African swine fever (ASF) is a contagious haemorrhagic fever that affects both domesticated and wild pigs. Since ASF reached Europe wild boar populations have been a reservoir for the virus. Collecting reliable data on infected individuals in wild populations is challenging, and this makes it difficult to deploy an effective eradication strategy. However, for diseases with high lethality rate, infected carcasses can be used as a proxy for the number of infected individuals at a certain time. Then R0 parameter can be used to estimate the time distribution of the number of newly infected individuals for the outbreak. We estimated R0 for two ASF outbreaks in wild boar, in Czech Republic and Belgium, using the exponential growth method. This allowed us to estimate both R0 and the doubling time (Td) for those infections. The results are R0 = 1.95, Td = 4.39 for Czech Republic and R0 = 1.65, Td = 6.43 for Belgium. We suggest that, if estimated as early as possible, R0 and Td can provide an expected course for the infection against which to compare the actual data collected in the field. This would help to assess if passive surveillance is properly implemented and hence to verify the efficacy of the applied control measures.

Department of Environmental and Agricultural Studies Public Service of Wallonia 5030 Gembloux Belgium

FARAH Research Center Faculty of Veterinary Medicine University of Liège 4000 Liège Belgium

ISPRA Istituto Superiore per la Ricerca e la Protezione Ambientale 40064 Ozzano E Italy

State Veterinary Administration of the Czech Republic 100 7 Slezská Prague Czech Republic

See more in PubMed

Rowlands R.J., Michaud V., Heath L., Hutchings G., Oura C., Vosloo W., Dwarka R., Onashvili T., Albina E., Dixon L.K. African Swine Fever Virus Isolate, Georgia, 2007. Emerg. Infect. Dis. 2008;14:1870–1874. doi: 10.3201/eid1412.080591. PubMed DOI PMC

Sánchez-Vizcaíno J.M., Mur L., Martínez-López B. African swine fever (ASF): Five years around Europe. Vet. Microbiol. 2013;165:45–50. doi: 10.1016/j.vetmic.2012.11.030. PubMed DOI

Dixon L.K., Stahl K., Jori F., Vial L., Pfeiffer D.U. African Swine Fever Epidemiology and Control. Annu. Rev. Anim. Biosci. 2019;8 doi: 10.1146/annurev-animal-021419-083741. PubMed DOI

Halasa T., Bøtner A., Mortensen S., Christensen H., Toft N., Boklund A. Simulating the epidemiological and economic effects of an African swine fever epidemic in industrialized swine populations. Vet. Microbiol. 2016;193:7–16. doi: 10.1016/j.vetmic.2016.08.004. PubMed DOI

Chenais E., Depner K., Guberti V., Dietze K., Viltrop A., Ståhl K. Epidemiological considerations on African swine fever in Europe 2014–2018. Porc. Health Manag. 2019;5:6. doi: 10.1186/s40813-018-0109-2. PubMed DOI PMC

EFSA. Boklund A., Cay B., Depner K., Földi Z., Guberti V., Masiulis M., Miteva A., More S., Olsevskis E., et al. Epidemiological analyses of African swine fever in the European Union (November 2017 until November 2018) EFSA J. 2018;16:e05494. PubMed PMC

Guberti V., Khomenko S., Masiulis M., Kerba S. African Swine Fever in Wild Boar Ecology and Biosecurity. FAO; OIE; EC; Rome, Italy: 2019. FAO Animal Production and Health Manual.

European Commission . European Commission Working Document—Strategic Approach to the Management of African Swine Fever for the EU—SANTE/7113/2015—Rev 11 2019. European Commission; Brussels, Belgium: 2019.

Morelle K., Jezek M., Licoppe A., Podgorski T. Deathbed choice by ASF-infected wild boar can help find carcasses. Transbound. Emerg. Dis. 2019;66:1821–1826. doi: 10.1111/tbed.13267. PubMed DOI

Halloran M.E. Epidemiologic Methods for the Study of Infectious Diseases. Oxford University Press; New York, NY, USA: 2001. Concepts of transmission and dynamics; pp. 63–64.

Guinat C., Porphyre T., Gogin A., Dixon L., Pfeiffer D.U., Gubbins S. Inferring within-herd transmission parameters for African swine fever virus using mortality data from outbreaks in the Russian Federation. Transbound. Emerg. Dis. 2018;65:e264–e271. doi: 10.1111/tbed.12748. PubMed DOI PMC

Gulenkin V.M., Korennoy F.I., Karaulov A.K., Dudnikov S.A. Cartographical analysis of African swine fever outbreaks in the territory of the Russian Federation and computer modeling of the basic reproduction ratio. Prev. Vet. Med. 2011;102:167–174. doi: 10.1016/j.prevetmed.2011.07.004. PubMed DOI

Bett B., Henning J., Abdu P., Okike I., Poole J., Young J., Randolph T.F., Perry B.D. Transmission Rate and Reproductive Number of the H5N1 Highly Pathogenic Avian Influenza Virus During the December 2005–July 2008 Epidemic in Nigeria. Transbound. Emerg. Dis. 2014;61:60–68. doi: 10.1111/tbed.12003. PubMed DOI

Ward M.P., Maftei D., Apostu C., Suru A. Estimation of the basic reproductive number (R0) for epidemic, highly pathogenic avian influenza subtype H5N1 spread. Epidemiol. Infect. 2009;137:219–226. doi: 10.1017/S0950268808000885. PubMed DOI

Apollonio M., Andersen R., Putman R. European Ungulates and Their Management in the 21st Century. Cambridge University Press; Cambridge, UK: 2010.

Keuling O., Strauß E., Siebert U. Regulating wild boar populations is “somebody else’s problem”!—Human dimension in wild boar management. Sci. Total Environ. 2016;554–555:311–319. doi: 10.1016/j.scitotenv.2016.02.159. PubMed DOI

Anderson R.M., May R.M. Infectious Diseases of Humans: Dynamics and Control. OUP Oxford; New York, NY, USA: 1992.

Iglesias I., Muñoz M.J., Montes F., Perez A., Gogin A., Kolbasov D., de la Torre A. Reproductive Ratio for the Local Spread of African Swine Fever in Wild Boars in the Russian Federation. Transbound. Emerg. Dis. 2016;63:e237–e245. doi: 10.1111/tbed.12337. PubMed DOI

Barongo M.B., Ståhl K., Bett B., Bishop R.P., Fèvre E.M., Aliro T., Okoth E., Masembe C., Knobel D., Ssematimba A. Estimating the Basic Reproductive Number (R0) for African Swine Fever Virus (ASFV) Transmission between Pig Herds in Uganda. PLoS ONE. 2015;10:e0125842. doi: 10.1371/journal.pone.0125842. PubMed DOI PMC

Korennoy F.I., Gulenkin V.M., Gogin A.E., Vergne T., Karaulov A.K. Estimating the Basic Reproductive Number for African Swine Fever Using the Ukrainian Historical Epidemic of 1977. Transbound. Emerg. Dis. 2017;64:1858–1866. doi: 10.1111/tbed.12583. PubMed DOI

Vynnycky E., White R. An Introduction to Infectious Disease Modelling. OUP Oxford; New York, NY, USA: 2010.

Sánchez-Cordón P.J., Nunez A., Neimanis A., Wikström-Lassa E., Montoya M., Crooke H., Gavier-Widén D. African Swine Fever: Disease Dynamics in Wild Boar Experimentally Infected with ASFV Isolates Belonging to Genotype I and II. Viruses. 2019;11:852. doi: 10.3390/v11090852. PubMed DOI PMC

Schulz K., Conraths F.J., Blome S., Staubach C., Sauter-Louis C. African Swine Fever: Fast and Furious or Slow and Steady? Viruses. 2019;11:866. doi: 10.3390/v11090866. PubMed DOI PMC

Bassi E., Battocchio D., Marcon A., Stahlberg S., Apollonio M. Scavenging on Ungulate Carcasses in a Mountain Forest Area in Northern Italy. Mamm. Study. 2018;43:33–43. doi: 10.3106/ms2016-0058. DOI

Iglesias I., Perez A.M., Sánchez-Vizcaíno J.M., Muñoz M.J., Martínez M., Torre A.D.L. Reproductive ratio for the local spread of highly pathogenic avian influenza in wild bird populations of Europe, 2005–2008. Epidemiol. Infect. 2011;139:99–104. doi: 10.1017/S0950268810001330. PubMed DOI

Risk of African swine fever virus transmission among wild boar and domestic pigs in Poland

Disease-Induced Mortality Outweighs Hunting in Causing Wild Boar Population Crash After African Swine Fever Outbreak