Impacts of acute hepatopancreatic necrosis disease on commercial shrimp aquaculture.

Acute hepatopancreatic necrosis disease (AHPND) has caused severe losses in farmed populations of marine shrimp Penaeus vannamei and P. monodon. The causative agents are unique strains of the bacteria Vibrio parahaemolyticus and related Vibrio species. The disease emerged in the People's Republic of China (China) and Vietnam in 2010 and spread throughout South-East Asia; it was later reported in countries in both North and South America. The disease has had significant economic impacts on the shrimp aquaculture industry. From 2010 to 2016, combined losses from China, Malaysia, Mexico, Thailand and Vietnam due primarily to outbreaks of AHPND, including losses at the farm gate and those resulting from a drop in feed sales and exports, were estimated at over US$ 44 billion. Other economic losses include those associated with processing facilities, decreased community revenues resulting from increased unemployment, financial investments, and the costs of implementing diagnostic and control measures. The reduced employment opportunities and increases in debt burden and investment risk have had sociological impacts. The responses to the disease have led to a gradual recovery of the shrimp industry in affected countries. These response efforts have included the implementation of changes in farming systems and management, including, among others, enhanced biosecurity and the use of AHPND-free and AHPND-resistant shrimp. This situation of losses and recovery illustrates the importance of having a multi-level response plan in place to prevent, or to reduce the risk of, outbreaks of disease.

La maladie de nécrose hépatopancréatique aiguë (AHPND, selon ses sigles en anglais) a occasionné des pertes importantes dans les élevages des espèces de crevettes marines Penaeus vannamei et P. monodon. La maladie est causée par des souches particulières de la bactérie Vibrio parahaemolyticus et d'autres espèces apparentées de Vibrio. Apparue en 2010 en République populaire de Chine et au Vietnam, la maladie s'est d'abord propagée dans toute l'Asie du SudEst avant d'être notifiée dans plusieurs pays d'Amérique du Nord et du Sud. Ses conséquences économiques sont très lourdes pour le secteur de la pénéiculture. On estime à plus de 44 milliards de dollars US les pertes cumulées enregistrées entre 2010 et 2016 par la Chine, la Malaisie, le Mexique, la Thaïlande et le Vietnam suite aux foyers d'AHPND (il s'agit aussi bien des pertes directes subies par les exploitations que de celles résultant de l'effondrement des ventes et des exportations d'aliments pour les élevages). D'autres pertes économiques sont associées aux établissements de transformation, aux pertes de revenus au sein des communautés locales par suite de l'augmentation du chômage, au déclin des investissements et aux coûts du diagnostic et des mesures de contrôle de la maladie. La réduction des perspectives d'emploi et l'augmentation du poids de la dette et des risques liés aux investissements ont affecté la société dans son ensemble. La mise en place de mesures appropriées a permis un redressement progressif du secteur de l'élevage de crevettes dans les pays atteints. Parmi ces mesures figurent les changements introduits dans les systèmes d'élevage et de gestion, en particulier l'amélioration de la biosécurité et l'utilisation de crevettes résistantes à la maladie ou indemnes. La situation décrite concernant ces pertes et ce redressement illustre l'importance de disposer d'un plan d'action à plusieurs niveaux afin de prévenir ou de réduire le risque de foyers.

La enfermedad de la necrosis hepatopancreática aguda (AHPND por sus siglas en inglés) ha infligido enormes pérdidas a las poblaciones de cultivo de camarones marinos de las especies Penaeus vannamei y P. monodon. Sus agentes etiológicos son determinadas cepas de las bacterias Vibrio parahaemolyticus y otras especies emparentadas del género Vibrio. La enfermedad apareció en 2010 en la República Popular de China y Vietnam y desde allí se propagó por todo el Sudeste asiático. Ulteriormente se notificó su presencia en Norteamérica y Sudamérica. La enfermedad ha tenido considerables consecuencias económicas para la industria camaronícola. El total de las pérdidas sufridas entre 2010 y 2016 por China, Malasia, México, Tailandia y Vietnam debidas principalmente a brotes de AHPND, sumando las sufridas en la explotación y las resultantes de la caída de las ventas de piensos y de las exportaciones, ascendieron según los cálculos a más de 44 000 millones de dólares estadounidenses. A estas pérdidas económicas se agregan otras, como las sufridas por las instalaciones de procesamiento, la caída de la renta comunitaria por el aumento del desempleo, la disminución de las inversiones financieras o los costos de aplicar medidas de diagnóstico y control. La reducción de las oportunidades de empleo y el aumento de la carga de la deuda y del riesgo de inversión han tenido también consecuencias sociológicas. Gracias a las medidas de lucha adoptadas, que trajeron consigo una serie de cambios en los sistemas acuícolas y en su gestión, entre ellos la mejora de la seguridad biológica y el uso de camarones no infectados y resistentes a la enfermedad, el sector camaronícola de los países afectados se ha ido recuperando gradualmente. Esta dinámica de pérdida y recuperación pone de manifiesto la importancia de tener instituido un plan de respuesta en múltiples eslabones para prevenir brotes de la enfermedad o reducir el riesgo de que se produzcan.

Historic emergence, impact and current status of shrimp pathogens in the Americas.

Shrimp farming in the Americas began to develop in the late 1970s into a significant industry. In its first decade of development, the technology used was simple and postlarvae (PLs) produced from wild adults and wild caught PLs were used for stocking farms. Prior to 1990, there were no World Animal Health Organization (OIE) listed diseases, but that changed rapidly commensurate with the phenomenal growth of the global shrimp farming industry. There was relatively little international trade of live or frozen commodity shrimp between Asia and the Americas in those early years, and with a few exceptions, most of the diseases known before 1980 were due to disease agents that were opportunistic or part of the shrimps' local environment. Tetrahedral baculovirosis, caused by Baculovirus penaei (BP), and necrotizing hepatopancreatitis (NHP) and its bacterial agent Hepatobacterium penaei, were among the "American" diseases that eventually became OIE listed and have not become established outside of the Americas. As the industry grew after 1980, a number of new diseases that soon became OIE listed, emerged in the Americas or were introduced from Asia. Spherical baculovirus, caused by MBV, although discovered in the Americas in imported live Penaeus monodon, was subsequently found to be common in wild and farmed Asian, Australian and African penaeids. Infectious hypodermal and hematopoietic necrosis virus (IHHNV) was introduced from the Philippines in the mid 1970s with live P. monodon and was eventually found throughout the Americas and subsequently in much of the shrimp farming industry in the eastern hemisphere. Taura syndrome emerged in Penaeus vannamei farms in 1991-1992 in Ecuador and was transferred to SE Asia with live shrimp by 1999 where it also caused severe losses. White Spot Disease (WSD) caused by White spot syndrome virus (WSSV) emerged in East Asia in ∼1992, and spread throughout most of the Asian shrimp farming industry by 1994. By 1995, WSSV reached the eastern USA via frozen commodity products and it reached the main shrimp farming countries of the Americas located on the Pacific side of the continents by the same mechanism in 1999. As is the case in Asia, WSD is the dominant disease problem of farmed shrimp in the Americas. The most recent disease to emerge in the Americas was infectious myonecrosis caused by IMN virus. As had happened before, within 3years of its discovery, the disease had been transferred to SE Asia with live P. vannamei, and because of its impact on the industry and potential for further spread in was listed by the OIE in 2005. Despite the huge negative impact of disease on the shrimp farming industry in the Americas, the industry has continued to grow and mature into a more sustainable industry. In marked contrast to 15-20years ago when PLs produced from wild adults and wild PLs were used to stock farms in the Americas, the industry now relies on domesticated lines of broodstock that have undergone selection for desirable characteristics including disease resistance.

A real-time PCR for the detection of hepatopancreatic parvovirus (HPV) of penaeid shrimp.

Hepatopancreatic parvovirus (HPV) causes a common shrimp disease that occurs in many shrimp farming regions, especially in the Indo Pacific, and infects most of the cultured penaeid species. There are seven geographic HPV isolates known, so a method to detect different HPV types is needed. We developed a sensitive and generic real-time PCR assay for the detection of HPV. A pair of primers and TaqMan probe based on an HPV sequence obtained from samples of Fenneropenaeus chinensis from Korea were selected, and they were used to amplify a 92 bp DNA fragment. This real-time PCR was found to be specific to HPV and did not react with other shrimp viruses. A plasmid (pHPV-2) containing the target HPV sequence was constructed and used for determination of the sensitivity of this assay. The assay could detect a single copy of plasmid DNA, and it was used successfully in finding HPV in shrimp samples from the China-Yellow Sea region, Taiwan, Korea, Thailand, Madagascar, New Caledonia and Tanzania.