Natural Occurrence of Tularemia in the Lone Star Tick, Amblyomma Americanum (Linn.), and in Dogs in Arkansas

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  • Public Health Service, Communicable Disease Center, Atlanta, Georgia


Epidemiological investigations of tularemia in Arkansas revealed that the highest incidence of human tularemia within the State occurred during the months of April through September, with approximately 56 per cent of the yearly reported cases having a history of tick bite. These epidemiological investigations prompted a cooperative project between the Communicable Disease Center and the Arkansas State Board of Health.

Data collected for two consecutive years indicate that the lone star tick is the predominant tick in Arkansas, followed by the American dog tick during the summer, as represented by collections from cattle and dogs and by dragging. The American dog tick was found to be the more widely distributed of the two species within the State. The lone star tick predominated in the more mountainous and heavily wooded areas.

Pasteurella tularensis was isolated from six different lots of lone star ticks (1 in 1951 and 5 in 1952) collected from dogs and cattle and by drags. Two of the positive lots were composed entirely of adult female lone star ticks. Though one large collection of American dog ticks was removed from the same hosts at the time the positive lone star ticks were collected, none of the American dog tick collections was found to be positive for tularemia.

Blood specimens were taken from the hosts from which the positive lots of ticks were removed. Of sera of seven dogs submitted for the tularemia agglutination tests, six were found positive in dilutions from 1:40 to 1:640. Three cow blood specimens gave positive tularemia reactions in dilutions of 1:80.