On March 25, 2024, a report by the US Federal officials was made that a Highly Pathogenic bird flu strain (H5N1) had been detected in dairy cows. By April 30, 2024, the USDA had confirmed infection in 34 dairy herds in 9 states. Genomic analysis showed the outbreak in cattle may have begun much earlier in late December 2023 or early January 2024 from wild birds to cattle. Recent data show the outbreak started from one farm and spread to others.

Although in the past, the spread of H5N1 has mainly been from wild birds to domestic poultry. H5N1 is one of the strains of the influenza virus that primarily infect birds, but can also infect humans. This type of flu is most often contracted by contact with sick birds. It can also be passed from person to person. Symptoms begin within two to eight days and can seem like the common flu. Cough, fever, sore throat, muscle aches, headache, and shortness of breath may occur. The disease can carry a high mortality in humans. Some antiviral drugs, if taken within two days of symptoms, may help. There are concerns that the current development of H5N1 to cows which are also mammals may show an increased risk of spread to humans. So far in this outbreak, there has been one probable human case.

With the risk of spread of infection from live animals, animal carcasses and concerns about the safety of animal products, the pressure to reduce the risk of human infection is high. 

Additionally, according to PAHO, several countries and territories are reporting outbreaks in the Region, indicating a large geographical extension of the virus. Highly pathogenic avian influenza virus (HPAI) has also been identified in mammals in North and South America. Moreover, three human infections were reported in the region in the last years and recently, in April 2024, it was reported that a person in the United States has tested positive for HPAI confirmed by the CDC.

Should we be concerned about the spread of H5N1 to humans from cows or are there other factors that we should be concerned about in this outbreak? Let us know what you think or suggest on what the next steps should be as this outbreak evolves.

Resources:

1. https://www.nature.com/articles/d41586-024-01256-5
2. https://www.nature.com/articles/d41586-024-01036-1
3. https://www.paho.org/en/topics/avian-influenza