Man Infected With H5N2 Bird Flu in Mexico Dies. Here’s the Latest on the Virus

A 59-year-old man in Mexico who was infected with H5N2 avian influenza has died, according to the World Health Organization (WHO). It’s the first time any person has tested positive for H5N2 and the first time a person in Mexico has tested positive for an H5 bird flu virus.

The patient had multiple underlying medical conditions and was bedridden for three weeks for other reasons before his acute symptoms began, per the WHO. Mexico’s health ministry says in a statement that the man died as a result of chronic conditions, not because of the virus. He had chronic kidney disease, type 2 diabetes and hypertension.

None of the patient’s close contacts near his residence or at the hospital where he died have tested positive for the virus, per the WHO. The agency says the current risk to the general population posed by the virus is low.

“The prompt follow-up in health care professionals and family members in contact with the infected patient provides reassurance at present this is an isolated case,” Ian Brown, the avian virology group lead at the Pirbright Institute in England, says to BBC News’ Michelle Roberts.

The case was a different strain of avian influenza from the H5N1 strain that has spread in dairy cattle across the United States and recently caused infections in three people.

“It is concerning that a new virus subtype has infected a human,” Troy Sutton, who studies avian influenza at Pennsylvania State University, tells NBC News’ Berkeley Lovelace Jr.

The WHO does not know how the person in Mexico became infected with H5N2. Infections have been reported in poultry in Mexico, but the patient had not been exposed to poultry or other animals.

“The fact there was no reported contact [with an infected bird] does raise the possibility that he was infected by someone else who visited him, but it’s premature to jump to those conclusions,” Richard Webby, a flu researcher at St. Jude Children’s Research Hospital, says to Mike Stobbe of the Associated Press (AP).

Ed Hutchinson, who studies influenza at the University of Glasgow in Scotland, tells BBC News that the person probably caught the virus from an infected animal.

In the U.S., two dairy farm workers in Michigan and one in Texas have tested positive for H5N1 following direct contact with infected cows in recent months. The most recent person to test positive, in Michigan, experienced a cough and eye discomfort, and their symptoms are resolving, per the Centers for Disease Control and Prevention (CDC). The other two people only reported symptoms in their eyes.

Meanwhile, infections have been detected in cows across 83 herds in nine states, including recent infections in Minnesota and Iowa identified for the first time.

Most H5 viruses are classified as low pathogenic, meaning they cause either asymptomatic or mild infections in poultry, per the CDC. The spread of highly pathogenic H5N1 in birds around the world has led to the deaths of tens of millions of birds over the last couple of years, either through fatal infections or preventative culling.

“Sporadic” H5 infections have occurred in humans, according to the CDC. Since 1997, such infections in 23 countries have resulted in death in about half of cases. Avian influenza in poultry can infect humans through direct exposure to the animals or from contaminated areas. There has not been historical evidence of a sustained spread of H5 viruses between humans, the WHO says.

The patient in Mexico developed fever, shortness of breath, diarrhea, nausea and general malaise on April 17, according to the WHO. He was hospitalized in Mexico City on April 24 and died later that day. Follow-up testing later found the person was infected with H5N2 at the time of his death.

“The person may have already been quite sick,” Sutton tells NBC News. “That changes the calculation a little bit more than, say, a healthy farm worker getting infected.”

Officials detected an outbreak of highly pathogenic H5N2 in a backyard poultry farm in a state neighboring the patient’s state of residence in March, per the WHO. Other outbreaks of low pathogenic H5N2 were reported in Mexico in March and April.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.