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. 2025 Mar 31;15(7):1007.
doi: 10.3390/ani15071007.

Farming Practices, Biosecurity Gaps, and Genetic Insights into African Swine Fever Virus in the Iringa and Ruvuma Regions of Tanzania

Agathe Auer  1   2 , Anderson Samwel Yohana  3 , Tirumala B K Settypalli  1 , Raphael Sallu  4 , Jelly Chang'a  3 , Stella Bitanyi  3 , Stella Gaichugi Kiambi  4 , Irene K Meki  1 , William G Dundon  1 , Artem Metlin  2 , Andriy Rozstalnyy  2 , Geofrey Hallan Mbata  3 , James Anset Okachu  3 , Henry Magwisha  4 , Sauda Ally Hamis  3 , Jeremia Theodos Choga  5 , Stela Lucas Chalo  5 , Joshua Kimutai  6 , Gerald Misinzo  7 , Solomon Wilson Nong'ona  5 , Joseph Edmund Lyimo  5 , Charles E Lamien  1
Affiliations

Farming Practices, Biosecurity Gaps, and Genetic Insights into African Swine Fever Virus in the Iringa and Ruvuma Regions of Tanzania

Agathe Auer et al. Animals (Basel). .

Abstract

African Swine Fever Virus (ASFV) genotype II dominates outbreaks in Tanzania's Southern Highlands, continuing to persist as the dominant strain over a decade after its first incursion in 2010. A total of 205 samples from 120 holdings were collected, with 21 confirmed ASFV-positive animals from 14 holdings. Molecular analysis revealed genetic uniformity among isolates, all clustering within ASFV genotype II. Poor biosecurity measures, such as feeding of untreated swill (80% of holdings) and lack of restrictions on visitors (90% of holdings), were identified as risk factors. Additionally, co-infection with porcine circovirus-2 (PCV-2) further complicates disease management. This study underscores the urgent need for enhanced biosecurity and farmer education to mitigate ASFV outbreaks in endemic regions.

Keywords: ASFV; Tanzania; biosecurity; molecular characterization; pig farming.

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Conflict of interest statement

The authors declare no conflicts of interest. The project or effort depicted was or is sponsored by the United States Department of Defense, Defense Threat Reduction Agency. The content of the information does not necessarily reflect the position or the policy of the Federal Government of the United States, and no official endorsement should be inferred. The views expressed in this publication are those of the author(s) and do not necessarily reflect the views or policies of the Food and Agriculture Organization of the United Nations.

Figures

Figure 1
Figure 1
Distribution of ASF confirmed cases in Tanzania from 2008 to 2024 as reported by WAHIS, indicating the number of succumbed animals and end date of the outbreak. The yellow square indicates the capitals on this map.
Figure 2
Figure 2
Geographical distribution of African Swine Fever (ASF) cases in Tanzania’s Southern Highland Zone (orange). The map highlights sampled districts (green) and wards with ASF-positive samples (red) within this livestock-intensive region.
Figure 3
Figure 3
Phylogenetic trees based on (A) partial p72 gene nucleotide sequences, inferred using the neighbor-joining method with evolutionary distances computed using the maximum composite likelihood method and (B) the complete p54 gene nucleotide sequences based on Minimum Evolution method and evolutionary distances computed using the Kimura two-parameter method. The 2024 ASFV isolates from Tanzania are highlighted in red triangles. Only bootstrap values greater than 70% are shown.
Figure 4
Figure 4
Maximum likelihood tree based on the partial amino acid sequence of the CD2v protein, showing the relationship between the 2024 ASFV isolates from Tanzania (in red triangles) and representatives of known ASFV serogroups as well as ASFVs clustering outside the eight established serogroups. The General Reversible Chloroplast model Gamma distribution was used. Only bootstrap values greater than 70% are shown.
Figure 5
Figure 5
Multiple sequence alignments of the ECOA intergenic region between I73R and I329L genes of the Tanzanian ASFV GII samples (in red) in comparison to representatives of known genotype II isolates. The highlighted regions show a deletion of a nucleotide internal repeat sequence (GAATATATAG) and a G/A Single-Nucleotide Polymorphism. The dots indicate the identical nucleotides in the alignment. In the figure, the nucleotides are color-coded as follows: A is shown in green, G is shown in black, T is shown in red, and C is shown in blue.
Figure 6
Figure 6
Assessment of risk factors on domestic pig holdings based on questionnaire results.
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