Interrupting Chagas disease transmission in Venezuela

Abstract

SUMMARYThe interruption of vectorial transmission of Chagas disease in Venezuela is attributed to the combined effects of ongoing entomoepidemiological surveillance, ongoing house spraying with residual insecticides and the concurrent building and modification of rural houses in endemic areas during almost five decades. The original endemic areas which totaled 750,000 km², have been reduced to 365,000 km². During 1958During -1968, initial entomological evaluations carried out showed that the house infestation index ranged between 60-80%, the house infection index at 8-11% and a house density index of 30-50 triatomine bugs per house. By 1990-98, these indexes were further reduced to 1.6-4.0%, 0.01-0.6% and 3-4 bugs per house respectively. The overall rural population seroprevalence has declined from 44.5% (95% C.I.: 43.4-45.3%) to 9.2% (95% C.I.: 9.0-9.4%) for successive grouped periods from 1958 to 1998. The annual blood donor prevalence is firmly established below 1%. The population at risk of infection has been estimated to be less than four million. Given that prevalence rates are stable and appropriate for public health programmes, consideration has been given to potential biases that may distort results such as: a) geographical differences in illness or longevity of patients; b) variations in levels of ascertainment; c) variations in diagnostic criteria; and d) variations in population structure, mainly due to appreciable population migration. The endemic areas with continuous transmission are now mainly confined to piedmonts, as well as patchy foci in higher mountainous ranges, where the exclusive vector is Rhodnius prolixus. There is also an unstable area, of which landscapes are made up of grasslands with scattered broad-leaved evergreen trees and costal plains, where transmission is very low and occasional outbreaks are reported.

Update on Chagas disease in Venezuela: a review

“…One additional fact that puts into evidence the general distribution of chronic T. cruzi-infection is the finding of the major proportion of this clinical condition in Falcon, a state located in a semiarid region in the coastal North-western part of the country. These findings clearly contrast with those of Aché and Matos (2001) who stated that the chagasic endemic areas in Venezuela are confined to geographical landscapes of piedmonts as well as patchy foci in higher mountain where the exclusive vector is R. prolixus.…”

“…The authors also detected and reported cases from the Llanos, in the central part of the country, to the mountains in the Andean region of Western Venezuela (Torrealba et al 1940(Torrealba et al , 1954(Torrealba et al , 1955a(Torrealba et al , b, 1958. The campaign against Chagas disease started in Venezuela in 1961 (Berti et al 1961, Acquatella 1987, Aché & Matos 2001. How-ever, in a survey carried out during the 1960s comprising 8 states and a total of 10,300 inhabitants, Pifano (1974) reported 43.9% of seropositives, including 4% positive to xenodiagnosis.…”

“…In this context, Maekelt (1983) reported that seropositives in the age group of 0-10 years fall from 20.4%, as demonstrated by Pifano (1974), to 3.2%. More recently, Aché and Matos (2001) summarized the official effort to interrupt Chagas disease transmission in Venezuela. They made an epidemiological description based on cumulative data from 1958 to 1998, available at the national Chagas disease control program archives.…”

Current epidemiological trends for Chagas disease in Latin America and future challenges in epidemiology, surveillance and health policy

“…The prevalence of infected blood in blood banks decreased from 1.16 % in 1993 to 0.78% in 1998 (Aquatella et al 1987, Aché & Matos 2001.…”

Seroepidemiología de la enfermedad de Chagas en dos localidades del municipio Costa de Oro, estado Aragua, Venezuela

“…Se estima que, en Venezuela, existen seis millones de personas en riesgo de contraer esta enfermedad, en el país el índice de seroprevalencia para el año 2000 fue de 8,3% y está distribuida principalmente en la región andina, en el piedemonte y en las montañas de la zona costera (3,4).…”