Bad development – bird flu often goes unnoticed among people in the US

“Despite ongoing efforts to monitor dairy workers for disease, test for H5N1, and provide antiviral treatment, several factors have prevented a comprehensive understanding of the extent of cow-to-human transmission,” the CDC says.

When testing employees in companies where the virus was found in cows, an infection rate of seven percent was found. The study collected a total of 115 blood samples from workers at factories in two states between June and August.

Eight of the samples showed that the employees had recently become infected with the H5N1 bird flu virus. Only a few of them showed mild symptoms of illness. All employees surveyed reported milking cows or cleaning the milking parlor, according to the CDC. According to current research, H5N1 is mainly transmitted between cows through milk.

Full extent unclear
H5N1 bird flu is currently widespread among wild birds around the world, and numerous wild mammals are also becoming infected. The virus has also recently led to outbreaks on poultry and dairy farms in the US. However, the extent of this is largely unclear due to a lack of data.

Since April this year, the CDC has recorded 46 human cases, mostly among dairy and poultry farm workers, with mild cases. Human-to-human transmission has not yet been proven. The CDC continues to assess the risk to the general population as low.

Now CDC says the 46 cases are likely just a portion of the actual infections. The employees are often not seriously ill and some companies do not want to participate in the tests.

Fear of mutations
Researchers fear the virus may become more adaptable to mammals if it circulates widely there. A study published in August showed transmission from mammals to mammals, including between species, such as from cows to cats. Mutations in the virus that would lead to better transmissibility of H5N1 to humans have not yet been discovered.