ClinQuiz: Fast tick facts, answer 3B

3B–Correct.

Although both the vector tick, I. scapularis, and the causative agent, B. burgdorferi, have been recovered from nature in the South, locally acquired, laboratory-confirmed infections of people or dogs in this region have not been definitively shown. 11,12 The difference appears to relate to the behavior of the ticks responsible for cycling the infection in different regions. In the South, immature I. scapularis prefer to feed on lizards rather than on rodents. Since lizards are not considered a competent reservoir host for B. burgdorferi, the tick is rarely infected in this region. The Ixodes species that cycle the infection in rodents do not frequently feed on dogs or people. 10 Without a bridge vector to carry infection from rodent reservoirs to dogs or people, locally acquired cases of classic Lyme borreliosis caused by B. burgdorferi appear to be rare in the South, if they occur at all. Furthermore, in areas of the United States where B. burgdorferi infection is not endemic, vaccinating dogs against Lyme disease is not routinely practiced. 13

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