title: Designing a risk-based surveillance program for Mycobacterium avium ssp. paratuberculosis in Norwegian dairy herds using multivariate statistical process control analysis.
abstract: Surveillance programs for animal diseases are critical to early disease detection and risk estimation and to documenting a population's disease status at a given time. The aim of this study was to describe a risk-based surveillance program for detecting Mycobacterium avium ssp. paratuberculosis (MAP) infection in Norwegian dairy cattle. The included risk factors for detecting MAP were purchase of cattle, combined cattle and goat farming, and location of the cattle farm in counties containing goats with MAP. The risk indicators included production data [culling of animals >3 yr of age, carcass conformation of animals >3 yr of age, milk production decrease in older lactating cows (lactations 3, 4, and 5)], and clinical data (diarrhea, enteritis, or both, in animals >3 yr of age). Except for combined cattle and goat farming and cattle farm location, all data were collected at the cow level and summarized at the herd level. Predefined risk factors and risk indicators were extracted from different national databases and combined in a multivariate statistical process control to obtain a risk assessment for each herd. The ordinary Hotelling's T(2) statistic was applied as a multivariate, standardized measure of difference between the current observed state and the average state of the risk factors for a given herd. To make the analysis more robust and adapt it to the slowly developing nature of MAP, monthly risk calculations were based on data accumulated during a 24-mo period. Monitoring of these variables was performed to identify outliers that may indicate deviance in one or more of the underlying processes. The highest-ranked herds were scattered all over Norway and clustered in high-density dairy cattle farm areas. The resulting rankings of herds are being used in the national surveillance program for MAP in 2014 to increase the sensitivity of the ongoing surveillance program in which 5 fecal samples for bacteriological examination are collected from 25 dairy herds. The use of multivariate statistical process control for selection of herds will be beneficial when a diagnostic test suitable for mass screening is available and validated on the Norwegian cattle population, thus making it possible to increase the number of sampled herds.
authors.affiliation: Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, PO Box 5003, NO-1432 Ås, Norway. Electronic address: anne.cathrine.whist@tine.no.
authors.forename: A C
authors.initials: AC
authors.lastname: Whist
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, NO-1432 Ås, Norway.
authors.forename: K H
authors.initials: KH
authors.lastname: Liland
authors.affiliation: Norwegian Veterinary Institute, PO Box 750 Sentrum, NO-0106 Oslo, Norway.
authors.forename: M E
authors.initials: ME
authors.lastname: Jonsson
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, NO-1432 Ås, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Sæbø
authors.affiliation: Norwegian Veterinary Institute, PO Box 750 Sentrum, NO-0106 Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Sviland
authors.affiliation: Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, PO Box 5003, NO-1432 Ås, Norway; Norwegian Cattle Health Services, Tine SA, the Norwegian Dairies, PO Box 58, NO-1431 Ås, Norway.
authors.forename: O
authors.initials: O
authors.lastname: Østerås
authors.affiliation: Norwegian Veterinary Institute, PO Box 750 Sentrum, NO-0106 Oslo, Norway.
authors.forename: M
authors.initials: M
authors.lastname: Norström
authors.affiliation: Norwegian Veterinary Institute, PO Box 750 Sentrum, NO-0106 Oslo, Norway.
authors.forename: P
authors.initials: P
authors.lastname: Hopp
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D003612:Dairying; D062665:Epidemiological Monitoring / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D005260:Female; D015511:Goat Diseases / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D006041:Goats; D007774:Lactation; D008892:Milk / Q000378:metabolism; D015999:Multivariate Analysis; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D009664:Norway / Q000453:epidemiology; D010283:Paratuberculosis / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors
keywords: Mycobacterium avium ssp. paratuberculosis; cattle; multivariate statistical process control; risk-based surveillance