Abstract
BackgroundTrypanosoma cruzi, the protozoan agent of Chagas disease, is comprised of at least 6 genetic lineages (TcI-TcVI). Their geographical distribution, clinical associations and reservoir hosts are not fully elucidated, as genotyping is hampered due to the difficulty in isolating representative populations of organisms. Lineage-specific serological techniques may address these issues.MethodsTrypanosoma cruzi lineage-specific serological assays were performed on human, canine, feline and armadillo sera from the Gran Chaco in northern Argentina, a region of ongoing transmission. Synthetic peptides representing lineage-specific epitopes of the trypomastigote small surface antigen (TSSA) were used in ELISA, and the TcII/V/VI shared epitope peptide (TSSApep-II/V/VI) was used in the Chagas Sero K-SeT rapid diagnostic test (RDT).ResultsChagas Sero K-SeT RDT, using Protein G to detect human and canine IgG, was at least as sensitive as TSSApep-II/V/VI ELISA using specific secondary antibodies. For sera from humans TSSApep-II/V/VI seroprevalence by Chagas Sero K-SeT was 273/393 (69.5%), for dogs 48/73 (65.8%) and for armadillos 1/7 (14.3%); by ELISA for cats 5/19 (26.3%). The seroprevalence for humans was similar to that for Bolivian patients, amongst whom we previously observed an association of TSSApep-II/V/VI seropositivity with severity of cardiomyopathy. In humans, prevalence of TSSApep-II/V/VI recognition was associated with locality, and with increasing and decreasing age within the Qom and Creole populations, respectively. For dogs TSSApep-II/V/VI recognition was associated with being born before community-wide insecticide spraying (P = 0.05) and with Qom household (P < 0.001).ConclusionsWe show here that Chagas Sero K-SeT RDT can replace ELISA for TSSApep-II/V/VI serology of humans and dogs; for humans there were statistically significant associations between a positive Chagas Sero K-SeT RDT and being resident in Area IV, and for dogs association with Qom household or with being born before the mass spraying campaign; we also show that with cats the TcII/V/VI epitope can be detected by ELISA. We assessed the lineage distribution in an unprecedented 83% of the human T. cruzi-seropositive population. These results form the basis for more detailed studies, enabling rapid in-the-field surveillance of the distribution and clustering of these lineages among humans and mammalian reservoirs of T. cruzi infection.
Highlights
Trypanosoma cruzi, the protozoan agent of Chagas disease, is comprised of at least 6 genetic lineages (TcI-TcVI)
Chagas Sero K‐SeT is more sensitive than TSSApep‐II/V/VI enzyme-linked immunosorbent assay (ELISA) for humans and dogs Comparing the TSSApep-II/V/VI ELISA and the Chagas Sero K-SeT rapid diagnostic test (RDT), all human samples that were positive by TSSApep-II/V/VI ELISA were positive by Chagas Sero K-SeT RDT for recognition of this peptide; Figure 2 shows examples of correspondence between these methods
This RDT identified 10 human samples as positive that were negative by TSSApep-II/V/ VI ELISA (Table 1), seropositive by conventional serology
Summary
Trypanosoma cruzi, the protozoan agent of Chagas disease, is comprised of at least 6 genetic lineages (TcI-TcVI). Their geographical distribution, clinical associations and reservoir hosts are not fully elucidated, as genotyping is hampered due to the difficulty in isolating representative populations of organisms. Chagas disease, caused by infection with the protozoan parasite Trypanosoma cruzi, remains a major public health problem in endemic regions of Latin America. Ongoing transmission is primarily maintained by contamination with T. cruzi infected faeces of the predominant local triatomine insect vector, Triatoma infestans, which infests rural dwellings, especially in the Gran Chaco region, where vector control has had limited success [4]. A wide range of sylvatic mammals carry T. cruzi infection [6]
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