1887

Abstract

The persistence of African swine fever virus (ASFV) in endemic areas, with small-scale but regular outbreaks in domestic pigs, is not well understood. ASFV has not been detected using conventional diagnosis in these pigs or adjacent populations of resistant African wild pigs, that could act as potential carriers during the outbreaks. However, such data are crucial for the design of evidence-based control strategies. We conducted cross-sectional (1107 pigs) and longitudinal (100 pigs) monitoring of ASFV prevalence in local pigs in Kenya and Uganda. The horizontal survey revealed no evidence of ASFV in the serum or blood using either conventional or real-time PCR. One pig consistently tested positive using ELISA, but negative using PCR assays on blood. Interestingly, the isotype of the antibodies from this animal were strongly IgA biased relative to control domestic pigs and warthogs, suggesting a role for mucosal immunity. The tissues from this pig were positive by PCR following post-mortem. Internal organ tissues of 44 healthy pigs (28 sentinel pigs and 16 pigs from slaughter slabs) were tested with four different PCR assays; 15.9 % were positive for ASFV suggesting that healthy pigs carrying ASFV exist in the swine population in the study area. P72 and p54 genotyping of ASFV revealed very limited diversity: all were classified in genotype IX at both loci, as were virtually all viruses causing recent ASF outbreaks in the region. Our study suggests that carrier pigs may play a role in ASF disease outbreaks, although the triggers for outbreaks remain unclear and require further investigation. This study significantly increases scientific knowledge of the epidemiology of ASF in the field in Africa, which will contribute to the design of effective surveillance and control strategies.

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2017-07-01
2024-03-28
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References

  1. FAOSTAT Meat Consumption in Uganda (2010) Food and Agriculture Organization of the United Nations 2010
    [Google Scholar]
  2. Oyewumi OA, Jooste A. Measuring the determinants of pork consumption in Bloemfontein, Central South Africa. Agrekon 2006; 45:185–197 [View Article]
    [Google Scholar]
  3. Penrith ML, Vosloo W. Review of African swine fever: transmission, spread and control. J S Afr Vet Assoc 2009; 80:58–62 [View Article][PubMed]
    [Google Scholar]
  4. Penrith ML, Vosloo W, Jori F, Bastos AD. African swine fever virus eradication in Africa. Virus Res 2013; 173:228–246 [View Article][PubMed]
    [Google Scholar]
  5. Eustace Montgomery R. On a form of swine fever occurring in British East Africa (Kenya Colony). J Comp Pathol Therap 1921; 34:159–191 [View Article]
    [Google Scholar]
  6. Achenbach JE, Gallardo C, Nieto-Pelegrín E, Rivera-Arroyo B, Degefa-Negi T et al. Identification of a new genotype of African swine fever virus in domestic pigs from Ethiopia. Transbound Emerg Dis doi: 10.1111/tbed.12511. [Epub ahead of print] [View Article][PubMed]
    [Google Scholar]
  7. Okoth E, Gallardo C, Macharia JM, Omore A, Pelayo V et al. Comparison of African swine fever virus prevalence and risk in two contrasting pig-farming systems in South-west and Central Kenya. Prev Vet Med 2013; 110:198–205 [View Article][PubMed]
    [Google Scholar]
  8. Gallardo MC, Reoyo AT, Fernández-Pinero J, Iglesias I, Muñoz MJ et al. African swine fever: a global view of the current challenge. Porcine Health Manag 2015; 1:21 [View Article][PubMed]
    [Google Scholar]
  9. Agüero M, Fernández J, Romero L, Sánchez Mascaraque C, Arias M et al. Highly sensitive PCR assay for routine diagnosis of African swine fever virus in clinical samples. J Clin Microbiol 2003; 41:4431–4434 [View Article][PubMed]
    [Google Scholar]
  10. Fernández-Pinero J, Gallardo C, Elizalde M, Robles A, Gómez C et al. Molecular diagnosis of African swine fever by a new real-time PCR using universal probe library. Transbound Emerg Dis 2013; 60:48–58 [View Article][PubMed]
    [Google Scholar]
  11. King DP, Reid SM, Hutchings GH, Grierson SS, Wilkinson PJ et al. Development of a TaqMan PCR assay with internal amplification control for the detection of African swine fever virus. J Virol Methods 2003; 107:53–61 [View Article][PubMed]
    [Google Scholar]
  12. Thomas LF, Bishop RP, Onzere C, Mcintosh MT, Lemire KA et al. Evidence for the presence of African swine fever virus in an endemic region of western Kenya in the absence of any reported outbreak. BMC Vet Res 2016; 12:192 [View Article][PubMed]
    [Google Scholar]
  13. Zsak L, Borca MV, Risatti GR, Zsak A, French RA et al. Preclinical diagnosis of African swine fever in contact-exposed swine by a real-time PCR assay. J Clin Microbiol 2005; 43:112–119 [View Article][PubMed]
    [Google Scholar]
  14. Muhangi D, Masembe C, Emanuelson U, Boqvist S, Mayega L et al. A longitudinal survey of African swine fever in Uganda reveals high apparent disease incidence rates in domestic pigs, but absence of detectable persistent virus infections in blood and serum. BMC Vet Res 2015; 11:106 [View Article][PubMed]
    [Google Scholar]
  15. Oura CA, Edwards L, Batten CA. Virological diagnosis of African swine fever–comparative study of available tests. Virus Res 2013; 173:150–158 [View Article][PubMed]
    [Google Scholar]
  16. Gallardo C, Soler A, Nieto R, Carrascosa AL, de Mia GM et al. Comparative evaluation of novel African swine fever virus (ASF) antibody detection techniques derived from specific ASF viral genotypes with the OIE internationally prescribed serological tests. Vet Microbiol 2013; 162:32–43 [View Article][PubMed]
    [Google Scholar]
  17. Atuhaire DK, Afayoa M, Ochwo S, Mwesigwa S, Mwiine FN et al. Prevalence of African swine fever virus in apparently healthy domestic pigs in Uganda. BMC Vet Res 2013; 9:263 [View Article][PubMed]
    [Google Scholar]
  18. Owolodun OA, Obishakin ET, Ekong PS, Yakubu B. Investigation of African swine fever in slaughtered pigs, Plateau state, Nigeria, 2004-2006. Trop Anim Health Prod 2010; 42:1605–1610 [View Article][PubMed]
    [Google Scholar]
  19. Gallardo C, Mwaengo DM, Macharia JM, Arias M, Taracha EA et al. Enhanced discrimination of African swine fever virus isolates through nucleotide sequencing of the p54, p72, and pB602L (CVR) genes. Virus Genes 2009; 38:85–95 [View Article][PubMed]
    [Google Scholar]
  20. Gallardo C, Okoth E, Pelayo V, Anchuelo R, Martín E et al. African swine fever viruses with two different genotypes, both of which occur in domestic pigs, are associated with ticks and adult warthogs, respectively, at a single geographical site. J Gen Virol 2011; 92:432–444 [View Article][PubMed]
    [Google Scholar]
  21. de Villiers EP, Gallardo C, Arias M, da Silva M, Upton C et al. Phylogenomic analysis of 11 complete African swine fever virus genome sequences. Virology 2010; 400:128–136 [View Article][PubMed]
    [Google Scholar]
  22. Bishop RP, Fleischauer C, de Villiers EP, Okoth EA, Arias M et al. Comparative analysis of the complete genome sequences of Kenyan African swine fever virus isolates within p72 genotypes IX and X. Virus Genes 2015; 50:303–309 [View Article][PubMed]
    [Google Scholar]
  23. Charleston B, Bankowski BM, Gubbins S, Chase-Topping ME, Schley D et al. Relationship between clinical signs and transmission of an infectious disease and the implications for control. Science 2011; 332:726–729 [View Article][PubMed]
    [Google Scholar]
  24. Lichoti JK, Davies J, Kitala PM, Githigia SM, Okoth E et al. Social network analysis provides insights into African swine fever epidemiology. Prev Vet Med 2016; 126:1–10 [View Article][PubMed]
    [Google Scholar]
  25. Nantima N, Davies J, Dione M, Ocaido M, Okoth E et al. Enhancing knowledge and awareness of biosecurity practices for control of African swine fever among smallholder pig farmers in four districts along the Kenya-Uganda border. Trop Anim Health Prod 2016; 48:727–734 [View Article][PubMed]
    [Google Scholar]
  26. Nantima N, Ocaido M, Ouma E, Davies J, Dione M et al. Risk factors associated with occurrence of African swine fever outbreaks in smallholder pig farms in four districts along the Uganda-Kenya border. Trop Anim Health Prod 2015; 47:589–595 [View Article][PubMed]
    [Google Scholar]
  27. Penrith ML, Thomson GR, Bastos ADS. African swine fever. In Coetzer JAW. (editor) Infectious Diseases of Livestock Oxford, UK: Oxford University Press; 2004 pp. 1088–1119
    [Google Scholar]
  28. Amimo JO, El Zowalaty ME, Githae D, Wamalwa M, Djikeng A et al. Metagenomic analysis demonstrates the diversity of the fecal virome in asymptomatic pigs in East Africa. Arch Virol 2016; 161:887–897 [View Article]
    [Google Scholar]
  29. Amimo JO, Junga JO, Ogara WO, Vlasova AN, Njahira MN et al. Detection and genetic characterization of porcine group A rotaviruses in asymptomatic pigs in smallholder farms in East Africa: predominance of P[8] genotype resembling human strains. Vet Microbiol 2015; 175:195–210 [View Article][PubMed]
    [Google Scholar]
  30. Kagira JM, Kanyari PW, Maingi N, Githigia SM, Ng'ang'a JC et al. Characteristics of the smallholder free-range pig production system in western Kenya. Trop Anim Health Prod 2010; 42:865–873 [View Article][PubMed]
    [Google Scholar]
  31. Agüero M, Fernández J, Romero L, Sánchez Mascaraque C, Arias M et al. Highly sensitive PCR assay for routine diagnosis of African swine fever virus in clinical samples. J Clin Microbiol 2003; 41:4431–4434 [View Article][PubMed]
    [Google Scholar]
  32. Malmquist WA, Hay D. Hemadsorption and cytopathic effect produced by African swine fever virus in swine bone marrow and buffy coat cultures. Am J Vet Res 1960; 21:104–108[PubMed]
    [Google Scholar]
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