Geospatial and age-related patterns of Taenia solium taeniasis in the rural health zone of Kimpese, Democratic Republic of Congo

Abstract

Background: Taenia solium infections are mostly endemic in less developed countries where poor hygiene conditions and free-range pig management favor their transmission. Knowledge on patterns of infections in both human and pig is crucial to design effective control strategies. The aim of this study was to assess the prevalence, risk factors and spatial distribution of taeniasis in a rural area of the Democratic Republic of Congo (DRC), in the prospect of upcoming control activities.

Methods: A cross-sectional study was conducted in 24 villages of the health zone of Kimpese, Bas Congo Province. Individual and household characteristics, including geographical coordinates were recorded. Stool samples were collected from willing participants and analyzed using the copro-antigen enzyme-linked immunosorbent assay (copro-Ag ELISA) for the detection of taeniasis. Blood samples were collected from pigs and analyzed using the B158/B60 monoclonal antibody-based antigen ELISA (sero-Ag ELISA) to detect porcine cysticercosis. Logistic regression and multilevel analysis were applied to identify risk factors. Global clustering and spatial correlation of taeniasis and porcine cysticercosis were assessed using K functions. Local clusters of both infections were identified using the Kulldorff's scan statistic.

Results: A total of 4751 participants above 5 years of age (median: 23 years; IQR: 11-41) were included. The overall proportion of taeniasis positivity was 23.4% (95% CI: 22.2-24.6), ranging from 1 to 60% between villages, with a significant between-household variance of 2.43 (SE=0.29, p<0.05). Taeniasis was significantly associated with age (p<0.05) and the highest positivity was found in the 5-10 years age group (27.0% (95% CI: 24.4-29.7)). Overall, 45.6% (95% CI: 40.2-51) of sampled pigs were sero-positive. The K functions revealed a significant overall clustering of human and pig infections but no spatial dependence between them. Two significant clusters of taeniasis (p<0.001; n=276 and n=9) and one cluster of porcine cysticercosis (p<0.001; n=24) were found.

Conclusion: This study confirms high endemicity and geographical dispersal of taeniasis in the study area. The role of age in taeniasis patterns and significant spatial clusters of both taeniasis and porcine cysticercosis were evidenced, though no spatial correlation was found between human and pig infections. Urgent control activities are needed for this endemic area.

Keywords: Democratic republic of Congo; Epidemiology; Porcine cysticercosis; Spatial clustering; Taeniasis.

Graphical abstract

Fig. 1

Map of the DRC showing the location of Kimpese health zone.

Fig. 2

Ripley’s K function for taeniasis positive cases in the health zone of Kimpese. The black line represents the observed L function and the dashed lines represent the confidence envelopes calculated from 999 simulations under the hypothesis of complete spatial randomness (CSR). The observed L function lies above the envelopes, showing significant clustering.

Fig. 3

Ripley’s K function for porcine cysticercosis cases in the health zone of Kimpese. The black line represents the observed L function and the dashed lines represent the confidence envelopes calculated from 999 simulations under the hypothesis of complete spatial randomness (CSR). The observed L function lies above the envelopes, showing significant clustering.

Fig. 4

Bivariate K function for the copro-antigen positive human (taeniasis) and seropositive pigs (porcine cysticercosis). The dashed line represents the confidence envelopes calculated using 1000 simulations under the random toroidal shifts method and the black line represents the observed L function. The observed L function lies between the confidence envelopes, which means a complete spatial random distribution of both human and pigs infections.

Fig. 5

(a) Map of taeniasis positivity in villages of the rural health zone of Kimpese including location of taeniasis significant clusters. (b) Map of porcine cysticercosis positivity in villages of the rural health zone of Kimpese including location of porcine cysticercosis significant cluster.