The Centers for Disease Control and Prevention has confirmed that a Colorado inmate tested positive for the highly contagious avian influenza A virus. The man had direct exposure to poultry and participated in the slaughter of suspected poultry infected with H5N1 avian influenza. This is the first recorded case.

The person, who is being held at a state correctional facility in Colorado’s Delta County, worked with poultry on a commercial farm in Montrose County as part of a pre-release employment program where participants have the opportunity to work for private employers and be paid a prevailing wage. The affected herd was euthanized and disposed of under the direction of the United States Department of Agriculture and the Colorado Department of Agriculture. All members of the response team, including other inmates, were issued personal protective equipment while working on the farm.

The adult man, believed to be under 40, is largely asymptomatic, reporting only fatigue. The patient is isolated and treated with oseltamivir, an antiviral flu drug. Although it is possible that the detection of H5 avian influenza in this sample was the result of surface contamination of the nasal membrane, this cannot be determined at this time and the positive test result meets the criteria for an H5 case. The appropriate public health response at this time is to assume it is an infection and take steps to contain and treat it.

The USDA confirmed the first case of highly pathogenic avian influenza (abbreviated as HPAI) in wild birds in South Carolina last January. A month later, the USDA announced the presence of HPAI in a commercial flock of turkeys in Dubois County, Indiana – the first commercial poultry case since 2020. Since then, the virus has been confirmed in 29 states, affecting more than 33 million domestic birds.

This case does not change the human risk assessment for the general public, which the CDC considers low. However, for those working in agriculture, especially people with occupational or recreational exposures to infected birds, who are at higher risk of infection, should take appropriate precautions outlined in CDC guidelines.

The CDC has been monitoring illness in people exposed to birds infected with the H5N1 virus since these outbreaks were detected in wild birds and poultry in the United States in late 2021 and through 2022. To date, H5N1 viruses have been found in US commercial and backyard birds in 29 states. and in wild birds in 34 states. The CDC has tracked the health of more than 2,500 people exposed to birds infected with the H5N1 virus and this is the only case that has been found so far. Others involved in the culling operation in Colorado have tested negative for H5 virus infection, but are being retested out of an abundance of caution.

This is the second human case associated with this specific group of currently predominant H5 viruses, and the first case in the United States. The first case internationally occurred in December 2021 in the UK in a person who had no symptoms and kept birds infected with the H5N1 virus. Over 880 human infections with earlier H5N1 viruses have been reported since 2003 worldwide, however, the predominant H5N1 viruses currently circulating among birds globally are different from earlier H5N1 viruses.

Infected birds excrete the H5N1 virus in their saliva, mucous membranes and feces. H5N1 virus infections in people are rare; however, human infections can occur when enough virus enters a person’s eyes, nose, or mouth, or is inhaled. People who have close or prolonged unprotected contact (not wearing respiratory or eye protection) with infected birds or places that sick birds or their mucous membranes, saliva or feces have touched may be at greater risk of infection by the H5N1 virus. In people with avian influenza virus infections, illnesses range from mild (eg, eye infection, upper respiratory tract symptoms) to severe illness (eg, pneumonia) that can lead to dead.