WHO said it has detected the H5N1 avian influenza virus at very high concentrations in the milk of infected cows, although it is unknown how long the virus will persist.
The information was stated by Ms. Wenqing Zhang, head of the global influenza program of the World Health Organization (WHO), at a meeting on April 19. Specifically, experts have detected “very high virus concentrations in raw milk” and are investigating exactly how long the virus can exist in milk.
Ms. Zhang recalled the case of a person in Texas (USA) who contracted bird flu after contact with dairy cows in early April. This is the second case of A/H5N1 influenza discovered in humans in the US and is The first case of the disease was due to contact with a mammal infected with the virus.
According to this expert, the concern is that the virus seems to be finding new hosts and that the virus’s spread to mammals means that it is getting closer to humans.
Meanwhile, the Texas Department of Health Services said the virus infection in cattle does not pose a concern to the commercial milk supply, as producers are required to destroy milk from infected cows. Pasteurization will also kill the virus. According to Zhang, the important thing to ensure is food safety, including the consumption of pasteurized milk and dairy products.
Cows at the World Dairy Expo in Madison, Wisconsin, USA, October 2018. Image: Reuters
Avian influenza A/H5N1 first appeared in 1996, but since 2020, the number of outbreaks in birds has increased exponentially. Besides, the number of infected mammals also increased. The virus has caused the deaths of tens of millions of poultry, wild birds, and terrestrial and marine mammals.
From 2003 to April 1 this year, WHO recorded 463 deaths and 889 cases of H5N1 infection in humans, in 23 countries, bringing the post-disease mortality rate to 52%, while the mortality rate Influenza mortality is usually 1-4%. Zhang noted that cases in Europe or the US in the past few years have had mild symptoms. To date, there is no evidence that H5N1 is transmitted from person to person, mainly through contact with infected animals.
There are currently nearly 20 influenza A/H5N1 vaccines licensed for use if a pandemic occurs, and these vaccines can be tailored to the specific virus strain circulating.