Public health officials confirmed six additional cases of bird flu infection of farmworkers, five in California and one in Oregon, raising the U.S. total to 52 this year. The Oregon infection was the first in the state and was tied to an outbreak of the H5N1 avian flu virus at an egg farm in Clackamas County, southeast of Portland.
To date, all of the infected people have had mild symptoms and responded to treatment, typically antiviral medication. Scientists are on the alert for any signs the avian influenza virus is evolving to become more transmissible among people.
The Oregon Health Authority said there was no evidence of person-to-person transmission in the state and the risk to the public was low. “The individual experienced only mild illness and has fully recovered,” said Dr. Sarah Present, the Clackamas County public health officer, in a statement. She said the county public health division “has been closely monitoring people exposed to the animal outbreak, which is how this case was identified.” Household contacts of the infected person were prescribed antiviral medication as a precaution.
A Canadian teenager with bird flu was hospitalized in critical condition last week in Vancouver. It was Canada’s first locally acquired case of H5N1 avian influenza in a person.
The six new U.S. cases were reported on Friday. “All individuals had contact with animals at different farms and all have experienced mild symptoms, including eye redness or discharge (conjunctivitis). None of the individuals have been hospitalized,” said California officials in a standard description of human infections in their state. “While the risk to the general public remains low, additional human cases of bird flu are expected to be identified and confirmed in California among individuals who have contact with infected dairy cattle.”
Bird flu was discovered for this first time in dairy cattle in late March and the first human infection of the year was confirmed on April 1, in Texas.
California has become the U.S. hot spot for bird flu since its first infected dairy herd was reported on Aug. 30. It accounts for 26 of the 52 human cases in seven states. Washington State was second with 11 cases and Colorado was third with 10 cases.
In addition, California is home to 294 of the 508 dairy herds in 15 states with bird flu. Colorado has had 64 infected herds and Idaho has 35.
Nearly 2.6 million birds in domestic flocks have died of highly pathogenic avian influenza so far this month, according to a USDA database. The largest outbreak was at an egg farm with 2.16 million hens in Kern County, in California’s Central Valley. Since the H5N1 virus appeared in U.S. flocks in early 2022, nearly 108 million birds have died of the virus and in efforts to prevent its spread.