A i

 Clinical Description  This image was taken 2 days post experimental inoculation with highly pathogenic avian influenza.

A 6 week old male is standing among several deceased 70 week old hens. The older females succumbed more rapidly to the HPAI than the younger males, due to the physiologic stress associated with molting. In HPAI, the duration of onset of clinical signs and severity of signs will vary depending on factors such as species, age, physiologic stress, and concurrent infections. As demonstrated here, HPAI is marked by high morbidity and mortality. Of the 20 chickens inoculated experimentally, 19 died within 5 days of exposure to the infection.

Some birds infected with HPAI die peracutely, showing no clinical signs prior to being found dead.