How do scientists know if individual wild birds are infected with avian influenza?

While rare, human infections with avian influenza viruses have occurred. The Centers for Disease Control (CDC) consider the risk to the general public from infections to be low. There have been human cases associated with the dairy cattle and wild bird strains of HPAI.  To date, most human cases have been associated with farm workers (poultry and dairy cattle operations) as well as people who have...

Wild birds can directly or indirectly spread avian influenza to domestic poultry. The indirect route is likely most common due to viral contamination of the farm environment (feed, equipment, boots, clothes).  The U.S. Department of Agriculture has found that farm-to-farm movement is also a major route for avian influenza spread, noting that farm biosecurity is critical to reduce the risk of avian...

Avian influenza (AI) type A viruses are divided into subtypes based on two proteins on the surface of the virus: Hemagglutinin (HA), of which there are 16 subtypes (H1-H16). Neuraminidase (NA), of which there are 9 subtypes (N1-N9). Many combinations of HA and NA proteins are possible, for example H5N1, H5N2, H7N2, and H7N8. AI viruses are also classified into two groups based on their ability to...

Avian influenza (AI) is caused by influenza type A viruses that historically have spread between wild birds (waterfowl and shorebirds) with occasional outbreaks in poultry (chickens, turkeys). These viruses can change over time and there has been a fundamental change with AI viruses now causing illness and death in wild birds, wild mammals, poultry, dairy cattle, cats, and people. Learn more...

West Nile Virus (WNV) has been detected in at least 48 species of mosquitoes, over 320 species of birds, at least 2 species of reptiles, and more than 25 mammalian species, including horses and humans. Birds are the natural host and reservoir of WNV. Although other animals are susceptible to WNV infection, only birds develop a high enough virus load to transmit the infection to an uninfected...

Chronic wasting disease (CWD) is a fatal, neurological illness occurring in North American cervids (members of the deer family), including white-tailed deer, mule deer, elk, and moose. Since its discovery in 1967, CWD has spread geographically and increased in prevalence locally. CWD is contagious; it can be transmitted freely within and among cervid populations. No treatments or vaccines are...

White-nose syndrome is an emergent disease of hibernating bats that has spread from the northeastern to the central United States at an alarming rate. Since the winter of 2007-2008, millions of insect-eating bats in at least 40 states and eight Canadian provinces have died from this devastating disease. The disease is named for the white fungus, Pseudogymnoascus destructans, that infects skin of...