Detection of visceral leishmaniosis in feral dogs in Bangladesh by conventional and molecular methods.
An investigation was carried out to recognize the occurrence of visceral leishmaniosis(VL) in cattle, goats and dogs in the endemic zone of VL at Mymensingh district, Bangladesh. Venous blood, liver and spleen from the cattle, goats and dogs (50 from each) were collected from slaughter house during 2011 to 2015. Detection of the parasite was through examination of stained smear, histopathology and using polymerase chain reaction (PCR) technique. The investigations have revealed amastigote stage of Leishmania in the splenic smears of three dogs. Microgranulomas were seen in the liver of two dogs but amastigote stage of the parasite was not seen in the cytoplasm of macrophages. The PCR protocol was carried out using DNA from the blood, liver and spleen, targeting kinitoplast minicircle DNA (kDNA). A 145 bp fragment of kDNA gene was amplified in positive cases of one cattle, seven goats and seven dogs. Two more PCR protocols were, adapted targeting 18S rRNA and cysteine proteases genes to support this observation. Genomic DNA from the blood, spleen and liver of cattle, goats and dogs while used in PCR amplified 18S rRNA and cysteine proteases gene specific fragments of Leishmania donovani in the spleen of two dogs. Phylogenetic analyses of 741 bp fragment of the cysteine proteases gene confirmed that the protozoa as L. donovani. PCR protocol targeting 18S rRNA and cysteine proteases genes of Leishmania was found to be specific to detect L. donovani. This is the first report from Bangladesh confirming the visceral leishmaniosis in feral dogs using PCR. Thus, further investigations involving canids and other carrier animals is required to curtail the incidence and or successful designing of VL elimination campaign in Bangladesh.