title: Is the infectiousness of dogs naturally infected with Trypanosoma cruzi associated with poly-parasitism?
abstract: Interactions among different species of parasites co-infecting the same host could be synergistic or antagonistic. These interactions may modify both the frequency of infected hosts and their infectiousness, and therefore impact on transmission dynamics. This study determined the infectiousness of Trypanosoma cruzi-seropositive dogs (using xenodiagnosis) and their parasite load (quantified by qPCR), and tested the association between both variables and the presence of concomitant endoparasites. A cross-sectional serosurvey conducted in eight rural villages from Pampa del Indio and neighboring municipalities (northeastern Argentina) detected 32 T. cruzi-seropositive dogs out of 217 individuals examined for infection. Both the infectiousness to the vector Triatoma infestans and parasite load of T. cruzi-seropositive dogs examined were heterogeneous. A statistically significant, nine-fold higher mean infectiousness was registered in T. cruzi-seropositive dogs co-infected with Ancylostoma caninum and a trematode than in T. cruzi-seropositive dogs without these infections. The median parasite load of T. cruzi was also significantly higher in dogs co-infected with these helminths. An opposite trend was observed in T. cruzi-seropositive dogs that were serologically positive to Toxoplasma gondii or Neospora caninum relative to dogs seronegative for these parasites. Using multiple logistic regression analysis with random effects, we found a positive and significant association between the infectiousness of T. cruzi-seropositive dogs and co-infections with A. caninum and a trematode. Our results suggest that co-infections may be a modifier of host infectiousness in dogs naturally infected with T. cruzi.
authors.affiliation: Laboratory of Eco-Epidemiology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina; Institute of Ecology, Genetics and Evolution of Buenos Aires (UBA-CONICET), Argentina.
authors.forename: G F
authors.initials: GF
authors.lastname: Enriquez
authors.affiliation: Laboratory of Clinical and Environmental Parasitology, Faculty of Exact and Natural Sciences, University of Buenos Aires, (IQUIBICEN-CONICET-UBA), Public Health Research Institute, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Garbossa
authors.affiliation: Laboratory of Eco-Epidemiology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina; Institute of Ecology, Genetics and Evolution of Buenos Aires (UBA-CONICET), Argentina.
authors.forename: N P
authors.initials: NP
authors.lastname: Macchiaverna
authors.affiliation: Laboratory of Eco-Epidemiology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina; Institute of Ecology, Genetics and Evolution of Buenos Aires (UBA-CONICET), Argentina.
authors.forename: H D
authors.initials: HD
authors.lastname: Argibay
authors.affiliation: National Institute of Parasitology Dr. M. Fatala Chaben, National Administration of Laboratories and Institutes of Health Dr. C.G. Malbrán, Buenos Aires, Argentina.
authors.forename: J
authors.initials: J
authors.lastname: Bua
authors.affiliation: Laboratory of Eco-Epidemiology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina; Institute of Ecology, Genetics and Evolution of Buenos Aires (UBA-CONICET), Argentina.
authors.forename: R E
authors.initials: RE
authors.lastname: Gürtler
authors.affiliation: Laboratory of Eco-Epidemiology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina; Institute of Ecology, Genetics and Evolution of Buenos Aires (UBA-CONICET), Argentina. Electronic address: mvcardinal@ege.fcen.uba.ar.
authors.forename: M V
authors.initials: MV
authors.lastname: Cardinal
mesh_terms: D000818:Animals; D014355:Chagas Disease / Q000150:complications / Q000469:parasitology / Q000662:veterinary*; D060085:Coinfection / Q000662:veterinary*; D004283:Dog Diseases / Q000469:parasitology*; D004285:Dogs; D006374:Helminthiasis, Animal / Q000150:complications / Q000469:parasitology / Q000473:pathology; D014349:Trypanosoma cruzi / Q000302:isolation & purification*
keywords: Dogs; Infectiousness; Interspecies interactions; Poly-parasitism; Trypanosoma cruzi