Dispersal of the Lyme Disease Spirochete Borrelia burgdorferi to Salivary Glands of Feeding Nymphal Ixodes scapularis (Acari: Ixodidae)

Salivary gland explant cultures from 3/16 (19%) of unfed nymphal Ixodes scapularis Say contained Lyme disease spirochetes, increasing to a maximum of 14/16 (88%) at 72 h of tick feeding. Homogenates of tick salivary glands did not produce infection in laboratory white mice unless harvested from ticks attached for > or = 60 h. Dispersal of spirochetes to the salivary glands appears to occur during the act of tick feeding, thus affecting the ability of ticks to transmit Borrelia burgdorferi.