Global Alert as H5N1 Avian Influenza Spreads Across Species, Including Cows and Humans

Health authorities worldwide are sounding the alarm over an unprecedented spread of highly pathogenic avian influenza A(H5N1), as the virus continues to jump species barriers—from birds to wild mammals and, increasingly, to livestock and humans.

The 2024–2025 outbreak has become the largest avian influenza epidemic in recorded history, with H5N1 detected in poultry, wild birds, and an expanding range of mammals—including sea lions, foxes, and, most notably, dairy cattle. This cross-species transmission has raised urgent concerns among global health officials.

As of November 2025, dozens of human H5N1 infections have been reported globally, primarily among individuals with direct exposure to infected birds in countries such as Cambodia, Chile, Ecuador, and the United States. In a significant development, U.S. health agencies confirmed in April 2025 that H5N1 had infected dairy cattle in multiple states—including Texas, Kansas, and Michigan—marking the first known instance of the virus circulating in U.S. livestock.

By mid-2025, the U.S. Centers for Disease Control and Prevention (CDC) verified at least three human cases linked to infected dairy farms. All affected individuals were farm workers who reported mild conjunctivitis and respiratory symptoms; no secondary human-to-human transmission has been observed.

In response, the World Health Organization (WHO) and the CDC are urging heightened surveillance at the human-animal interface, stricter biosecurity measures on farms, and rapid culling of infected animal herds. Governments and pharmaceutical companies are also accelerating the development and stockpiling of pre-pandemic H5N1 vaccines for human use, with clinical-grade seed viruses already distributed to manufacturers through WHO’s Global Influenza Surveillance and Response System.

Although the current public health risk to the general population remains low, health agencies stress the importance of monitoring, early detection, and international cooperation to prevent a potential spillover event that could trigger a global health emergency.