Presence of Leishmania amastigotes in peritoneal fluid of a dog with leishmaniasis from Alagoas, Northeast Brazil

Epidemiology of canine leishmaniasis in southern Bahia, Brazil

Leishmaniosis is a zoonosis caused by protozoa of the genus Leishmania. American cutaneous leishmaniosis (ACL) is mainly caused by the species L. amazonensis and L. braziliensis, and American visceral leishmaniosis (AVL) is caused by L. infantum chagasi. In addition to their proven roles as reservoirs of AVL, dogs are also suspected by researchers to be reservoirs of ACL due to reports of this infection in domestic environments and of infected dogs in endemic areas. The aim of this study was to detect Leishmania sp. infection in dogs from Vila Operária, Buerarema, Bahia, using parasitological tests, indirect immunofluorescent assay (IFA) and polymerase chain reaction (PCR). Furthermore, this study also aimed to identify risk factors associated with illness in dogs in this locality by conducting an epidemiological survey. For this purpose, 292 dogs were clinically evaluated for the presence of skin lesions, and the dogs that showed these changes were submitted to scarification injury to enable preparation of slides for microscopic study of amastigotes. Subsequently, the dogs underwent blood sampling for serological (IFA) and molecular (PCR) tests. Additionally, the owners of the dogs answered an epidemiological questionnaire to facilitate the identification of risk factors for exposure of dogs to pathogens of ACL. Of the 292 dogs studied, 13 (4.5%) had lesions suggestive of ACL, but with a negative parasitological examination and 147 (50.3%) were seropositive according to the IFA. Of the 273 dogs studied using PCR test, 10 (3.66%) were positive for L. braziliensis, and all samples were negative for L. infantum chagasi. Wastelands in the peridomicile and the presence of light in the household were risk factors associated with ACL. The results show that Vila Operária has asymptomatic dogs with ACL and that the detection sensitivity of the IFA was higher than that of PCR for the infected dogs.

Directions for the diagnosis, clinical staging, treatment and prevention of canine leishmaniosis

Canine leishmaniosis (CanL) due to Leishmania infantum is a life threatening zoonotic disease with a wide distribution in four continents and importance also in non-endemic regions. The purpose of this report is to present a consensus of opinions on the diagnosis, treatment, prognosis and prevention of CanL in order to standardize the management of this infection. CanL is a disease in which infection does not equal clinical illness due to the high prevalence of subclinical infection among endemic canine populations. The most useful diagnostic approaches include serology by quantitative techniques and PCR. High antibody levels are associated with severe parasitism and disease and are diagnostic of clinical leishmaniosis. However, the presence of lower antibody levels is not necessarily indicative of disease and further work-up is necessary to confirm CanL by other diagnostic methods such as cytology, histopathology and PCR. We propose a system of four clinical stages, based on clinical signs, clinicopathological abnormalities and serological status. Suitable therapy and expected prognosis are presented for each of the stages. The combination of meglumine antimoniate and allopurinol constitutes the first line pharmaceutical protocol. However, although most dogs recover clinically after therapy, complete elimination of the parasite is usually not achieved and infected dogs may eventually relapse. Follow-up of treated dogs with blood counts, serum biochemistry, urinalysis, serology and PCR is essential for prevention of relapses. Protection against sand fly bites by topical insecticides is effective in reducing infection, and recent development of vaccines has indicated that prevention by vaccination is feasible.

Canine vector-borne diseases in Brazil

Canine vector-borne diseases (CVBDs) are highly prevalent in Brazil and represent a challenge to veterinarians and public health workers, since some diseases are of great zoonotic potential. Dogs are affected by many protozoa (e.g., Babesia vogeli, Leishmania infantum, and Trypanosoma cruzi), bacteria (e.g., Anaplasma platys and Ehrlichia canis), and helminths (e.g., Dirofilaria immitis and Dipylidium caninum) that are transmitted by a diverse range of arthropod vectors, including ticks, fleas, lice, triatomines, mosquitoes, tabanids, and phlebotomine sand flies. This article focuses on several aspects (etiology, transmission, distribution, prevalence, risk factors, diagnosis, control, prevention, and public health significance) of CVBDs in Brazil and discusses research gaps to be addressed in future studies.

The role of dogs as reservoirs of Leishmania parasites, with emphasis on Leishmania (Leishmania) infantum and Leishmania (Viannia) braziliensis

Leishmania parasites cause a group of diseases collectively known as leishmaniases. The primary hosts of Leishmania are sylvatic mammals of several orders (Rodentia, Marsupialia, Carnivora, etc.). Under certain circumstances, particularly in peridomestic and domestic transmission foci, synanthropic and domestic animals can act as source of infection for phlebotomine sand fly vectors. Dogs have long been implicated as the main domestic reservoirs of Leishmania (Leishmania) infantum, the aetiological agent of zoonotic visceral leishmaniasis, and there exists an increasing trend to regard dogs as the main domestic reservoirs of Leishmania (Viannia) braziliensis, the most widespread aetiological agent of American tegumentary leishmaniasis. However, insights derived from recent research indicate that not dogs but humans are probably the most important domestic reservoirs of L. (V.) braziliensis. In the present article, the role of dogs as reservoirs of Leishmania parasites, with emphasis on L. (L.) infantum and L. (V.) braziliensis, is reviewed.