Chagas Disease

Chagas Disease

Date: 
01/11/2004
Investigation Line: 

Abstract

We studied the seroprevalence of antibodies against Trypanosoma cruzi in the human population along with domiciliary infestation by triatomine bugs in an area endemic for Chagas disease in the Chaco Province of Argentina. In addition, we carried out parasitologic surveys in patients, dogs, wild mammals, and vectors. The mean seroprevalence in humans was 27.81% (109 of 392) and 24.14% (63 of 261) in 1-15-year-old children. The minimum domiciliary infestation rate was 13.33%, with certain areas reaching 53.85%. The prevalence was 15.09% (16 of 106) in dogs and 35.71% (10 of 28) in opossums. Infection with T. cruzi was detected in 30.10% (59 of 196) of the Triatoma infestans tested. Compared with nationwide studies, our data suggest that 1) there are zones requiring immediate sanitary action, and 2) nationwide estimates are based on very heterogeneous epidemiologic situations. This heterogeneity emphasizes the importance of in-depth studies of restricted areas to provide additional information for a better understanding of the present status of Chagas disease in Argentina.

Date: 
15/09/2003
Investigation Line: 

Abstract

A set of 65 Trypanosoma cruzi stocks from dogs, opossums, insect vectors and humans was isolated in a geographically restricted endemic area for Chagas' disease in Argentina and was analysed by multilocus enzyme electrophoresis for 15 loci. The results show that at least five multilocus genotypes (clonets) circulate in the study area, one belonging to T. cruzi IIe, one to T. cruzi IId and three clonets belonging to T. cruzi I; and they confirm the presence of these lineages in the country. The three clonets attributed to T. cruzi I were identical to each other for all loci except for Sod-2, where three different patterns were identified. These patterns suggest the presence of two homozygous genotypes and one heterozygous genotype. Our results also suggest association of clonet IIe with dogs, clonet IId with humans and the three T. cruzi I clonets with Didelphis albiventris. On the other hand, there was no significant association between Triatoma infestans and any particular clonet circulating in the area. These findings are consistent with the hypothesis of natural selection, from mixed populations of T. cruzi in vectors, toward more restricted populations in mammals. The epidemiological implications of the possible selection of different clonets by different mammal hosts and the significance of two homozygous genotypes and one heterozygous genotype for the Sod-2 locus are discussed.

Date: 
01/01/2000
Investigation Line: 

Abstract

Toxocara canis and Ancylostoma spp. are geohelmints that parasites dogs and can eventually affect humans, mainly children, causing visceral and cutaneous larva migrans respectively, constituting a serious public health problem. This study was carried out in two towns located in the xerophilous forest Chaco salteño where humans live closely with many animals, including dogs. Hematological values and anti-Toxocara canis antibodies, determined by ELISA in serum, were evaluated in 98 children from this area. Thirty-six children presented with eosinophilia of 10% or higher in peripheral blood. Twenty out of 98 (20.4%) children had antibodies against antigen from L2 larvae of Toxocara canis. A high percentage (55.6%) of the children with eosinophilia presented anti-Toxocara canis antibodies. Nine children had multiple serpiginous lesions typical of cutaneous larva migrans. Feces from dogs were collected in the area where children lived, in order to search for parasite contamination. Three different techniques of stool examination were employed and eggs were counted. Out of the 106 feces examined, parasites were found in 82 samples (77.4%). Ancylostoma spp eggs were found in 74 (69.8%) samples and eggs from Toxocara canis were found in 19 (17.2%). The average number of T. canis and Ancylostoma spp eggs/gr of feces, were 200 and 3,871 respectively. Giardia spp (14.5%), Trichuris vulpis (7.6%), Genus Endamoeba (2.8%) and Taenia spp (1.9%) were also identified in the stools. Sanitary control and health education in order to control these parasitoses are emphasized.

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