A new variant of avian flu, H5N2, has been detected in Mexico City following the death of a 59-year-old man. Unlike the H5N1 strain that infected three dairy farm workers in the U.S., this strain has not been previously observed in humans. Concerns are heightened as the deceased man was bedridden at home with no known exposure to birds or animals.
The man had underlying diabetes and chronic kidney failure, conditions that increase susceptibility to infections. He developed symptoms on April 17, including fever, shortness of breath, and diarrhea, and passed away on April 24. None of his contacts have tested positive for flu A so far, but serology is pending for 12 contacts identified near his residence, as reported by El Universal. H5N2 has been circulating in birds in the area.
The multitude of flu strain names—H5N1, H5N2, bird flu, swine flu, flu A, flu B, and more—can be confusing to keep track of. The three main types of flu, A, B, and C, are named after core proteins. Influenza A, the most serious type, caused the deadly 1918 outbreak, while Influenza B is usually less severe and leads to infections every few years. Influenza C has not triggered epidemics.
The "H" and "N" in the strain names denote surface proteins—hemagglutinin and neuraminidase—that aid the virus in attaching to and invading cells. Occasionally, strains mutate and exchange genetic material, increasing their infectivity. This occurred when H1N1 and H2N2 combined and mutated in birds, resulting in a strain capable of infecting humans, leading to the 1957 influenza pandemic in Asia from H2N2, a novel strain.
Strains are categorized into highly pathogenic avian influenza (HPAI) or low pathogenic. The primary concern in recent months has been HPAI H5N1.
H5N1 has ravaged poultry flocks and dairy herds. Although it has caused illness in a few individuals, the full extent remains unclear due to limited and inadequate testing.
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