title: Comparison of risk factors for seropositivity to feline immunodeficiency virus and feline leukemia virus among cats: a case-case study.
abstract: BACKGROUND
  Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are reported to have similar risk factors and similar recommendations apply to manage infected cats. However, some contrasting evidence exists in the literature with regard to commonly reported risk factors. In this study, we investigated whether the known risk factors for FIV and FeLV infections have a stronger effect for either infection. This retrospective study included samples from 696 cats seropositive for FIV and 593 cats seropositive for FeLV from the United States and Canada. Data were collected during two cross sectional studies, where cats were tested using IDEXX FIV/FeLV ELISA kits. To compare the effect of known risk factors for FIV infection compared to FeLV, using a case-case study design, random intercept logistic regression models were fit including cats' age, sex, neuter status, outdoor exposure, health status and type of testing facility as independent variables. A random intercept for testing facility was included to account for clustering expected in testing practices at the individual clinics and shelters.
  
  
  RESULTS
  In the multivariable random intercept model, the odds of FIV compared to FeLV positive ELISA results were greater for adults (OR = 2.09, CI: 1.50-2.92), intact males (OR = 3.14, CI: 1.85-3.76), neutered males (OR = 2.68, CI: 1.44- 3.14), cats with outdoor access (OR = 2.58, CI: 1.85-3.76) and lower for cats with clinical illness (OR = 0.60, 95% CI: 0.52-0.90). The variance components obtained from the model indicated clustering at the testing facility level.
  
  
  CONCLUSIONS
  Risk factors that have a greater effect on FIV seropositivity include adulthood, being male (neutered or not) and having access to outdoors, while clinical illness was a stronger predictor for FeLV seropositivity. Further studies are warranted to assess the implications of these results for the management and control of these infections.
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada. bchhetri@uoguelph.ca.
authors.forename: Bimal K
authors.initials: BK
authors.lastname: Chhetri
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada. oberke@uoguelph.ca.|Department of Mathematics and Statistics, University of Guelph, Guelph, ON, Canada. oberke@uoguelph.ca.|Institute of Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hanover (Foundation), Hanover, Germany. oberke@uoguelph.ca.
authors.forename: Olaf
authors.initials: O
authors.lastname: Berke
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada. dpearl@uoguelph.ca.
authors.forename: David L
authors.initials: DL
authors.lastname: Pearl
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada. dbienzle@uoguelph.ca.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Bienzle
mesh_terms: D000367:Age Factors; D000818:Animals; D002371:Cat Diseases / Q000209:etiology / Q000821:virology*; D002415:Cats; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D016089:Immunodeficiency Virus, Feline; D016180:Lentivirus Infections / Q000209:etiology / Q000662:veterinary*; D005256:Leukemia Virus, Feline; D008297:Male; D012189:Retrospective Studies; D012192:Retroviridae Infections / Q000209:etiology / Q000662:veterinary*; D012307:Risk Factors; D012737:Sex Factors; D014412:Tumor Virus Infections / Q000209:etiology / Q000662:veterinary*