Absence of both circadian rhythm and Trypanosoma cruzi periodicity with xenodiagnosis in chronic chagasic individuals / Ausência de ritmo circadiano e de periodicidade do Trypanosoma cruzi ao xenodiagnóstico em chagásicos crônicos

Realizamos xenodiagnósticos de 3 em 3 horas com 10 ninfas do 3§ estágio de Triatoma infestans por um período de 24 a 72 horas, em 18 chagásicos crônicos que tinham sorologia e/ou xenodiagnóstico positivos. Näo houve diferença estatisticamente significante na positividade entre as testes realizados durante o dia (9:00 às 18:00h) e à noite (21:00 às 6:00h), (X² = 0,1526 p = 0,696). Dez dos pacientes fizeram também xenodiagnósticos diários, durante 13 dias sucessivos, näo havendo periodicidade dos testes positivos

Positividad del xenodiagnóstico según edad en personas con serología positiva para enfermedad de Chagas / Positive xenodiagnosis according to age in people with seropositive Chagas's disease

An analytical study of positive xerodiagnosis (XD), according age distribution, in people with a positive indirect hemagglutination test (IHAT) for Chagas's disease has been carried out. A total of 1,137 IHAT for Chagas's disease positive persons were submitted to two wooden XD boxes containing 7 triatoma infestans nymphs III each. The positivity in percentage 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 ò 60 (43,3). The 60,8 positivy 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 inmunological mechanisms, which decrease with the age increasing