title: [Yielding of xenodiagnosis, according to the number of boxes used in 1,181 persons with chronic chagasic infection diagnosed with indirect hemagglutination reaction].
abstract: A study for evaluation of the yielding of xenodiagnosis (XD) in 1,181 persons with a previous positive indirect hemagglutination test (IHAT) for Trypanosoma cruzi infection was carried out. The infection of these people was detected during epidemiological surveys performed in rural-periurban and urban sections of the endemo-enzootic area of Chagas' disease in Chile, which involves the first seven, out of the thirteen political-administrative regions of the country. The sex distribution was 75.0% females and 25.0% males, varying the ages between 2 and 80 years. According to individual and geographical possibilities each person was submitted to 1-8 XD, which consisted in cylindrical wooden boxes containing seven third instar nymphs, laboratory reared, of Triatoma infestans. The boxes, covered with a piece of tulle fixed with a rubber band were applied on the skin of the posterior side of the arm of the subject to be examined, held with a linen bracelet during 25-30 min. After the insects were fed the boxes were maintained in the laboratory at 27 degrees C and 85% relative environmental humidity. Posteriorly, all the nymphs of each box were examined at 30, 60 and 90 days after the application. A drop of abdominal content of each of them, homogenized with a drop of saline, was examined at the microscope looking for T. cruzi. XD resulted positive in 503 (42.6%) people. The positiveness of XD showed a trend of increasing according to the number of boxes used, from 11.4% with one to 51.6% with six. Under a practical point of view, the simultaneous application of four XD boxes seems to be advisable.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad de Chile, Santiago.
authors.forename: H
authors.initials: H
authors.lastname: Schenone
authors.forename: M C
authors.initials: MC
authors.lastname: Contreras
authors.forename: A
authors.initials: A
authors.lastname: Rojas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D014355:Chagas Disease / Q000175:diagnosis* / Q000469:parasitology; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005260:Female; D006386:Hemagglutination Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D014224:Triatoma / Q000469:parasitology; D014345:Trypanosoma / Q000302:isolation & purification
vernacular_title: Rendimiento del xenodiagnóstico, según el número de cajas utilizadas, en 1.181 personas con infección chagásica crónica diagnosticada mediante la reacción de hemaglutinación indirecta.