Intra-domiciliary transmission of Chagas’ disease in rural areas of Yucatan Mexico

With the objective to describe the relationship between T. cruzi infection in humans and sinantropic reservoir and vectors in the rural conditions a study was performed in municipalities of the Yucatan state in Mexico. Blood samples from humans, dogs and opossum were taken from the households. Vectors were also collected and the infection and infestation indexes were calculated. Serum samples were evaluated by indirect hemagglutination (IH) and indirect immunofluorescence (IFI) to determine IgG antibodies against Trypanosoma cruzi. The polymerase chain reaction (PCR) was also performed in the samples taken from humans and reservoirs. Blood smears were performed in reservoirs. Sampled humans underwent to an electrocardiographic study to identify functional and conduction alterations of the heart. Household building characteristics were noted. A total of 367 blood samples were collected from people. The presence of IgG antibodies was 16.6% and 71.0% at PCR. Electrocardiographic studies revealed that 31% of patients seropositive to T. cruzi have a medical condition. 20.0% of dogs were seropositive and 68.5 positive to PCR. At the direct detection 13.6% resulted positive. In opossum 29.1% were seropositive and 72.9% positive to PCR. A total of 269 triatomineos were captured and 52.7% were infected with T. cruzi. The infection and infestation index were 52.4% and 60.8% respectively. The presence of adult vectors and their nymph’s were more frequently found in households made with wattle roofs (45.2 and 73.9 % respectively) than other kind of building materials. Electrocardiographic abnormalities found in positive persons were: Incomplete right bundle branch block (55%), tachycardia (35%), old myocardial infarction (5%) and incomplete block of the left bundle (5%). This work highlights the importance of comprehensive studies on the transmission of T. cruzi in the Yucatan where the link between human infection in synanthropic reservoirs and vectors is established. This information is important to design programs for the epidemiological surveillance and control to break the chain of transmission of the disease.