The ongoing bird flu outbreak is the largest ever in Europe and North America, and recent reports suggest the disease has passed from mammal to mammal, raising the risk of a spillover into humans, said a U.S. medical journal. The director general of the World Health Organization said that while the risk to people remained low, the reported infections in mink, otters, and sea lions “must be monitored closely.”
Martin Beer, head of the Institute of Diagnostic Virology in Germany, told the medical journal JAMA that an outbreak on a mink farm in Spain last October deserved special attention. “Spread between mammals might allow for further adaptations to the mammalian host,” he said. Fewer than 900 human cases of H5N1 avian influenza, the type now circulating, have been reported in two decades. But while few cases have occurred, “we cannot assume that will remain the case,” said WHO director Tedros Adhanom Ghebreyesus, reported Fortune.
More than 58 million birds in domestic U.S. flocks, mostly chickens and turkeys, have died of highly pathogenic avian influenza or from the culling of infected flocks since outbreaks began a year ago, according to USDA data. The European Food Safety Authority (EFSA) said 50 million birds were affected on farms in 37 European nations in the year ended last Sept. 30.
“The unusual persistence of HPAI in wild birds and poultry throughout the summer of 2022 means that for the first time, there was no clear separation between the end of the first year of the epidemic and the beginning of this year’s HPAI season, which began in October 2022,” said the EFSA in December.