title: The role of neighboring infected cattle in bovine leukemia virus transmission risk.
abstract: A cohort study was conducted to evaluate the risk of bovine leukemia virus (BLV) transmission to uninfected cattle by adjacent infected cattle in 6 dairy farms. Animals were initially tested in 2010-2011 using a commercial ELISA kit. Uninfected cattle were repeatedly tested every 4 to 6 months until fall of 2012. The Cox proportional hazard model with frailty showed that uninfected cattle neighboring to infected cattle (n=53) had a significant higher risk of seroconversion than those without any infected neighbors (n=81) (hazard ratio: 12.4, P=0.001), implying that neighboring infected cattle were a significant risk factor for BLV transmission. This finding provides scientific support for animal health authorities and farmers to segregate infected cattle on farms to prevent spread of BLV.
authors.affiliation: Viral Diseases and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Sota
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Tsutsui
authors.forename: Takehisa
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hayama
authors.forename: Norihiko
authors.initials: N
authors.lastname: Muroga
authors.forename: Misako
authors.initials: M
authors.lastname: Konishi
authors.forename: Ken-Ichiro
authors.initials: K
authors.lastname: Kameyama
authors.forename: Kenji
authors.initials: K
authors.lastname: Murakami
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying; D016583:Enzootic Bovine Leukosis / Q000635:transmission* / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D001909:Leukemia Virus, Bovine / Q000502:physiology; D016016:Proportional Hazards Models; D012307:Risk Factors