The U.S. Centers for Disease Control and Prevention on Friday confirmed two additional cases of bird flu in Colorado poultry farm workers.
Last week, Colorado reported four confirmed infections of H5N1 bird flu and was checking on the status of a fifth suspected case.
The two new cases were in poultry workers with exposure to infected poultry during depopulation and disposal activities, the CDC said on Friday.
The cases are part of an outbreak of H5N1 bird flu that has been spreading globally in wild birds, infecting poultry and various species of mammals.
The CDC said on Monday that it deployed a nine-member field team comprising epidemiologists, veterinarians, clinicians and an industrial hygienist to support Colorado's assessment of the outbreak and the human cases.
Overall, the genetic analysis of the H5N1 virus in Colorado supports the CDC's conclusion that the human health risk currently remains low, the agency said.
The health agency also said preliminary results from blood samples collected from 35 people who work in dairy farms in Michigan with infected herds did not show neutralizing antibodies specific to the H5N1 virus.
The CDC added that additional data is necessary to fully understand the occupational risks of exposure to the currently circulating avian influenza viruses.
