title: Bottlenecks in domestic animal populations can facilitate the emergence of Trypanosoma cruzi, the aetiological agent of Chagas disease.
abstract: Faeces-mediated transmission of Trypanosoma cruzi (the aetiological agent of Chagas disease) by triatomine insects is extremely inefficient. Still, the parasite emerges frequently, and has infected millions of people and domestic animals. We synthesize here the results of field and laboratory studies of T. cruzi transmission conducted in and around Arequipa, Peru. We document the repeated occurrence of large colonies of triatomine bugs (more than 1000) with very high infection prevalence (more than 85%). By inoculating guinea pigs, an important reservoir of T. cruzi in Peru, and feeding triatomine bugs on them weekly, we demonstrate that, while most animals quickly control parasitaemia, a subset of animals remains highly infectious to vectors for many months. However, we argue that the presence of these persistently infectious hosts is insufficient to explain the observed prevalence of T. cruzi in vector colonies. We posit that seasonal rains, leading to a fluctuation in the price of guinea pig food (alfalfa), leading to annual guinea pig roasts, leading to a concentration of vectors on a small subpopulation of animals maintained for reproduction, can propel T. cruzi through vector colonies and create a considerable force of infection for a pathogen whose transmission might otherwise fizzle out.
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru mzlevy@mail.med.upenn.edu.
authors.forename: Michael Z
authors.initials: MZ
authors.lastname: Levy
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Tustin
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Castillo-Neyra
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Tarub S
authors.initials: TS
authors.lastname: Mabud
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Katelyn
authors.initials: K
authors.lastname: Levy
authors.affiliation: Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Corentin M
authors.initials: CM
authors.lastname: Barbu
authors.affiliation: Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Victor R
authors.initials: VR
authors.lastname: Quispe-Machaca
authors.affiliation: Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Jenny
authors.initials: J
authors.lastname: Ancca-Juarez
authors.affiliation: Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Katty
authors.initials: K
authors.lastname: Borrini-Mayori
authors.affiliation: Universidad Peruana Cayetano Heredia/University of Pennsylvania Chagas Disease Field Laboratory, Arequipa, Peru.
authors.forename: Cesar
authors.initials: C
authors.lastname: Naquira-Velarde
authors.affiliation: Cary Institute of Ecosystem Studies, Millbrook, NY, USA.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Ostfeld
mesh_terms: D000818:Animals; D014355:Chagas Disease / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D003430:Cross-Sectional Studies; D004197:Disease Reservoirs / Q000469:parasitology / Q000662:veterinary; D006168:Guinea Pigs; D007303:Insect Vectors / Q000469:parasitology* / Q000502:physiology; D018512:Parasitemia / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission / Q000662:veterinary; D010568:Peru / Q000453:epidemiology; D011157:Population Dynamics; D015995:Prevalence; D012376:Rodent Diseases / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D014224:Triatoma / Q000469:parasitology* / Q000502:physiology; D014349:Trypanosoma cruzi / Q000502:physiology*
keywords: Chagas disease; Triatoma infestans; Trypanosoma cruzi; bottleneck; guinea pigs