Date Key facts
As of 1 November 2026, two more residents of Yakima County, Washington State, the United States (US), were confirmed to be infected with avian influenza A(H5N1). One of the infected people has died. Overall, three human cases with avian influenza A(H5N1) have been reported in Yakima county. The…
On 15 October 2026, a confirmed human case of avian influenza A(H5N1) was reported in a resident of Yakima County, Washington state, USA, following occupational exposure to infected dairy cattle at a local dairy farm. The case had mild symptoms and was not hospitalised. Since 1 April 2024, and as of…
The United States Centers for Disease Control and Prevention (US CDC) conducted two separate investigations into previously reported human cases of avian influenza A(H5N1): a serology study related to a child in San Francisco and a sequencing analysis related to a case in Ohio. The serology study…
On 26 February, the US CDC has published the analysis of the genetic sequence of the avian influenza A(H5N1) virus isolated from the case in Wyoming (case reported in CDTR on 20 Feb 2025). The isolated virus belongs to clade 2.3.4.4.b, genotype D1.1, with the mutation E627K in the PB2 segment…
On 21 February, the first A(H5N1) influenza case in Ohio was confirmed. The case is an adult with exposure related to depopulation activities at a commercial poultry farm. The person was hospitalised, but is now recovering at home. Since 1 April 2024, and as of 25 February 2025, a total of 70 human…
On 19 February, the first A(H5N1) influenza case in Wyoming was confirmed. The case is an adult with exposure related to backyard flocks . The person is hospitalised. Since 1 April 2024, and as of 10 February 2025, a total of 69 human cases of avian influenza A(H5) have been reported from 12 states…
On 14 February, the A(H5N1) influenza case reported earlier in Nevada, was confirmed as caused by the virus clade 2.3.4.4b, genotype D1.1. The case is an adult with occupational exposure to infected dairy cattle. The person experienced conjunctivitis and is now recovering. This is the first human…
On 10 February 2025, the United States Centers for Disease Control and Prevention (US CDC) reported one human case of A(H5N1) infection in the state of Nevada, US. The case is an adult person with occupational exposure to infected dairy cattle. The person experienced conjunctivitis and is now…
On January 31, 2025, the USDA confirmed by whole genome sequence the first detection of HPAI A(H5N1) clade 2.3.4.4b, genotype D1.1 in dairy cattle (all previous detections of HPAI in cattle have been A(H5N1) clade 2.3.4.4b, genotype B3.13). One of the concerns related to this event is that genotype…
The United States Centers for Disease Control and Prevention (US CDC) has confirmed an additional human case of avian influenza A(H5) in California. The source of exposure is currently unknown. No other details about the case have been released. US CDC has provided additional details of individuals…
On 6 January 2025, the US CDC reported the patient that was hospitalised with severe avian influenza H5N1 in Louisiana has passed away.  As of 6 January 2025, a total of 66 human cases of avian influenza A(H5) have been reported from 10 states in the United States (US) during 2024. Of these, 40…
 As of 2 January 2025, a total of 66 human cases of avian influenza A(H5) have been reported from 10 states in the United States (US) during 2024. Of these, 40 were individuals exposed to dairy cattle known or presumed to be infected with A(H5N1) and 23 were workers exposed to outbreaks of HPAI A…
One case of severe zoonotic avian influenza A(H5) has been confirmed on 13 December in Louisiana, United States (US). The case was exposed to sick and dead birds in backyard flocks . The case has been hospitalized with severe symptoms. This marks the first instance of severe illness linked to the…
One new case of zoonotic avian influenza A(H5) has been reported in Louisiana, United States (US). The case was exposed to sick and dead birds.  As of 17 December 2024, a total of 61 human cases of avian influenza A(H5) have been reported from seven states in the US during 2024, including the most…
Two new cases of zoonotic avian influenza A(H5) have been reported in California, United States (US). Both were exposed to infected dairy cattle. As of 13 December 2024, a total of 60 human cases of avian influenza A(H5) have been reported from seven states in the US during 2024, including the two…
Two new cases of zoonotic avian influenza A(H5) have been reported in California, United States (US). Both were exposed to cattle . As of 03 December 2024, a total of 57 human cases of avian influenza A(H5) have been reported from seven states in the US during 2024, including the two most recent…
Three new cases of zoonotic avian influenza A(H5) have been reported in California, United States (US). Of these, two adults were exposed to cattle and one child did not report any exposure to possible infected animals. As of 22 November 2024, a total of 55 human cases of avian influenza A(H5) have…
Six new cases of zoonotic avian influenza A(H5) have been reported in the United States (US). Five cases detected in California had exposure to cattle, and the one in Oregon had exposure to infected poultry. As of 15 November 2024, a total of 52 human cases of avian influenza A(H5) have been…
Two new cases of zoonotic avian influenza A(H5) have been reported in the United States (US). The case detected in California had exposure to cattle, and the one in Washington had exposure to infected poultry. As of 6 November 2024, a total of 46 human cases of avian influenza A(H5) have been…
Four new cases of zoonotic avian influenza A(H5) have been reported in California, United States (US), with exposure to cattle, and one new case with exposure to poultry has been confirmed but the location is still pending. As of 04 November 2024, a total of 44 human cases of avian influenza A(H5)…
Three new cases of zoonotic avian influenza A(H5) have been reported in Washington State, the United States (US), bringing the total number to nine confirmed cases in the state since 24 October 2024. The cases are individuals working with infected poultry. As of 30 October 2024, a total of 39 human…
Two new cases of zoonotic avian influenza A(H5) infections in humans have been reported by United States Centres for Disease Control and Prevention. The case reported in California is in a person with exposure to infected cattle, while the case reported in Washington is in a person with exposure to…
Three new cases of zoonotic avian influenza A(H5) have been reported in Washington state, United States, bringing the total number to five confirmed cases in the state since 24 October 2024. The cases are individuals working with infected poultry. According to the US CDC, the risk to the general…
On 24 October 2024, two cases of zoonotic avian influenza A(H5) in Washington state were reported by US CDC. US CDC is performing confirmatory testing on other samples from the state. Both cases are individuals working with infected poultry at a commercial egg farm. According to the US CDC, the risk…
Two new cases of zoonotic avian influenza A(H5) have been reported in California, United States, bringing the total number to 15 confirmed cases since 3 October 2024. 13 cases reported previously were in dairy workers with exposure to sick or infected dairy cattle. No information is available on…