The H5N1 bird flu is rapidly spreading across dairy farms in California, the leading milk-producing state in the U.S. From last Thursday to the following Monday, the number of confirmed cases in cow herds shockingly jumped from 17 to 34, as reported by state and federal authorities.
With these latest figures, California now holds the second position nationwide for the most herds impacted by avian influenza. Colorado is the only state with more affected herds, numbering 64, largely due to its comprehensive bulk milk-tank monitoring system. Remarkably, California only disclosed its first three cases on August 30, despite the outbreak’s initial confirmation in dairies on March 25, believed to have started late the previous year.
As of now, 232 herds across 14 states have contracted the bird flu.
California officials, in an announcement last week, indicated that the newly tested positive herds were specifically chosen for testing due to their recent interactions with the initially infected premises. They described these results as “not unexpected” and in line with the state’s strategy to detect infections at an early stage. “Early detection allows us to collaborate with farms to swiftly initiate improved biosecurity, cow care, and protection for workers,” they stated.
Upon disclosing the state’s initial cases, Karen Ross, Secretary of the California Department of Food and Agriculture, emphasized the state’s preparedness and expertise gained from past experiences with this strain of avian influenza in poultry. Ross reassured dairy farmers of their full and immediate attention to the outbreak.
Worrisome Spread
The situation raises alarms among public health experts due to a mysterious case of H5 bird flu in a Missouri resident, who suffered from other health issues but had no direct contact with animals. This infection marks the 14th human case linked to the dairy cow outbreak this year. Previously, all infections were among farm workers, with nine cases in poultry workers and four in dairy workers. There are no recent reports of H5N1 among Missouri’s dairy herds or poultry establishments.
The individual from Missouri has since recovered, but health officials remain baffled by how the infection occurred. Earlier this month, a representative from the Centers for Disease Control and Prevention (CDC) suggested it might be an isolated incident. However, another household member fell ill simultaneously, hinting at a potential shared exposure to the virus. This family member wasn’t tested for the flu but has also recovered. The CDC is now performing serological tests to determine if this person has developed antibodies against the bird flu, suggesting a past infection.
Additionally, the CDC noted that a healthcare worker who cared for the Missouri patient developed symptoms but tested negative for the flu. Recently, another healthcare worker exhibited mild respiratory symptoms after contact with the Missouri case; however, this individual was not tested for the flu and recovered before any investigation could begin. The CDC plans to conduct serological testing for this healthcare worker as well.
Despite no confirmed cases of human-to-human transmission, health professionals are concerned due to insufficient testing of contacts, animals, and farm workers, which might allow undetected transmission. As the virus continues to spread and reach new mammalian hosts, it evolves with increased chances to adapt to humans and potentially cause more severe illnesses. Influenza experts have long warned of the pandemic potential of this virus.
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