[Positivity of xenodiagnosis, according to age, in persons with positive serology for Chagas disease].

: An analytical study of positive xenodiagnosis (XD), according to age distribution, in people with a positive indirect hemagglutination test (IHAT) for Chagas' disease has been carried out. A total of 1,137 IHAT for Chagas' disease positive persons were submitted to two wooden XD boxes containing 7 Triatoma infestans nymphs III each. The positivity (%) of XD in the different age groups was: 0-9 year-old (60.8), 10-19 (35.8), 20-29 (31.5), 30-39 (28.7), 40-49 (30.0), 50-59 (34.3) and > or = 60 (43.3). The 60.8% positivity of XD in children under 10 years of age is possibly due to the rather recent Trypanosoma cruzi infection in this age group and to diverse immunological mechanisms, which decrease with the age increasing.