Sero-prevalence and risk factors associated with African swine fever on pig farms in southwest Nigeria

Abstract

BackgroundAfrican swine fever (ASF) is one of the major setbacks to development of the pig industry in Nigeria. It is enzootic in southwest Nigeria. We determined the sero-prevalence and factors associated with ASF among-herd seropositivity in 144 pig farms in six States from southwest Nigeria during the dry and rainy seasons using indirect Enzyme Linked Immunosorbent Assay (ELISA) for ASF IgG antibodies. An interviewer-administered questionnaire was used to collect information on demography, environmental and management factors. We performed descriptive statistics, and univariate and multivariable analyses to determine the among-herd sero-prevalence of ASF and its associated factors.ResultsThe overall herd sero-prevalence of ASF was 28 % (95 % Confidence interval (95 % CI) 21 – 36); it was significantly higher (P <0.05) in the dry season (54 %; 95 % CI 37 – 70) than the rainy season (18 %; 95 % CI 11 – 27). In the univariate analysis, having a quarantine/ isolation unit within 100 m radius of a regular pig pen (OR = 3.3; 95 % CI 1.3 – 8.9), external source of replacement stock (OR = 3.2; 95 % CI 1.3 – 8.3) and dry season (OR = 5.3; 95 % CI 2.2 – 12.7) were risk factors for ASF among-herd seropositivity. In the multivariable logistic regression, there was interaction between season and herd size. Our final model included season, source of replacement stock, herd size and interaction between herd size and season. Herds with an external source of replacement always had higher ASF sero-prevalence compared with herds with an internal source. The herd size effect varied between seasons.ConclusionsThe ASF herd level sero-prevalence in southwest Nigeria was higher in pig herds with an external source of replacement stock and in the dry season. The effect of season of the year the samples were taken on ASF seropositivity was modified by herd size. We encourage strict compliance with biosecurity measures, especially using an internal source of replacement stock and measures that minimize movement on pig farms in southwest Nigeria, in order to enhance ASF free farms.

Disease burden affecting pig production in Nigeria: Review of current issues and challenges

“…Over 500,000 pigs died from ASF in Nigeria within the first few years of the confirmed outbreaks (Majiyagbe et al, 2004). The confirmed outbreaks of ASF in Nigeria ( Figure 2) affected Plateau, Nasarawa, Benue, Oyo, Kaduna, Bauchi, Taraba, Adamawa, Lagos, Enugu, Ogun, Akwa Ibom, Cross Rivers, Rivers, Gombe, Osun, Ondo, Ekiti, Anambra, Edo, and Delta States (Majiyagbe et al, 2004;Babalobi et al, 2007;Mailafia and Iliya, 2009;Fasina et al, 2010;Owolodun et al, 2010aOwolodun et al, , 2010bAbwage et al, 2015;Adenaike et al, 2016;Awosanya et al, 2015;Ayas et al, 2016). Therefore, pigs in 21 (56.8%) out of 36 states and the Federal Capital Territory (FCT) were involved in outbreaks.…”

“…The acute disease in pigs causes multifocal skin hemorrhages on the ventral abdomen, interstitial pneumonia, acute orchitis and meningitis, lymphoid necrosis, and focal hemorrhages in nervous tissues (Otesile et al, 2005). Outbreaks of the disease in the country occurred in 1997, 1998, 2001, and the subclinical disease has persisted as an enzootic condition (Otesile et al, 2005;Babalobi et al, 2007;Awosanya et al, 2015). Over 500,000 pigs died from ASF in Nigeria within the first few years of the confirmed outbreaks (Majiyagbe et al, 2004).…”

“…Revue d'élevage et de médecine vétérinaire des pays tropicaux, 2018, 71 (1-2) : 87-95 Omotainse et al, 2000;Majiyagbe et al, 2004;Babalobi et al, 2007;Fasina et al, 2010;Owolodun et al, 2010b;Ngbede et al Majiyagbe et al, 2004;Babalobi et al, 2007;Ugbomoiko et al, 2008;Fasina et al, 2010;Owolodun et al, 2010b;Awosanya et al, 2015 had delayed recovery after therapy (Otesile et al, 1992), suggesting that inadequate energy and other nutritional factors might be contributing to the pathogenic effects of T. brucei (Igbokwe, 1995).…”

“…Babalobi et al, 2007;Fasina et al, 2010;Owolodun et al, 2010b; Awosanya et al., 2010;Owolodun et al, 2010b;Ademola and Onyiche, 2013;Awosanya et al, 2015; Aiki-Raji et alet al, 1990;Majiyagbe et al, 2004;Babalobi et al, 2007;Fasina et al, 2010;Owolodun et al, 2010a;Owolodun et al, 2010b; Gagman et alet al, 2010b;Abwage et al, 2015; Karshima et al, 2016 Yobe …”

Diagnostic specificity of the African swine fever virus antibody detection enzyme‐linked immunosorbent assay in feral and domestic pigs in the United States

“…ASF is a reportable disease, and concern has been raised due to the continued spread of the virus throughout the parts of Europe and the endemic of the virus in Africa (Awosanya, Olugasa, Ogundipe, & Grohn, ; Olsevskis et al., ). The outbreaks of the late 1970s through the early 1980s in South America and the Caribbean Islands highlight the risk associated with international movement.…”