Second US Dairy Worker Infected with Bird Flu Confirmed in Michigan, Reports Reuters

By Tom Polansek, Julie Steenhuysen, and Leah Douglas

CHICAGO/WASHINGTON – U.S. officials announced on Wednesday that a second human case of bird flu has been confirmed in the country, following the virus’s detection in dairy cattle in late March.

The new infection involves a dairy worker in Michigan, marking an extension of an outbreak that has predominantly affected poultry for years. Despite the confirmed cases, the U.S. Centers for Disease Control and Prevention (CDC) maintains that the risk to the general public remains low.

During a recent press call, the CDC reported that they have tested nearly 40 individuals, including the Michigan worker, since the outbreak began. All tested individuals were linked to or had exposure to a dairy farm. A Texas dairy worker was also confirmed to have the virus in April.

Michigan and Texas are among nine states that have reported instances of bird flu in dairy herds. According to findings from the U.S. Food and Drug Administration, approximately 20% of retail milk samples contained H5N1 virus particles, suggesting that the outbreak may be more widespread.

Similar to the Texas case, the Michigan patient displayed only eye symptoms and has since recovered, as noted by the state’s Department of Health and Human Services. The patient had routine exposure to livestock infected with bird flu, and public health officials believe the case likely resulted from cow to human transmission.

The CDC indicated that “additional human cases could be identified,” given the prevalence of the virus in raw milk from infected cows and the extent of the outbreak in dairy cattle.

Experts in influenza voiced concerns over the second case linked to dairy cattle exposure. Scott Hensley, a vaccine specialist at the University of Pennsylvania, expressed worry that the widespread infection among cows could lead to mutations in the virus, potentially increasing risk for humans.

Bird flu has previously caused severe and often fatal infections in people who had close contact with infected birds or poultry, heightening fears of a possible global health crisis. Dr. Angela Rasmussen, a virologist from the University of Saskatchewan, noted that while this situation does not appear to signal the onset of a pandemic, it is critical to determine whether more human cases have occurred.

In response to the outbreak, the U.S. Department of Agriculture (USDA) indicated that unpasteurized milk is the primary means of transmission among cows, although the exact mechanisms remain unclear. To mitigate the spread, the USDA has mandated that dairy cows test negative for bird flu before being transported across state lines.

The USDA will also provide financial support to farmers whose herds have not tested positive for the virus, assisting in the development and implementation of biosecurity and testing measures. Additionally, farmers whose herds have been infected will receive compensation for lost milk.

Dr. Amesh Adalja, an infectious disease expert, stated that further cases are likely among farm workers exposed to infected cows and their milk, emphasizing the importance of comprehensive testing.

Nirav Shah, the CDC’s principal deputy director, reported that the agency confirmed the Michigan worker’s positive test result shortly after receiving the sample. Investigations are ongoing to ascertain whether the worker utilized or was provided any protective equipment during exposure.

While a nasal swab from the worker returned negative for influenza, an eye swab was sent to the CDC and tested positive for the bird flu virus. The CDC recommended isolation, rather than quarantine, for the close contacts of the confirmed case, and offered antiviral medication to those individuals.

The U.S. government is also engaging in discussions with mRNA vaccine manufacturers for a potential human vaccine. Recently, the government initiated the production of about 4.8 million doses tailored to the currently circulating H5N1 strain, a step towards enhancing the nation’s preparedness.