Pirbright Institute, Ash Road, Pirbright, Woking, United Kingdom; Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom; Department of Infectious Disease Epidemiology, MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom; State Department of Livestock, Ministry of Agriculture, Livestock and Fisheries, P.O. Private Bag, Kabete, Kangemi, Nairobi, Kenya
Lyons, N.A., Pirbright Institute, Ash Road, Pirbright, Woking, United Kingdom, Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom; Alexander, N., Department of Infectious Disease Epidemiology, MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom; Stärk, K.D.C., Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom; Dulu, T.D., State Department of Livestock, Ministry of Agriculture, Livestock and Fisheries, P.O. Private Bag, Kabete, Kangemi, Nairobi, Kenya; Rushton, J., Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom; Fine, P.E., Pirbright Institute, Ash Road, Pirbright, Woking, United Kingdom
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). © 2015 Lyons et al.; licensee BioMed Central.