(Reuters) -Michigan will soon begin testing dairy farm workers for signs of prior infection with avian flu, a county health official told Reuters.
An ongoing outbreak of avian flu in dairy cattle has affected 67 herds in 9 states since March, according to U.S. Centers for Disease Control and Prevention (CDC) data.
Three dairy workers - one in Texas and two in Michigan - have tested positive for the virus. Two of the workers had conjunctivitis, or pink eye, and recovered. In the third case, reported on Thursday by Michigan, the worker had respiratory symptoms and is recovering.
The third worker also had a cough without fever and eye discomfort, the CDC said in a statement on Thursday confirming the infection. The patient was given antiviral drugs and is isolating at home. No other workers at the same farm have reported symptoms and all staff are being monitored, CDC said.
CDC officials have been eager to test blood samples of farm workers for signs of prior infection to help understand the scope of the bird flu outbreak.
Michigan county and state officials will collaborate with the CDC on the testing effort, said Chad Shaw, health officer and environmental health director with the Ionia County Health Department. The details of the plan for testing have not been previously reported.
Ionia County has reported avian flu infections in four dairy cattle herds and four poultry flocks, according to state data.
The goal of the testing is to discern how the virus is spreading from farm to farm, including whether humans have carried the virus asymptomatically, Shaw said, adding that he did not know when the testing would begin or how many workers would be tested.
A CDC spokesman confirmed the testing and said the agency will be providing technical assistance to the state, which is coordinating the effort.
Testing for prior infection is important for determining how widespread the virus is among humans, said Michael Osterholm, a bird flu expert at the University of Minnesota. Widespread exposure could increase the chances that the virus will mutate to become more easily transmissible in humans.
If testing shows very few infections, he said, that would be an indication that "the barrier is still substantial for this virus to jump to humans."
(Reporting by Leah Douglas in Washington and Julie Steenhuysen in Chicago; Editing by Bill Berkrot)
By Leah Douglas and Julie Steenhuysen
