Asymptomatic Leishmaniosis in Dogs

Often more than 50% of dogs with a proven Leishmania infection are asymptomatic carriers. They are usually not presented to the veterinarian but can transmit the disease and therefore help maintaining a Leishmania infection in an endemic area. In fected dogs without clinical signs may be translocated to previously non-endemic regions. General protection of dogs by using a repellent parasiticide against sand flies could reduce the vector-host contact in infected symptomatic and asymp tomatic carriers, and therefore will help to control this canine vectorborne disease (CVBD) as well as the corresponding zoonotic disease of visceral leishmaniosis. Canine leishmaniosis (canL) is a severe, chronic, zoonotic, vector-borne disease with an endemic distribution in the Mediterranean basin, Asia and Latin America. The main agent for viscerocutaneous leishmaniosis in dogs is the protozoan Leishmania (donovani) infantum, syn. L. chagasi in the New World that also may cause visceral leishmaniosis (VL) in humans (Fig. 1). L. infantum is an (obligate) heteroxenous parasite, i.e. it needs two hosts to develop. The insect hosts of Leishmania are phlebotomine sand flies of the genus Phlebotomus (Old W orld) and Lutzomyia (New World) (Fig. 2). Regarding the vertebrates, the principal hosts of L. infantum are dogs and other members of the Canidae family (foxes, jackals, wolves).