Influenza Importance Influenza Viruses Are Highly Variable RNA Viruses That Can Affect Birds and Mammals Including Humans
Influenza Importance Influenza viruses are highly variable RNA viruses that can affect birds and mammals including humans. There are currently three species of these viruses, Flu, Grippe, Avian Influenza, designated influenza A, B and C. A new influenza C-related virus recently detected in Grippe Aviaire, Fowl Plague, livestock has been proposed as “influenza D.”1-6 Swine Influenza, Hog Flu, Influenza A viruses are widespread and diverse in wild aquatic birds, which are Pig Flu, Equine Influenza, thought to be their natural hosts. Poultry are readily infected, and a limited number of Canine Influenza viruses have adapted to circulate in people, pigs, horses and dogs. In the mammals to which they are adapted, influenza A viruses usually cause respiratory illnesses with Last Full Review: February 2016 high morbidity but low mortality rates.7-29 More severe or fatal cases tend to occur mainly in conjunction with other diseases, debilitation or immunosuppression, as well as during infancy, pregnancy or old age; however, the risk of severe illness in healthy Author: humans can increase significantly during pandemics.7,9,11,12,14,20,30-47 Two types of Anna Rovid Spickler, DVM, PhD influenza viruses are maintained in birds. The majority of these viruses are known as low pathogenic avian influenza (LPAI) viruses. They usually infect birds asymptomatically or cause relatively mild clinical signs, unless the disease is 7,46,48-56 exacerbated by factors such as co-infections with other pathogens. However, some LPAI viruses can mutate to become highly pathogenic avian influenza (HPAI) viruses, which cause devastating outbreaks of systemic disease in chickens and turkeys, with morbidity and mortality rates as high as 90-100%.50-52 Although influenza A viruses are host-adapted, they may occasionally infect other species, and on rare occasions, a virus will change enough to circulate in a new host.
[Show full text]