Abstract
In canine leishmaniosis caused by the protozoan Leishmania infantum, little is known about how co-infections with or co-seropositivities for other pathogens can influence aggravation of this disease. Therefore, the objectives of this study were to evaluate the frequency of co-infections with or co-seropositivities for certain pathogens in dogs seropositive for L. infantum and their relationship with clinical signs, histological changes and L. infantum load. Sixty-six L. infantum-seropositive dogs were submitted to clinical examination, collection of blood and bone marrow, culling, and necropsy. Antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato, Ehrlichia spp. and Toxoplasma gondii and Dirofilaria immitis antigens were investigated in serum. Samples from different tissues were submitted to histopathology and immunohistochemistry for the detection of Leishmania spp. and T. gondii. Quantitative real-time PCR was used to assess the L. infantum load in spleen samples. For detection of Coxiella burnetii, conventional PCR and nested PCR were performed using bone marrow samples. All 66 dogs tested positive for L. infantum by qPCR and/or culture. Fifty dogs (76%) were co-seropositive for at least one pathogen: T. gondii (59%), Ehrlichia spp., (41%), and Anaplasma spp. (18%). Clinical signs were observed in 15 (94%) dogs monoinfected with L. infantum and in 45 (90%) dogs co-seropositive for certain pathogens. The L. infantum load in spleen and skin did not differ significantly between monoinfected and co-seropositive dogs. The number of inflammatory cells was higher in the spleen, lung and mammary gland of co-seropositive dogs and in the mitral valve of monoinfected dogs. These results suggest that dogs infected with L. infantum and co-seropositive for certain pathogens are common in the region studied. However, co-seropositivities for certain pathogens did not aggravate clinical signs or L. infantum load, although they were associated with a more intense inflammatory reaction in some organs.
Highlights
In Brazil, visceral leishmaniosis (VL) caused by the protozoan Leishmania (Leishmania) infantum is a zoonosis of important public health concern
The objectives of this study were to evaluate the frequency of co-infections with or co-seropositivities for certain pathogens in dogs infected with L. infantum and their relationship with clinical signs, histological changes and L. infantum load
The following frequencies of co-seropositivity for certain pathogens were observed in the 66 dogs investigated: T. gondii (59%), Ehrlichia spp. (41%), and Anaplasma spp. (18%)
Summary
In Brazil, visceral leishmaniosis (VL) caused by the protozoan Leishmania (Leishmania) infantum is a zoonosis of important public health concern. Studies that evaluate the parasite load and histological changes in different organs together with clinical changes in co-infections with or co-seropositivities for L. infantum in dogs are scarce Such investigations would be important to determine whether dogs infected with L. infantum and co-infected with or co-seropositive for certain pathogens have a greater potential for transmission of L. infantum, and to subsequently develop preventive and control measures for the involved agents. Within this context, the objectives of this study were to evaluate the frequency of co-infections with or co-seropositivities for certain pathogens in dogs infected with L. infantum and their relationship with clinical signs, histological changes and L. infantum load
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