Rickettsia Diaporica and American Q Fever

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Davis and Cox (1) have reported the isolation of a filter-passing, infectious agent from Dermacentor andersoni collected near Nine Mile Creek, Montana; Parker and Davis (2) its experimental transmission by the tick; Cox (3) has reported its riokettsia-like nature and Dyer (4) the occurrence of the infection in a laboratory worker. More recently Cox (5) has suggested the name Rickettsia diaporica for this organism and Dyer (6) has pointed out its close relationship to that of Q fever of Australia. For lack of a better term the name “Nine Mile” fever was temporarily used to designate the disease (7, 12). We now feel that the name American Q fever is preferable.

Cross Immunity Tests

Tests carried out with guinea pigs have shown that American Q fever shows no cross immunity with Rocky Mountain spotted fever, Brazilian spotted fever, boutonneuse fever or epidemic and endemic typhus.