Tripanossomatídeos: uma revisão sistemática da infecção natural por Leishmania em quirópteros e avaliação de antígeno de carboidrato no diagnóstico da infecção pelo Trypanosoma cruzi em humanos

Abstract

Due to their high mortality and morbidity rates, leishmaniasis and Chagas disease stand out among the neglected tropical illnesses and pose a severe threat to global public health. A better understanding of the participation of chiropterans in the transmission cycle of Leishmania species is a crucial point for understanding the dynamics of leishmaniasis, which can contribute to the definition of new effective and sustainable strategies for the surveillance and control of these diseases. Although Chagas disease was discovered more than 100 years ago, there are still limitations regarding its diagnosis, given the diversity of discrete typing units (DTUs) of Trypanosoma cruzi, and genetic differences between human populations. In this scenario, two studies on diseases caused by trypanosomatids were carried out. The first study aimed to perform a systematic review on the occurrence of Leishmania species in chiroptera to verify associations between feeding habits and the type of sample collected from these animals with the occurrence of infection by Leishmania species. The keywords "bats" and "Leishmania" and their synonyms were used to search the literature for studies that used molecular techniques to identify parasites. 20 of the 68 original studies that we discovered were used in the review. No significant association was observed between feeding habits, type of sample investigated and the presence of infection in these mammals. However, the review demonstrated that chiropterans can become infected with a wide variety of Leishmania species and likely play an important role in maintaining the transmission cycle of leishmaniasis. The second study aimed to investigate the carbohydrate α-Gal as a potential candidate for the diagnosis of chronic Chagas disease, since the protozoan T. cruzi has a cell surface abundant in immunogenic glycoconjugates that contains the epitope α-Gal. For this, the enzyme-linked immunosorbent assay (ELISA) was used to test the Qβ-VLP platform coupled to α-Gal against sera of individuals infected by T. cruzi (99 treated and 99 untreated), uninfected individuals (68) and individuals with visceral leishmaniasis (VL) (10). All samples were from individuals living in areas endemic for CD and VL in the North of Minas Gerais, Brazil. The standardization of the assays was performed using different dilutions of the antigen, primary and secondary antibody. The differences between the groups were evaluated by the Kruskall-Wallis test with Bonferroni post hoc, assuming a p <0.05 as significant. The analysis of the ROC curve was performed to determine the sensitivity and specificity of the diagnostic test. The α-Gal antigen showed an reasonable performance in the ELISA test, presenting 73.7% sensitivity and 87.2% specificity, with excellent discrimination between individuals infected and not infected by T. cruzi, with an area over the curve of 0.84. Regarding the individuals infected by T. cruzi, the untreated group presented higher production of antibodies when compared to the treated group (p<0.001). The results showed that the carbohydrate α-Gal-Qβ-VLP has potential for the diagnosis of T. cruzi infection in the chronic phase and for verification of the response to the etiological treatment of CD.