title: Heterogeneous infectiousness in guinea pigs experimentally infected with Trypanosoma cruzi.
abstract: Guinea pigs are important reservoirs of Trypanosoma cruzi, the causative parasite of Chagas disease, and in the Southern Cone of South America, transmission is mediated mainly by the vector Triatoma infestans. Interestingly, colonies of Triatoma infestans captured from guinea pig corrals sporadically have infection prevalence rates above 80%. Such high values are not consistent with the relatively short 7-8 week parasitemic period that has been reported for guinea pigs in the literature. We experimentally measured the infectious periods of a group of T. cruzi-infected guinea pigs by performing xenodiagnosis and direct microscopy each week for one year. Another group of infected guinea pigs received only direct microscopy to control for the effect that inoculation by triatomine saliva may have on parasitemia in the host. We observed infectious periods longer than those previously reported in a number of guinea pigs from both the xenodiagnosis and control groups. While some guinea pigs were infectious for a short time, other "super-shedders" were parasitemic up to 22 weeks after infection, and/or positive by xenodiagnosis for a year after infection. This heterogeneity in infectiousness has strong implications for T. cruzi transmission dynamics and control, as super-shedder guinea pigs may play a disproportionate role in pathogen spread.
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, PA, USA; Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: rcastillo@jhu.edu.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Castillo-Neyra
authors.affiliation: Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: yttakbm@gmail.com.
authors.forename: Katty
authors.initials: K
authors.lastname: Borrini Mayorí
authors.affiliation: Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: rendaths@gmail.com.
authors.forename: Renzo
authors.initials: R
authors.lastname: Salazar Sánchez
authors.affiliation: Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: jenyma14@gmail.com.
authors.forename: Jenny
authors.initials: J
authors.lastname: Ancca Suarez
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, PA, USA. Electronic address: xiex@vet.upenn.edu.
authors.forename: Sherrie
authors.initials: S
authors.lastname: Xie
authors.affiliation: Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: cesar.naquira@gmail.com.
authors.forename: Cesar
authors.initials: C
authors.lastname: Náquira Velarde
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, PA, USA. Electronic address: mzlevy@mail.med.upenn.edu.
authors.forename: Michael Z
authors.initials: MZ
authors.lastname: Levy
mesh_terms: D000818:Animals; D014355:Chagas Disease / Q000469:parasitology* / Q000635:transmission*; D004197:Disease Reservoirs / Q000469:parasitology*; D006168:Guinea Pigs; D018512:Parasitemia; D015995:Prevalence; D012463:Saliva / Q000469:parasitology; D013020:South America; D013997:Time Factors; D014224:Triatoma / Q000469:parasitology*; D014349:Trypanosoma cruzi / Q000502:physiology* / Q000648:ultrastructure; D020525:Xenodiagnosis
keywords: Cavia porcellus; Guinea pig; Infectiousness; Super-shedder; Triatoma infestans; Trypanosoma cruzi; Xenodiagnosis