Diagnosis and genotyping of African swine fever viruses from 2015 outbreaks in Zambia

Abstract

In early 2015, a highly fatal haemorrhagic disease of domestic pigs resembling African swine fever (ASF) occurred in North Western, Copperbelt, and Lusaka provinces of Zambia. Molecular diagnosis by polymerase chain reaction targeting specific amplification of p72 (B646L) gene of ASF virus (ASFV) was conducted. Fourteen out of 16 domestic pigs from the affected provinces were found to be positive for ASFV. Phylogenetic analyses based on part of the p72 and the complete p54 (E183L) genes revealed that all the ASFVs detected belonged to genotypes I and Id, respectively. Additionally, epidemiological data suggest that the same ASFV spread from Lusaka to other provinces possibly through uncontrolled and/or illegal pig movements. Although the origin of the ASFV that caused outbreaks in domestic pigs in Zambia could not be ascertained, it appears likely that the virus may have emerged from within the country or region, probably from a sylvatic cycle. It is recommended that surveillance of ASF, strict biosecurity, and quarantine measures be imposed in order to prevent further spread and emergence of new ASF outbreaks in Zambia.

Co-circulation of multiple genotypes of African swine fever viruses among domestic pigs in Zambia (2013-2015)

“…The 2015 outbreaks that occurred on the Copperbelt (Kitwe), North‐Western (Solwezi) and Lusaka Provinces have been described in detail elsewhere (Thoromo et al., ).…”

“…DNA extraction and molecular diagnosis of ASF were essentially conducted as previously described (Thoromo et al., ; Yabe et al., ). Briefly, DNA was extracted from tissue homogenates using proteinase K digestion.…”

“… The p72 and p54 genes of ASFVs detected in 2015 were sequenced in the previous study (Thoromo et al, ). …”

“…More recently, particularly during 2013–2015, Zambia experienced unprecedented widespread outbreaks of ASF in domestic pigs (World organisation for Animal Health (OIE) (); Yabe et al., ; Thoromo et al., ). Preliminary data obtained through genotypic characterization of ASFVs detected in pigs in 2015 indicated the involvement of genotype I viruses (Thoromo et al., ).…”

“…More recently, particularly during 2013–2015, Zambia experienced unprecedented widespread outbreaks of ASF in domestic pigs (World organisation for Animal Health (OIE) (); Yabe et al., ; Thoromo et al., ). Preliminary data obtained through genotypic characterization of ASFVs detected in pigs in 2015 indicated the involvement of genotype I viruses (Thoromo et al., ). To improve our understanding of the transmission and dissemination pathways of ASFVs in Zambia during 2013–2015 outbreaks, genetic characterization of viruses detected in clinical tissue samples obtained from six provinces was conducted using standardized genotyping procedures (World Organisation for Animal Health (OIE) ).…”