U.S. health officials have confirmed a second human case of H5N1 bird flu in Missouri with no known exposure to farm animals, intensifying concerns about the virus's transmission patterns. This individual shared a home with the first Missouri patient who was hospitalized with bird flu in August, according to the U.S. Centers for Disease Control and Prevention (CDC).
The investigation revealed that both household members had identical symptom onset dates, suggesting "a single common exposure to bird flu rather than person-to-person spread within the household," the CDC stated in its latest update. Neither individual had documented exposure to infected animals nor had consumed raw milk products that might have carried the virus.
"To date, human-to-human spread of H5 bird flu has not been identified in the United States," the agency emphasized. "CDC believes the immediate risk to the general public from H5N1 bird flu remains low, but people with exposure to infected animals are at higher risk of infection."
Rising Case Numbers Across Multiple States
The nationwide total of human H5N1 cases has now reached 67, with California reporting the highest number at 38 cases. Most recently, California confirmed a case involving a San Francisco child who developed fever and conjunctivitis but was not hospitalized and has fully recovered.
Washington state has reported two confirmed poultry workers infected with bird flu and five others presumed positive. With the exception of the two Missouri cases, all other infections have been linked to exposure to infected poultry or cattle.
Dr. James Lawler, co-director of the University of Nebraska's Global Center for Health Security, expressed significant concern about the situation. "We should be very concerned at this point," he told the New York Times. "Nobody should be hitting the panic button yet, but we should really be devoting a lot of resources into figuring out what's going on."
Expanding Outbreak in Livestock
The bird flu outbreak continues to spread through U.S. livestock. More than 338 dairy herds across 14 states have been infected since the outbreak in dairy cows was first confirmed in March. Avian influenza has been circulating in wild and domestic birds in the United States for several years.
Dr. Matthew Binnicker, director of the clinical virology laboratory at the Mayo Clinic, noted the concerning nature of the Missouri cases. "I'm really hoping that they ultimately find out that there was some likely animal exposure, because the alternative is a little bit scary," Binnicker told NBC News, referring to the possibility of human-to-human transmission.
High-Risk Groups and Prevention Measures
While the CDC maintains that the risk to the general public remains low, certain groups face elevated risk, including:
- Farm workers exposed to sick animals or their byproducts
- Backyard bird flock owners
- Animal care workers
- Public health responders
The CDC recommends several preventive measures to reduce transmission risk:
- Avoid direct contact with wild birds and other animals infected with or suspected to be infected with avian influenza viruses
- Wear recommended personal protective equipment when contact with potentially infected animals is necessary
- Avoid touching surfaces or materials contaminated with saliva, mucus, or feces from animals with confirmed or suspected bird flu infection
- Do not consume raw milk or products made from raw milk, especially from animals with confirmed or suspected infection
Surveillance and Testing
The CDC has been conducting antibody testing to monitor potential spread. Tests on symptomatic healthcare workers who cared for the first Missouri patient have shown no evidence of H5N1 infection, providing some reassurance that the virus is not easily transmitted between humans in healthcare settings.
Health officials continue to monitor the situation closely, particularly watching for any genetic changes in the virus that could increase its ability to spread between humans or cause more severe disease, factors that would significantly elevate the public health threat level.
