Simulation studies of African horse sickness in Spain
Factors affecting epidemics of African horse sickness in Spain were studied using a mathematical model. The model examined the likelihood of an epidemic after the introduction of the virus, and the effectiveness of vaccination strategies. Two host species (horses and donkeys) and one vector species (the biting midge Culicoides imicola) were included. A stratified random sampling method (Latin hypercube sampling) was used for sensitivity analysis of the likelihood of an epidemic. Systematic variation of vaccination parameters was used to consider alternative control strategies. In general, when an epidemic occurred most potential hosts became infected. The peak prevalence in C. imicola was low, and never exceeded 3%. The most significant factors in the likelihood of an epidemic were vector population size, the recovery rate in horses and the time of year when the virus was introduced. The lag between virus introduction and protection, the proportion of hosts vaccinated, and including donkeys in vaccination programmes where the factors that most strongly affected the success of different vaccination strategies. These factors should be priorities for empirical research, and should be considered in the design of control strategies in areas at risk of virus introduction.
KeywordsVaccination Strategy Latin Hypercube Sampling Bluetongue Virus Peak Prevalence Entomological Society
Unable to display preview. Download preview PDF.
- 1.Agresti A (1990) Categorical data analysis. Wiley, New YorkGoogle Scholar
- 6.Blythe SP, Gurney WSC, Maas P, Nisbet RM (1990) User guide for SOLVER, revision 4. 0. APIC, GlasgowGoogle Scholar
- 7.Borland International (1992) Turbo Pascal user’s guide. Borland International, Scotts Valley, CAGoogle Scholar
- 9.Braverman Y, Linley JR, Marcus R, Frish K (1985) Seasonal survival and expectation of infective-life of Culicoides spp. (Diptera: Ceratopogonidae) in Israel, with implications for bluetongue virus transmission and a comparison of the parous rate in C. imicola from Israel and Zimbabwe. J Med Entomol 22: 476–484PubMedGoogle Scholar
- 12.Iman RL, Shortencarrier MJ (1984) A Fortran 77 program & users guide for the generation of Latin Hypercubes & random samples for use with computer models. NUREG/CR-3624, SAND83–365. Sandia National Laboratories, Albuquerque, NMGoogle Scholar
- 13.Jones RH, Foster NM (1971) Transovarian transmission of bluetongue virus unlikely for Culicoides variipennis. Mosq News 31: 434–437Google Scholar
- 16.Meiswinkel R, Nevill EM, Venter GJ (1994) Vectors: Culicoides spp. In: Coetzer JAW, Thomson GR, Tustin RC (eds) Infectious diseases of livestock with special reference to southern Africa, vol 1. Oxford University Press, Oxford, pp 68–89Google Scholar
- 17.Mellor PS (1990) The replication of bluetongue virus in Culicoides vectors. In: Walton TE, Osburn BI (eds) Bluetongue, African horse sickness, and related orbiviruses: Proceedings of the Second Symposium. Curr Top Microbiol Immunol 162: 143–161Google Scholar
- 20.Nunamaker RA, Sieburth PJ, Dean VC, Wigington JG, Nunamaker CE, Mecham JO (1990) Absence of transovarial transmission of bluetongue virus in Culicoides variipennis: immunogold labelling of bluetongue virus antigen in developing oocytes from Culicoides variipennis ( Coquillett ). Comp Biochem Physiol 96A: 19–31CrossRefGoogle Scholar
- 21.Rawlings P, Mellor PS (1994) African horse sickness and the overwintering of Culicoides spp. in the Iberian peninsula. Rev Sci Tech Off Int Epiz 13: 753–761Google Scholar
- 23.SAS Institute (1988) SAS user’s guide. SAS Institute, Cary, NCGoogle Scholar
- 27.Venter GJ, Williams R, Nevill EM (1992) The value of donkeys as sentinels for African horse sickness. In: Walton TE, Osburn BI (eds) Bluetongue, African horse sickness and related orbiviruses: proceedings of the second symposium, Paris 1991. CRC Press, Boca Raton, pp 825–831Google Scholar