Colorado Issues Warning as New Human Bird Flu Case Detected

Colorado public health officials are warning residents to avoid contact with sick animals after this year’s fourth U.S. case of H5N1 bird flu in a human was detected.

The Colorado Department of Public Health and Environment (CDPHE) said in a news release on Wednesday that a case of avian influenza was identified at an unspecified date in a man who had been exposed to an infected cow while working on a dairy farm in the northeastern portion of the state.

Recent U.S. cases of bird flu in humans have been linked to an outbreak of the virus in dairy cows that began earlier this year. All of the cases involved dairy farm workers—one infection was reported in Texas on April 1, while the other two were detected in Michigan in May.

The U.S. Centers for Disease Control and Prevention (CDC) said on Wednesday that the unnamed Colorado dairy worker was treated with the antiviral drug oseltamivir and had fully recovered, with his only symptom having been conjunctivitis, or “pink eye.”

CDPHE warned the public against touching sick or dead animals, while also pointing out that drinking pasteurized milk was safe and that “proper handling and cooking of poultry, meat, and eggs kills bacteria and viruses, including avian flu viruses.”

“Coloradans should not touch sick or dead animals,” the agency’s release said. “If you must handle sick or dead animals, wear recommended personal protective equipment, including an N95 respirator, eye protection, and gloves.”

“If possible, wash your hands with soap and water afterward,” it continued. “If soap and water are not available, use an alcohol-based hand rub.”

A CDC spokesperson told Newsweek via email that “CDC continues to assess that the risk to the general population from the current outbreak among dairy cattle is low,” while noting that people working with animals are “at greater risk of infection.”

Dr. Rachel Herlihy, CDPHE’s state epidemiologist, also said that “the risk to most people remains low” in a statement, while pointing out that avian flu viruses “are not adapted to spread from person to person.”

“Right now, the most important thing to know is that people who have regular exposure to infected animals are at increased risk of infection and should take precautions when they have contact with sick animals,” Herlihy said.

The CDC offered similar advice and added the following: “People should also avoid unprotected exposures to animal poop, bedding (litter), unpasteurized (‘raw’) milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A(H5N1) virus.”

H5N1 avian flu is very rare in humans, with only five U.S. cases having ever been reported. The first case detected in the U.S. was in a Colorado poultry worker in 2022 who reported fatigue as their only symptom. The recent cases all resulted in conjunctivitis, while the CDC said that one of the Michigan patients also had “typical symptoms of acute respiratory illness.”