Probability of Infection with Trypanosoma cruzi of the Vector Triatoma infestans Fed on Infected Humans and Dogs in Northwest Argentina

Ricardo E. Gurtler Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Maria C. Cecere Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Monica B. Castanera Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Delmi Canale Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Marta A. Lauricella Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Roberto Chuit Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Joel E. Cohen Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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Elsa L. Segura Laboratorio de Ecologia General, Departmento de Ciencias Biologicas, Universidad de Buenos Aires, Laboratory of Populations, Rockefeller University, Servicio Nacional de Chagas, Instituto Nacional de Chagas Dr. Mario Fatala Chaben, Direccion de Epidemiologia, Ministerio de Salud y Accion Social de la Nacion, Buenos Aires, Argentina

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DOI:
https://doi.org/10.4269/ajtmh.1996.55.1.TM0550010024
Volume/Issue:
Volume 55: Issue 1
Page(s):
24–31
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The probability that an uninfected Triatoma infestans would become infected with Trypanosoma cruzi after a single feed on people or dogs seropositive for T. cruzi was estimated in Amama, a rural village in northwest Argentina where transmission had resurged four years earlier. The prevalence of seropositivity for T. cruzi was 34.2% among 225 people tested, and 65.1% among 83 dogs tested. Parasitemia was detected by xenodiagnosis in 29.3% of 41 seropositive persons and in 85.3% of 34 seropositive dogs. Parasitemia decreased with age more sharply in seropositive people than in seropositive dogs. Seropositive humans infected 2.6% (95% confidence interval = 1.6%–3.6%) of 963 third or fourth instar nymphs fed once on them, whereas dogs infected 48.7% (44.7%–52.7%) of 610 nymphs. The probability of bug infection increased significantly with instar and was positively related to molting success. The infectivity to bugs of seropositive dogs was 12 times higher than that of seropositive children, and 100 times higher than that of seropositive adults. The weighted probability of infection of an uninfected bug fed randomly on any dog (0.3082) was about 50 times higher than that of bugs fed on any human (0.0062). Such differences in relative infectivity, combined with the relative host-feeding preference of domiciliary Triatoma infestans for dogs, reinforces the important role of domestic dogs as a risk factor for the domestic transmission of T. cruzi.

Author Notes

Copyright:
Copyright © 1996 by The American Society of Tropical Medicine and Hygiene 1996
Published Online:
Jul 1996
Cover The American Journal of Tropical Medicine and Hygiene
The American Journal of Tropical Medicine and Hygiene
Print ISSN:
0002-9637
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