A simplified molecular tool for detecting the Chagas etiological agent using a vector feces sample in field conditions

• Published in: Journal of invertebrate pathology 2024-09, Vol.206, p.108161, Article 108161
• Main Authors: Larocca, Luciana, Stolowicz, Fabiana G., Vojnov, Adrian A., Cano Suarez, Florencia, Salvá, Liliana, Meli, Sergio, Carbajal-de-la-Fuente, Ana Laura, Carrillo, Carolina
• Format: Article
• Language: English
• Subjects: Chagas disease; Detection method; LAMP; Triatoma infestans; Trypanosoma cruzi
• ISSN: 0022-2011; 1096-0805; 1096-0805
• DOI: 10.1016/j.jip.2024.108161

Simplified LAMP test to detect Trypanosoma cruzi in Triatoma infestans feces. The diluted triatomine feces sample is evaluated through three simple steps: 1) Reaction dropping: the sample (10 μL) is inoculated in a reaction tube with a drop of each dropper containing the reaction components (30 μL + 30 μL). 2) Amplification: the reaction is incubated at 64 °C for 60 min. 3) Result Reading: a drop of developing solution and a LFD are added to the reaction tube. After 3–5 min of capillarity progression, the lines on the strip are visible. [Display omitted] •Urban presence of triatomines demands simple and affordable tools for Chagas management.•The assayed LAMP kit detects T. cruzi in triatomine feces without extraction steps.•The test is sensible, specific and simple, then applicable in real field conditions.•This LAMP tool is feasible for implementation in Integrated Vector Management. Triatomine bugs are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease in the American continent. Here, we have tested a loop-mediated isothermal amplification (LAMP) test for a direct detection of T. cruzi in feces of Triatoma infestans, the main vector of this parasite in the Southern Cone of America. The analytical evaluation showed positive results with samples of triatomine feces artificially inoculated with DNA from strains of T. cruzi corresponding to each Discrete Typing Units (I-VI), with a sensitivity of up to one parasite per reaction. Conversely, the reaction yielded negative results when tested with DNA from Trypanosoma rangeli and other phylogenetically related and unrelated organisms. In triatomines captured under real field conditions (from urban households), and defined as positive or negative for T. cruzi using the reference microscopy technique, the LAMP test achieved a concordance of 100 %. Our results demonstrate that this LAMP reaction exhibits excellent analytical specificity and sensitivity without interference from the fecal matrix, since all the reactions were conducted without purification steps. This simple molecular diagnostic technique can be easily used by vector control agencies under field conditions.