CDC Calls for Increased Bird Flu Testing Among Farmworkers Following New Evidence of Infections
Source: DairyNews.today
Federal health officials on Thursday urged expanded testing of farmworkers exposed to bird flu, following new findings that some dairy workers showed signs of infection despite reporting no symptoms. The U.S. Centers for Disease Control and Prevention (CDC) now recommends that farmworkers in close contact with infected animals be tested and offered preventative treatment, even if asymptomatic.
The updated guidance follows a CDC study of 115 farmworkers in Michigan and Colorado, which revealed that eight individuals—about 7%—had antibodies indicating prior exposure to Type A H5N1 bird flu. "These actions are designed to protect workers, limit human transmission of H5, and minimize the virus’s potential to mutate," said Dr. Nirav Shah, CDC principal deputy director.
The study provides the most comprehensive look to date at potential human infection from the bird flu virus, first identified in U.S. dairy cows in March. It suggests more human infections than previously recorded, with the total number of infected farmworkers rising to 46 as of Thursday, most of whom had exposure to infected cattle or poultry.
Experts say the CDC’s response marks a significant shift. Earlier guidance advised testing only symptomatic workers, but the new approach recognizes the virus’s heightened risk. "This step reflects an increased assessment of H5N1’s risk to humans," said Dr. Gregory Gray, an infectious disease expert at the University of Texas Medical Branch.
Each new infection, whether in animals or humans, gives the virus a chance to evolve, potentially in dangerous ways, warned Angela Rasmussen, a virologist at the University of Saskatchewan. "This situation underscores our inadequate response to the H5N1 outbreak. Allowing the virus to spread across species could lead to unpredictable consequences," Rasmussen said.
The CDC study involved 45 workers in Michigan and 70 in Colorado tested between June and August. Among the eight workers with positive blood tests, four had no symptoms. All were responsible for cleaning milking areas, and none wore respiratory protection, although three used eye protection. Infected cows’ milk showed high viral loads, heightening exposure risk, researchers noted.
Monitoring efforts have faced challenges, with reluctance from some farm owners and workers to participate in testing, the report indicated. Critics like Rasmussen argue that the federal response has been sluggish and inadequate. "These assessments should have been prioritized and conducted months ago," she said.
The bird flu virus has been confirmed in at least 446 cattle herds across 15 states. Last week, the U.S. Department of Agriculture reported the first bird flu case in a U.S. pig, found on a farm in Oregon.
The study provides the most comprehensive look to date at potential human infection from the bird flu virus, first identified in U.S. dairy cows in March. It suggests more human infections than previously recorded, with the total number of infected farmworkers rising to 46 as of Thursday, most of whom had exposure to infected cattle or poultry.
Experts say the CDC’s response marks a significant shift. Earlier guidance advised testing only symptomatic workers, but the new approach recognizes the virus’s heightened risk. "This step reflects an increased assessment of H5N1’s risk to humans," said Dr. Gregory Gray, an infectious disease expert at the University of Texas Medical Branch.
Each new infection, whether in animals or humans, gives the virus a chance to evolve, potentially in dangerous ways, warned Angela Rasmussen, a virologist at the University of Saskatchewan. "This situation underscores our inadequate response to the H5N1 outbreak. Allowing the virus to spread across species could lead to unpredictable consequences," Rasmussen said.
The CDC study involved 45 workers in Michigan and 70 in Colorado tested between June and August. Among the eight workers with positive blood tests, four had no symptoms. All were responsible for cleaning milking areas, and none wore respiratory protection, although three used eye protection. Infected cows’ milk showed high viral loads, heightening exposure risk, researchers noted.
Monitoring efforts have faced challenges, with reluctance from some farm owners and workers to participate in testing, the report indicated. Critics like Rasmussen argue that the federal response has been sluggish and inadequate. "These assessments should have been prioritized and conducted months ago," she said.
The bird flu virus has been confirmed in at least 446 cattle herds across 15 states. Last week, the U.S. Department of Agriculture reported the first bird flu case in a U.S. pig, found on a farm in Oregon.
