The present study deals with the evaluation of the effectiveness of the measures employed in the control of Triatoma infestans, the vector of Trypanosoma cruzi infection (Chagas' disease), in the IV region of Chile through a serological follow up program. For this reason, a serological survey has been carried out in 2,783 children, from 0 to 10 years, who live in rural high endemic areas of the region. The sera were tested using an indirect hemagglutination test (IHAT) and ELISA techniques with results agreeing in 99.9% of the samples. In children with positive serology xenodiagnosis was performed and blood samples from the corresponding mothers were submitted to serology for Chagas' disease. These additional tests should allow to distinguish between congenital infection and vectorial transmission. It was observed that vectorial transmission of T. cruzi was interrupted in some localities where entomological control has been applied for 10 years, or lowered in those which have been submitted to desinsectations in the last 5 years. On the other hand, a relatively high prevalence of the infection has been detected in some localities. These results suggest an apparent increase of vectorial transmission, indicating the need of readjusting the dwellings insecticide sprayings activities to improve the measures against the vector.

Animals↗

PubMedDate not supplied

[Evaluation of vectors of Chagas' disease eradication programs in Chile by serological study of children under 10 years old].

Chagas' disease is a parasitic zoonosis with high prevalence in Chile. It is distributed in rural and periurban section in the northern most seven out of thirteen regions in which the country is divided, and affects about 142,000 individuals dispersed in most of the 165 counties sited in the chagasic zone. Triatoma infestans--intradomiciliary species--is the main and practically exclusive vector of Trypanosoma cruzi. Diverse tools may be utilized in order to interrupt the domestic cycle of transmission of T. cruzi: health education, housing improvement and elimination of vectors by dwelling insecticide sprayings. This last resource has received priority in Chile in the last 12 years. To evaluate the effectivity of the programs for eliminating T. infestans a serological study for Chagas' disease--comprising 8,767 children less than 10 years old from 27 rural counties insecticide sprayed in the last 12 years--was carried out. A global total of 125 (1.4%) children resulted positive, figure significantly lower than 5.4% found in 1982-1990 in the same age group. Distribution by regions of positive individuals showed a decrease of prevalence in each of them: III Region, from 9.8 to 1.0%, IV Region, 7.2 to 2.0%, V Region, 5.2 to 1.9%, and Metropolitan Region, 1.4% to 0.6. Even though positive children have still been found in 46.7% of localities of the studied counties, it is possible to affirm that the vector control programs have been effective and must be maintained, and increased in those localities with T. cruzi infection in children under 10 years of age, with the general aim of eradicate Chagas' disease transmission in Chile before 2000.

Animals↗

PubMedDate not supplied

[Yield of xenodiagnosis and PCR in the evaluation of specific chemotherapy of Chagas' disease in children].

Amplification by the polymerase chain reaction (PCR) of Trypanosoma cruzi kinetoplastic DNA was used to enhance sensitivity in the detection of the parasite in blood, with the ultimate goal of improving the parasitological diagnosis of Chagas' disease in 0-10 year-old infected children. Twenty eight children were evaluated by using xenodiagnosis (XD) and PCR. Whereas XD detected 75.0% of the cases PCR was positive in 96.8%. The usefulness of the PCR was further investigated in the 28 children who have received specific treatment with nifurtimox. Negativation of XD after three and six months post treatment was observed in all the cases, but only 21.4% and 35.8% negativation of the PCR after three and six months post treatment respectively. These observations suggest that PCR is the most sensitive and quick technique available for direct detection of T. cruzi in chagasic children and that it can be a very useful tool for the follow-up of infected subjects after specific chemotherapeutical treatment.

Chagas Disease↗