Map Shows States With Human Bird Flu Cases

The Centers for Disease Control and Prevention (CDC) has announced a second recent case of a farm worker contracting the H5N1 virus from dairy cows, expanding the U.S. map of states where the virus has been discovered in humans.

The CDC announced on Wednesday a new case of the "highly pathogenic avian influenza virus" had been discovered in Michigan. On April 1, it was reported that a dairy worker in Texas had previously been diagnosed with the bird flu, while the only other human case was detected in a Colorado poultry worker in April 2022.

Although there have only been two recent U.S. instances of the virus being detected in humans, a continuing outbreak among dairy cows has raised concerns about the possibility of the bird flu becoming a dangerous disease in humans. Some have suggested that H5N1 could develop into a pathogen capable of sparking the next pandemic.

However, the CDC said that the risk the virus poses to humans remains "low," while noting that the only symptom that both people who were infected this year experienced was conjunctivitis, also known as "pink eye." The agency speculated that the infections may have been caused by "a splash of contaminated fluid," while saying that "high levels" of the virus "have been found in unpasteurized milk from H5N1-infected cows."

"CDC has been watching influenza surveillance systems closely, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in syndromic surveillance," a CDC press release states. "This infection does not change CDC's current H5N1 bird flu human health risk assessment for the U.S. general public, which the agency considers to be low."

"This development underscores the importance of recommended precautions in people with exposure to infected or potentially infected animals," it continues. "People with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection."

On Tuesday, CDC Principal Deputy Director Nirav Shah said during a meeting with health leaders that flu surveillance programs should "continue operating at enhanced levels" due to the potential for more human infections during the impending summer season, while infections continue to spread on dairy and poultry farms.

The following map shows where this year's H5N1 human infections have been detected, in Texas and Michigan.

A Newsweek map created in the aftermath of the Texas infection announcement included the 2022 Colorado human infection and the then-current five states experiencing outbreaks among dairy cows.

Dairy cow infections have since been detected in four additional states. The nine states where H5N1 has been detected in cows as of Wednesday are: Texas, Michigan, Ohio, North Carolina, Kansas, South Dakota, Idaho, Colorado and New Mexico. A total of 52 herds are believed to be affected.

The virus has also been discovered in poultry in 48 states and 524 counties, affecting over 90 million birds as of Wednesday. The CDC says that the bird flu has also been found in tests of 9,352 wild birds.