AP BIOLOGY

Detailed explanation-1: -Influenza A viruses are found in many different animals, including ducks, chickens, pigs, whales, horses, seals and cats. Influenza B viruses circulate widely only among humans.

Detailed explanation-2: -Flu is a respiratory illness in various animals. Influenza viruses affect several different animals, such as; horses, cats, dogs, birds, swine, and people. It is contagious and spreads rapidly among susceptible animals. Many influenza A viruses infect poultry. Clinical signs are mainly in chickens and turkeys.

Detailed explanation-3: -Influenza A virus subtypes currently endemic in humans are H3N2 and H1N1 viruses. Examples of different influenza A virus subtypes currently endemic in animals include H1N1 and H3N2 in pigs (different strains than those found in humans), H3N8 in horses, H3N2 in dogs, and H5N1 in wild water birds and domestic poultry.

Detailed explanation-4: -There are four types of influenza viruses: A, B, C, and D. Influenza A and B viruses cause seasonal epidemics of disease in people (known as flu season) almost every winter in the United States. Influenza A viruses are the only influenza viruses known to cause flu pandemics (i.e., global epidemics of flu disease).

Detailed explanation-5: -The predominant natural reservoir of influenza viruses is thought to be wild waterfowl (Webster et al. 1992). Periodically, genetic material from avian virus strains is transferred to virus strains infectious to humans by a process called reassortment.