Risks of Drinking Raw Milk Infected with H5N1

Study Overview

Scientists from the US National Institutes of Health have issued a warning regarding the consumption of raw milk contaminated with the H5N1 virus, commonly known as bird flu. While drinking such milk may not be fatal, it could render individuals infectious. Their findings were published in the research journal Nature, detailing an experiment involving macaque monkeys.

Research Findings

In the study, researchers administered unpasteurized raw milk infected with bovine H5N1 to six macaque monkeys. They compared this group to two other groups, each consisting of six monkeys, who were exposed to the virus via the nose or throat.

Infection Outcomes

The monkeys that received the virus through the windpipe experienced the most severe effects, developing a significant respiratory infection within a week. Those infected through the nasal route exhibited mild symptoms that peaked after approximately ten days. The monkeys that consumed the infected milk did develop an infection, but they did not present the typical flu symptoms.

Implications for Human Health

Although the absence of symptoms in the milk-fed monkeys might seem encouraging, it raises concerns for human health. As evidenced by the COVID-19 pandemic, a lack of visible symptoms does not preclude the possibility of being infectious.

Potential for Transmission

Individuals consuming unpasteurized milk containing the H5N1 virus could unknowingly become carriers. The viral particles may persist in their gastric and intestinal tissues, multiplying and potentially spreading to surfaces such as door handles, faucets, shopping items, and public transport handrails.

CDC’s Response

In light of these findings, the Centers for Disease Control and Prevention (CDC) is working to provide H5N1 testing at regional centers across the United States. There is hope that their logistical capabilities will surpass those of raw milk distributors.

Visual Representation of H5N1

Accompanying this research, a colorized transmission electron micrograph depicts the H5N1 flu virus (in yellow) within epithelial cells (in purple). This image was captured using an electron microscope, with pseudo colors applied for enhanced visibility.

Source Attribution

The study titled “Subclinical Disease in Monkeys Exposed to H5N1 by Mouth and Stomach” was published by the National Institute of Allergy and Infectious Diseases on January 15, 2025. The research can be accessed at https://www.niaid.nih.gov/news-events/h5n1-nhp. The study is authored by Rosenke K, Giffin A, Kaiser F, et al. and can be found in Nature with the DOI: 10.1038/s41586-025-08609-8.