Most Cases of Asian H5N1 in People Have Been Linked to Contact with Infected Poultry
In the majority of cases, people got HPAI Asian H5N1 virus infection after direct or close contact with sick or dead poultry that were infected with the virus.
Other risk factors include visiting a live poultry market and having prolonged, unprotected close contact with patients infected with HPAI Asian H5N1.. For some HPAI Asian H5N1 cases, the source of exposure is unknown.
The timing of many human cases of HPAI Asian H5N1 has corresponded to the seasonality of HPAI Asian H5N1 virus outbreaks among poultry. Poultry outbreaks occur more often during relatively cooler periods found in months at the beginning and end of the year. However, human cases can occur at any time, especially in countries where HPAI Asian H5N1 is endemic in poultry. Currently, HPAI Asian H5N1 virus is considered endemic in poultry in six countries (Bangladesh, China, Egypt, India, Indonesia, and Vietnam), although other counties have experienced poultry outbreaks.