Is it seasonal influenza or bird flu? Here's how to tell

(Salon) Last month, researchers published a report in the New England Journal of Medicine (NEJM) detailing how a 13-year-old in Canada fought for her life after contracting a severe bird flu infection from an unknown source. In addition to going on life support with an ECMO machine, the teenager received a plasma exchange and multiple antiviral treatments. But her case didn’t initially start severe. Her symptoms began with double conjunctivitis, also known as pink eye, and turned into a fever and coughing. When she first went to the hospital she tested positive for influenza A — but not the seasonal subtype. Further testing suggested she had a high viral load of a novel influenza A infection, which researchers eventually discovered to be avian flu caused by the H5N1 virus.

As the Centers for Disease Control and Prevention (CDC) explains, bird flu is a disease caused by the influenza A virus. At the same time, recent CDC data shows that seasonal influenza A is rising across the U.S. — specifically the H1N1 (swine flu) and H3N2 strains. While it may just seem like a tiny change in numbers, these differences in flu viruses can mean they are more pathogenic and deadly. But how do researchers know that if a person tests positive for influenza A, it’s not H5N1 avian flu?

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Jetelina elaborated that when it comes to rapidly discerning whether or not a person is infected with H5N1, or another type of flu A, people are reliant on clinicians to decide whether or not further testing is necessary. This is usually triggered by symptoms — like red eyes for H5N1 or a history of having exposure to sick animals. According to the CDC, 66 humans have been infected with H5N1 in the last year. On Friday, the San Francisco Department of Public Health reported a presumptive case of H5N1 bird flu in a child, which the CDC hasn't confirmed yet. The patient experienced symptoms of fever and conjunctivitis but did not require hospitalization and have since fully recovered.

While a majority of those cases occurred from contact with infected poultry or dairy herds, two sources of infected cases remain unclear. To date, most cases haven’t been severe. But last week the CDC reported the first bird flu death in the United States. ................(more)

https://www.salon.com/2025/01/13/is-it-seasonal-influenza-or-bird-flu-heres-how-to-tell/