A recent report from the CDC uncovers alarming evidence: bird flu may be spreading to humans undetected. With respiratory illnesses on the rise and diseases like tuberculosis re-emerging, this new threat demands attention.
The latest Morbidity and Mortality Weekly Report reveals three cases of highly pathogenic avian influenza H5N1. These cases involve US veterinarians who primarily work with cattle. Shockingly, two of these cases have no clear exposure source.
Despite the lack of flu-like symptoms and no confirmed human-to-human transmission, experts remain concerned. Researchers warn that with just a few genetic mutations, the virus could soon spread between humans.
THE SURPRISING DISCOVERY OF UNDETECTED INFECTIONS
These cases came to light during antibody tests conducted on 150 veterinarians across 46 US states in September. The tests revealed that bird flu is spreading beyond known infection zones. One affected veterinarian works with livestock in Georgia and South Carolina—states with no reported cases of bird flu in dairy herds.
“There are clearly infections happening that we’re missing,” says Emory University virologist Seema Lakdawala.
COW MILK AND H5N1: A NEW THREAT?
In an unsettling turn, researchers have confirmed that H5N1 can be transmitted through cow milk. This raises the stakes for public health and calls for enhanced monitoring. Health officials are urging states to join the national milk testing program. Each failure to contain the virus provides more opportunities for mutations that could lead to human-to-human transmission.
“If cases are occurring more frequently than detected in humans, we risk missing small changes. These changes may allow the virus to begin to spread much more easily,” warns University of Nebraska infectious disease expert Lauren Sauer.
THE NEVADA CASE AND NEW STRAINS
The first human case of H5N1 in Nevada was reported last week, bringing the total number of known human cases in the US to 68. Nevada has also detected a new strain, H5N1 D1.1, in cows—one that may be better suited to replicate in mammal cells.
“Tracking viruses is key to stopping transmission,” explains Emory University epidemiologist Jodie Guest. This message has never been more critical, especially after the first human death from H5N1 in the US was confirmed on January 6, 2025.
DELAYS AND INFORMATION GAPS: A GROWING CHALLENGE
The fight against bird flu is complicated by delays in sharing crucial data. Federal health agencies, including the CDC, have restricted communication, making it harder to track and manage the spread of the virus.
Previously accessible data is no longer available to global platforms like FluNet and FluID, according to WHO epidemiologist Maria Van Kerkhove. “We are communicating with them, but we haven’t heard anything back,” she notes.
LESSONS FROM PAST STRAINS: CAN H5N1 TRANSMIT BETWEEN CATS AND HUMANS?
While previous strains of bird flu have transmitted from cats to humans, there is no evidence yet of H5N1 spreading this way. However, two pet cats in Oregon were recently euthanized after consuming raw pet food contaminated with the virus.
Health officials are advising the public to avoid raw dairy products and to refrain from feeding pets raw meat. It’s also recommended to avoid contact with wildlife and to wear protective gear when handling potentially infected livestock.
HOW TO PROTECT YOURSELF AND YOUR PETS
Signs of animal infection include fever, lethargy, coordination loss, head tilting, and difficulty standing or flying. If you notice these symptoms in animals, report them to local authorities immediately.
