A farmworker in Michigan has been diagnosed with bird flu, marking the second human case associated with the outbreak in cows. The individual contracted the virus, known as H5N1, after exposure to infected livestock. Fortunately, they only experienced mild symptoms and have fully recovered. Officials did not disclose additional details to protect the privacy of the farm and the farmworker. This case comes after the first confirmed human case of H5N1 in the United States was reported in Colorado in 2022, and another case was reported in a Texas dairy farm worker last month. However, officials stated that the risk to the general public remains low, as there is no evidence of sustained human-to-human transmission of the virus.
The virus has been detected in 51 dairy herds in nine states, according to the U.S. Department of Agriculture, but it is believed to be more widespread. In Michigan alone, four infected herds were not included in the federal count. Additionally, traces of the virus have been found in 20 percent of dairy products sampled from grocery shelves in 17 states, indicating the extent of the outbreak. Scientists believe the virus was transmitted from wild birds to dairy cows in a single spillover event in the Texas Panhandle as early as last December. The virus spread undetected among cows, with studies finding infected herds with no known links to affected farms, suggesting transmission among asymptomatic cows.
The spread of the virus between cows is believed to have occurred through contaminated milk, which contains high levels of the virus. It has also spread from dairy farms to poultry farms, possibly through the movement of contaminated vehicles or equipment. The transport of infected cows from Texas may have contributed to spreading the infection to states as far as North Carolina and Michigan. During the outbreak, the virus has acquired numerous new mutations, some of which may make it more adept at spreading between species. The Texas farmworker diagnosed in April had severe conjunctivitis, but recovered fully, indicating varying symptoms in those infected with the virus.
Farm owners have been hesitant to test their workers or cattle, fearing financial consequences. Federal and state officials are unable to compel farmers or farmworkers to get tested unless under extraordinary circumstances. Veterinarians have observed some farmworkers developing flu-like symptoms but few have agreed to be tested. In Michigan, farmworkers exposed to infected animals have been encouraged to report even mild symptoms, with testing for the virus made available. The Centers for Disease Control and Prevention reported that the individual in Michigan tested negative for the H5N1 virus in a nasal swab but positive in an eye swab, indicating the potential for different detection methods.
In conclusion, the discovery of a farmworker in Michigan diagnosed with bird flu highlights the ongoing threat of the outbreak in cows and the potential for human exposure to the virus. The rapid spread of the virus among dairy herds across multiple states underscores the challenges in containing and tracking the outbreak. Efforts to monitor and test farmworkers, as well as the adoption of safety measures on farms, are crucial in preventing further human cases. The mutations detected in the virus raise concerns about its ability to spread between species and the need for continued vigilance in monitoring the situation.
