Global Distribution of Canine Visceral Leishmaniasis and the Role of the Dog in the Epidemiology of the Disease

Abstract

Visceral leishmaniasis is a disease caused by protozoa of the species Leishmania (Leishmania) infantum (syn=Leishmania chagasi) and Leishmania (Leishmania) donovani, which are transmitted by hematophagous in-sects of the genera Lutzomyia and Phlebotomus. The domestic dog (Canis familiaris) is considered the main ur-ban reservoir of the parasite due to the high parasite load on its skin, serving as a source of infection for sand-fly vectors and, consequently, perpetuating the disease in the urban environment. Some factors are consid-ered important in the perpetuation and spread of canine visceral leishmaniasis (CVL) in urban areas, such as stray dogs with their errant behavior and houses that have backyards with trees, shade, and organic materi-als, creating an attractive environment for sandfly vectors. CVL is found in approximately 50 countries with the number of infected dogs reaching millions and, due to the difficulty of controlling and diagnosing the disease, the number of infected animals could be even greater. In the four continents endemic for CVL there are reports of disease expansion in endemic countries such as Brazil, Italy, Morocco, and Tunisia, as well as in areas where CVL is not endemic, for example, Uruguay. Socio-environmental factors, such as migration, drought, deforestation, and global warming, have been pointed out as one of the reasons for expansion to ar-eas where it had been absent. Thus, the objective of this review is to address (i) the distribution of CVL in endemic areas (ii) the role of the dog in the visceral leishmaniasis epidemiology and the factors that influence dog infection and spread of the disease, and (iii) the challenges faced in the control of CVL.