Competence of American robins as reservoir hosts for Lyme disease spirochetes

To explore the competence of American robins as a reservoir for Lyme diseas e spirochetes, we determined the susceptibility of these birds to tickborne spirochetes and their subsequent infectivity for larval vector ticks. Robi ns acquired infection and became infectious to almost all xenodiagnostic ti cks soon after exposure to infected nymphal ticks. Although infectivity wan ed after 2 months, the robins remained susceptible to reinfection, became i nfectious again, and permitted repeated feeding by vector ticks. In additio n, spirochetes passaged through birds retained infectivity for mammalian ho sts. American robins become as infectious for vector ticks as do reservoir mice, but infectivity in robins wanes more rapidly.