African Swine Fever Perception, Risk Factors, and Socioeconomic Disparities Among Smallholder Domestic Pig Farmers in Serengeti, Tanzania

Abstract

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.

Keywords: African swine fever; African swine fever virus; Serengeti National Park; Tanzania; biosecurity; domestic pigs; risk factors.

Figure 1

Map of Tanzania showing the study villages of Serengeti National Park's (SNP's) wildlife management area (WMA) in Serengeti district, Tanzania. The map was developed by the authors using QGIS version 3.4.4 [62].

Figure 2

(a, b) Depict freely roaming domestic pigs on streets and near pigpens, as observed in the villages studied. (c, d) Capture freely roaming domestic pigs scavenging on garbage, exposing domestic pigs to uncontrolled waste materials, thus, posing significant biosecurity risks in Nattambiso village, Serengeti district, Tanzania.

Figure 3

(a, b) Illustrate the delivery and preparation process for the slaughtering activities. (c, d) Depict domestic pig slaughtering practices conducted in homesteads within the studied villages. These activities present potential risk factors for the spread of ASF.

Figure 4

Agarose gel indicating ASFV confirmation in the collected samples with 478 bp expected band size, samples (1–10), control (NC, negative control; PC, ASF positive control), and marker (M).