Diagnosis of visceral leishmaniasis

Abstract

The aim of this thesis was to establish the accuracy measures of diagnostic tests for canine visceral leishmaniasis (CVL) and to carry out serological and molecular diagnosis of abandoned dogs and cats in the Central region of Colombia, identifying the circulating species of Leishmania spp. Through a systematic review and meta-analysis, studies were selected that calculated the diagnostic sensitivity (DSe) and diagnostic specificity (DSp) of CVL diagnostic tests. These data were then recalculated taking into account whether or not asymptomatic and cross-reacting animals were used. The direct agglutination test (DAT) with crude Leishmania donovani antigen showed the best results, both for DSe [0.9942 (95% CI: 0.9892-0.9969)] and DSp [0.9796 (95% CI: 0.9492-0.9920)] and it was also found that DSe values decrease as asymptomatic animals are added and that DSp values decrease when cross-reacting animals are added. Serological tests are the most commonly used and the DAT- L. donovani showed the best results. The CVL diagnosis of abandoned dogs in Colombia took place in a shelter in Girardot and involved a clinical examination, laboratory tests, serological diagnosis, molecular diagnosis and genomic sequencing. Seropositivity was 25.3% and 37.5% in both serological techniques, the rKDDR-plus immunochromatographic test (ICTrKDDR- plus) and the rKDDR-plus enzyme-linked immunosorbent assay (ELISArkDDR- plus). In the polymerase chain reaction (PCR) using the RV1-RV2 gene, 10.5 per cent of the animals tested positive and in the multiplex PCR, 11.8 per cent of the animals tested positive. The sequenced sample showed 99.0% similarity to L. infantum. The presence of L. infantum in the Central region of Colombia was confirmed for the first time, which emphasises the need to develop strategies to control and prevent this zoonosis in the region. The serological and molecular diagnosis of leishmaniasis in abandoned cats in Colombia took place at the same shelter in Girardot. It found 100.00% seropositivity in the ELISA-rKDDR-plus and 37.5% seropositivity in the ICTrKDDR- plus and in the PCR with the HSP-70 gene it was 33.0%. Therefore, felines were found to be serologically and molecularly positive for leishmaniasis, suggesting the involvement of this species in the transmission cycle of this disease. This partnership between Brazil and Colombia has made it possible to realise that L. infantum is present in both territories, as well as the possibility of sharing knowledge with new insights and advancing research on the subject.