Absence of Lyme disease spirochetes in larval progeny of naturally infected Ixodes scapularis (Acari:Ixodidae) fed on dogs.
I determined whether transovarial passage of Lyme disease spirochetes occurred more efficiently in Ixodes scapularis Say fed on reservoir-competent dogs. Unlike deerfed ticks, spirochetes are not diminished in dog-fed ticks, and significantly higher transovarial infection rates have been reported for the latter. Females of field-infected I. scapularis (North Salem strain) were used to induce experimental Lyme disease in specific pathogen-free dogs as part of another study. Seventy-four (48 of 65) percent of the females examined were infected with spirochetes, and larvae from infected females were tested for Borrelia burgdorferi within 1 mo of eclosion. No spirochetes were found in 14,700 larvae (225 larvae per female [n = 12] and 750 larvae per female [n = 16]) examined individually by fluorescent antibody (FA) tests or in triturated larval suspensions (approximately 1,500 larvae per female (n = 20]) examined by FA and polymerase chain reaction. Larvae remain an unlikely source of B. burgdorferi infection in the peridomestic setting because transovarial transmission is highly inefficient in I. scapularis.
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Department of Entomology, Cornell University, Ithaca, NY 14853, USA.
D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D015748:Borrelia burgdorferi Group / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004269:DNA, Bacterial / Q000032:analysis; D004285:Dogs / Q000469:parasitology; D005260:Female; D005408:Flagellin / Q000235:genetics; D019085:Fluorescent Antibody Technique, Direct; D018884:Ixodes / Q000382:microbiology*; D007814:Larva; D008193:Lyme Disease / Q000382:microbiology*; D008297:Male
D000942:Antigens, Bacterial; D004269:DNA, Bacterial; D005408:Flagellin