Dissemination and Salivary Delivery of Lyme Disease Spirochetes in Vector Ticks (Acari: Ixodidae)

Abstract

The spirochetal agent of Lyme disease, Borrelia burgdorferi, disseminated from the guts of infected Ixodes dammini ticks following host attachment and appeared in saliva before rapid engorgement commenced. In about half of the adult ticks studied, spirochetes disseminated to the hemocoel at 4 days after attachment. Of these, half produced saliva containing spirochetes. Infected nymphs correspondingly produced spirochete-containing saliva at 3 days postattachment, the time at which saliva was first collected. We conclude that contact between spirocheteinfected ticks and a host provides the stimulus that ultimately results in dissemination of infection and delivery via saliva. This salivary route of infection appears to be the route of Lyme disease transmission in nature.