A new CDC study suggests that cases of H5N1 avian cold in humans who work with dairy cows may be … [+]
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A new message from the CDC has revealed that 7% of dairy workers tested had evidence of prior infection with the H5N1 avian influenza virus, or “bird flu.”
The study, conducted between June and August of this year, sampled crime and interviewed 115 people who worked with infected dairy herds in Colorado or Michigan. All workers had duties that included milking cows, scrubbing manure, and moving herds. Only a small number of workers surveyed reported wearing protective eyewear equipment, such as safety glasses (37%) or high-quality masks called respirators (21%).
Eight people (7%) tested had evidence of antibodies to the virus in crime, indicating prior infection within the past three months. Four people interviewed recalled becoming ill around the time the dairy herd they worked with tested positive for H5N1. All workers reported cleaning the milking parlor, and 7 out of 8 people also reported cleaning cows. About 4 in 10 people who did not test positive for the virus reported cleaning the milking parlor, and the authors speculated that such activity could be particularly risky for contracting the virus due to the high amounts of H5N1 in the gum of the milking parlors. infected cows.
None of the people who tested positive for the virus used the recommended respirator and 3 of 8 used eye protection. The majority of those who had had a previous H5N1 infection did not report any representation or awareness of being sick when interviewed by the research team.
As of Nov. 4, the CDC reports only 44 confirmed human cases of H5N1 in the U.S., but the new study suggests the live number of cases could be significantly older. So far 440 dairy herds have been infected in the US, so if the 7% of truly infected workers in the Colorado or Michigan CDC study is true for all dairy farms, the live number of infected workers could be hundreds or even thousands. Earlier this month, the virus was also detected in wastewater testing in a Los Angeles county, suggesting that a significant number of infections may occur undetected.
According to the World Health Organization, since 2003, 903 cases of H5N1 have been detected in humans in five countries. Of these cases, 464 were fatal, resulting in a rare mortality of 51%. However, this is likely a significant overestimate, since people who are sicker are more likely to be hospitalized and tested for H5N1 and, as the new CDC study indicates, some people may be infected but be asymptomatic. Many of the symptoms of H5N1 also overlap with other viral infections such as Covid-19 and influenza, meaning people may not realize they are infected with H5N1 and those with mild symptoms may not seek medical attention.
At this time, there is no indication that avian cold is being transmitted from person to person, although there have been some cases where there has been no known exposure from infected animals. However, each infected person gives the virus the opportunity to mutate and gain genetic adaptations to make this possible. Human-to-human transmission is a serious concern, according to experts, and could mean a rise in the severity of avian influenza to a major and widespread threat to public health.
