The World Health Organization said its ability to assess and manage the risk posed by H5N1 avian influenza — bird flu — cases around the world is hampered by limited surveillance of animal and human cases of the disease.

At a news briefing at agency headquarters in Geneva on Thursday, WHO Director-General Tedros Adhanom Ghebreyesus said the United States last week reported a fourth human case following exposure to infected dairy cows.

The U.S. Centers for Disease Control and Prevention said the patient was a worker on a dairy farm where cows had tested positive for the virus. The person had limited symptoms, was treated and recovered. No human-to-human transmission of the virus was reported.

Tedros said Cambodia also reported two cases in children who had contact with sick or dead chickens.

He said the WHO continues to assess the risk of bird flu to the public as low but said it is difficult to make accurate assessments when surveillance for influenza viruses in animals is so limited globally.

“Understanding how these viruses are spreading and changing in animals is essential for identifying any changes that might increase the risk of outbreaks in humans, or the potential for a pandemic,” Tedros said.

He called on all countries to strengthen influenza surveillance and reporting in animals and humans and to share virus samples with the WHO. Tedros also urged protection be provided for farm workers who may be exposed to infected animals.

COVID-19 update

At the same briefing, Tedros provided a brief update on COVID-19 cases globally. He said the virus continues to kill an average of 1,700 people per week worldwide. He also cited data showing vaccine coverage has declined among health workers and people over 60, two of the most at-risk groups for the virus.

The WHO chief said the agency recommends people in the highest-risk groups receive a COVID-19 vaccine within 12 months of their last dose.

Monkeypox update

Tedros also gave an update on MPox, formerly known as monkeypox, which he said remains a global threat with 26 countries reporting cases this month.

He said an outbreak in Congo continues, with 11,000 total cases, including 445 deaths this year, with children most affected.

South Africa has recently reported 20 cases, including three deaths, the first cases in that country since 2022. The cases were all men, and most of them self-identified as men who have sex with men. None had reported any history of international travel, which suggests the confirmed cases are a small proportion of all cases, and that community transmission is ongoing.