title: Impact of foot-and-mouth disease on mastitis and culling on a large-scale dairy farm in Kenya.
abstract: Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057).
authors.affiliation: The Pirbright Institute, Ash Road, Pirbright, Woking, GU240NF, UK. nick.lyons@pirbright.ac.uk.|Veterinary Epidemiology, Economics, and Public Health Group, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, UK. nick.lyons@pirbright.ac.uk.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Lyons
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. neal.alexander@lshtm.ac.uk.
authors.forename: Neal
authors.initials: N
authors.lastname: Alexander
authors.affiliation: Veterinary Epidemiology, Economics, and Public Health Group, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, UK. kstaerk@rvc.ac.uk.
authors.forename: Katharina D C
authors.initials: KD
authors.lastname: Stӓrk
authors.affiliation: State Department of Livestock, Ministry of Agriculture, Livestock and Fisheries, P.O. Private Bag Kabete, Kangemi, 00625, Nairobi, Kenya. nanetia@gmail.com.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Dulu
authors.affiliation: Veterinary Epidemiology, Economics, and Public Health Group, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, UK. jrushton@rvc.ac.uk.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rushton
authors.affiliation: The Pirbright Institute, Ash Road, Pirbright, Woking, GU240NF, UK. paul.fine@lshtm.ac.uk.
authors.forename: Paul E M
authors.initials: PE
authors.lastname: Fine
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D015331:Cohort Studies; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D003612:Dairying; D004196:Disease Outbreaks / Q000662:veterinary*; D005260:Female; D005536:Foot-and-Mouth Disease / Q000453:epidemiology* / Q000821:virology; D029544:Foot-and-Mouth Disease Virus / Q000502:physiology*; D007630:Kenya / Q000453:epidemiology; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology