Chagas disease (ChD), a complex and persistent parasitosis caused by Trypanosoma cruzi, represents a natural model of chronic infection, in which some people exhibit cardiac or digestive complications that can result in death 20-40 years after the initial infection. Nonetheless, due to unknown mechanisms, some T. cruzi-infected individuals remain asymptomatic throughout their lives. Actually, no vaccine is available to prevent ChD, and available treatments for chronic ChD patients are controversial. Chronically T. cruzi-infected individuals exhibit a deterioration of T cell function, an exhaustion state characterized by poor cytokine production and increased inhibitory receptor coexpression, suggesting that these changes are potentially related to ChD progression. Moreover, an effective antiparasitic treatment appears to reverse this state and improve the T cell response. Taking into account these findings, the functionality state of T cells might provide a potential correlate of protection to detect individuals who will or will not develop the severe forms of ChD. Consequently, we investigated the T cell response, analyzed by flow cytometry with two multicolor immunofluorescence panels, to assess cytokines/cytotoxic molecules and the expression of inhibitory receptors, in a murine model of acute (10 and 30 days) and chronic (100 and 260 days) ChD, characterized by parasite persistence for up to 260 days postinfection and moderate inflammation of the colon and liver of T. cruzi-infected mice. Acute ChD induced a high antigen-specific multifunctional T cell response by producing IFN-, TNF-, IL-2, granzyme B, and perforin; and a high frequency of T cells coexpressed 2B4, CD160, CTLA-4, and PD-1. In contrast, chronically infected mice with moderate inflammatory infiltrate in liver tissue exhibited monofunctional antigen-specific cells, high cytotoxic activity (granzyme B and perforin), and elevated levels of inhibitory receptors (predominantly CTLA-4 and PD-1) coexpressed on T cells. Taken together, these data support our previous results showing that similar to humans, the T. cruzi persistence in mice promotes the dysfunctionality of T cells, and these changes might correlate with ChD progression. Thus, these results constitute a model that will facilitate an in-depth search for immune markers and correlates of protection, as well as long-term studies of new immunotherapy strategies for ChD.

In 2015, we investigated Bartonella quintana and typhus group rickettsiae in body lice from homeless persons in Bogotá, Colombia. We found B. quintana-infected body lice and seroprevalence of this microorganism in 19% of homeless persons and typhus group rickettsiae in 56%. Public health professionals should start preemptive measures and active vector control.

Introduction: Bats have become an epidemiologically significant source of pathogenic microorganisms, such as leptospires, the causative agents of leptospirosis. However, little information exists about bats and their potential role as a reservoir of pathogenic Leptospira spp. in Colombia. The aim of this study was to evaluate the presence of pathogenic Leptospira spp. in the kidneys of bats from the Caribbean region of Colombia deposited in the collection of mammals of the Museo Javeriano de Historia Natural (MPUJ-MAMM). Methodology: DNA was extracted from twenty-six kidney samples from a total of 13 species of bats captured in Colombia. First, 16S ribosomal RNA conventional PCR was performed to detect the presence of Leptospira spp. Then, in samples that tested positive, LipL32 PCR was performed to detect pathogenic Leptospira spp. by sequencing and phylogenetic analysis. Results: The presence of Leptospira spp. was observed in 7/26 (26.9%) bats from the following 6 species: Carollia perspicillata, Glossophaga soricina, Dermanura phaeotis, Uroderma bilobatum, Desmodus rotundus, and Lophostoma silvicolum, and pathogenic Leptospira spp. were detected in 4/26 samples (15.4%). Conclusions: This study suggests that bats present in the Caribbean region of Colombia could be potential reservoirs of pathogenic Leptospira spp.

Trypanosomatids are early divergent parasites which include several species of medical interest.Trypanosoma rangeliis not pathogenic for humans but shows a high immunological cross-reactivity withTrypanosoma cruzi, the causative agent of Chagas' disease that affects more than 17 million people throughout the world. Recent studies have suggested thatT. cruziKMP-11 antigen could be a good candidate for the induction of immunoprotective cytotoxic responses againstT. cruzinatural infection. In the present paper the genes coding for theT. rangelikinetoplastid membrane protein-11 have been characterized. The results show that the locus encoding this protein is formed by 4 gene units measuring 550 nucleotides in length, organized in tandem, and located in different chromosomes in KP1(+) and KP1(−) strains. The gene units are transcribed as a single mRNA of 530 nucleotides in length. Alignment of theT. rangeliKMP-11 deduced amino acid sequence with the homologous KMP-11 protein fromT. cruzirevealed an identity of 97%. Interestingly, the T and B cell epitopes of theT. cruziKMP-11 protein are conserved in theT. rangeliKMP-11 amino acid sequence.

Rickettsia typhi and Rickettsia felis (Rickettsiales: Rickettsiaceae) are flea-transmitted pathogens. They are important causes of acute febrile illness throughout the world. We, therefore, sought to identify the rickettsial species present in the fleas of dogs and cats in the department of Cauca, Colombia. In this study, we collected 1,242 fleas from 132 dogs and 43 fleas from 11 cats. All fleas were morphologically identified as Ctenocephalides felis (Bouché) adults and organized in pools for DNA extraction (234 pools from dogs and 11 from cats). The gltA gene from rickettsiae was targeted for screening amplification using conventional PCR. In total, 144 of the 245 pools (58.7%) were positive. The positive samples were then processed for the amplification of the 17kDa antigen gene (144/144; 100% positive) and sca5 gene (140/144; 97.2% positive). In addition, restriction enzyme length polymorphism analysis using NlaIV on the amplified product of the sca5 gene demonstrated several organisms: 21/140 (15%) were R. felis, 118/140 (84.3%) were Rickettsia asemboensis, and 1/140 (0.7%) were Candidatus Rickettsia senegalensis. Subsequent sequencing confirmed Candidatus Rickettsia senegalensis in C. felis collected from dogs the first reported from Colombia.