title: Spatial distribution of soil contamination by Toxoplasma gondii in relation to cat defecation behaviour in an urban area.
abstract: In urban areas, there may be a high local risk of zoonosis due to high densities of stray cat populations. In this study, soil contamination by oocysts of Toxoplasma gondii was searched for, and its spatial distribution was analysed in relation to defecation behaviour of cats living in a high-density population present in one area of Lyon (France). Sixteen defecation sites were first identified. Cats were then repeatedly fed with marked food and the marked faeces were searched for in the defecation sites. Of 260 markers, 72 were recovered from 24 different cats. Defecation sites were frequented by up to 15 individuals. Soil samples were also examined in order to detect the presence of T. gondii using real-time PCR. The entire study area was then sampled according to cat density and vegetation cover type. Only three of 55 samples were positive and all came from defecation sites. In a second series of observations, 16 defecation sites were sampled. Eight of 62 samples tested positive, originating in five defecation sites. Laboratory experiments using experimental seeding of soil showed that the inoculated dose that can be detected in 50% of assays equals 100-1000oocysts/g, depending on the strain. This study shows that high concentrations of oocysts can be detected in soil samples using molecular methods and suggests that spatial distribution of contamination areas is highly heterogeneous. Positive samples were only found in some of the defecation sites, signifying that at-risk points for human and animal infection may be very localised.
authors.affiliation: Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne F-69622, France. afonso@biomserv.univ-lyon1.fr
authors.forename: Eve
authors.initials: E
authors.lastname: Afonso
authors.forename: Mélissa
authors.initials: M
authors.lastname: Lemoine
authors.forename: Marie-Lazarine
authors.initials: ML
authors.lastname: Poulle
authors.forename: Marie-Caroline
authors.initials: MC
authors.lastname: Ravat
authors.forename: Stéphane
authors.initials: S
authors.lastname: Romand
authors.forename: Philippe
authors.initials: P
authors.lastname: Thulliez
authors.forename: Isabelle
authors.initials: I
authors.lastname: Villena
authors.forename: Dominique
authors.initials: D
authors.lastname: Aubert
authors.forename: Muriel
authors.initials: M
authors.lastname: Rabilloud
authors.forename: Benjamin
authors.initials: B
authors.lastname: Riche
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Gilot-Fromont
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000453:epidemiology* / Q000469:parasitology; D002415:Cats; D004609:Eliminative Behavior, Animal; D005243:Feces / Q000469:parasitology*; D005602:France / Q000453:epidemiology; D006801:Humans; D033661:Oocysts / Q000254:growth & development*; D010270:Parasite Egg Count; D012987:Soil / Q000469:parasitology*; D014122:Toxoplasma / Q000254:growth & development*; D014124:Toxoplasmosis, Animal / Q000453:epidemiology / Q000469:parasitology*; D014504:Urban Health; D014675:Vegetables / Q000469:parasitology
chemical_list: D012987:Soil