Black rats (Rattus rattus) receiving Leishmania tropica injected intradermally into the ear were studied for the persistence of parasites and infectivity to natural sand fly vector. The mammalian host, the parasite, and the vector all originated from the endemic focus of Urfa, Turkey. Rats did not develop lesions or any apparent signs of disease, although at the site of inoculation they harboured live parasites capable of infecting sand flies. The number of L. tropica amastigotes detected in the inoculated ear by quantitative real-time PCR ranged from 5 x 10(3) to 10(6). Parasite DNA was also present in the tail and contralateral ear, sites distant from inoculation. After feeding on the ears of asymptomatic rats, Phlebotomus sergenti became infected with L. tropica. The average infection rate was 2.9%, and rats were infective for sand flies even 24 months post infection. The infectivity of the vertebrate host for insect vector was therefore not linked to the symptomatic stage of the infection. Such lack of correlation between clinical symptoms and infectivity to sand flies was reported previously for Leishmania infantum, the agent of visceral leishmaniasis; for species causing cutaneous leishmaniasis, however, this is the first evidence of transmission from a host without any visible cutaneous changes. If confirmed in the field, transmission from the asymptomatic host would be of great epidemiological significance.

Department of Parasitology Faculty of Science Charles University Vinicná 7 128 44 2 Prague Czech Republic

References provided by Crossref.org

Infectiousness of Asymptomatic Meriones shawi, Reservoir Host of Leishmania major

Promastigote secretory gel from natural and unnatural sand fly vectors exacerbate Leishmania major and Leishmania tropica cutaneous leishmaniasis in mice

Host competence of African rodents Arvicanthis neumanni, A. niloticus and Mastomys natalensis for Leishmania major

The Biting Midge Culicoides sonorensis (Diptera: Ceratopogonidae) Is Capable of Developing Late Stage Infections of Leishmania enriettii

Hyaluronidase of bloodsucking insects and its enhancing effect on leishmania infection in mice