A man in Mexico died of one strain of bird flu, but US officials are still targeting another

NEW YORK (AP) – The mysterious death of a man in Mexico who had a strain of bird flu is unrelated to other outbreaks on U.S. dairy farms, experts say.

Here’s a look at the situation and the different types of bird flu.


A 59-year-old man in Mexico who had been bedridden due to chronic health problems developed fever, shortness of breath and diarrhea in April. He died a week later, and the World Health Organization reported this week.

The WHO said this is the first time a variant of bird flu – H5N2 – has been seen in a human.


Another strain of bird flu – H5N1 – has been infecting poultry flocks for several years, killing millions of birds. It is also spreading among all kinds of animals around the world.

This year, that flu was detected in US dairy farms. Dozens of herds have seen infections in Iowa and Minnesota recently.

The cow outbreak has been linked to three reported illnesses in farm workers, one in Texas and two in Michigan. All had only mild symptoms.


Influenza A viruses, as they are called, are the only viruses linked to human influenza pandemics, so their appearance in animals and humans is a cause for concern. These viruses are divided into subtypes based on the types of proteins they have on their surface – hemagglutinin (H) and neuraminidase (N).

Scientists say there are 18 different “H” subtypes and 11 different “N” subtypes, and they appear in scores of combinations. H1N1 and H3N2 are common causes of seasonal flu in humans. Many variants are also seen in animals.

H5N1, the variant that has recently worried some US scientists, historically appeared mainly in birds, but in recent years has spread to a wide range of mammals.


H5N2 has long appeared in Mexican poultry, and farms vaccinate against it.

He is also no stranger to the United States. An outbreak of H5N2 struck a flock of 7,000 chickens in south-central Texas in 2004, the first time in two decades that dangerous-to-poultry bird flu had appeared in the US

H5N2 was also primarily responsible for wave outbreaks at US commercial poultry farms in 2014 and 2015.

How Dangerous is H5N2?

Over the years, H5N2 has teetered between being considered a mild threat to birds and a serious threat, but it is not considered to be much of a human threat at all.

Ten years ago, researchers used mice and ferrets to study the strain that was affecting US poultry at the time, and concluded that it was less likely to spread and less deadly. than H5N1. Officials also said there was no evidence it was spreading among people.

Rare cases of animal infections are reported each year, so it is not unexpected that someone has been diagnosed with H5N2.

“If you’re a glass-half-full kind of person, you’d say, ‘Here’s the system doing exactly what it’s supposed to do: detect and document these rare human infections, where we’ve been in the dark for years. ago,’ ” said Matthew Ferrari, director of Penn State’s Center for Infectious Disease Dynamics.

In fact, Mexico’s Health Secretary Jorge Alcocer said that the man’s death was caused by kidney and respiratory failure – not the virus.

Some experts said it is worth mentioning that it is not known how it caught the man who caught H5N2.

“The fact that there was no reported contact (with an infected bird) raises the possibility that it was infected by another person who visited it, but it is too early to jump to those conclusions,” said Richard Webby, a flu researcher at St . Jude Children’s Research Hospital in Memphis.


At this point, H5N2 is still considered a minor threat compared to some of the other bird flu strains out there. Most human illnesses have been attributed to H7N9, H5N6 and H5N1 bird flu viruses.

From early 2013 to October 2017, five outbreaks of H7N9 were blamed for killing more than 600 people in China. And at least 18 people in China died during the H5N6 outbreak in 2021, according to the US Centers for Disease Control and Prevention.

H5N1 was first identified in 1959, but it did not become a concern for health officials until an outbreak in Hong Kong in 1997 resulted in serious human illness and death.

H5N1 cases have continued since then, most involving direct contact between humans and infected animals. Worldwide, there have been more than 460 known human deaths since 2003, according to WHO statistics which suggest it could kill as many as half of those reported to be infected.

Like other viruses, H5N1 evolved over time, spawning newer versions of itself. In recent years, the larger version of the virus has spread rapidly among a wide range of animals, but the number of human deaths has slowed.


Associated Press writer María Verza in Mexico City contributed to this story.


The Associated Press Health and Science Section is supported by the Howard Hughes Medical Institute Science and Media Education Group. The AP is solely responsible for all matters.

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