title: Analysis of risk factors associated with bovine leukemia virus seropositivity within dairy and beef breeding farms in Japan: a nationwide survey.
abstract: This cross-sectional study evaluated risk factors associated with farm-level bovine leukemia virus (BLV) seropositivity in 563 dairy and 490 beef farms throughout Japan. Twenty randomly selected cattle on each farm were serologically tested, and farm epidemiologiocal information was obtained through face-to-face interviews. Due to the large number of zero-prevalence dairy and beef farms, data analysis was performed using a zero-inflated negative binomial model, which revealed that the common risk factors associated with higher within-farm seroprevalence were past detection of clinical leukemia and presence of blood-sucking insects. Loose housing on dairy farms and direct contact between calves and adult cattle on beef farms were also identified as risk factors. With regard to farm-level presence of BLV, the presence of purchased cattle was found to be a risk factor in both sectors. Sending heifers to a common ranch was identified as an additional risk factor for dairy farms.
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Hidano
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsutsui
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hayama
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nishida
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Muroga
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Konishi
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kameyama
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki, Japan. Electronic address: muraken@iwate-u.ac.jp.
authors.forename: K
authors.initials: K
authors.lastname: Murakami
mesh_terms: D000818:Animals; D002417:Cattle; D003430:Cross-Sectional Studies; D016583:Enzootic Bovine Leukosis / Q000453:epidemiology / Q000821:virology*; D007564:Japan / Q000453:epidemiology; D001909:Leukemia Virus, Bovine / Q000302:isolation & purification*; D008297:Male; D015999:Multivariate Analysis; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D011795:Surveys and Questionnaires
keywords: Bovine leukemia virus; Epidemiology; Risk factors; ZINB model