Infectious hypodermal and haematopoietic necrosis,
Canada
Information received on 16/08/2019 from Dr Jaspinder Komal, Deputy Chief Veterinary Officer, Canadian Food Inspection Agency, Canadian Food Inspection Agency, Ottawa, Canada
Summary
Report type Immediate notification
Date of start of the event 14/06/2019
Date of confirmation of the event 14/08/2019
Report date 16/08/2019
Date submitted to OIE 16/08/2019
Reason for notification First occurrence of a listed disease in the country
Causal agent Infectious hypodermal and haematopoietic necrosis virus
Nature of diagnosis Laboratory (advanced)
This event pertains to the whole country
Related reports Immediate notification (16/08/2019)
Follow-up report No. 1 (23/08/2019)
New outbreaks (1)
Outbreak 1 Calgary, Alberta
Date of start of the outbreak 14/06/2019
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) 0 (scale 0 to 5) 0 (scale 0 to 5) 555000 5550 0 0 0
Affected population Canada received a notification on June 14, 2019 from a country that exports shrimp for culture to Canada that IHHN had been detected in the export facility. This outbreak cluster applies to four separate premises with white leg shrimp in Canada who all imported shrimp from the affected exporting facility. In one premises, the imported shrimp all died which was believed to be a transport issue. However, the rearing water for these shrimp was not disposed or treated before new shrimp from a domestic source were introduced. No clinical signs were noted in this population. The other 3 premises exhibited noticeable variation in shrimp size but this could not be attributed solely to IHHN; other issues may have been responsible for the variation. Some mortality above baseline levels were noted but was attributed to other causes.
Summary of outbreaks Total outbreaks: 1
Total animals affected
Species Susceptible Cases Deaths Killed and disposed of Slaughtered
Whiteleg shrimp (Litopenaeus vannamei) 555000 5550 0 0 0
Outbreak statistics
Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost*
Whiteleg shrimp (Litopenaeus vannamei) 1.00% 0.00% 0.00% 0.00%
*Removed from the susceptible population through death, destruction and/or slaughter
Epidemiology
Source of the outbreak(s) or origin of infection
  • Introduction of new live animals
Epidemiological comments All the four premises are epidemiologically-linked due to a common source of imported shrimp post-larvae. The additional infected premises are located in British Columbia and Ontario. The total number of susceptible animals for the outbreak cluster is 2435300, and the estimated number of cases is 24353. Some morbidity and mortality was observed at three premises but it is impossible to attribute to infection of the populations with IHHNV as other concurrent issues could explain the morbidity and mortality. This explains why morbidity and mortality were reported as 0. Sampling and testing for this outbreak investigation was designed to detect IHHNV at a 1% prevalence detection limit. This 1% detection limit was used to estimate the number of cases. All these premises are land-based closed-contained recirculation operations with no effluent discharge. There are no known IHHNV wild susceptible species in natural environment in Canada. The 4 infected premises are under official quarantine and any movements of animals and things in or out of the quarantine sites are under official supervision. Once all affected animals are removed, all the premises will be required to undergo cleaning and disinfection under official supervision. The goal of the investigation is to eradicate IHNNV from these premises and the country. Besides these four premises, there is only one more premises in Canada that cultures Litopenaeus vannamei. This premises was also investigated and has tested negative for IHHNV. The first follow-up report will be prepared and submitted when new information on any of the 4 premises that are part of this outbreak cluster becomes available or when any of the applied control measures identified have been carried out and completed.
Control measures
Measures applied
  • Movement control inside the country
  • Traceability
  • Quarantine
  • Vaccination permitted (if a vaccine exists)
  • No treatment of affected animals
Measures to be applied
  • Killing for commercial use or own use
  • Disinfection
Diagnostic test results
Laboratory name and type Species Test Test date Result
Gulf Biocontainment Unit (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) histopathological examination 14/08/2019 Inconclusive
Gulf Biocontainment Unit (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) in situ hybridisation (ISH) 14/08/2019 Positive
Gulf Fisheries Centre (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) gene sequencing 08/08/2019 Positive
Gulf Fisheries Centre (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) polymerase chain reaction (PCR) 08/08/2019 Positive
Pacific Biological Station (National laboratory) Whiteleg shrimp (Litopenaeus vannamei) real-time PCR 26/07/2019 Positive
Future Reporting
The event is continuing. Weekly follow-up reports will be submitted.
Map of outbreak locations