Canine Leishmaniosis: An Expanding Disease

Canine leishmaniosis (CanL) is an endemic and zoonotic disease in South Europe, North Africa, Medium Orient, China and South America. In the Old World Phlebotomus is the insect vector of Leishmania while in the New World the genus Lutzomyia transmits the parasite L. infantum/chagasi but also other species of Leishmania causing American tegumentary leishmaniosis. Other alternative ways of transmission such as direct contact, blood transfusion, vertical and venereal transmission have also been referred. The disease follows the geographical distribution of the vectors and is continuously expanding, particularly in South America. After the sand fly female bit the host and deposit the metacycle promastigote forms of L. infantum, the parasite is phagocyted by neutrophils and macrophages and taken to organs like spleen, lymph node, bone marrow and skin where replicates. The type of immune response developed by the host plays an important role in determining the evolution of disease. Symptomatic dogs show several clinical signs like emaciation, enlargement of lymph nodes and spleen, onicogriphosis, epistaxis, renal failure, diarrhea and variation on biochemical and haematological values. Besides the clinical evaluation, laboratorial diagnosis techniques, either conventional or molecular approaches, are extremely useful mainly in detecting asymptomatic dogs once they may be a source of infection to healthy animals and man. Treatment of CanL can be done using antimoniates, miltefosin, allopurinol, and other drugs but usually is not effective. In fact, total remission of this chronic disease is rare and relapses are common. Prophylaxis measures directed to the vector or the hosts are useful tools to restrain the spreading of this canine disease. An efficient vaccine against CanL, conferring long last immunity, being safe and affordable should be the most cost effective way to control zoonotic visceral leishmaniosis. However, with exception of Brazil, there is no available vaccine for this parasitic disease. The sequencing of L. infantum and dog genomes associated to the better understanding of the host immune response and the availability of new technologies bring new opportunities for the development of new tools able to efficiently control CanL. In this chapter, the authors propose to critically review the most relevant aspects of canine leishmaniosis, including the epidemiology of the disease, the pathology, the clinic and laboratorial diagnostic as well as the interaction of the parasite with the dog immune response, reflecting on the availability of control strategies in association with the most important current research promises underway on this area.