Man with First Human Case of H5N2 Bird Flu Variant Dies in Mexico
A 59-year-old man in Mexico who contracted a type of bird flu known as A(H5N2) died in April, the World Health Organization said June 5. The source of the infection is unknown.
This is the first laboratory-confirmed human case of infection with an A(H5N2) virus worldwide, and the first avian H5 virus reported in a person in Mexico, the WHO said.
The agency said the current risk of A(H5N2) virus to the general population in Mexico is low.
During a conference for the Association of Health Care Journalists, Mandy Cohen, MD, PhD, Director for the Centers for Disease Control and Prevention (CDC) and the Administrator of the Agency for Toxic Substances and Disease Registry, addressed the death in Mexico.
“This is H5N2, which is different from H5N1, which is what we’re seeing here in our dairy cattle right now….This was an older gentleman with a lot of underlying conditions.”
Cohen also said she thought that public health authorities in Mexico were doing “a great job of doing contact tracing.”
“The only piece that we are still awaiting is some further genetic analysis, which they are sending samples to CDC, we hope to be able to do a deeper characterization of the genetics there,” Cohen said. (edited)
The man affected by A(H5N2) is a resident of the State of Mexico and was hospitalized in Mexico City on April 24 and died on the same day due to complications of his illness.
A week earlier, he had developed fever, shortness of breath, diarrhea, nausea, and general discomfort, WHO said.
“Although the source of exposure to the virus in this case is currently unknown, A(H5N2) viruses have been reported in poultry in Mexico,” WHO said in a statement.
In March, an outbreak of high pathogenicity avian influenza A(H5N2) occurred in backyard poultry in the state of Michoacán, which borders the State of Mexico where the man was living, according to the agency.
That month, there were also two outbreaks of low-pathogenicity avian influenza A(H5N2) in poultry in the State of Mexico.
This virus has also spread in the United States. H5N2 was responsible for outbreaks at U.S. commercial and backyard farms in 2014 and 2015.
“Thus far, it has not been possible to establish if this human case is related to the recent poultry outbreaks [in Mexico],” the WHO said.
The man who died had no known history of exposure to poultry or other animals. However, he had multiple underlying medical conditions, the WHO said. His family reported that he had been bedridden for three weeks due to other reasons prior to the start of his symptoms of A(H5N2), the agency said.
Reuters reports that Mexico’s Health Ministry said the man had type 2 diabetes and chronic kidney disease.
These and other chronic health conditions can increase a person’s chances of developing serious complications from influenza.
Mexico’s Health Ministry said there is no evidence of person-to-person transmission related to this case, according to Reuters.
Samples collected from people who had close contact with the man or lived near his residence tested negative for influenza and SARS-CoV-2, the virus that causes COVID-19, the WHO said.
“The thing to remember is that this is an isolated case,” said Maria Ruiz, MD, an infectious diseases physician at George Washington University, and director of the GW Travelers Clinic.
“Although the person was quite sick for several weeks, so far, none of his contacts have tested positive for avian flu. So there’s been no human-to-human transmission related to this virus,” she told Healthline.
There are many types, or strains, of avian flu viruses.
“These viruses, such as H5N1 and now H5N2, primarily circulate among birds, with occasional spillover into mammals, including humans, under the right circumstances,” said Daniel Pastula, MD, MHS, chief of neuro-infectious diseases and global neurology at the University of Colorado and Colorado School of Public Health.
Wild birds such as gulls, terns, ducks, and geese are the natural hosts for avian influenza A viruses. But the viruses can also infect domestic poultry, and wild mammals such as seals, otters and foxes, and domestic animals such as cats.
People can become infected through close contact with an infected animal or by touching a contaminated surface.
In the United States, the bird flu virus A(H5N1) has been spreading among dairy cattle herds since March. So far, herds have been affected in nine states, including Texas, Kansas and Idaho.
Domestic cats on dairy farms have also become infected, with some dying. In addition, the U.S. Department of Agriculture reported that A(H5N1) has been found in several house mice in New Mexico, potentially putting more people in closer contact with this virus.
So far, three cases of A(H5N1) have been reported in people. Two had only eye infections, but the third had a respiratory illness caused by the virus. All three cases had direct contact with infected cows, according to the Centers for Disease Control and Prevention.
There is no indication of person-to-person spread of A(H5N1) related to exposure to dairy cattle, the agency said in a release.
“Cases like these show the importance of supporting our public health surveillance and response systems at the local, state, federal, and international levels,” said Pastula, “as we need strong biodefense lines.”
“There are many emerging infections out there beyond avian influenza viruses, and we need to be prepared if and when they jump to humans,” he said.
“Overall, there is currently a low risk of avian influenza viruses circulating in humans as they generally do not transmit easily between humans,” Pastula told Healthline. “However, that could always change in the future if a virus mutates enough to allow more efficient human-to-human transmission.”
People who work closely with birds and animals, particularly those that may be sick, should use appropriate protective equipment and wash their hands after handling the animal, he said.
For the general public, Ruiz advises people not to handle sick or dead wild birds or other animals that may be sick with avian flu.
“If there is a situation where you have to move a dead animal, wear gloves and a face mask,” she said, “and be careful with hand hygiene, such as not touching the animal and then touching your face without washing your hands.”
For overall influenza prevention, Pastula recommends that “people wash their hands regularly, get recommended [seasonal] influenza vaccines, stay at home when sick from a respiratory infection (or wear a mask when around others) and seek medical care when appropriate.”
The World Health Organization reports that a 59-year-old man in Mexico who contracted a type of bird flu known as A(H5N2) died in April. He had symptoms such as fever, shortness of breath, diarrhea, nausea, and general discomfort.
The source of the man’s infection is unknown. He had no known contact with poultry or wild animals, but the WHO reports that H5N2 outbreaks have occurred this year in poultry flocks in Mexico. The man had multiple underlying medical conditions, which may have increased his risk of severe illness from flu.
This virus is separate from the A(H5N1) avian flu virus that is spreading among dairy cattle in the United States, and is known to have infected three people. Two of these cases involved only eye infections, but the third included a respiratory infection.
Additional reporting by Gillian Mohney
