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Evaluation of PCR techniques for the identification and characterization of Visceral Leishmaniasis in different tissues of seropositive dogs

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Thaynan Fernandes Cunha Martins
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Medicina Tropical de São Paulo (IMT)
Defense date:
Examining board members:
Paulo Cesar Cotrim; Vera Lucia Pereira Chioccola; Marcia Dalastra Laurenti
Advisor: Paulo Cesar Cotrim

Currently, one of the major problems related to leishmaniasis is the lack of a specific diagnosis capable of identifying and differentiating Leishmania species quickly and accurately. The development of molecular methods such as Polymerase Chain Reaction ( PCR ) allows the diagnosis of Canine Visceral Leishmaniasis (CVL) to become more accurate and eventually, easy to perform, since that important limitations in terms of sensitivity and specificity of this technique are being described especially when using clinical samples. In order to better evaluate the efficiency of PCR for the diagnosis of CVL, we selected different clinical samples (spleen, lymph node aspirate, skin with and without lesions and blood samples) from 26 dogs with positive serology for leishmaniasis submitted to euthanasia by the Agency of Epidemiological Surveillance of Embu das Artes - SP. Therefore, we performed a comparative analysis between the kDNAPCR-RFLP HaeIII and hsp70PCR-RFLP BsaJI/EcoRII with two traditional diagnostic methods (direct parasitological test, and in vitro culture). Additionally, clinical samples from 28 dogs with negative serology for CVL in the same region were used as negative reactions control. We noted that the PCR showed greater sensitivity in all clinical samples tested when compared with traditional methods. The results indicate that the kDNAPCR-RFLP HaeIII is the most efficient test for the diagnosis of CVL, with a positivity index of 96.15 % in skin lesions samples. Related to the discrimination of the Leishmania species involved in the infection, our results of kDNAPCR-RFLP HaeIII indicate Leishmania infantum chagasi as the agent involved in canine infection in Embu das Artes city. Moreover, the analysis of real-time PCR (qPCR) showed that some blood samples has not showed the same pattern associated with Leishmania infantum chagasi suggesting a possible co-infection with other canine parasite. Our group also followed 184 children between 4 to 10 years old (risk population) living in the same region of autochthonous transmission of canine disease, as well a survey was conducted on the sandfly species in the region (by SUCEN). So far, we found no human infection, nor the main species involved in the transmission of the parasite (Lutzomyia longipalpis). We believe that these results can significantly contribute to the improvement of the diagnosis and identification of Leishmania species involved in the CVL worldwide. (AU)