Epidemiology of Porcine Cysticercosis in Eastern and Southern Africa: Systematic Review and Meta-Analysis

Abstract

Taenia solium cysticercosis is the most common cause of acquired epilepsy in pig-raising and pork-consuming parts of Africa, Latin America, and Asia. This review aimed to systematically compile and synthesize data on the epidemiology of porcine cysticercosis in the Eastern and Southern Africa (ESA) region. Comprehensive searching strategies were employed to retrieve the studies published or reported between January 1,1997 and March 1, 2021, from Pub Med, Hinari, and Google Scholar databases and search platforms. The identified studies that met the inclusion criteria were then appraised for methodological quality. Finally, 44 studies obtained from nine countries were selected and included in this review. Relevant data were extracted using standardized templates for qualitative synthesis and meta-analysis. The overall pooled prevalence estimate of porcine cysticercosis in the ESA region was 17% (95% CI: 14-20%). The prevalence level between and within countries showed high variability. The pooled estimate showed high heterogeneity among the reports (the inverse variance index value (I²) of 98.99%, p < 0.05). The meta-analysis sub-grouped by the type of diagnostic test showed the pooled prevalence estimate of 27% (95% CI: 9-50) by carcass dissection; 23% (95% CI: 14-33) by Antibody-based immunodiagnostic techniques; 23% (95% CI: 18-29) by antigen detecting (Ag)-ELISA, 12% (95% CI: 7-18) by meat inspection, and 9% (95% CI: 7-11) by lingual examination. The meta-analysis sub-grouped by region showed a relatively higher pooled prevalence estimate for the Southern region 22% (95% CI: 15-30) compared to 13% (95% CI: 11-15) in the Eastern region. The highest country-based pooled prevalence was obtained from South Africa (33%, 95% CI: 20-48) and Zambia (22%, 95% CI: 16-29), whereas the lowest pooled prevalence was identified in Madagascar (5%, 95% CI: 4-5) and Rwanda (7%, 95% CI: 6-8). The lack of latrine, traditional pig husbandry practices, unprotected water sources, and increase in age were identified as significant risk factors for the occurrence of porcine cysticercosis in the pooled studies. The findings of this review will provide context-specific input to prioritize the possible intervention programs for T. solium control in the ESA region. More sensitive and specific test-based prevalence estimates, detailed risk factor investigations, and financial losses analysis are needed to establish feasible control strategies.

Systematic review registration: http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021238931.

Keywords: Eastern and Southern Africa; epidemiology; meta-analysis; porcine cysticercosis; systematic review.

Figure 1

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram (left) and summary of publications available by country (right).

Figure 2

Type of diagnostic techniques employed in the reviewed studies.

Figure 3

The distribution of porcine cysticercosis in the Eastern and Southern Africa (ESA) region based on the reviewed studies.

Figure 4

Prevalence of porcine cysticercosis in countries within ESA region.

Figure 5

Forest plot showing the studies reporting porcine cysticercosis in the ESA region. The box shows the weight and estimate of the study; the length of the horizontal lines indicates the 95% CI; the vertical broken red line indicates the pooled estimate; the diamond-shaped box at the bottom represents the 95% CI; the solid line indicates the point of null assumption.

Figure 6

Forest plot showing subgroup analysis of prevalence reports grouped by the diagnostic technique (left) and region (right).

Figure 7

Overview of the meta-analyses results of pooled odds ratio (OR) for significant risk factors of porcine cysticercosis in ESA (n, number of studies that are included in the analysis).