch centers and concomitant funding support for marine aquaculture development and extension services; establishment of local shrimp hatcheries and provision of hands-on trainings for farmers; and strengthening collaborations among provincial officers, researchers and farmers network should be accordingly instituted.
Conference paperSingapore has a small shrimp farming industry with approximately 54 metric tons (MT) of shrimps produced in one year from both land and coastal farms. There is also one shrimp farm producing broodstock for export. Singapore has the capability to diagnose acute hepatopancreatic necrosis disease (AHPND) through histopathology and the isolation of its causal agent which is Vibrio parahaemolyticus. The polymerase chain reaction (PCR) method for AHPND detection in shrimp is currently being undertaken to further strengthen its laboratory and diagnostic capacity. Notably, Singapore is still AHPND-free. On the contrary, white spot disease caused by white spot syndrome virus (WSSV) is a disease of concern as it affects the trade for ornamental crustaceans. Singapore has an active surveillance program for WSSV and other transboundary pathogens of penaeid shrimps. Positive detections would be followed by movement controls and stamping out protocols.
Current status of acute hepatopancreatic necrosis disease (AHPND) and other transboundary diseases of farmed shrimps in Indonesia Transboundary diseases have been a constant challenge for the aquaculture industry in Indonesia. In spite of this, Indonesian aquaculture has experienced a steady growth since 2010. Early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) is a serious emerging transboundary disease of cultured shrimp that has not been reported in Indonesia. On the contrary, hepatopancreatic microsporidiosis (HPM) was first detected in 2015. Other previously reported transboundary diseases of shrimp and fish include white spot disease (WSD), Taura syndrome and infectious myonecrosis (IMN), and viral nervous necrosis (VNN) and koi herpesvirus (KHV), respectively. These diseases have been included in the surveillance program conducted in 2016. To avert the spread of these transboundary pathogens in the Indonesian aquaculture facilities and natural waters, competent authorities have been tasked to implement stringent control measures including government policy and regulation, active and passive surveillance, and strengthening farmers and stake holders awareness of the importance of disease control and health maintenance.
Status of acute hepatopancreatic necrosis disease (AHPND) and other emerging diseases of penaeid shrimps in Viet Nam Acute hepatopancreatic necrosis disease (AHPND), formerly called early mortality syndrome (EMS), was first reported in 2010 among penaeid shrimps cultivated in the Mekong Delta Region of Viet Nam albeit without any laboratory confirmation. The disease subsequently spread to a wide range of shrimp production areas in the same region (Soc Trang: 1,719 ha; Bac Lieu: 346 ha; and Ca Mau: 3,493 ha), so that the Government of Viet Nam requested for technical assistance from the Food and Agriculture Organization (FAO) of the United Nations in 2011. In 2012, FAO supported Viet Nam through the project TCP/VIE/3304 Emergency assistance to control the spread of an unknown disease affecting shrimps in Viet Nam, under which the Department of Animal Health of Viet Nam (DAH) collaborated with the University of Arizona and FAO experts to carry out indepth studies to identify the etiologic agent of the disease. As a result, unique isolates of Vibrio parahaemolyticus was identified as the causative agent of AHPND in 2013. Viet Nam has been vigilant and transparent with regard to aquatic animal diseases through official notifications to the World Organization for Animal Health (OIE) and the Network of Aquaculture Centres in Asia-Pacific (NACA). AHPND outbreaks have no clear temporal pattern with black tiger (Penaeus monodon) and whiteleg (P. vannamei) shrimps showing similar incidence risk. The disease occurs at any stage of shrimp cultivation, i.e. on average about 35 days after stocking. To date, unwarranted outbreaks of AHPND in major shrimp-producing provinces in Viet Nam have been apparently regulated. Aside from AHPND, white spot disease (WSD) has also been a persistent problem responsible for serious economic losses in many shrimp-producing areas in Viet Nam. To prevent and control the further spread of infectious diseases of shrimps including AHPND and WSD, multiple control measures have been implemented including guidance of farmers to improve production conditions, facilities and biosecurity application, active surveillance of shrimp production areas for early warning, screening of broodstock and postlarvae for any OIE listed diseases, regulation on movement of stocks, and collaboration with regional and international organizations in carrying out in-depth epidemiological studies that will be needed in the formulation of pragmatic and holistic disease interventions.
Current status and impact of early mortality syndrome (EMS)/acute hepatopancreatic necrosis disease (AHPND) and hepatopancreatic microsporidiosis (HPM) outbreaks on Thailand s shrimp farming Outbreak of early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) in whiteleg shrimp (Penaeus vannamei) and black tiger shrimp (P. monodon) was first documented in August 2011 in Eastern Thailand. The disease subsequently spread to almost all shrimp production areas in 2012 until the early part of 2016. These episodes of AHPND outbreaks consequently impacted the shrimp industry as evidenced by significant reduction in the production of farmed shrimps, shortage of raw materials for the shrimp export industry, and reduction of global shrimp supply from Thailand. Following the discovery of Vibrio parahaemolyticus as the causal agent of AHPND, PCR techniques subsequently became available for the rapid and accurate detection of AHPND in cultivated shrimps. The Department of Fisheries (DOF) consequently included AHPND in the National Surveillance Program focusing on the investigation of risk factors responsible for the outbreak and concomitant spread of the disease. As a result, the quality of broodstock and postlarvae (PL) and as well as farm management practices, i.e. pond bottom and water preparation, stocking density, feeds and feeding practices, and water quality fluctuations were identified as key risk factors associated with AHPND outbreaks. By and large, the DOF has undertaken mitigating measures to control and prevent further outbreaks of AHPND including the improvement of sanitation in marine shrimp broodstock and PL hatcheries, quality evaluation and disease screening of broodstocks and PL, detection of pathogens in soil and water samples, and acquisition of new broodstocks for improved genetic diversity. To date, Thailand s shrimp industry has gradually recovered from the devastating effects of AHPND since 2015. Heptopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP), a sporeforming microsporidian, is another emerging disease of cultured penaeids in Thailand. EHP was first documented in farmed P. monodon in 2004, however, its impact was not clearly evaluated at that time. EHP was again observed in P. vannamei in 2014 at the same period of AHPND outbreak in Thailand. In the field, EHP could be transmitted horizontally through feeding of the EHPcontaminated feed and feces from infected shrimp. Samples collected from numerous shrimp farms showed that EHP was heavily present in both ponds with successful and failed crops indicating that EHP infection in shrimp may not be a significant contributing factor to a failed production run. In vitro challenge likewise showed that there was no correlation between EHP and white feces syndrome. However, EHP infection at significantly high levels could affect shrimp growth. One of the mitigating measures to control EHP infection in cultured shrimp is the reduction of contamination in hatcheries and grow-out facilities. Despite the negative impacts of AHPND and HPM on the shrimp industry of Thailand, all parties of the shrimp sector have been working in concert to attain the projected annual shrimp production volume of approximately 300,000 metric tons (MT) in 2016.
Conference paperExtensive cultivation of the black tiger shrimp (Penaeus monodon) started in the 1970 s in Myanmar using trap and hold method. P. monodon postlarvae (PL) were trapped into the ponds measuring approximately 50 to 100 hectares (ha) during high tide. Because these large ponds have no inputs in terms of pond preparation, eradication of predators, water fertilization, and feeding, production volume during the early years of the shrimp industry in the country provided some lucrative income for the farmers. With this promise, a 3-year project aimed at developing the shrimp culture systems into extensive, extensive plus and semi-intensive was implemented by the Department of Fisheries (DoF), Ministry of Livestock and Fisheries (MLF) in 2010. Unfortunately, in that same year, an outbreak of white spot disease (WSD) caused by white spot syndrome virus (WSSV) occurred in ponds stocked with imported postlarvae and devastated the shrimp industry of the country. Moreover, P. monodon samples from Ayeyarwaddy Division (western part of Myanmar) were also found positive for Taura syndrome virus (TSV) and infectious hypodermal and haematopoietic necrosis virus (IHHNV) by polymerase chain reaction (PCR) method in 2010. In addition, yellow head virus (YHV) was also detected in shrimp samples for export in 2014. Fortunately, acute hepatopancreatic necrosis disease (AHPND) has not yet been detected in cultivated shrimps in Myanmar. Because of disease problems, majority of the shrimp farmers have shifted to extensive or traditional shrimp farming. The Aquatic Animal Health and Disease Control Section (AAHDCS) of the DoF formulates the action plans for aquatic animal health and disease control. Thus to keep abreast with the novel techniques used for the detection and management of previously reported and newly emerging diseases of penaeid shrimps, upgrading of laboratory equipment and facilities, and improving the capacity of the departmental personnel on aquatic animal health management are currently being undertaken.
OIE initiatives on acute hepatopancreatic necrosis disease (AHPND) and other aquatic animal diseases in Asia The World Organization for Animal Health (OIE) is an intergovernmental organization established in 1924 responsible for improving animal health and welfare worldwide to facilitate safe international trade of animals and animal products while avoiding unnecessary impediments to trade. OIE, as a reference organization of the World Trade Organization (WTO), works to set and update its international standards (OIE Codes and Manuals) regularly through transparent and democratic procedures. The Aquatic Code defines an OIE list of notifiable aquatic animal diseases according to the criteria for listing, which comprise consequences, spread and diagnosis. To be listed, a disease should meet the criteria of each characteristic defined in the Aquatic Code. The acute hepatopancreatic necrosis disease (AHPND) has been officially included in the OIE-listed diseases since May 2015 and officially enforced since 1 January 2016. To fulfill its overall vision which can be summarized by its slogan Protect animals and Preserve our Future, the OIE Regional Representation in Tokyo, Japan and Sub-Regional Representation in Bangkok, Thailand, are working in concert to provide regionally adapted services to OIE Members so that surveillance and control of animal diseases in the region may be strengthened.
Conference paperAcute hepatopancreatic necrosis disease (AHPND) is caused by unique strains of Vibrio parahaemolyticus (VPAHPND) and V. harveyi that have transferrable plasmid carrying the virulent PirAB-like toxin genes. The genomes of VPAHPND strains and V. harveyi from Thailand and Viet Nam, respectively, have been characterized by our group. The genome of VPAHPND strains from Mexico, Viet Nam, and China have also been studied by other groups. We have developed a conventional polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) methods for the detection of AHPND using a primer set that targets the PirAB-like toxin genes of VPAHPND. We have characterized the toxin genes of VPAHPND strains and also constructed a recombinant plasmid (broad host range) carrying PirAB-like toxin genes. Non-VPAHPND strain N7 which does not carry the plasmid and strain FP11 which is carrying a plasmid not coding for the toxin genes were transformed with the plasmid carrying PirAB-like toxin genes. As a result, the transformed N7 and FP11 strains became virulent and killed whiteleg shrimp (Penaeus vannamei) similar to or at par with the virulence of VPAHPND strain. We then fed the whiteleg shrimp with commercial feed containing the formalin-killed VPAHPND strain. After 2 days of feeding, all of the whiteleg shrimp died. These results clearly indicate that the PirAB-like toxin is the virulence factor of VPAHPND. We have been investigating the virulence mechanism of the PirAB-like toxin produced by VPAHPND strains. First, we calculated the copy number of plasmid encoding the PirAB-like toxin genes of several VPAHPND strains. The copy number of the plasmid varied, ranging from 1 to 36 copies. Interestingly, VPAHPND strains carrying low copy number of plasmid were more virulent than VPAHPND strains carrying high copy number of the plasmid. These results imply that the copy number of toxin genes is not an important factor responsible for the degree of virulence of the VPAHPND strains. We are also studying other factors associated with the virulence of PirAB-like toxin. Likewise, we are developing prevention methods against AHPND including the use of formalin-killed cell vaccine, IgY additive in feed, and nano-bubble treatment of rearing water. This paper summarizes the current R&D on the disease.
Book | Conference publication
Addressing acute hepatopancreatic necrosis disease (AHPND) and other transboundary diseases for improved aquatic animal health in Southeast Asia: Proceedings of the ASEAN Regional Technical Consultation on EMS/AHPND and Other Transboundary Diseases for Improved Aquatic Animal Health in Southeast Asia, 22-24 February 2016, Makati City, Philippines - 2016 - Aquaculture Department, Southeast Asian Fisheries Development Center
Conference paperA report about a disease problem in cultured whiteleg shrimp (Penaeus vannamei) was first received by the National Fish Health Research Center (NaFisH) in 2011 from Perak State showing signs of white feces and slow death leading to serious mortality rate. Later, in September of the same year, the Malaysian Shrimp Farmers Association (MSFA) reported to Department of Fisheries (DOF) severe mortalities in almost all of the whiteleg shrimp farms throughout Peninsular Malaysia. Sampling of shrimps for disease diagnosis was then conducted by NaFisH. The bacteriological and histopathological examinations revealed respectively the isolation of V. parahemolyticus and massive sloughing of hepatopancreatic epithelial cells. The disease was subsequently identified as acute hepatopancreatic necrosis disease (AHPND). From our 3-year study, the annual prevalence rates of AHPND were 50%, 26% and 73% in 2011, 2012 and 2013, respectively. At present, AHPND still persists in Malaysia but at a lower prevalence. The risk factors associated with the disease were studied, however, varied environmental and management data analyzed were inconclusive to relate any one parameter directly to the disease. To help ensure the early detection of AHPND, an experimental observation study on `gut scorecard was carried out and this was confirmed by PCR and histopathology. Validation of this technique has yet to be carried out to ensure its reliability. We also examined the potential use of some commercial products such as probiotics and disinfectants available in the market but unfortunately results showed that they were not effective in controlling AHPND. Control measures applied by the farmers such as the use of probiotics were also verified but data generated likewise appeared to be inconclusive. On the contrary, our preliminary study on the antibacterial property of the plant extracts, i.e. betel and lemongrass, incorporated in the feed showed some prophylactic and chemotherapeutic potential against AHPND. However, comprehensive in vitro and in vivo trials are still currently being undertaken to elucidate its efficacy and practical applications. To ensure the shrimp industry s sustainability in Malaysia, results of our ongoing and future studies aimed at preventing and controlling unwarranted outbreaks of AHPND and other emerging transboundary diseases of penaeid shrimps will be continually disseminated to shrimp farmers and pertinent stakeholders.
Conference paperShrimp is the fourth most important aquaculture commodity in the Philippines in terms of production quantity and second in terms of export value. The two species of shrimp being cultivated in the Philippines are the black tiger shrimp (Penaeus monodon) and Pacific white shrimp (P. vannamei). Although shrimp production markedly declined in the 1990 s due to luminescent vibriosis and white spot disease caused by Vibrio harveyi and white spot syndrome virus (WSSV), respectively, the industry was able to recover due to collaborative and participatory efforts of both the public and private sectors. Recovery programs focused on improving culture technologies, prevention and control of disease introduction and outbreaks and environmental enhancement. However, serious outbreaks of an emerging transboundary disease named acute hepatopancreatic necrosis disease (AHPND) caused by unique strains of V. parahaemolyticus have recently caused heavy economic losses among shrimps growers in some major shrimp producing provinces in the country, thereby threatening production growth and export expansion of the Philippine shrimp industry. This paper presents the status of AHPND in cultured penaeids and activities of the National Shrimp Health Management Program (NSHMP) of the Bureau of Fisheries and Aquatic Resources (BFAR) on importation policies, disease surveillance, monitoring and reporting, disease diagnosis, and preventive and control measures against AHPND and other transboundary diseases of cultured penaeids in the Philippines.
Conference paperThe gross product from sea culture in Japan was about USD 3.4 billion in 2013 with kuruma shrimp Marsupenaeus japonicus constituting 2% of the total production. In recent years, annual shrimp production has reached about 1,600 metric tons (MT) and 99% of the species produced comprised of M. japonicus. Kuruma shrimp is highly traded at market price of USD 40-60 per kg. At present, 65% of cultured kuruma shrimp are produced in Okinawa and Kagoshima prefectures. To increase or maintain kuruma shrimp fishery in the natural environment, 200 million fry have been annually released into the sea along the coast of Japan. In addition, whiteleg shrimp Penaeus vannamei has also been produced in a private farm since 2007 with an annual production of approximately 40 MT. Recently, the number of farms that ventured into whiteleg shrimp culture has increased. The most serious obstacle faced by the kuruma shrimp industry in Japan in the 1990s was the outbreaks of white spot disease (WSD) caused by white spot syndrome virus (WSSV). The seed production of kuruma shrimp has been dependent on captured wild broodstocks. However, broodstocks obtained from the wild could be carriers of WSSV that may vertically transmit the virus to fertilized eggs. To prevent the spread of WSD, measures for disinfecting WSSV-infected fertilized eggs of shrimp and detection of the causative virus by polymerase chain reaction (PCR) have been developed. Lately, with the application of an improved technology for broodstock rearing, production losses ascribed to WSD have significantly decreased because majority of the hatcheries have been using specific WSSV-free shrimps. In the last decade, in kuruma shrimp hatcheries and grow-out ponds, vibriosis due to Vibrio penaeicida has been frequently encountered. Fusariosis caused by Fusarium solani is also common. The first cases of vibriosis and fusariosis in Japan occurred in 1973 and 1972, respectively. Taking the case of Okinawa prefecture as example, production losses in 2005 due to vibriosis and fusariosis were 66% and 34%, respectively. Cleaning of the pond bottom prior to the commencement of grow-out culture has been recommended to prevent vibriosis. Some antibiotics have also been orally administered to reduce mortality of shrimps affected by vibriosis. However, farmers have been properly cautioned regarding their use as emergence of antibiotic-resistant bacteria could consequently arise. Because no practical treatment for fusariosis is currently available, farmers either dispose or harvest infected shrimps followed by disinfection of ponds with 10 ppm chlorine. Acute hepatopancreatic necrosis disease (AHPND) has not yet been detected in Japan. As kuruma shrimp is also susceptible to the disease, the Government of Japan plans to designate AHPND as Specific Disease. Under Japanese law, enlistment of AHPND as a quarantinable disease will also be instituted to prevent the introduction of this disease into Japanese hatcheries and grow-out facilities. However, in case an AHPND outbreak inadvertently occurs, Prefectural Fisheries Experimental Stations (PES) could immediately conduct preliminary diagnosis using the AP4 polymerase chain reaction (PCR) method. In addition, confirmatory diagnosis using AP4 nested PCR method and sequencing could be conducted at the National Research Institute of Aquaculture (NRIA), a central laboratory for aquatic animal health. NRIA s task is not only to perform confirmatory diagnosis but likewise disseminate diagnostic techniques to the staff of the National Quarantine and PES.