The H5N1 bird flu virus, which could cause a pandemic if it gains the ability to transmit efficiently from person to person, has already infected at least 42 species of mammals, three international agencies warned in a joint statement released on July 12.
Human-to-human transmission of H5N1 to date has been sporadic, with only eight cases of the most worrisome variant reported worldwide since December 2021. But the spread of the virus among mammals “causes concern that it may adapt to infect to humans more easily,” the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO) and the World Organization for Animal Health (WHO) say in the statement.
In addition, they add, if two different strains of influenza viruses infect an animal at the same time, “new viruses may emerge that could be more harmful to animals and people.” Therefore, the three organizations “urge countries to work together” to prevent H5N1 infections, strengthen surveillance to detect outbreaks in animals quickly, share genetic sequences of the virus and ensure that they are prepared for a possible flu pandemic.
The H5N1 subtype of the influenza virus was first detected in China in 1996 and has caused outbreaks in birds ever since. A variant of the virus -called clade 2.3.4.4b- has caused numerous outbreaks with high mortality in farmed and wild birds in Africa, Asia and Europe since 2020, and in the last two years, also in the Americas.
Since the beginning of 2022, 81 countries on five continents have reported H5N1 outbreaks in birds. Ten countries on three continents have reported them in mammals -among them, Spain, which registered an outbreak in a mink farm in Galicia. Affected mammals include -among others- cats, canids, bears, dolphins and seals.
“There is a recent paradigm shift in the ecology and epidemiology of avian influenza that has increased global concern as the disease has spread to new geographic regions and caused unusual mortality in wild birds, and an alarming increase in cases. in mammals”, declares in the statement Gregorio Torres, scientific director of the OMSA.
“With the information available so far, the virus does not appear to be able to be transmitted from person to person easily,” adds Sylvie Briand, WHO Director of Pandemic Preparedness and Prevention. “But vigilance is necessary to identify any evolution in the virus that could change this.”
In the few cases of H5N1 infection recorded in people, the virus “can cause severe illness with high mortality,” the WHO, OMSA and FAO report. Most of these cases “are related to close contact with infected birds and contaminated environments.”
