|A) Some or all of the following clinical signs are evident in infected birds: |
quietness and extreme depression;
sudden drop in production of eggs, many of which are soft-shelled or shell-less;
wattles and combs become swollen and congested;
swelling of the skin under the eyes;
coughing, sneezing and nervous signs;
odema (swelling) and congestion of the combs;
hemorrhages on the hock;
a few deaths may occur over several days, but an outbreak may follow, killing hundreds or thousands of birds each day.
Diagnosis of avian influenza may be made on the basis of clinical signs and events leading to the disease. However, since the signs and course of avian influenza are similar to other diseases, laboratory diagnosis is essential.