GENEVA, Switzerland (AFP) — The WHO said Tuesday it was being frequently updated by Washington about the bird flu outbreak in the United States — the only country so far where dairy cows have been infected.

Earlier this month, US authorities said a person working on a dairy farm in Texas was recovering from bird flu after having been exposed to cattle.

“We have been receiving information and we have been receiving almost daily updates,” said Wenqing Zhang, head of the global influenza programme at the World Health Organization.

“The response update has been updated routinely and in transparency. So we’ve got the information when it’s available and we update our risk assessment,” she told a press conference.

Zhang was questioned by reporters over whether US authorities had been transparent enough over the emerging situation.

She said serological studies were under way but may take time to complete, adding that genetic sequencing data had been made available, some “at a very early stage” of the US cattle outbreak.

Furthermore, “the genetic sequence data of the human case was immediately available when it came out”, she added.

WHO spokesman Christian Lindmeier added: “The fact that this got picked up, the fact that we now know about individual cases somewhere in some farm — that shows that the surveillance system works.”

Avian influenza A(H5N1) first emerged in 1996. The 2.3.4.4b clade of the virus, first detected in 2020, is behind an exponential growth in the number of outbreaks in birds.

The strain has led to the deaths of tens of millions of poultry, with wild birds and land and marine mammals also infected.

Cows and goats joined the list last month — a surprising development for experts because they were not thought to be susceptible to this type of influenza.

US health authorities said Friday that milk sold in US stores was “safe” from bird flu because pasteurisation effectively kills the virus.

The virus fragments found in pasteurised milk are not infectious, the WHO confirmed Tuesday.

“Ongoing sampling suggests that raw milk from infected cows can have live virus in it, which may pose a threat, especially to farm workers,” said the UN health agency.

Zhang said that as of April 24, the virus had been detected in cattle in eight US states, “but I think the figure is likely increased in the last week”, she said.

She said it was not clear whether cow-to-cow transmission was taking place.

“We assess the current overall public health risk posed by A(H5N1) to be low, and for those with exposure to infected birds or animals or contaminated environments, the risk of infection is considered low to moderate,” said Zhang.

Human cases remain very rare, and there is no current evidence of human-to-human transmission.