As a highly contagious avian influenza virus spread through the U.S.'s poultry population in 2015, something else began catching on: the word "depopulation."

The avian influenza epidemic of 2015 required a cooperative effort between state and federal agricultural officials and the poultry industry. Wisconsin's Department of Agriculture, Trade and Consumer Protection worked with affected farms to confirm the presence of H5N2 and drew on its own expertise and personnel, as well as those of federal agencies and ag-industry partners to coordinate a response.

Wild birds, particularly migratory waterfowl, can contract and transmit both low and highly pathogenic avian influenza viruses. The Animal and Plant Health Inspection Service with the U.S. Department of Agriculture encourages hunters and other persons engaging in outdoor recreation to help track the avian flu.

Avian influenzas, including the highly pathogenic varieties, can infect birds both wild and domesticated. Birds carrying the virus can pass it on to other birds through airborne contact, as it is found in respiratory secretions and saliva.