BACKGROUND: According to the reported cases of transfusion‐acquired Trypanosoma cruzi infection, the risk of T. cruzi transfusion transmission appears to be higher with platelet (PLT) products than with other blood components. The aim of this study was to investigate by quantitative real‐time polymerase chain reaction (qPCR) the parasitic load detected in leukoreduced plasma and PLT concentrates collected by apheresis from seropositive T. cruzi blood donors and compare them with peripheral whole blood (WB).STUDY DESIGN AND METHODS: During 2011 to 2013, a prospective study was carried out in a group of blood donors originating from Chagas‐endemic areas but who are now living on the island of Majorca, Spain. Leukoreduced plasma and PLT concentrates were collected by apheresis from seropositive blood donors with detectable parasitemias in peripheral WB.RESULTS: Seropositivity was found in 23 of 1201 donors studied (1.9%), and T. cruzi DNA with less than 1 parasite equivalent/mL was detected in peripheral WB in 60.86% (14 of 23) of these. The study in blood components obtained by apheresis from these donors showed that T. cruzi DNA with a mean ± SD parasitic load of 5.33 ± 6.12 parasite equivalents/mL was detected in 100% of the PLT concentrate samples. Parasite DNA was undetectable in the extract taken from plasma collected from donors with a positive qPCR in peripheral WB.CONCLUSION: The higher parasitic load found in PLT concentrates compared to plasma and peripheral WB would explain the higher transfusion transmission risk of Chagas disease associated with PLT transfusions described in the reported cases of transfusion‐acquired T. cruzi infection.

Molecular techniques based on real-time polymerase chain reaction (qPCR) allow the detection and quantification of DNA but are unable to distinguish between signals from dead or live cells. Because of the lack of simple techniques to differentiate between viable and nonviable cells, the aim of this study was to optimize and evaluate a straightforward test based on propidium monoazide (PMA) dye action combined with a qPCR assay (PMA-qPCR) for the selective quantification of viable/nonviable epimastigotes of Trypanosoma cruzi. PMA has the ability to penetrate the plasma membrane of dead cells and covalently cross-link to the DNA during exposure to bright visible light, thereby inhibiting PCR amplification. Different concentrations of PMA (50–200 μM) and epimastigotes of the Maracay strain of T. cruzi (1 × 10⁵–10 parasites/mL) were assayed; viable and nonviable parasites were tested and quantified by qPCR with a TaqMan probe specific for T. cruzi. In the PMA-qPCR assay optimized at 100 μM PMA, a significant qPCR signal reduction was observed in the nonviable versus viable epimastigotes treated with PMA, with a mean signal reduction of 2.5 logarithm units and a percentage of signal reduction > 98%, in all concentrations of parasites assayed. This signal reduction was also observed when PMA-qPCR was applied to a mixture of live/dead parasites, which allowed the detection of live cells, except when the concentration of live parasites was low (10 parasites/mL). The PMA-qPCR developed allows differentiation between viable and nonviable epimastigotes of T. cruzi and could thus be a potential method of parasite viability assessment and quantification.

Climate change, competent vectors, and reservoir animals are the main factors for developing vector-borne zoonotic diseases. These diseases encompass a significant and widespread category of pathogens (e.g., viruses, bacteria, protozoa, and helminths) transmitted by blood-feeding arthropods, including ticks, fleas, lice, triatomines, mosquitoes, sandflies, and blackflies. In Chile, several studies have explored the role of dogs as reservoirs of vector-borne pathogens; however, there is a lack of research investigating the presence of pathogens in arthropods. Specifically, within the order Diptera, limited knowledge exists regarding their roles as carriers of pathogens. This study aimed to examine the presence of zoonotic filarial nematodes in mosquitoes and dogs within a previously unstudied semi-rural area of Central Chile. Two hundred samples of dog blood and seven hundred and twenty-four mosquitoes were collected during 2021–2022 and studied for filarial nematodes by PCR. The prevalence of microfilaremic dogs detected by Knott’s test was 7.5%, with Acanthocheilonema reconditum being the only species identified. Aedes (Ochlerotatus) albifasciatus was the most abundant mosquito species collected, and 15 out of 65 pools were positive for filarial nematodes. Among these pools, 13 tested positive for Acanthocheilonema reconditum, and two tested positive for Setaria equina through PCR. Additionally, five Culex pipiens specimens were positive for Acanthocheilonema reconditum. Despite the absence of zoonotic filarial species, these findings underscore the significance of monitoring pathogens in mosquitoes and animal hosts and continued research into the dynamics of vector-borne diseases, particularly in unexplored regions.