Fecha: 
01/09/2016
Linea de Investigacion: 

Abstract

In regions where Chagas disease is endemic, canine Trypanosoma cruzi infection is highly correlated with the risk of transmission of the parasite to humans. Herein we evaluated the novel TcTASV protein family (subfamilies A, B, C), differentially expressed in bloodstream trypomastigotes, for the detection of naturally infected dogs. A gene of each TcTASV subfamily was cloned and expressed. Indirect enzyme-linked immunosorbent assays (ELISA) were developed using recombinant antigens individually or mixed together. Our results showed that dogs with active T. cruzi infection differentially reacted against the TcTASV-C subfamily. The use of both TcTASV-C plus TcTASV-A proteins (Mix A+C-ELISA) enhanced the reactivity of sera from dogs with active infection, detecting 94% of the evaluated samples. These findings agree with our previous observations, where the infected animals exhibited a quick anti-TcTASV-C antibody response, coincident with the beginning of parasitaemia, in a murine model of the disease. Results obtained in the present work prove that the Mix A+C-ELISA is a specific, simple and cheap technique to be applied in endemic areas in screening studies. The Mix A+C-ELISA could help to differentially detect canine hosts with active infection and therefore with high impact in the risk of transmission to humans.

Autor/es: 
Fecha: 
01/06/2016
Linea de Investigacion: 

Abstract

After more than eighty years dengue reemerged in Argentina in 1997. Since then, the largest epidemic in terms of geographical extent, magnitude and mortality, was recorded in 2009. In this report we analyzed the DEN-1 epidemic spread in Orán, a mid-size city in a non-endemic tropical area in Northern Argentina, and its correlation with demographic and socioeconomic factors. Cases were diagnosed by ELISA between January and June 2009. We applied a space-time and spatial scan statistic under a Poisson model. Possible association between dengue incidence and socio-economic variables was studied with the Spearman correlation test. The epidemic started from an imported case from Bolivia and space-time analysis detected two clusters: one on February and other in April (in the south and the northeast of the city respectively) with risk ratios of 25.24 and 4.07 (p<0.01). Subsequent cases spread widely around the city without significant space-temporal clustering. Maximum values of the entomological indices were observed in January, at the beginning of the epidemic (B=21.96; LH=8.39). No statistically significant association between socioeconomic variables and dengue incidence was found but positive correlation between population size and the number of cases (p<0.05) was detected. Two mechanisms may explain the observed pattern of epidemic spread in this non-endemic tropical city: a) Short range dispersal of mosquitoes and people generates clusters of cases and b) long-distance (within the city) human movement contributes to a quasi-random distribution of cases.

Autor/es: 
Fecha: 
30/09/2015
Linea de Investigacion: 

Abstract

BACKGROUND:

Soil-transmitted helminth (STH) infections are a public health problem in resource-limited settings worldwide. Chronic STH infection impairs optimum learning and productivity, contributing to the perpetuation of the poverty-disease cycle. Regular massive drug administration (MDA) is the cardinal recommendation for its control; along with water, sanitation and hygiene (WASH) interventions. The impact of joint WASH interventions on STH infections has been reported; studies on the independent effect of WASH components are needed to contribute with the improvement of current recommendations for the control of STH. The aim of this study is to assess the association of lacking access to water and sanitation with STH infections, taking into account the differences in route of infection among species and the availability of adequate water and sanitation at home.

METHODS AND FINDINGS:

Cross-sectional study, conducted in Salta province, Argentina. During a deworming program that enrolled 6957 individuals; 771 were randomly selected for stool/serum sampling for parasitological and serological diagnosis of STH. Bivariate stratified analysis was performed to explore significant correlations between risk factors and STH infections grouped by mechanism of entry as skin-penetrators (hookworms and Strongyloides stercoralis) vs. orally-ingested (Ascaris lumbricoides and Trichuris trichiura). After controlling for potential confounders, unimproved sanitation was significantly associated with increased odds of infection of skin-penetrators (adjusted odds ratio [aOR] = 3.9; 95% CI: 2.6-5.9). Unimproved drinking water was significantly associated with increased odds of infection of orally-ingested (aOR = 2.2; 95% CI: 1.3-3.7).

CONCLUSIONS:

Lack of safe water and proper sanitation pose a risk of STH infections that is distinct according to the route of entry to the human host used by each of the STH species. Interventions aimed to improve water and sanitation access should be highlighted in the recommendations for the control of STH.

Fecha: 
10/02/2015
Linea de Investigacion: 

Abstract

BACKGROUND:

Traditional faecal-based methods have poor sensitivity for the detection of S. stercoralis, therefore are inadequate for post-treatment evaluation of infected patients who should be carefully monitored to exclude the persistence of the infection. In a previous study, we demonstrated high accuracy of five serology tests for the screening and diagnosis of strongyloidiasis. Aim of this study is to evaluate the performance of the same five tests for the follow up of patients infected with S. stercoralis.

METHODS:

Retrospective study on anonymized, cryo-preserved samples available at the Centre for Tropical Diseases (Negrar, Verona, Italy). Samples were collected before and from 3 to 12 months after treatment. The samples were tested with two commercially-available ELISA tests (IVD, Bordier), two techniques based on a recombinant antigen (NIE-ELISA and NIE-LIPS) and one in-house IFAT. The results of each test were evaluated both in relation to the results of fecal examination and to those of a composite reference standard (classifying as positive a sample with positive stools and/or at least three positive serology tests). The associations between the independent variables age and time and the dependent variable value of serological test (for all five tests), were analyzed by linear mixed-effects regression model.

RESULTS:

A high proportion of samples demonstrated for each test a seroreversion or a relevant decline (optical density/relative light units halved or decrease of at least two titers for IFAT) at follow up, results confirmed by the linear mixed effects model that showed a trend to seroreversion over time for all tests. In particular, IVD-ELISA (almost 90% samples demonstrated relevant decline) and IFAT (almost 87%) had the best performance. Considering only samples with a complete negativization, NIE-ELISA showed the best performance (72.5% seroreversion).

CONCLUSIONS:

Serology is useful for the follow up of patients infected with S. stercoralis and determining test of cure.

Fecha: 
09/08/2014
Linea de Investigacion: 

Abstract

BACKGROUND:

Robust reference values for fecal egg count reduction (FECR) rates of the most widely used anthelmintic drugs in preventive chemotherapy (PC) programs for controlling soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm) are still lacking. However, they are urgently needed to ensure detection of reduced efficacies that are predicted to occur due to growing drug pressure. Here, using a standardized methodology, we assessed the FECR rate of a single oral dose of mebendazole (MEB; 500 mg) against STHs in six trials in school children in different locations around the world. Our results are compared with those previously obtained for similarly conducted trials of a single oral dose of albendazole (ALB; 400 mg).

METHODOLOGY:

The efficacy of MEB, as assessed by FECR, was determined in six trials involving 5,830 school children in Brazil, Cambodia, Cameroon, Ethiopia, United Republic of Tanzania, and Vietnam. The efficacy of MEB was compared to that of ALB as previously assessed in 8,841 school children in India and all the above-mentioned study sites, using identical methodologies.

PRINCIPAL FINDINGS:

The estimated FECR rate [95% confidence interval] of MEB was highest for A. lumbricoides (97.6% [95.8; 99.5]), followed by hookworm (79.6% [71.0; 88.3]). For T. trichiura, the estimated FECR rate was 63.1% [51.6; 74.6]. Compared to MEB, ALB was significantly more efficacious against hookworm (96.2% [91.1; 100], p<0.001) and only marginally, although significantly, better against A. lumbricoides infections (99.9% [99.0; 100], p = 0.012), but equally efficacious for T. trichiura infections (64.5% [44.4; 84.7], p = 0.906).

CONCLUSIONS/SIGNIFICANCE:

A minimum FECR rate of 95% for A. lumbricoides, 70% for hookworm, and 50% for T. trichiura is expected in MEB-dependent PC programs. Lower FECR results may indicate the development of potential drug resistance.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01087099 NCT01379326.

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