ECDC Update & Risk Assessment On H5N1

 

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Over the past week we've seen several reports of avian H5N1 infection in domestic cats and (1) dog, from both the United States and Canada.  While both species have been affected by avian flu viruses in the past (see 2015's HPAI H5: Catch As Cats Can) this is a reminder of how much virus is circulating in the wild.

Canada CFIA & PHAC: Domestic Dog Tests Positive for Avian Influenza in Canada

Wyoming State Veterinary Lab Statement: Domestic Cat Infected With HPAI

Nebraska Veterinary Diagnostic Center (NVDC) Report: 2 Domestic Cats Infected With HPAI H5N1

Via this week's ECDC Communicable Disease Threats Report, Week 15, 9-15 April 2023, we get the following update on H5N1, with a focus on recent animal infections. 

Influenza A(H5N1) – Multi-country (World) – Monitoring human cases 

Overview

Update: 

On 4 April 2023, the Canadian Food Inspection Agency reported a case of A(H5N1) infection in a domestic dog in Oshawa, Ontario. The dog died with respiratory system involvement after chewing on a wild goose.

In addition, five domesticated cats were reported from the US with A(H5N1) infection, all of which died due to severe symptoms following a likely exposure to wild birds. One cat was reported in Wyoming on 6 April 2023, and four cats with symptoms and death in January 2023 were reported retrospectively in Nebraska and Oregon. Previously, a cat with A(H5N1) infection had been reported in France in December 2022.

Summary: 

Globally, as of 30 March 2023, there have been 874 human cases, including 458 deaths (case-fatality rate: 52.4%), of human infection with avian influenza A(H5N1) reported in 23 countries since 2004. To date, no human-to-human transmission has been detected. 

Sources: ECDC Avian influenza, ECDC Avian influenza overview: Latest situation update of the avian influenza in EU/EEA, the Ministry of Health of Chile, WHO PAHO briefing

ECDC assessment: 

A few cats and dogs have been found to be infected recently after direct exposure to infected wild birds. No human infection related to the cats and dogs has been identified to date. The level of information about the incidences is limited and further information is required to assess the likelihood of transmission through pets. Pet owners should be vigilant and in general keep pets away from sick and dead wild birds and other wild animals such as foxes. If avian influenza virus detections are reported in close proximity, dogs should be kept on leashes and cats indoors if possible. When pets are in direct contact with potentially infected dead or sick birds, pet owners should closely monitor animals for respiratory but possibly also other symptoms and consult a veterinarian to consider testing for avian influenza viruses.

Sporadic human cases of different avian influenza A(H5Nx) subtypes have previously been reported globally. Current epidemiological and virological evidence suggests that A(H5N1) viruses remain avian-like. Transmission to humans remains a rare event and no sustained transmission between humans has been observed. 

Overall, the risk of zoonotic influenza transmission to the general public in EU/EEA countries is considered to be low. The risk to occupationally exposed groups such as cullers has been assessed as low to medium. Direct contact with infected birds or a contaminated environment is the most likely source of infection and the use of personal protective measures for people exposed to dead birds or their droppings will minimise the remaining risk.

The recent severe cases in Asia and South America in children and people exposed to infected sick and dead backyard poultry underline the risk associated with unprotected contacts with infected birds in backyard farm settings and suggests the appropriate use of personal protective equipment. 

Actions: 

ECDC monitors avian influenza strains through its influenza surveillance programme and epidemic intelligence activities in collaboration with the European Food Safety Authority (EFSA) and the EU reference laboratory for avian influenza in order to identify significant changes in the virological characteristics and epidemiology of the virus. ECDC, together with EFSA and the EU reference laboratory for avian influenza, produces a quarterly updated report of the avian influenza situation. The most recent report was published in March 2023.