Avian Influenza Outbreak: Mammal-to-Mammal Transmission Raises Concerns for Humans

The avian influenza outbreak has taken a concerning turn, with a new Cornell University study providing evidence of mammal-to-mammal transmission of the highly pathogenic H5N1 virus between cows, cats, and a raccoon. This is one of the first instances of efficient and sustained mammalian-to-mammalian transmission of the virus.

Study Findings

The study, published in Nature, found that the virus has been transmitted from birds to dairy cattle across several U.S. states, and subsequently from cow to cow, cat, and raccoon. The researchers used whole genome sequencing of the virus, modeling, and epidemiological information to determine the cases of transmission.

The virus has shown a high tropism for the mammary gland and high infectious viral loads shed in milk from affected animals. This has significant implications for the dairy industry and human health.

Human Cases

So far, 11 human cases have been reported in the U.S., with the first case dating back to April 2022. All cases have been reported with mild symptoms, and four have been linked to cattle farms, while seven have been linked to poultry farms.

The researchers suspect that the virus likely originated from dairy farms in the same county, as the recent patients fell ill with the same strain identified in the study as circulating in dairy cows.

Concerns and Implications

The concern is that potential mutations could arise that could lead to adaptation to mammals, spillover into humans, and potential efficient transmission in humans in the future. While the virus has the ability to infect and replicate in people, the efficiency of those infections is low.

It is therefore critical to continue to monitor the virus in affected animals and also in any potential infected humans. The U.S. Department of Agriculture has funded programs for H5N1 testing, at no cost to producers.

Early testing, enhanced biosecurity, and quarantines in the event of positive results would be necessary to contain any further spread of the virus.

Frequently Asked Questions

What is avian influenza?

Avian influenza, also known as bird flu, is a viral infection that affects birds and can occasionally be transmitted to humans.

What is H5N1?

H5N1 is a highly pathogenic strain of avian influenza that can cause severe illness and death in humans.

How is H5N1 transmitted?

H5N1 can be transmitted from birds to humans through direct contact with infected birds, contaminated surfaces, or airborne transmission. Human-to-human transmission is rare but possible.

What are the symptoms of H5N1?

The symptoms of H5N1 in humans can range from mild to severe and include fever, cough, sore throat, and shortness of breath.

Conclusion

The avian influenza outbreak has raised concerns about the potential for mammal-to-mammal transmission and the risk of adaptation to humans. It is essential to continue monitoring the virus and taking measures to prevent further spread. By staying informed and taking precautions, we can reduce the risk of transmission and protect human and animal health.

Stay vigilant, stay informed!