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Q FEVER

Epidemiology

Q fever was so named by Derrick in 1937 as ‘query fever’ before the causative organism was discovered, and not after Queensland where he discovered it. The strange name has persisted, despite the discovery and naming of the causative agent Coxiella burnetii. The disease has also been known as ‘Balkan grippe', ‘Red River fever’ (Zaire) and ‘Nine Mile fever’ (from a creek in the Rocky Mountains). C. burnetii is a 0.3–0.7 μm-long pleomorphic Gram-negative coccobacillus. A spore stage exists, which explains why C. burnetii is particularly resistant to heat and drying. C. burnetii undergoes a phase variation. The virulent phase I exists in nature and in laboratory animals; and, due to chromosomal deletions,[61] the avirulent phase II develops following repeated passage of phase I bacteria in embryonated chicken eggs. In nature, C. burnetii exists in arthropods, rodents, birds and even fish, and arthropods, including ticks, transmit bacteria to domestic goats, sheep and cattle. Humans …