Marisel Maldonado

Pyrethroid insecticide evaluation on different house structures in a Chagas disease endemic area of the Paraguayan Chaco

Insecticide effects of deltamethrin 2.5% SC (flowable solution) on different substrates and triatomine infestation rates in two indigenous villages (Estancia Salzar and Nueva Promesa) of the Paraguayan Chaco are reported. This field study was carried out to determine the extent to which variability in spray penetration may affect residual action of the insecticide. A total of 117 houses in the two villages were sprayed. Filter papers discs were placed on aluminium foil pinned to walls and roofs in selected houses and the applied insecticide concentration was determined by high pressure liquid chromatography (HPLC). The target dose rate was 25 mg a.i./m2. The mean actual applied dose in Estancia Salazar was 11.2 +/- 3.1 mg a.i./m2 in walls and 11.9 +/- 5.6 mg a.i./m2 in roofs while in Nueva Promesa, where duplicates were carried out, the mean values were 19.9 +/- 6.9 mg a.i./m2 and 34.7 +/- 10.4 mg a.i./m2 in walls and 28.8 +/- 19.2 mg a.i./m2 and 24.9 +/- 21.8 mg a.i./m2 in roofs. This shows the unevenness and variability of applied doses during spraying campaigns, and also the reduced coverage over roof surfaces. However, wall bioassays with Triatoma infestans nymphs in a 72 h exposure test showed that deposits of deltamethrin persisted in quantities sufficient to kill triatomines until three months post spraying. Knockdown by deltamethrin on both types of surfaces resulted in 100% final mortality. A lower insecticidal effect was observed on mud walls. However, three months after treatment, sprayed lime-coated mud surfaces displayed a twofold greater capacity (57.5%) to kill triatomines than mud sprayed surfaces (25%). Re-infestation was detected by manual capture only in one locality, six months after spraying.

Genetic and Morphometric Variability of Triatoma sordida (Hemiptera: Reduviidae) from the Eastern and Western Regions of Paraguay

Triatoma sordida is widely distributed throughout the Chaco and the Eastern Region of Paraguay. It is associated to palm trees and artificial ecotopes located in peridomestic environments. The aim of this work was to determine genetic and morphometric variability and feeding behavior among population of T. sordida captured in domicile and peridomicile areas of Paraguay. Feeding contents and levels of genetic and morphometric variation were determined in 124 T. sordida from domicile and peridomicile populations of San Pedro and Paraguarí departments of the Eastern Region and Boquerón and Presidente Hayes departments of the Western region using Double Diffusion Gel, random amplified polymorphic DNA (RAPD), and head and wings morphometry. Morphometric analysis revealed isolation of populations by geographic region and larger size in triatomine populations from the Western Region. RAPD showed no specific patterns for domicile and peridomicile populations. The estimator of diversity (FST; 0.08) and high gene flow obtained (Nm; 5.7) did not allow the establishment of genetic differentiation within the same region. The blood meal source showed that poultry feeding was 38% of host preferences, and human blood was the second feeding preference (24%) in the insects from the Eastern Region while poultry feeding was predominant in those from the Western Region (30%). This work showed homogeneity between T. sordida populations of the same region and between domicile and peridomicile. The genetic diversity was determined among T. sordida populations of both geographical regions suggesting differentiation associated to eco-geographical isolation by distance. It is important to notice that pattern feedings were different between the two regions. Further studies should be focused on how phenetic and genetic variations could be related to the adaptation capacity of these triatomine populations to domicile, increasing their vector potentiality in the transmission of Chagas disease.

Finding of leishmanicidal activity of 14-hydroxylunularin in mice experimentally infected with Leishmania infantum

In this study, we report the in vivo efficacy of 14-hydroxylunularin evaluated in BALB/c mice experimentally infected with promastigotes of Leishmania infantum (syn L. chagasi), the major causative agent of visceral leishmaniasis in Latin America. Seven days post-infection, treatment with 14-hydroxylunularin started and it was administered by oral and subcutaneous routes in doses of 10 and 25 mg/kg of weight for ten days using Glucantime® as reference drug. In the liver, the evaluated compound showed parasite reduction above 90% by both administration routes being the oral route the most effective at both doses. Significant decreased numbers of parasites were also observed when the treated group was compared with the control group (p≤0.05). The subcutaneous route presented a remarkable difference with at least 80% parasite suppression in liver and spleen at 10 mg/kg dose and 90% in liver at 25 mg/kg. The leishmanicidal activity of 14-hydroxylunularin against L. infantum revealed by this study is another evidence in favor of this compound as a potential candidate for the development of a new oral treatment for leishmaniasis.

Course of serological tests in treated subjects with chronic Trypanosoma cruzi infection: A systematic review and meta-analysis of individual participant data

Highlights • This is the first meta-analysis of individual data in chronic Trypanosoma cruzi infection after treatment.• The probability of seroreversion is variable along the course of follow-up.• An interaction was found between age at treatment and country setting.• The course of parasitological/molecular tests after treatment needs to be assessed.