Fact sheet - Infectious Hypodermal and Haematopoitic Necrosis
What is Infectious Hypodermal and Haematopoitic Necrosis (IHHN)?
IHHN is an infectious disease that affects crustaceans. It is caused by the Infectious Hypodermal and Haematopoitic Necrosis Virus (IHHNV), which belongs to the family Parvoviridae and Genus Penstyldensovirus.
What species of crustaceans can be infected by IHHNV?
The species of crustaceans that can be infected by IHHNV are listed below:
- Farfantepenaeus aztecus (northern brown shrimp)
- Farfantepenaeus californiensis (yellow leg shrimp)
- Litopenaeus setiferus (northern white shrimp)
- Litopenaeus stylirostris (blue shrimp)
- Penaeus monodon (giant tiger prawn)
- Litopenaeus vannamei (white leg shrimp)
Litopenaeus vannamei is currently the only species of shrimp cultured in land-based facilities in Canada. This species does not naturally exist in Canada's aquatic environment. None of the other susceptible species naturally exists in Canada.
The terms "shrimp" and "prawn" can both be used interchangeably.
Is IHHN a risk to human health?
No. IHHN cannot be transferred to humans and does not affect food safety.
What are the clinical signs of IHHN?
IHHNV causes disease that varies in severity in different shrimp species. For example:
- L. stylirostris experience the most severe effects in which up to 90% of deaths can be observed within a few weeks of the first signs of the disease
- L. vannamei often experience chronic infections with no or very little mortality observed over long periods of time. Even though deaths may not be significant in infected L. vannamei, they may still exhibit any of the following signs:
- poor feed conversion ratio
- stunted growth
- large variation in sizes of shrimps in population
- appearance of shrimps with deformed shell, rostrum, appendages, abdomen and tail and soft and mottled shell
Not all infected crustaceans will show clinical or visible signs of disease.
Is IHHN/IHHNV found in Canada?
In August 2019, IHHNV was confirmed in three provinces in land-based fully contained recirculating facilities culturing Litopenaeus vannamei. The outbreaks were linked to import of IHHNV-infected post-larvae of L. vannamei. The CFIA conducted responses at affected facilities to mitigate risk of disease spread.
How is IHHNV spread?
IHHNV is spread between crustaceans by:
- water contaminated with the virus shed by infected animals and released from the decomposition of dead animals
- infected broodstock who pass it to their progeny
Animals do not have to be visibly sick to transmit the virus. Animals that appear healthy can transmit the virus.
People can spread the disease by moving any of the following:
- infected live or dead crustaceans
- contaminated equipment
- contaminated water
How is IHHN diagnosed?
IHHN may be suspected based on clinical signs. However, diagnosis of the disease must be confirmed by laboratory testing.
How is IHHN treated?
There are no treatment options currently available for IHHN.
What measures can be taken to prevent the introduction and spread of IHHN?
- Implement biosecurity measures
- If you frequently handle or work with crustaceans, be aware of the clinical signs of IHHN
- Ensure that all imports of susceptible species are from countries approved for import
- Information on approved countries can be found in CFIA Automated Import Reference System
- Do not introduce live crustaceans from another country or province into the natural waters of Canada without authorization from the appropriate authorities
- People releasing crustaceans into the natural waters or into rearing facilities within Canada should check if federal/territorial/provincial /municipal permits are required
- Live aquatic animals, aquatic animal carcasses, parts of a carcass or offal and things suspected of IHHNV contamination should be disposed in a bio-secure manner
- Do not use crustaceans that were bought in a grocery store as bait for catching fish or other aquatic animals
- If you have travelled to another country and visited a shrimp aquaculture site, or had contact with wild crustaceans, the following biosecurity measures should be taken before visiting any premises with susceptible crustaceans in Canada:
- wear separate footwear or thoroughly wash and disinfect the footwear you wore to the site or when you were in contact with wild crustaceans.
- wash your clothing thoroughly and dry it at a high temperature.
What is done to protect Canadian aquatic animals from IHHN?
IHHN is an immediately notifiable disease in Canada. Therefore any laboratory that diagnoses or suspects the appearance of IHHN in an animal is required by law to notify the CFIA.
If IHHN is found in Canada, the CFIA would implement disease response activities to help control its spread. These may include:
- inspection and testing of animals
- controlling the movements of infected animals that people own or work with
- ordering removal of imported contaminated live or dead aquatic animals, carcasses part of carcasses or offal, aquatic animal products
- humanely destroying infected animals
- ordering cleaning and disinfecting of facilities and equipment that is contaminated
The chosen control measures would depend on the situation.
What do I do if I think crustaceans that I am raising or keeping have IHHN?
If you suspect a crustacean that you are raising or keeping may have IHHN, you should immediately consult your veterinarian or contact the nearest CFIA Animal Health Office.
How do I get more information?
Please visit Aquatic Animal Health for more information on reportable and notifiable diseases, or contact your local CFIA Animal Health Office to confirm the availability of inspection staff and office hours. Report suspected cases of federally reportable disease immediately to a CFIA district veterinarian.
- Atlantic: 506-777-3939
- Quebec: 514-283-8888
- Ontario: 226-217-8555
- West: 587-230-2200
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