Dynamic Transmission of African Horse Sickness in Horse Populations during the First Epidemic in Thailand


  • Weesuda Phisitsak Mahidol University International Demonstration School
  • Anuwat Wiratsudakul Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University
  • Nuttawut Nuchprayoon Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University


African horse sickness, dynamic transmission, herd immunity, mathematical model


Thailand faced the first outbreak of African horse sickness (AHS) in its history in 2020. The virus firstly attacked Nakhon Ratchasima province, where a large number of naïve horses lived.  In this outbreak, over four hundred horses were infected and died within three months. This study applied DengueME application to simulate how the virus spread in the horse populations with the susceptible-infectious-removed (SIR) modeling framework in horses and susceptible-infectious (SI) in vectors. The basic reproduction number (R0), herd immunity threshold, and vaccine coverage requirement were subsequently calculated. We estimated R0 at 3.3. With the herd immunity threshold of 69.7%, we suggested vaccinating 86.1% of horse populations to prevent future outbreaks. Our model is applicable as a baseline to test interventions such as vector control and to monitor the dynamic transmission of AHS in horse populations.


Backer JA, Nodelijk G. Transmission and control of African horse sickness in the Netherlands: a model analysis. PLoS One. 2011;6(8):1-12.

Boreta SEB, Escalante R, Villasana M. Mathematical modelling of zika virus in Brazil. arXiv:1708.01280.2017:1-26.

Bunpapong N, Charoenkul K, Nasamran C, Chamsai E, Udom K, Boonyapisitsopa S, et al. African horse sickness virus serotype 1 on horse farm, Thailand, 2020. Emerg Infect Dis. 2021;27(8):2208-11.

Castillo-Olivares J. African horse sickness in Thailand: Challenges of controlling an outbreak by vaccination. Equine Vet J. 2021;53(1):9-14.

Cooper I, Mondal A, Antonopoulos CG. A SIR model assumption for the spread of COVID-19 in different communities. Chaos Solitons Fractals. 2020;139:1-14.

Dennis SJ, Meyers AE, Hitzeroth II, Rybicki EP. African horse sickness: a review of current understanding and vaccine development. Viruses. 2019;11(9):1-24.

Devi R, Devachoudhury BK. SIR model for transmission of chickenpox in Kamrup Metro District of Assam. Int J Eng Sci Technol. 2018;8(2S):98-102.

Diarra M, Fall M, Fall AG, Diop A, Lancelot R, Seck MT, et al. Spatial distribution modelling of Culicoides (Diptera: Ceratopogonidae) biting midges, potential vectors of African horse sickness and bluetongue viruses in Senegal. Parasit Vectors. 2018;11(1):341.

DLD. African horse sickness (AHS) in Thailand [internet]. Department of Livestock Development. 2020. [cited 2022 Sep 21]. Available from: https://rr-asia.woah.org/wp-content/uploads/2020/06/1-update-on-situation-in-thailand.pdf.

Doungmo Goufo EF, Oukouomi Noutchie SC, Mugisha S. A fractional SEIR epidemic model for spatial and temporal spread of measles in metapopulations. Abstr Appl Anal. 2014;2014:1-6.

Grewar JD, Weyer CT, Guthrie AJ, Koen P, Davey S, Quan M, et al. The 2011 outbreak of African horse sickness in the African horse sickness controlled area in South Africa. J S Afr Vet Assoc. 2013;84(1):1-7.

Guan Y, Chen H, Li K, Riley S, Leung G, Webster R, et al. A model to control the epidemic of H5N1 influenza at the source. BMC Infect Dis. 2007;7:1-8.

Gubbins S. Using the basic reproduction number to assess the risk of transmission of lumpy skin disease virus by biting insects. Transbound Emerg Dis. 2019;66(5):1873-83.

Hemida M, Alhammadi M, Daleb A, Alnaeem A. Molecular and serological surveillance of African horse sickness virus in Eastern and Central Saudi Arabia. Rev Sci Tech Off Int Epiz. 2017;36(3):1-22.

Huppert A, Katriel G. Mathematical modelling and prediction in infectious disease epidemiology. Clin Microbiol Infect. 2013;19(11):999-1005.

Kajaysri J, Toompong J. African horse sickness: the emerging infectious diseases in thailand. APHEIT Journal. 2020;1:1-8.

Ketusing N. African horse sickness in Thailand [internet]. Division of International Livestock Cooperation. 2020 [cited 2022 Sep 21]. Available from: https://rr-asia.woah.org/wp-content/uploads/2020/11/thailand_ahs-situation_10nov2020.pdf.

King S, Rajko-Nenow P, Ashby M, Frost L, Carpenter S, Batten C. Outbreak of African horse sickness in Thailand, 2020. Transbound Emerg Dis. 2020:1-4.

Lahariya C. Vaccine epidemiology: A review. J Family Med Prim Care. 2016;5(1):7-15.

Lord CC, Woolhouse MEJ, Heesterbeek JAP, Mellor PS. Vector-borne diseases and the basic reproduction number: a case study of African horse sickness. Med Vet Entomol. 1996;10:19-28.

Lord CC, Woolhouse MEJ, Mellor PS. Simulation studies of vaccination strategies in African horse sickness. Vaccine. 1997;15(5):519-24.

Lord CC, Woolhouse MEJ, Mellor PS. Simulation studies of African horse sickness in Spain. In: Mellor PS, Baylis M, Hamblin C, Mertens PPC, Calisher CH, editors. African horse sickness. Vienna: Springer; 1998. p. 103-11.

MacIntyre CR, Costantino V, Trent M. Modelling of COVID-19 vaccination strategies and herd immunity, in scenarios of limited and full vaccine supply in NSW, Australia. Vaccine. 2022;40:2506-13.

McKenna TSC. Overview of African horse sickness [internet]. MSD Veterinary Manual. 2015 [cited 2022 Aug 16]. Available from: https://www.msdvetmanual.com/generalized-conditions/african-horse-sickness/overview-of-african-horse-sickness.

Meade BJ. The transmission dynamics of equine herpes virus type 1 (EHV-1) infection in outbreaks characterized predonminately by neurological or respiratory illness. Lexington: University of Kentucky; 2012.

Mellor PS, Hamblin C. African horse sickness. Vet Res. 2004;35(4):445-66.

Pandey A, Mubayi A, Medlock J. Comparing vector–host and SIR models for dengue transmission. Math Biosci. 2013;246(2):252-9.

Porphyre T, Grewar JD. Assessing the potential of plains zebra to maintain African horse sickness in the Western Cape Province, South Africa. PloS One. 2019;14(10):1-24.

Portas M, Boinas FS, Oliveira J, Sousa E, Rawlings P. African horse sickness in Portugal: a successful eradication programme. Epidemiol Infect. 1999;123:337-46.

Putri RG, Jaharuddin, Bakhtiar T. Sirs-Si Model of malaria disease with application of vaccines, anti-malarial drugs, and spraying. IOSR J Math. 2014;10(5):66-72.

Satou K, Nishiura H. Basic reproduction number for equine-2 influenza virus A (H3N8) epidemic in racehorse facilities in Japan, 1971. J Equine Vet Sci. 2006;26(7):310-6.

Schwartz EJ, Smith RJ. Identifying the conditions under which antibodies protect against Infection by equine infectious anemia virus. Vaccines (Basel). 2014;2(2):397-421.

Sellers RF, Pedgley DE, Tucker MR. Possible spread of African horse sickness on the wind. J Hyg. 1977;79:279-98.

Slama D, Babba H, Chaker E. Culicoides spp. (Diptera: Ceratopogonidae) in Tunisia. In: Shields VDC, editor. Biological Control of Pest and Vector Insects. Culicoides spp. (Diptera: Ceratopogonidae) in Tunisia: IntechOpen; 2017. p. 213-29.

Spickler AR. 2015. African horse sickness. The Center for Food Security & Public Health. p. 1-6.

Thepparat A, Tsuruishi T, Ketavan C. Species Diversity and Abundance of Culicoides (Diptera : Ceratopogonidae) in Sakaew Province. Ramkhamhaeng University Journal of Research. 2012;15(2):65-80.

Thompson GM, Jess S, Murchie AK. A review of African horse sickness and its implications for Ireland. Ir Vet J. 2012;65(9):1-8.

Venter GJ, Koekemoer JJO, Paweska JT. Investigations on outbreaks of African horse sickness in the surveillance zone in South Africa. Rev Sci Tech Off Int Epiz. 2006;25(3):1097-109.

Wiratsudakul A, Suparit P, Modchang C. Dynamics of Zika virus outbreaks: an overview of mathematical modeling approaches. PeerJ. 2018;6:1-30.

WOAH. African horse sickness [internet]. WOAH 2020 [cited 2022 Aug 16]. Available from: https://www.woah.org/en/disease/african-horse-sickness/.

Yothakol C. Protocol for horse transportation after vaccination (in Thai language) [internet]. Department of Livestock Development. 2019 [cited 2022 Aug 16]. Available from: http://dcontrol.dld.go.th/webnew/index.php/th/news-menu-2/african-horse-sickness/4110-african-horse-sickness-2563.




How to Cite

Phisitsak, W., Wiratsudakul, A., & Nuchprayoon, N. (2022). Dynamic Transmission of African Horse Sickness in Horse Populations during the First Epidemic in Thailand. Journal of Applied Animal Science, 15(1), 47–62. Retrieved from https://he02.tci-thaijo.org/index.php/jaas_muvs/article/view/258977



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