Acute hepatopancreatic necrosis disease,
Japan
Information received on 21/10/2020 from Dr Norio Kumagai, Director, Chief Veterinary Officer, Animal Health Division, Food Safety and Consumer Affairs Bureau, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
Summary
Report type Immediate notification
Date of start of the event 08/10/2020
Date of confirmation of the event 18/10/2020
Report date 21/10/2020
Date submitted to OIE 21/10/2020
Reason for notification First occurrence of a listed disease in the country
Causal agent Vibrio parahaemolyticus
Nature of diagnosis Laboratory (basic), Laboratory (advanced)
This event pertains to a defined zone within the country
New outbreaks (1)
Outbreak 1 Ogimi village, Okinawa
Date of start of the outbreak 08/10/2020
Outbreak status Continuing (or date resolved not provided)
Epidemiological unit Farm
Water type Salt water
Population type Farmed
Production system Closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
Whiteleg shrimp (Litopenaeus vannamei) 98 % 98 % 100000 98000 98000 2000 0
Summary of outbreaks Total outbreaks: 1
Total animals affected
Species Susceptible Cases Deaths Killed and disposed of Slaughtered
Whiteleg shrimp (Litopenaeus vannamei) 100000 98000 98000 2000 0
Outbreak statistics
Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost*
Whiteleg shrimp (Litopenaeus vannamei) 98.00% 98.00% 100.00% 100.00%
*Removed from the susceptible population through death, destruction and/or slaughter
Epidemiology
Source of the outbreak(s) or origin of infection
  • Unknown or inconclusive
Epidemiological comments 9th August: An on-land farm introduced juveniles of whiteleg shrimp (Litopenaeus vannamei) that were imported from Thai. The inspection at the destination for imported aquatic animals by the prefecture (for 6 months) was started. 8th -13th October: The prefectural experimental station conducted field survey at the farm and PCR test for several pathogens in shrimp. As a result of nested PCR, AHPND was detected from the shrimp on 13th October. 16th -18th October: Fisheries Technology Institute, which is in charge of confirmatory diagnosis in aquatic animals, confirmed the positive for AHPND by nested PCR and sequencing of the PCR product. 19th October: Killing all of shrimp in the farm and disinfecting the farm by sodium hypochlorite were started. * Said farm is on-land farm with recirculation filtration system. And no juveniles introduced on 9th August has been distributed to other places.
Control measures
Measures applied
  • Disinfection
  • Stamping out
  • Quarantine
  • Traceability
  • Movement control inside the country
  • Vaccination permitted (if a vaccine exists)
  • No treatment of affected animals
Measures to be applied
  • Surveillance outside infected and/or protection zone
Diagnostic test results
Laboratory name and type Species Test Test date Result
Okinawa Prefectural Fisheries Research and Extension Center (Local laboratory) Whiteleg shrimp (Litopenaeus vannamei) nested RT-PCR 13/10/2020 Positive
Fisheries Technology Institute of Japan Fisheries Research and Education Agency (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) gene sequencing 18/10/2020 Positive
Fisheries Technology Institute of Japan Fisheries Research and Education Agency (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) nested RT-PCR 18/10/2020 Positive
Future Reporting
The event is continuing. Weekly follow-up reports will be submitted.
Map of outbreak locations