Even while no case of H5N1 infection in humans has been reported after consuming raw milk, scientists believe that the virus can be transmitted via an infected cow’s milk that has not been pasteurised. The lone reported human case in the current outbreak in cattle spread across 49 herds in nine States in the U.S. has been a dairy farm worker who had direct exposure to cows and developed conjunctivitis. The Atlanta-based CDC has advised people to desist from consuming uncooked dairy food products such as raw, unpasteurised milk, or raw cheeses from animals with suspected or confirmed H5N1 bird flu virus infection.
While FAO noted that H5N1 virus was detected in “high concentrations in milk from infected dairy cattle and at levels greater than that seen in respiratory samples”, there are no reports of viable H5N1 virus being found in raw milk samples. “I have not come across any report of actual isolation of influenza viruses from raw milk. Most reports on viral loads in milk are based on molecular sequencing data rather than actual isolation of the virus from milk. It will be RT-PCR or sequencing of fragments,” immunologist Dr. Vineeta Bal, a visiting faculty at IISER Pune says in an email to The Hindu.
Despite CDC warning people to avoid consuming raw milk, sales of raw milk in the U.S. has increased sharply since the H5N1 outbreak in cattle was first reported there on March 25 this year. Yet, there has not been any reported case of human infection after raw milk intake. Even as it makes eminent sense to avoid consuming raw milk especially in places where H5N1 outbreak in cattle has been reported in the U.S., how likely are people to be infected with H5N1 via raw milk? “We need to remember that viruses outside a cell do not have life of their own. The biological plausibility of transmission through milk is very limited,” Dr. Chandrakant Lahariya, physician epidemiologist and a public policy and health systems expert says in an email to The Hindu.
