Washington state health officials have confirmed the first human case of H5N5 avian influenza, a subtype never before detected in humans. Important news from a scientific point of view, but which – experts assure – does not change the level of risk for the population, which remains very low.
But let’s take stock of what happened.
The first human case of H5N5
The patient was a resident of Grays Harbor County, Washington State, United States. It was an elderly man with previous pathologies who at the beginning of November was hospitalized in serious conditions due to high fever, confusion and breathing difficulties and unfortunately eventually died.
According to health authorities, the man lived in a house where he kept a small family flock of domestic poultry exposed to wild birds, a probable route of transmission of the virus. Two of the birds had died in the previous weeks, while the others are currently healthy.
The Department of Health had initially reported influenza A H5, but further testing by the University of Washington Virology Laboratory identified the virus as H5N5, already known in animals but never before confirmed in humans.
This is not a new virus nor a “super strain”, but the first documented human case of a virus already circulating in nature.
The risk to the population remains low
Bird flu rarely infects humans, and when it does, it mostly causes mild symptoms. In most cases, contagion occurs through close contact with sick or dead birds or contaminated environments.
It is important to underline that:
The spread of avian influenza in animals
The context is that of intense circulation among birds: since the beginning of the epidemic, over 4.1 million birds have been infected in Washington State. This fall the virus was detected in wild birds, a commercial farm, and a backyard farm.
Nationwide, about 70 people have tested positive for avian viruses in recent years, with only one death recorded in Louisiana.
Although the H5N5 case is the first documented, experts remind us that the appearance of a human infection with a new subtype is possible and expected when: viruses circulate widely in animals, domestic or amateur farms are exposed to wild birds and people come into direct contact with sick birds without adequate protection.
The H5N5 case therefore confirms a known risk, which has been monitored and under control for some time. No alarms therefore, but constant monitoring.
Experts assure that the virus is not spreading between people and that the surveillance systems are working. It is a reminder, however, of the need to maintain high attention on avian influenza, intensive farming, contact between wildlife and domestic animals and responsible management of poultry.
