Bird Flu Alert: Global Health Risks and Economic Impact

Avian influenza continues to present a complex global challenge, impacting wildlife, livestock, and public health. Recent developments highlight a widening scope of infection, including the spread of the H5N1 strain into dairy cattle and sporadic human cases among workers in the United States.

The U.S. Centers for Disease Control and Prevention (CDC) reports that A(H5) bird flu is widespread in wild birds globally and is causing outbreaks in poultry and U.S. Dairy cows. Since February 2024, there have been 71 total reported human cases of A(H5) bird flu in the United States. Of these, 64 cases were detected through human monitoring and seven were identified through national flu surveillance.

Impact on Dairy Cattle and Food Systems

The transmission of highly pathogenic avian influenza (HPAI) to dairy cattle represents a significant shift in the virus’s behavior. As of May 10, 2024, HPAI cases had been reported in 36 licensed dairy herds across nine U.S. States, out of 26,290 licensed herds.

Unlike poultry, where HPAI viruses cause severe disease and high mortality, infected cattle do not face the same level of mortality. However, they may experience short-term losses in milk production. Because of this, dairy cows do not necessarily need to be culled after infection, though the outbreaks have caused instability in livestock markets.

Regarding food safety, the Food and Drug Administration (FDA) and the CDC have stated that the domestic milk supply remains safe because it is pasteurized. The U.S. Department of Agriculture (USDA) reported on May 1, 2024, that early testing of retail ground beef was negative for H5N1.

Public Health Risk and Human Transmission

The CDC maintains that the current public health risk to the general population is low. Human infections in the U.S. Have been sporadic and primarily limited to dairy and poultry workers. Presumptive risk factors for human infection include exposure to infected animals or the consumption of unpasteurized milk.

While the World Health Organization (WHO) has documented 889 cases of H5N1 influenza infection in humans across 23 countries and 463 deaths since 2003, current monitoring focuses on the potential for the virus to adapt. To date, no human-to-human transmission of the current HPAI strain has been identified.

To manage the risk, the CDC streamlined its updates on July 7, 2025, integrating A(H5) bird flu data with routine influenza updates and reporting human monitoring data on a monthly basis.

Economic and Ecological Implications

The economic ramifications of avian influenza extend beyond immediate healthcare costs. The disease can lead to the culling of poultry, which impacts food systems and reduces production and profit for agribusinesses and pastoralists.

Livestock diseases generally diminish income and asset values while constraining nutrition for households that depend on these animals for livelihoods. The broader economy in the United States, particularly the dairy cattle sector, faces potential risks if the outbreak expands.

Surveillance and Biosecurity

Managing the crisis relies heavily on biosecurity measures and rigorous surveillance. The CDC continues to work with states to monitor individuals with animal exposures and utilizes flu surveillance systems to track A(H5) activity in people.

Current monitoring efforts distinguish between confirmed and probable cases. According to the Council of State and Territorial Epidemiologists (CSTE) guidance, a case is reported as probable when a public health laboratory tests positive for A(H5), but the CDC is unable to confirm the infection.