Guidelines for prevention of leishmaniasis in dogs

Human infections with Leishmania protozoan parasites, transmitted by the bite of phlebotomine sand flies, cause visceral, cutaneous, or mucocutaneous leishmaniasis. Eighty-eight countries are affected, with > 2 million new infections worldwide each year.1 The most severe disease forms are anthroponotic VL due to Leishmania donovani in the Indian subcontinent and parts of central Asia and Africa and zoonotic VL due to Leishmania infantum (Leishmania chagasi) in the Mediterranean, parts of Asia, and Latin America. Domestic dogs are the only confirmed domestic reservoir of zoonotic VL.2 Reports3–5 from various areas suggest that the geographic range of leishmaniasis in dogs is changing, including detection of new foci in northern Italy and an extension of disease distribution in Israel and France. Moreover, there is some evidence that leishmaniasis in dogs could be enzootic in the United States. Sporadic autochthonous cases of disease have been reported in North America since early 1980.6 Of particular importance is the outbreak of leishmaniasis in Foxhounds at a New York kennel, which was first detected in 1999. A subsequent survey involving Foxhounds, other breeds of dogs, and wild canids revealed that leishmaniasis in dogs is enzootic in 18 states and 2 Canadian provinces. The lack of spread from Foxhounds to the wider dog population or local wild canid population suggests that sand fly transmission could not be involved, and thus infection in these dogs must be maintained by non–sand fly transmission routes. Neglected by researchers and funding agencies, leishmaniasis control strategies have varied little for decades, but in recent years, there have been advances in diagnosis, treatment, and prevention of the disease. Advances in prevention include evidence that the incidence of zoonotic VL, both in humans and dogs, can be reduced by treating dogs with dermal application of synthetic pyrethroids.7 In a broad sense, the term prevention includes the application of measures intended to avoid instances of infection by a pathogen or the pathological outcome of such instances. Vaccination against pathogens is regarded as a milestone in the field of infectious disease prevention; however, this important tool is not yet available worldwide for prevention of leishmaniasis in dogs. Guidelines developed by the Canine Leishmaniasis Working Group for diagnosis, clinical classification, and treatment of leishmaniasis in dogs have been published.8,9 Here, we review preventive strategies by updating guidelines previously published in Italian in Veterinaria, the official journal of the Italian Society of Veterinarians of Companion Animals.10 The guidelines reported here are a result of a thorough review of international literature and, where inadequate or incomplete information existed, the experience of working group members. For completeness, we include a summary of research conducted to produce safe Leishmania vaccines for dogs. Therefore, the guidelines concern available preventive measures against phlebotomine sand flies, the only established Leishmania vector. It should be pointed out, however, that non–sand fly transmission routes have long been suspected and some have been confirmed experimentally, such as transplacental11 and sexual12 routes as well as via blood transfusion,13 although no evidence exists for transmission via saliva or conjunctiva fluids. All these transmission routes could be particularly important in areas in which autochthonous leishmaniasis in dogs has been reported in the absence of sand flies (eg, northern Europe)14 or in which local sand fly species have not yet been implicated in enzootic transmission of leishmaniasis (eg, North America). In such circumstances, our guidelines may not be effective or relevant.