influenza

An acute contagious viral infection of humans, characterized by inflammation of the respiratory tract and by fever, chills, muscular pain, and prostration.

Any of various viral infections of domestic or wild animals, generally characterized by fever and respiratory involvement.

An epidemic catarrh of an aggravated kind, attended with serious febrile symptoms and rapid prostration.

A prevailing influence; an epidemic.

Influenza is an acute infectious disease of which the most prominent symptoms are fever, general prostration, pains in various parts of the body, and inflammatory processes attacking the serous or mucous membranes, the lungs, or the nerves. The onset is usually abrupt with headache, backache, fever, and loss of strength. According to the organs most affected in its further progress, the disease is said to be of the respiratory, nervous, or gastro-intestinal form. Influenza is noteworthy for the rapidity with which an epidemic sweeps over entire countries and even from one continent to another, and for the large proportion of the population attacked when it is prevalent. The disease is caused by a small, non-motile bacillus which occurs in great numbers in the nasal and bronchial secretions of the patients. Influenza has a low death rate, but its effect on the general health is often severe and lasting, and many grave sequelæ are possible. One attack does not protect against a second. The ordinary influenza or ‘grippe,’ though in some ways simulating true epidemic influenza, is a different and much milder disease.