At least 200 people have been monitored for possible exposure to the H5N1 bird flu virus and 30 people have been tested, but a dairy worker in Texas is the only person known to contract the disease from cattle, said the Centers for Disease Control. “No additional human cases have been detected” since bird flu was discovered for the first time in cattle six weeks ago.
The agency said it was working with medical firms for creation of an H5N1 tests that would be widely available to consumers.
Meanwhile, USDA officials pointed without elaboration to “significant differences in the management practices of beef and dairy cattle” when asked why the H5N1 virus has been found only on dairy farms in Texas. To date, 36 infected dairy herds have been confirmed in nine states; 12 of the herds are in Texas.
“We continue to investigate all factors that may have led to introduction of HPAI into the original dairy herd,” said the USDA. There are 642,000 dairy cattle among 12 million head of cattle in the Lone Star State.
Beef cattle have stockier builds than dairy cattle, and produce less milk — just enough to feed their calves — than dairy cows. In March, U.S. dairy cows produced an average of 7.9 gallons a day. Dairy cattle are milked at least twice a day and housed together. Beef cattle might graze in pastures but also may be in feedlots if they are being fattened for slaughter.
“The focus of our current efforts is to control and eliminate the virus in dairy cattle by identifying dairy herds that have the virus, treat and recover sick cattle, and prevent the virus from spreading from the farm,” said the USDA. “The most effective way for producers to prevent the spread of the disease is to practice good biosecurity.”
The risk of the H5N1 virus to the general public is low, said the CDC, but “people with close, prolonged, or unprotected exposures to infected birds, cattle, or other animals, to unpasteurized [raw] milk, or to environments contaminated by infected birds, cattle, or other animals or by raw milk, are at a higher risk of infection.”
In a letter to a medical journal, CDC scientists said the Texas dairy worker infected by the H5N1 virus developed conjunctivitis in his right eye in late March. He had direct contact with dairy cattle but not with sick or dead birds or other animals. He wore gloves but not respiratory or eye protection, said a summary published by CIDRAP at the University of Minnesota. The worker later developed redness in his left eye. He and his housemates were given an antiviral drug. None of the housemates developed symptoms.
The researches said they were unable to conduct follow-up investigation of the worker or other workers at the dairy farm.