Decapod iridescent Virus 1 (DIV1) infection,
Chinese Taipei
Information received on 25/12/2020 from Dr Wen-Jane Tu, Chief Veterinary Officer, Director General, Bureau of Animal and Plant Health Inspection and Quarantine, Council of Agriculture, Executive Yuan, Taipei, Chinese Taipei
Summary
Report type Follow-up report No. 1
Date of start of the event 18/05/2020
Date of confirmation of the event 20/05/2020
Report date 25/12/2020
Date submitted to OIE 25/12/2020
Reason for notification Emerging disease
Morbidity 13 %
Mortality 13 %
Zoonotic impact No
Causal agent Decapod iridescent virus 1 (DIV1)
Serotype Pending
Related reports Immediate notification (09/07/2020)
Follow-up report No. 1 (25/12/2020)
New outbreaks (8)
Outbreak 1 (2020-17) Nanzhuang Township, Miaoli County
Date of start of the outbreak 12/08/2020
Outbreak status Resolved (27/08/2020)
Epidemiological unit Pond
Water type Fresh water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 75 % 75 % 10000 7500 7500 2500 0
Outbreak 2 (2020-18) Jiadong Township, Pingtung County
Date of start of the outbreak 16/08/2020
Outbreak status Resolved (10/09/2020)
Epidemiological unit Pond
Water type Fresh water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 0 % 0 % 1600000 15 0 1600000 0
Outbreak 3 (2020-19) Jiuru Township, Pingtung County
Date of start of the outbreak 23/09/2020
Outbreak status Resolved (09/10/2020)
Epidemiological unit Pond
Water type Fresh water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 0 % 0 % 10200 3 0 10200 0
Outbreak 4 (2020-20) Wujie Township, Yilan County
Date of start of the outbreak 06/10/2020
Outbreak status Resolved (26/10/2020)
Epidemiological unit Pond
Water type Brackish water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
whiteleg shrimp (Litopenaeus vannamei) 50 % 50 % 290000 145000 145000 145000 0
Outbreak 5 (2020-21) Sanzhi District, New Taipei City
Date of start of the outbreak 15/10/2020
Outbreak status Resolved (07/12/2020)
Epidemiological unit Pond
Water type Brackish water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
whiteleg shrimp (Litopenaeus vannamei) 100 % 100 % 90000 90000 90000 0 0
Outbreak 6 (2020-22) Wujie Township, Yilan County
Date of start of the outbreak 20/10/2020
Outbreak status Resolved (06/11/2020)
Epidemiological unit Pond
Water type Fresh water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 21 % 0 % 48 10 0 48 0
Outbreak 7 (2020-23) Sanzhi District, New Taipei City
Date of start of the outbreak 26/10/2020
Outbreak status Resolved (07/12/2020)
Epidemiological unit Pond
Water type Brackish water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
whiteleg shrimp (Litopenaeus vannamei) 100 % 100 % 900000 900000 900000 0 0
Outbreak 8 (2020-24) Qigu District, Tainan City
Date of start of the outbreak 02/11/2020
Outbreak status Resolved (07/11/2020)
Epidemiological unit Pond
Water type Fresh water
Population type Farmed
Production system Semi-closed
Affected animals
Species Morbidity Mortality Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 0 % 0 % 10200 15 0 10200 0
Summary of outbreaks Total outbreaks: 8
Total animals affected
Species Susceptible Cases Deaths Killed and disposed of Slaughtered
redclaw crayfish (Cherax quadricarinatus) 1630448 7543 7500 1622948 0
whiteleg shrimp (Litopenaeus vannamei) 1280000 1135000 1135000 145000 0
Outbreak statistics
Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost*
redclaw crayfish (Cherax quadricarinatus) 0.46% 0.46% 99.43% 100.00%
whiteleg shrimp (Litopenaeus vannamei) 88.67% 88.67% 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 Samples from Yilan County, New Taipei City, Miaoli County, Tainan City and Pingtung City were sent to the National Laboratory, Animal Health Research Institute (AHRI), for diagnosis. Five redclaw crayfish (Cherax quadricarinatus) farms and three whiteleg shrimp (Litopenaeus vannamei) farms were confirmed with positive reaction to nucleic acid of decapod iridescent virus 1 (DIV1) by AHRI. Active surveillance is still ongoing, and any positive result will be included in follow-up reports.
Control measures
Measures applied
  • Disinfection / Disinfestation
  • Screening
  • Traceability
  • Quarantine
  • Surveillance outside containment and/or protection zone
  • Official disposal of carcasses, by-products and waste
  • Stamping out
  • Control of vectors
  • Vaccination permitted (if a vaccine exists)
  • No treatment of affected animals
Measures to be applied
  • No other measures
Diagnostic test results
Laboratory name and type Species Test Test date Result
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) gene sequencing 17/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) gene sequencing 24/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) gene sequencing 28/09/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) gene sequencing 27/10/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) gene sequencing 04/11/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) polymerase chain reaction (PCR) 17/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) polymerase chain reaction (PCR) 24/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) polymerase chain reaction (PCR) 28/09/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) polymerase chain reaction (PCR) 27/10/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) polymerase chain reaction (PCR) 04/11/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) real-time PCR 17/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) real-time PCR 24/08/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) real-time PCR 28/09/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) real-time PCR 27/10/2020 Positive
Animal Health Research Institute (National laboratory) redclaw crayfish (Cherax quadricarinatus) real-time PCR 04/11/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) gene sequencing 08/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) gene sequencing 22/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) gene sequencing 30/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) polymerase chain reaction (PCR) 08/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) polymerase chain reaction (PCR) 22/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) polymerase chain reaction (PCR) 30/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) real-time PCR 08/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) real-time PCR 22/10/2020 Positive
Animal Health Research Institute (National laboratory) whiteleg shrimp (Litopenaeus vannamei) real-time PCR 30/10/2020 Positive
Future Reporting
The event is continuing. Weekly follow-up reports will be submitted.
Map of outbreak locations