Why the New Human Case of Bird Flu Is So Alarming

Rick Bright

The third human case of H5N1, reported on Thursday in a farmworker in Michigan who was experiencing respiratory symptoms, tells us that the current bird flu situation is at a dangerous inflection point. The virus is adapting in predictable ways that increase its risk to humans, reflecting our failure to contain it early on. The solutions to this brewing crisis — such as comprehensive testing — have been there all along, and they’re becoming only more important. If we keep ignoring the warning signs we have only ourselves to blame.

H5N1 has long been more than a bird problem. The virus has found its way into dairy cattle across nine states, affecting 69 herds that we know about. Of the three human cases of H5N1 that have been identified, all involve farmworkers who were in direct contact with infected cows or milk. The first two cases were relatively mild, involving symptoms like eye irritation, or conjunctivitis. However, the most recent case has shown more concerning signs, including coughing.

The emergence of respiratory symptoms is disconcerting because it indicates a potential shift in how the virus affects humans. Coughing can spread viruses more easily than eye irritation can.

New symptoms should be expected as the virus continues to spread and adapt to humans. Yet our response to this looming danger has been woefully inadequate, particularly in the area of testing.

Testing is our first line of defense in identifying and controlling infectious diseases. It allows health responders to understand the extent of an outbreak, identify who is infected and take measures to prevent further spread.

In the case of H5N1, human testing is crucial not only for diagnosing current infections but also for understanding how the virus is spreading. Serology testing, which looks for antibodies in the blood, can help us determine how many people have been infected with the virus even if they did not develop symptoms.

Despite its importance and repeated calls for its use, serology testing for H5N1 has been virtually non-existent in this outbreak. Without serology testing by state or local health officials, we are most likely missing many cases, particularly among asymptomatic people or those with mild symptoms. This underreporting skews our understanding of the virus’s spread and hampers our ability to respond effectively.

Undetected cases of H5N1 mean that infected people may continue to spread the virus unknowingly. This is especially dangerous in farming communities where close contact with animals and other workers is common. Each missed case is a potential link in a chain of transmission that could lead to a wider outbreak.

Moreover, failing to detect cases undermines the ability to have targeted public health interventions. If we don’t know the full extent of the outbreak, we can’t effectively allocate resources such as vaccines and antiviral treatments to those who need them most.

There’s also a human cost. Farmworkers, often working long hours in proximity to infected animals, bear the brunt of this oversight. They are at higher risk for infection and yet many lack health insurance and paid sick leave, making it difficult for them to seek testing and treatment. They may also be reluctant to report symptoms or seek medical care out of fear of losing their jobs or facing immigration-related repercussions. As a result, many may continue working while infected, further spreading the virus.

This is why we need a robust national testing strategy, coordinated by the Centers for Disease Control and Prevention, that includes both diagnostic and serology testing. This should be coupled with outreach efforts from state and local health departments to ensure that farmworkers have access to testing and feel safe using it. This means providing clear information in multiple languages, ensuring that testing is free and accessible, and offering support for those who test positive, such as paid sick leave and medical care. All health workers should be trained and equipped with tests that can provide a rapid diagnosis that will prompt timely and appropriate treatment.

The United States must also improve surveillance and data collection to get a clearer picture of the outbreak. This includes ramping up testing in areas with known infections, conducting regular screenings of at-risk populations by state and local health departments and using innovative approaches such as wastewater surveillance to detect the virus in communities early.

To further cloud our understanding of the outbreak, the U.S. Department of Agriculture has been slow to share critically important virus sequence data from animals infected with the H5N1 virus. While several states are continually reporting new infections in cows, the U.S.D.A. has not shared a virus sequence collected from a cow in several weeks.

This H5N1 outbreak is a warning. The report of respiratory symptoms is not a good sign, and this is not a good way to prevent a pandemic.