H5 HPAI outbreaks in poultry flocks in the USA

Since December 2014, the United States Department of Agriculture (USDA) has confirmed H5 Highly Pathogenic Avian Influenza (HPAI) in commercial and backyard poultry flocks in the United States. At least 142 separate incidents have been detected through May 7, 2015; most are the H5N2 virus.[1] According to USDA, more than 29 million birds have been infected including chickens, ducks, pheasants, and turkeys mostly in commercial poultry flocks. Chickens represent about 81% of all infected poultry followed by turkeys with 18% of the total.

In addition to the poultry flock infections in the United States, at least 60 incidents of detection of H5 HPAI in wild birds have also been reported since early December 2014 from the 13 states [2] shown in the map below.

H5 HPAI has been detected in poultry flocks in 13 states as well. However, there is no on-to-one correspondence between the states reporting wild bird infections and those with poultry flock infections as show on the map below.

Based on the number of infected birds, the geographic distribution of the H5 HPAI poultry outbreaks is concentrated in the Upper Midwest. There is no sign that the poultry flock infections are declining. The good news is that no human cases of these H5 subtypes have been reported from the United States. And according the Center for Disease Control, the risk of human infection from these H5 avian influenza subtypes is low.[3]

[1] Update on Avian Influenza Findings - Poultry Findings Confirmed by USDA’s National Veterinary Services Laboratories

[2] Wild Bird Highly Pathogenic Avian Influenza Cases in the United States (USDA)

[3] H5 Viruses in the United States