The performance of laboratory tests in the management of a large outbreak of orally transmitted Chagas disease

Abstract

Orally transmitted Chagas disease (ChD), which is a well-known entity in the Brazilian Amazon Region, was first documented in Venezuela in December 2007, when In Venezuela, effective control measures successfully reduced the annual incidence of Trypanosoma cruzi infections from 10/1,000 individuals in the 1950s to 1/1,000 in the 1980s (Feliciangeli et al. 2003). Since then, the recorded outbreaks of acute Chagas disease (ChD) have been as follows: between 1988-1996, 59 cases occurred in the western states of Venezuela (Añez et al. 1999), after which nine cases involving two deaths occurred during the period of January 2006-March 2007 in the same endemic area (Añez et al. 2007). In 2004 and 2006, the deaths of two children near Caracas were documented ). Nevertheless, an outbreak of orally transmitted ChD (OChD) in a school in a middle class neighbourhood in Caracas was the warning signal that ChD was re-emerging via a different mode of transmission, i.e., the oral route (Alarcón de Noya et al. 2010b Noya et al. 2010b), an outbreak occurred in an urban school that was presumably linked to the ingestion of contaminated home-made juice that had been prepared in a different part of the city where triatomines were present.The aim of this study is to provide information about the parasitological, immunological and molecular laboratory tests used in diagnosing ChD to gleam further knowledge from the largest OChD outbreak ever reported. SUBJECTS, MATERIALS AND METHODSStudy population -The study population consisted of students, teachers and administrative personnel from a school located in the municipality of Chacao in Caracas, Venezuela. Once the primary case was diagnosed (Martín et al. 2009) and the epidemiological link to another case was established (Alarcón de Noya et al. 2010c), parasitological examinations and serological tests were carried out in these cases, in addition to other symptomatic patients who voluntarily requested medical attention at the Tropical Medicine Institute (IMT), Universidad Central de Venezuela in Caracas. After the death of a five-year-old student, most of the school community was managed as part of an on-site emergency, both in the school and at the hospital, where several of the patients were hospitalised. T. cruzi infection was diagnosed by collecting only one tube of blood for serological testing, except for in people who were symptomatic at the time of the interview and from whom additional blood was taken for parasitological or molecular testing (Supplementary data). For logistical and ethical reasons, a unique protocol could not be followed and, consequently, the results are simply presented as they were obtained over time. It was not possible to re-sample the blood of individuals with positive serological tests to isolate the parasite before treatment because the treatment had to begin before the group dispersed for the Christmas holiday.Direct parasitological tests -Observations of the parasite were performed using fresh blood smears as well as Giemsa-stained preparations (W...

Update on oral Chagas disease outbreaks in Venezuela: epidemiological, clinical and diagnostic approaches

“…Based on the initial results, second samples from some individuals were evaluated by in vitro culture and PCR. Hence, identifying the parasite in all patients was not possible, except for the first group of school teachers and the girl index case ( Alarcón de Noya et al 2010a , 2012 ). In subsequent outbreaks handled at the IMT, the three above-recommended samples have been collected initially from all people at risk of infection.…”

“…A laboratory diagnostic approach - Regarding infection acquisition, a large group of people can most likely be infected simultaneously, which occurred in the orally transmitted Chagas disease microepidemics in Venezuela ( Alarcón de Noya & Martínez 2009 , Alarcón de Noya et al 2010a ). Diagnostic methods that provide rapid and accurate results for immediate treatment are need ( OPS 2009 , Alarcón de Noya et al 2012 ).…”

Correlation between Presence of Trypanosoma cruzi DNA in Heart Tissue of Baboons and Cynomolgus Monkeys, and Lymphocytic Myocarditis

“…4,18 The S35/S36 primer set used for PCR amplification of T. cruzi is based on the amplification of kinetoplast DNA. 19 The Southwest National Primate Research Center (SNPRC) located in San Antonio, TX, is home to~2,500 nonhuman primates, including baboons, chimpanzees, and two species of macaque, most of which are housed in large, open, outdoor cages.…”

“…Non-vector-borne routes of transmission include blood transfusion, organ or tissue transplantation, congenital, laboratory exposure, and consumption of contaminated foods. [1][2][3][4] The disease is widespread in Central and South America, where currently about 8 million people are estimated to be infected and 109 million are at risk of infection. 3 In 2006, an estimated 12,500 people died caused by complications arising from chronic, symptomatic Chagas' disease in Latin America, primarily from heart pathologies.…”

Chagas disease: control, elimination and eradication. Is it possible?

“…The basic control measures comprise: education for the population to avoid domestication of triatomines, improvement of housing and separation from henhouses, pigsties and animal pens, spraying of homes and annex buildings infested by triatomines, using residual insecticides (e.g., pyrethroids), control over blood donors using at least two serological reactions with different principals (e.g., ELISA and immunofluorescence), cooking foods thoroughly or applying hygiene measures to foods that should be eaten raw, such as salads and fruits, which should be well washed, with special care in preparing and consuming fruit juices such as acai, bacaba, guava and sugar cane, among others, which have been held responsible for outbreaks of Chagas disease through oral transmission ( Coura 2006 , Pinto et al 2008 , Coura & Dias 2009 , Dias 2009 , Valente et al 2009 , Coura & Junqueira 2012 , Noya et al 2012 , Shikanai-Yasuda & Carvalho 2012 , Souza-Lima et al 2013 ).…”