Colorized transmission electron micrograph of avian influenza A H5N1 virus particles (yellow) grown in Madin-Darby Canine Kidney (MDCK) epithelial cells. Microscopy by CDC; repositioned and recolored by NIAID. Credit: CDC and NIAID

The World Health Organization on Wednesday warned that it has only "limited information" about the spread of bird flu in the United States, which has all but cut communications with the global health body.

Shortly after his inauguration last month, US President Donald Trump signed an executive order directing the United States to withdraw from the WHO, an organization he has repeatedly criticized over its handling of the COVID-19 pandemic.

WHO chief Tedros Adhanom Ghebreyesus has repeatedly said the UN health agency regrets the US decision, and hopes it will reconsider.

On Wednesday, he warned that there were actions the US government was taking "that are unrelated to its intended withdrawal from WHO but which we are concerned are having a serious impact on global health".

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Among the concerns, he told reporters, was that WHO now has "limited information about the spread of avian influenza among dairy cattle in the US, or human cases".

Just days into Trump's second term, the WHO stopped receiving communications on influenza from the US Centers for Disease Control and Prevention (CDC), the WHO said.

The cutoff came amid fears that outbreaks of H5N1 bird flu in the United States, which has significantly impacted the poultry industry and have spread to US dairy cattle, could evolve into a human pandemic.

Those fears have been compounded by Trump's efforts to rapidly cut federal spending, with experts warning staff and programme reductions could impact public health monitoring.

Maria Van Kerkhove, the WHO's epidemic and pandemic preparedness and prevention director, told reporters the organisation was "confident that the US has detection capabilities to identify zoonotic influenza in animals, in humans who are working with... infected animals".

But she voiced concern at the lack of communication from US authorities.

"Prior to a few weeks ago, we had active dialogue with our colleagues" at various US agencies, as well as regular technical exchanges, she said.

But since January 24, "we have not had direct communication with CDC related to influenza", she lamented.

"We are communicating with them -- but we haven't heard anything back."

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Van Kerkhove stressed that the United States was continuing to report cases of avian influenza and other diseases through the International Health Regulations channels.

But the daily communication that had for years been going through WHO's own global platforms had ceased.

"We encourage that reporting to continue," she said.

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© Agence France-Presse