A Colorado man who works on a poultry farm, and has direct exposure to domestic birds, is the first known human case in the United States of avian flu (the H5N1 virus). 

The Colorado Department of Public Health and Environment tested the man and the positive test was confirmed by the Center for Disease Control (CDC). 

The man showed no symptoms other than fatigue, and subsequent tests were negative. He is quarantining and receiving the influenza antiviral drug oseltamivir (tamiflu), the treatment recommended by the CDC.

“We might never know if this individual was truly infected, meaning the virus was replicating in his body, or if the virus was just transiently present in his nose and picked up by the nasal swab test,” said Dr. Rachel Herlihy, Colorado state epidemiologist.

The birds on the infected farm have been euthanized. 

The virus has been detected in Denver and in other parts of Colorado, prompting the Denver Zoo and other zoos all across the country to bring their bird exhibits inside, away from the public, to prevent transmission of the avian flu, which is very contagious. 

US Department of Agriculture inspectors found avian flu in backyard chickens in Colorado earlier in April.The first case of infection in the US since 2020 was in commercial turkeys in Indiana in February, according to the US Department of Agriculture. 

The disease has been found in wild birds all across the country. The US Department of Agriculture states that the United States has the strongest avian flu surveillance program in the world. The Animal and Plant Health Inspection Service (APHIS) collects and tests samples from wild birds and often detects avian flu in these samples. The APHIS also monitors commercial and backyard birds.

Avian flu viruses are very contagious, and can sicken and kill domesticated birds, such as chickens, ducks and turkeys.

The avian flu typically spreads among poultry and wild birds and doesn’t usually infect humans or spread among humans. There are no known cases of spread from person to person. Scientists believe that the risk is low for the public. 

The CDC said they have studied over 2,500 people who were exposed to the avian virus, and the case in Colorado is the only human case that has been found. 

While cases of avian flu in humans are very rare, people should avoid contact with dead or sick birds, and avoid touching areas that may have bird feces. People who handle sick or dead poultry in their professions should wear gloves and face masks, and wash their hands with soap and water to prevent possible transmission. 

“We know that in general the risk to the general public is very low,” Dr. Rachel Herlihy said. “That risk is elevated in individuals who do have close contact or prolonged contact with infected birds.”