This disease advisory describes the history, known host range, clinical signs and PCR detection methods for viral covert mortality disease (VCMD). Crustaceans currently known to be susceptible to VCMD include Penaeus vannamei, P. chinensis, P. japonicus, P. monodon, Macrobrachium rosenbergii, Procambarus clarkii, Exopalaemon carinicauda, Ocypode cordimanus, Diogenes edwardsii, Corophium sinense, Parathemisto gaudichaud and Tubuca arcuate. Fish species including Mugilogobius abei, Carassius auratus, and Paralichthys olivaceusmay also be susceptible to the virus.
The 84th edition of the Quarterly Aquatic Animal Disease Report contains information from eleven governments. The foreword discusses meetings of the ad hoc Steering Committee of the Regional Collaboration Framework on Aquatic Animal Health in Asia and the Pacific.
Infection with DIV1 is an emerging disease in farmed Cherax quadricarinatus and Penaeus vannamei suffering a high mortality. This disease card provides information on signs of disease at pond and animal level (levels I - III diagnoses), the disease agent, known host range and distribution in the Asia-Pacific region, molecular diagnostic methods and provides key expert contact points.
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This disease advisory describes the history, known host range, clinical signs and PCR detection methods for decapod iridescent virus 1 (DIV1). Preventative strategies are suggested. Currently known susceptible species of DIV1 include Penaeus vannamei, Macrobrachium rosenbergii, Exopalaemon carinicauda, M. nipponense, Procambarus clarkii, and Cherax quadricarinatus. Clinical signs of infected P. vannamei are not typical, including slightly reddish body, hepatopancreatic atrophy with colour fading, and empty stomach and guts.
Urgent warning: Positive PCR detection results for infectious myonecrosis virus (IMNV) and decapod iridescent virus 1 (DIV1) in captured Penaeus monodon from the Indian Ocean; COVID-19 news; Urgent announcement on usefulness of the lymphoid organ (LO) as an additional prime target for diagnosis of decapod iridescent virus 1 (DIV1) in diseased P. vannamei; Fresh or frozen seafood?; Report of the Eighteenth Meeting of the Asia Regional Advisory Group on Aquatic Animal Health; COVID-19 fallout could push half a billion people into poverty in developing countries; Simple techniques double crablet production.
This report was prepared by the 18th Asia Regional Advisory Group on Aquatic Animal Health (AG) that met at Bangkok, Thailand on 18-19 November 2019. The group discussed OIE standards and global issues, review of regional disease status, reports on the aquatic animal health programmes of partner agencies, and disease reporting.
From a survey of wild, adult Penaeus monodon of potential broodstock size from the Indian Ocean in April 2018, we obtained positive nested RT-PCR test results for infectious myonecrosis virus (IMNV) and positive nested PCR test results for DIV1. As a confirmatory step, a second round of nested PCR tests was carried out using new, in-house primers designed from regions of the respective viral genomes distant from the target regions used in the first round of tests. These results suggested the possibility that the grossly normal, PCR-positive captured P. monodon specimens might be infected with the respective viruses at the carrier level. If so, they might serve as potential vehicles for introduction of IMNV and/or DIV1 into crustacean culture systems, especially if they were used in hatcheries for production of PL for distribution to shrimp farmers without proper precautions in place.
We carried out laboratory injection challenges that employed extracts prepared from shrimp naturally-infected with decapod iridovirus 1 (DIV1). We found that diseased shrimp from the injection trials showed pathognomonic lesions for DIV1 in the hematopoietic tissue that matched those reported for DIV1 in P. vannamei from China (Qiu et al. 2017. Scientific Reports. 7). In addition, we also found distinctive lesions in the lymphoid organ that could be used as an additional indicator in confirming diagnosis of DIV1 disease. Also, the lesions from shrimp challenged with the 10x dilution were more severe than those from 100x dilution, and for some shrimp in the 100x dilution, the lesions were very clear in the LO but absent in the HPT. Altogether, the results suggested that histology of the HPT and LO could be used together to help in the diagnosis of DIV1 in conjunction with RT-PCR, amplicon sequencing and in situ hybridization (ISH) analysis. This is particularly important in confirming the presence of virulent isolates of DIV1 in new geographical locations.
The 83rd edition of the Quarterly Aquatic Animal Disease report contains information from twelve governments. The foreword discusses the upcoming 11th Symposium on Diseases in Asian Aquaculture (DAA 11), which will be held from 29 September to 2 October 2020, at the Borneo Convention Center, Kuching, Sarawak, Malaysia.