African swine fever (ASF) is a hemorrhagic disease of domestic pigs and wild boars. The ASF virus (ASFV), a sole member of the family Asfarviridae and genus Asfivirus, causes this devastating disease. In sub-Saharan Africa, ASFV is maintained through three interlinked cycles: the domestic cycle, the pig-tick cycle, and the sylvatic cycle, which collectively sustain its endemic presence in the region. Interaction between wild and domestic pigs at livestock-wildlife interfaces, particularly in protected areas, poses a significant threat to smallholder farmers. This study aimed to investigate the socioeconomic impact and identify potential risk factors associated with ASF in Serengeti National Park's (SNP's) wildlife management area (WMA) in Tanzania. A cross-sectional study involving 110 domestic pig-keeping households in the five villages of SNP's WMA was carried out. A semistructured questionnaire was used to collect data on risk factors and socioeconomic impact associated with ASF from consenting smallholder farmers. Additionally, the observational approach was used to assess pig production's facilities, behaviors and practices involved in domestic pig production and management. Tissue samples including spleen, lymph nodes, and kidney were also collected from dead domestic pigs belonging to two villages, Nattambiso and Robanda, to confirm the existence of the virus in the study area by using polymerase chain reaction (PCR). Descriptive statistics, univariable, and multivariable logistic analyses were performed to determine risk factors associated with ASF occurrence between October 2021 and April 2022 in the study area. A total of 12 ASF outbreaks affecting 1198 cases that led to 969 domestic pig deaths were reported. The ASFV was confirmed to be positive in all domestic pigs from which tissue samples were collected in the included villages. The case fatality rates (CFRs) from the reported previous ASF incidence varied from 77.5% to 85.2% with an overall CFR of 80.8%. A sum of 163,300,000 Tanzanian Shillings (approximately equivalent to 70,085 USD) loss was recorded in the studied WMA. The major risk factors that correlated with ASF occurrence were encountered ASF previously (odds ratio [OR] = 13.58, 95% confidence interval [CI] = 2.79-87.28), selling pig products with ASF before (OR = 9.43, CI = 1.76-70.02), whilst taking no risk action to prevent loss (OR = 0.14, CI = 0.03-0.63) and swill treatment (OR = 0.10, CI = 0.01-0.54) negatively correlated with ASF. Improving awareness on farm-level biosecurity, husbandry, and management practices is vital to preventing ASF outbreaks and wildlife spillover, safeguarding livestock health, and promoting economic stability in wildlife-livestock-human interfaces.

Two near-complete genomes of genotype II African swine fever viruses (ASFV) recovered from domestic pigs in Mbozi district, Tanzania, in 2017 were generated using tiled amplicon Oxford nanopore sequencing. These two ASFV genomes described in this study were closely related to other genotype II isolates reported worldwide.

African swine fever (ASF) is a devastating viral hemorrhagic disease caused by the ASF virus (ASFV) that can kill up to 100% of domestic pigs and wild boars. The domestic pig industry in Rwanda is highly threatened by ASF, with several outbreaks reported yearly to the World Organization for Animal Health. Despite the endemic status, no ASFV from Rwanda has been genetically characterized. This study reports, for the first time, the ASFV genotypes causing outbreaks in Rwanda. The ASF confirmation was performed by polymerase chain reaction followed by molecular characterization of the causative ASFV by partial and complete genome sequencing and phylogenetic reconstruction. After genetic analysis, the ASFV strains responsible for the 2021 outbreak in eastern Rwanda clustered within genotype II, while the strain from the 2023 outbreak in northern Rwanda clustered within genotype IX. The extension of the geographical range of genotype II in eastern Africa is of concern. In the countries of the East African Community, this ASFV genotype was reported for the first time in Tanzania at the Tanzania-Malawi border in 2011, followed by a relentless spread of the virus northwards along major highways within Tanzania before the detection of this genotype in Rwanda in 2021. This ASFV genotype will most likely reach other eastern African countries threatening the regional domestic pig industry. The ongoing spread of ASFV genotypes II and IX across Africa impacts food and nutritional security, and hinders the realization of the United Nations Sustainable Development Goal 1 (No Poverty) and·Goal 2 (Zero hunger). The results of this study call for science-driven and regional approaches to enable the timely identification of ASF outbreaks for effective prevention and containment.

African swine fever (ASF) caused by ASF virus (ASFV) is an infectious transboundary animal disease notifiable to the World Organization for Animal Health causing high mortality in domestic pigs and wild boars threatening the global domestic pig industry. To date, twenty-four ASFV genotypes have been described and currently genotypes II, IX, X, XV and XVI are known to be circulating in Tanzania. Despite the endemic status of ASF in Tanzania, only one complete genome of ASFV from the country has been described. This study describes the first complete genome sequence of ASFV genotype XV. In addition, the first Tanzanian complete genome of ASFV genotype IX and three ASFV strains belonging to genotype II collected during ASF outbreaks in domestic pigs in Tanzania were determined in this study using Illumina sequencing and comparative genomics analysis. The generated ASFV complete genome sequences ranged from 171,004 to 184,521 base pairs in length with an average GC content of 38.53% and encoded 152 to 187 open reading frames. The results of this study provide insights into the genomic structure of ASFV and can be used to monitor changes within the ASFV genome and improve our understanding of ASF transmission dynamics.

For over 100 years after the description of the first case of African swine fever (ASF) in Kenya, ASF virus (ASFV) cross-border spread in eastern and southern Africa has not been fully investigated. In this manuscript, we reviewed systematically the available literature on molecular epidemiology of ASF in Tanzania and its eight neighboring countries in order to establish the transmission dynamics of ASFV between these countries. Data were retrieved from World Animal Health Information System (WAHIS), Google Scholar, PubMed, Scopus, and CrossRef databases, using the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and reviewed to document ASF outbreaks and ASFV genotypes distribution. Using phylogeographic approach applied to ASFV p72 sequence dataset, the evolutionary history and the dispersal pattern of the ASFV strains were assessed. From 2005 to 2019, a total of 1588 ASF outbreaks affecting 341,742 cases that led to 302,739 domestic pig deaths were reported. The case fatality rates (CFR) varied from 15.41% to 98.95% with an overall CFR of 88.58%. Fifteen different p72 ASFV genotypes were reported and the time to the most recent common ancestor (TMRCA) for ASFV strains dated back to 1652.233 (1626.473, 1667.735) with an evolutionary rate of 4.805 × 10−5 (2.5857 × 10−5, 9.7789 × 10−5). Phylogeographic dispersal analysis revealed several transboundary spread events of ASFV strains between these countries. These results suggest persistent circulation of ASFV in these countries and advocate for more research to improve our understanding of the transmission dynamics of the virus and for a regional approach to mitigate the spread of ASFV.

Several African swine fever (ASF) outbreaks in domestic pigs have been reported in Burundi and Malawi and whole-genome sequences of circulating outbreak viruses in these countries are limited. In the present study, complete genome sequences of ASF viruses (ASFV) that caused the 2018 outbreak in Burundi (BUR/18/Rutana) and the 2019 outbreak in Malawi (MAL/19/Karonga) were produced using Illumina next-generation sequencing (NGS) platform and compared with other previously described ASFV complete genomes. The complete nucleotide sequences of BUR/18/Rutana and MAL/19/Karonga were 176,564 and 183,325 base pairs long with GC content of 38.62 and 38.48%, respectively. The MAL/19/Karonga virus had a total of 186 open reading frames (ORFs) while the BUR/18/Rutana strain had 151 ORFs. After comparative genomic analysis, the MAL/19/Karonga virus showed greater than 99% nucleotide identity with other complete nucleotides sequences of p72 genotype II viruses previously described in Tanzania, Europe and Asia including the Georgia 2007/1 isolate. The Burundian ASFV BUR/18/Rutana exhibited 98.95 to 99.34% nucleotide identity with genotype X ASFV previously described in Kenya and in Democratic Republic of the Congo (DRC). The serotyping results classified the BUR/18/Rutana and MAL/19/Karonga ASFV strains in serogroups 7 and 8, respectively. The results of this study provide insight into the genetic structure and antigenic diversity of ASFV strains circulating in Burundi and Malawi. This is important in order to understand the transmission dynamics and genetic evolution of ASFV in eastern Africa, with an ultimate goal of designing an efficient risk management strategy against ASF transboundary spread.

African swine fever (ASF) is a contagious viral disease that causes high mortality, approaching 100%, in domestic pigs and wild boars. The disease has neither a cure nor a vaccine, and it is caused by an ASF virus (ASFV), the only member of the family Asfarviridae, genus Asfivirus, and the only known DNA arbovirus. Twenty-four genotypes of ASFV have been described to date, and all of them have been described in Africa. ASF is endemic in Burundi, and several outbreaks have been reported in the country; the disease continues to economically impact on small-scale farmers. This study aimed at genetic characterization of ASFV that caused an ASF outbreak in the Rutana region, Burundi, in the year 2018. Tissue samples from domestic pigs that died as a result of a severe hemorrhagic disease were collected in order to confirm the disease using polymerase chain reaction (PCR) and to conduct partial genome sequencing. Nucleotide sequences were obtained for the B646L (p72) gene, the intergenic fragment between the I73R and I329L genes, and the central variable region (CVR) of the B602L gene. Phylogenetic analysis of the Burundian 2018 ASFV grouped the virus within B646L (p72) genotype X and clustered together with those reported during the 1984 and 1990 outbreaks in Burundi with high nucleotide identity to some ASFV strains previously reported in neighboring East African countries, indicating a regional distribution of this ASFV genotype. Analysis of the intergenic fragment between I73R and I329L genes showed that the Burundian 2018 ASFV described in this study lacked a 32–base pair (bp) fragment present in the reference genotype X strain, Kenya 1950. In addition, the strain described in this study had the signature AAABNAABA at the CVR (B602L) gene and showed 100% amino acid sequence identity to viruses responsible for recent ASF outbreaks in the region. The virus described in this study showed high genetic similarities with ASFV strains previously described in domestic pigs, wild suids, and soft ticks in East African countries, indicating a possible common wild source and continuous circulation in domestic pigs in the region.

Background African swine fever (ASF) is a highly fatal viral hemorrhagic disease of domestic pigs that threatens livelihoods and food security. In Africa, ASF virus (ASFV) circulates in sylvatic (transmission between warthogs and soft argasid ticks) and domestic (transmission between domestic pigs) cycles, with outbreaks resulting from viral spill-over from sylvatic cycle. The present study investigated ASFV transmission patterns through virus genotyping. Results Genotypes II, IX, X, XV and XVI of ASFV were found to circulate and maintained by transmission between domestic pigs. Methods In addition to archived samples, tissue samples were collected from domestic pigs during outbreaks at different locations in Tanzania between 2015 and 2017 followed by nucleotide sequencing and phylogenetic analysis of B646L gene of ASFV. Conclusion Maintenance of ASFV in the domestic cycle was due to bleach of quarantine and transportation of affected pigs via major highways. Appropriate control measures including sanitary measures at the slaugher slabs and quarantine measures adherence are recommended to prevent ASF emergence and re-emergence in Tanzania. Transportation of pig and pig products for regional market should be controlled to prevent ASFV spreading to other states of the East African Community , as ASFV genotype II has spread beyond its geographical range.