| Spanish influenza | Influenza that caused several waves of pandemic in 1918-1919, resulting in more than 20 million deaths worldwide; it was particularly severe in Spain (hence the name), but now is thought to have originated in the U.S. As a form of swine influenza. (05 Mar 2000) |
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| swine influenza | An acute respiratory disease of swine caused by strains of influenza virus type A; it is believed to have become adapted to swine in the United States during the great human pandemic in 1918; fatal cases, as in such cases of pandemic influenza in man, are commonly associated with secondary bacterial pneumonia. (05 Mar 2000) |
| swine influenza viruses | Strains of influenza virus type A which cause influenza of swine and can infect humans. (05 Mar 2000) |
| duck influenza virus | An influenza A virus, a member of the family Orthomyxoviridae, distinct from human influenza A strains on bases of haemagglutination-inhibition. (05 Mar 2000) |
| immunization, influenza | See Immunization, flu. (12 Dec 1998) |
| influenza | An acute viral infection involving the respiratory tract, occurring in isolated cases, in epidemics or in pandemics striking many continents simultaneously or in sequence. It is marked by inflammation of the nasal mucosa, the pharynx and conjunctiva and by headache and severe, often generalised myalgia. Fever, chills and prostration are common. Involvement of the myocardium and of the central nervous system occur infrequently. A necrotising bronchitis and interstitial pneumonia are prominent features of severe influenza and account for the susceptibility of patients to secondary bacterial pneumonia due to Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus. The incubation period is one to three days and the disease ordinarily lasts for three to ten days. Influenza is caused by a number of serologically distinct strains of virus, designated A (with many subgroups), B and C. Synonym: flu, grippe. (18 Nov 1997) |
| influenza a | A particular genus of influenza virus. Prone to genetic variability, the influenza vaccine must be updated annually. Symptoms of influenza include fever, muscle aches, headache, malaise, chills, cough and sore throat. (27 Sep 1997) |
| influenza a virus | The type species of the genus influenzavirus a, b that causes influenza and other diseases in humans and animals. Antigenic variation occurs frequently between strains, allowing classification into subtypes and variants. Transmission is by aerosol (human and most non-aquatic hosts) or waterborne (ducks). (12 Dec 1998) |
| influenza a virus, avian | Strains of influenza a virus causing influenza in birds. Transmission is caused by close contact or is waterborne in aquatic species. (12 Dec 1998) |
| influenza a virus, human | Strains of influenza a virus causing influenza and sometimes pneumonia in humans. Transmission is by aerosol. (12 Dec 1998) |
| influenza a virus, porcine | Strains of influenza a virus causing influenza and pneumonia in domestic pigs. (12 Dec 1998) |
| influenza B | Influenza caused by strains of influenza virus type B; outbreaks are usually more limited than those due to influenza virus type A, although infections by the two types are clinically indistinguishable; occasionally associated with Reye's syndrome. (05 Mar 2000) |
| influenza bacillus | <bacteria> Bacterium sometimes associated with influenza virus infections, causes pneumonia and meningitis. (18 Nov 1997) |
| influenza b virus | Species of the genus influenzavirus a, b that cause influenza and other diseases in humans only. Antigenic variation is less extensive than in type a viruses (influenza a virus) and consequently there is no basis for distinct subtypes or variants. Epidemics are less likely than with type a and there have been no pandemics. (12 Dec 1998) |
| influenza C | Influenza caused by strains of type C influenza virus; the disease is milder than that caused by types A and B and has become uncommon in recent years. (05 Mar 2000) |