We describe a procedure for the introduction of Borrelia burgdorferi, the spirochetal agent of Lyme disease, into larvae of the tick vector Ixodes scapularis. Internalized spirochetes were observed in larvae examined after 15 or 45 min immersion at 32°C in liquid culture suspensions of low passage B. burgdorferi strain B31. Larval ticks immersed in low passage strain B31 were able to feed to repletion on white-footed mice. Midguts of larvae contained many spirochetes 1 wk postengorgement, while larvae incubated with high passage strain B31 were free of detectable spirochetes at the same interval. Larvae incubated with low passage strain B31 were competent to transmit the pathogen to mice, as shown by serology, reisolation of B. burgdorferi from mice, and xenodiagnosis. Ticks maintained the infection transstadially to the nymphal stage and transmitted the infection to naive mice, replicating an essential aspect of natural infection. This method requires no special equipment and allows artificial infection of large numbers of ticks at the larval stage. It will facilitate studies of the contribution of specific B. burgdorferi genetic loci to tick colonization.
Journal of Medical Entomology is published bimonthly in January, March, May, July, September, and November. The journal publishes reports on all phases of medical entomology and medical acarology, including the systematics and biology of insects, acarines, and other arthropods of public health and veterinary significance. The journal is divided into the following sections: Morphology, Systematics, Evolution; Sampling, Distribution, Dispersal; Development, Life History; Population and Community Ecology; Behavior, Chemical Ecology; Population Biology/Genetics; Molecular Biology/Genomics; Neurobiology, Physiology, Biochemistry; Vector Control, Pest Management, Resistance, Repellents; Arthropod/Host Interaction, Immunity; Vector/Pathogen/Host Interaction, Transmission; Vector-Borne Diseases, Surveillance, Prevention; Direct Injury, Myiasis, Forensics; Modeling/GIS, Risk Assessment, Economic Impact. In addition to full-length research articles, the journal publishes interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.