GlobalHealth Threats

30 August: Health officials have released details on the cluster of human influenza A(H5) cases linked to poultry exposure. The outbreak was traced to two poultry facilities where workers were involved in depopulating infected birds. The depopulation process, which includes handling and disposing of both dead and live birds, significantly exposed workers to the virus. The risk was particularly high in cage-free facilities, where birds move freely and must be caught by hand, increasing the chances of exposure.

Challenges were reported in providing and properly using personal protective equipment (PPE). Many workers were hired urgently, leading to difficulties in acquiring, distributing, and training them on the correct use of PPE. Workers themselves reported low usage of some PPE items. Extreme heat conditions was also responsible for the inconsistent or improper use of PPE. These findings highlight the need for improved safety measures and comprehensive training to protect workers in these high-risk environments. This outbreak also emphasises the need for public health agencies to prepare for similar situations, prioritising rapid response, adequate PPE distribution, and culturally sensitive communication strategies to protect the health of agricultural workers.

25 July: The US Centers for Disease Control and Prevention (CDC) has confirmed three additional bird flu infections among poultry workers. The people affected worked directly with infected poultry at a farm in Northeast Colorado/Weld County where an H5 bird flu outbreak was reported. All individuals had mild symptoms and received antiviral treatment. This brings the total number of human cases linked to the current poultry outbreaks in Colorado to nine.

The CDC’s risk assessment remains unchanged, maintaining that the overall risk to human health is low. There are no signs of unusual flu activity in Colorado or other affected states, and no genetic mutations in the virus have been found that would increase the risk of human-to-human transmission.

19 July: CDC has confirmed an additional human bird flu infection in a Colorado poultry farm worker. The presumptive positive reported earlier has also been confirmed. All had exposure to infected poultry and developed mild symptoms. This brings the total number of human infections with avian influenza A (H5) this year to ten, with six exposed to infected poultry and four exposed to infected dairy cattle.

Viral sequencing analysis was performed on one of the samples collected from the infected Colorado poultry farm worker. Other samples could not be fully sequenced. In summary, this human viral sequence:

• Closely matches sequences from recent outbreaks in poultry and infected dairy cows.
• Contains the marker for mammalian adaptation, PB2 M63L. Over 99% of dairy cow sequences and one of the Michigan human cases also contain this change.
• Does not contain the PB2 E627K marker for mammalian adaptation.
• Does not contain markers associated with influenza antiviral resistance.
• Closely matches two HPAI A(5) candidate vaccine viruses.

15 July: Four people are confirmed infected with bird flu in Colorado, including one presumption positive infection which is pending confirmation. All five individuals worked at a farm with an outbreak of H5N1 amongst the poultry.

12 July: Health authorities have reported three presumptive positive cases of H5N1 bird flu among workers at a poultry facility in northeast Colorado, likely due to direct exposure to infected poultry. The affected individuals showed mild symptoms, including conjunctivitis (pink eye) and typical respiratory infection symptoms. None of them required hospitalisation.

Earlier this month, a bird flu infection linked to dairy cattle was reported in Colorado, where the affected individual also experienced mild symptoms.