African Swine Fever Virus Circulation between Tanzania and Neighboring Countries: A Systematic Review and Meta-Analysis

Abstract

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.

Domestication Explains Two-Thirds of Differential-Gene-Expression Variance between Domestic and Wild Animals; The Remaining One-Third Reflects Intraspecific and Interspecific Variation

“…Furthermore, columns viii and ix of Table 8 translate a log2 value of a gene in an animal into either low or excessive expression of this gene during divergence of both domestic and wild forms of this animal from their most recent common ancestor. Recently [ 57 , 58 ], an RNA-Seq data analysis was based on this oldest phylogeny concept [ 59 ] widely used elsewhere [ 60 , 61 , 62 , 63 ]. Let us look at these orthologous genes one by one and discuss effects of their expression changes on reproductive potential in humans as well as during divergence of domestic and wild animals from their most recent com-mon ancestor [ 24 , 25 , 28 , 29 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 ] ( Table 8 ).…”

Seroprevalence and Risk Factors of Crimean-Congo Hemorrhagic Fever in Cattle of Smallholder Farmers in Central Malawi

“…Local and cross-border uncontrolled animal movement (through movements of viremic hosts) in Africa, Europe, and the Middle East, has been suggested as one of the mechanisms by which a vector-borne virus closely related to CCHFV, Rift Valley Fever virus is spreading in these regions [47][48][49]. In addition, uncontrolled animal movement due to porous borders in eastern, central, and southern Africa, has contributed to the spreading of different genotypes of the African swine fever virus (ASF) [50,51]. Similarly, this may also explain the spread of other infectious agents such as CCHFV within the region.…”

A bioinformatic search for correspondence between differentially expressed genes of domestic versus wild animals and orthologous human genes altering reproductive potential

“…A total of 3080 DEGs of domestic versus wild animals were analyzed here, which are freely available in the PubMed database (Lu, 2011), as described in Table 2 and characterized by examples in Table 3. At the same time, according to (Klimova et al, 2021;Vasiliev et al, 2021), here, RNA-Seq data were examined in accordance with one of the oldest (Samet, 1985), widely used (Sun et al, 2008;Morozova et al, 2020;Hakizimana et al, 2021), and fundamental (Zhang et al, 2021) concepts of phylogenetic analysis -"most recent common ancestor" (Samet, 1985). In this regard, domestic animals and their wild relatives were studied by means of oppositely directed equivalent changes in gene expression in comparison with their unknown most recent common ancestor.…”