In a ProMED Report dated Wednesday, July 3rd, a fourth case of conjunctivitis was reported in a dairy herd worker in Colorado. Symptoms were confined to the patient’s conjunctiva with recovery following administration of oseltamivir. To date Colorado has confirmed 40 cases of bovine influenza-H5N1 with a possible extension to a large laying complex.
This and the previous three cases are not unexpected given the number of workers potentially exposed to infected cows in dairy herds. Since all cases have been mild, there is no current risk to humans with the present circulating virus. To protect against possible conjunctivitis or upper respiratory infection, CDC has recommended the use of appropriate PPE. Whether workers will use protective face shields correctly and consistently is questionable even if they are available.
There should be no risk of bovine influenza-H5N1 for consumers given that fluid milk should be pasteurized before bottling or incorporation into dairy products.
It will be necessary to continue to monitor the genome of bovine and human isolates to detect possible mutations that could predict enhanced infectivity or pathogenicity.