Avian flu H5N1

When the World Health Organization declared COVID-19 a pandemic on March 11, 2020, humans had been the only species with reported cases of the disease. While early genetic analyses pointed to horseshoe bats as the evolutionary hosts of SARS-CoV-2, the virus that causes COVID-19, no reports had yet surfaced indicating it could be transmitted from humans to other animal species. Less than two weeks later, a report from Belgium marked the first infection in a domestic cat – presumably by its owner. Summer 2020 saw news of COVID-19 outbreaks and subsequent cullings in mink farms across Europe and fears of similar calls for culling in North America. Humans and other animals on and around mink farms tested positive, raising questions about the potential for a secondary wildlife reservoir of COVID-19. That is, the virus could infect and establish a transmission cycle in a different species than the one in which it originated. Researchers have documented this phenomenon of human-...

Colorado has highly pathogenic avian influenza – also known as HPAI or bird flu – on a dairy farm, the ninth state with confirmed cases. The U.S. Department of Agriculture’s National Veterinary Services Laboratories confirmed the virus on April 25, 2024, in a herd in northeast Colorado. This farm is one of 35 dairy farms across the U.S. with verified cases of bird flu in cattle as of May 7, 2024, according to the USDA. Bird flu is not new to Colorado. The state experienced an outbreak in poultry that began in 2022. Since then, the USDA’s Animal and Plant Health Inspection Service has reported that 6.3 million birds in nine commercial flocks and 25 backyard flocks have been affected by the virus. The most recent detection was in February 2024. But this is the first time the disease has made cattle in Colorado sick. I’m a veterinarian and epidemiologist at Colorado State University who focuses on infectious diseases in dairy cows. I spent many years...

Recent reports that the H5N1 avian flu virus has been found in cow’s milk have raised questions about whether the U.S. milk supply is safe to drink. According to the federal Food and Drug Administration, the answer is yes, as long as the milk is pasteurized. Nonetheless, raw (unpasteurized) milk sales are up, despite health experts’ warning that raw milk could contain high levels of the virus, along with many other pathogens. As an extension food scientist in a state where raw milk sales are legal, I provide technical support to help processors produce high-quality, safe dairy foods. I also like to help people understand the confusing world of pasteurization methods on their milk labels, and why experts strongly discourage consuming raw milk and products made from it. What can make milk unsafe Dairy products, like many foods, have inherent risks that can cause a variety of illnesses and even death. Our milk comes from animals that graze outdoors and live in bar...

The discovery of fragments of avian flu virus in milk sold in U.S. stores, including in about 20% of samples in initial testing across the country, suggests that the H5N1 virus may be more widespread in dairy cattle than previously realized. The Food and Drug Administration, which announced the early results from its nationally representative sampling on April 25, 2024, was quick to stress that it believes the commercial milk supply is safe. The FDA said initial tests did not detect any live, infectious virus. However, highly pathogenic avian influenza virus can make cows sick, and the flu virus’s presence in herds in several states and new federal restrictions on the movement of dairy cows between states are putting economic pressure on farmers. Five experts in infectious diseases in cattle from the University of California, Davis – Noelia Silva del Rio, Terry Lehenbauer, Richard Pereira, Robert Moeller and Todd Cornish – explain what the test results mean, ho...

An outbreak of H5N1 avian influenza that started in 2021 has become the largest bird flu outbreak in history, both in the U.S. and worldwide. In the U.S. the virus has led to the destruction of millions of commercially raised chickens, turkeys, ducks and geese, and has killed thousands of wild birds. Many virologists are concerned that this virus could spill over to humans and cause a new human pandemic. University of Colorado Boulder virologists Sara Sawyer, Emma Worden-Sapper and Sharon Wu summarize the compelling story of H5N1 and why scientists are closely watching the outbreak. 1. Is this virus a serious threat to humans? H5N1 is a specific type of influenza virus, predominantly harbored by birds, that was first detected on a goose farm in China in 1996. Recently it has begun infecting an exploding diversity of bird and mammalian species around the globe. The virus is highly pathogenic to birds, meaning that infections often cause extreme symptoms, including death. But...