title: Network simulation modeling of equine infectious anemia in the non-racehorse population in Japan.
abstract: An equine infectious anemia (EIA) transmission model was developed by constructing a network structure of horse movement patterns in a non-racehorse population. This model was then used to evaluate the effectiveness and efficiency of several EIA surveillance strategies. Because EIA had not been detected in Japan since 1993, it was appropriate to review the current surveillance strategy, which aims to eradicate EIA by intensive testing, and to consider alternative strategies suitable for the current EIA status in Japan. The non-racehorse population was divided into four sectors based on horse usage: the equestrian sector, private owner sector, exhibition sector, and fattening sector. To evaluate the risk of disease spread within and between sectors accompanied by horse movements, a stochastic individual-based network model was developed based on a previous survey of horse movement patterns. Surveillance parameters such as targeting sectors and frequency of testing were added into the model to compare surveillance strategies. The disease spread heterogeneously among sectors. Infection occurred mainly in the equestrian sector; the infection was less disseminated in other sectors. Therefore, we considered that the equestrian sector posed a higher risk of disease dissemination within and between sectors through horse movements. However, surveillance strategies targeting only the equestrian sector were not effective enough for early detection of the disease. Alternatively, targeting horses that moved permanently and those in the private owner sector in addition to the equestrian sector is recommended to achieve effectiveness equivalent to that of the current surveillance. In terms of surveillance efficacy, by increasing the testing interval (once yearly to once every 3 years), this testing scheme could reduce the number of tested horses to 44% of the current surveillance, while maintaining almost equivalent effectiveness. Intensive strategies targeting high-risk populations are considered to enhance effectiveness and efficiency of surveillance. The approach in this study may be helpful in the decision-making process that is involved in setting up strategies for risk-based surveillance.
authors.affiliation: Epidemiological Research Team, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan. hayama@affrc.go.jp
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hayama
authors.forename: Sota
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishida
authors.forename: Norihiko
authors.initials: N
authors.lastname: Muroga
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Tsutsui
mesh_terms: D000818:Animals; D001947:Breeding; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D004859:Equine Infectious Anemia / Q000453:epidemiology / Q000635:transmission*; D006736:Horses / Q000145:classification*; D006799:Housing, Animal / Q000592:standards; D007564:Japan / Q000453:epidemiology; D008954:Models, Biological; D011159:Population Surveillance / Q000379:methods*; D018570:Risk Assessment