The near-universal socio-economic and psychological burden of onchocerciasis in endemic communities of Bo District, Sierra Leone: an explanatory sequential mixed-methods study

Abstract

**Background:** Onchocerciasis (river blindness) persists in Bo District, Sierra Leone, despite decades of ivermectin-based mass drug administration (MDA). Previous programmatic efforts prioritized parasitological and ocular outcomes. The socio-economic and psychological burden within affected communities remains poorly quantified. We quantified the magnitude and multidimensionality of this burden using two composite indices socio-economic and psychological which revealed a near-universal impact, with 89.9% and 95.8% of respondents affected in each respective dimension. Statistical analysis demonstrated that these dimensions are independent (ρ=.026,p=.311), confirming the multidimensional nature of the burden. Furthermore, we found the distribution to be remarkably uniform, with no significant variation across the five chiefdoms (F=1.91,p=.106) or between sexes (t=0.26,p=.796), suggesting that onchocerciasis-related distress is a generalized community condition rather than one patterned by demographic or geographic factors." Methods : We used an explanatory sequential mixed-methods design. In the quantitative phase, we used multistage cluster sampling to survey 1,500 adults across five endemic chiefdoms (Bagbwe, Baoma, Gbo, Selenga, Tikonko).We operationalized the non-clinical burden of onchocerciasis using two formative composite indices. The socio-economic impact index (0–2) was calculated by summing two binary items (yes/no): experienced economic hardship, such as income loss or reduced work capacity, and encountered obstacles to education or employment. The psychological impact index (0–3) was calculated by summing three binary items: impaired emotional well-being (anxiety/sadness) social stigma or isolation, and negative shifts in self-esteem. A formative measurement approach was selected because these items represent distinct, non-interchangeable components of the burden that collectively contribute to the construct rather than being manifestations of a single latent trait. The choice of indicators specifically stigma and economic productivity is supported by established models of the social burden of neglected tropical diseases, which identify these as core dimensions of patient experience. Similar research in endemic settings has successfully utilized such categorical impacts to quantify the welfare assault of onchocerciasis. To ensure linguistic and cultural validity, all instruments were forward- and back-translated into Mende and reviewed by an expert panel. We conducted cognitive testing and a pilot study (N=30) to establish reliability. Our pilot results demonstrated adequate internal consistency (Cronbach’s α=0.76 for knowledge and 0.81 for stigma items) and strong stability over time (test–retest intraclass correlation: 0.79"-" 0.85). Data were collected on Android tablets using Open Data Kit Collect. We performed descriptive statistics, chi-square tests, one-way ANOVA, independent-samples t-tests, and Spearman correlations in JASP. We performed thematic analysis on eleven key informant interviews and eight focus group discussions to explain quantitative findings.

**Results:** The burden was extensive and multidimensional. Economic hardship affected 71.7% of respondents, emotional well-being 65.9%, social stigma or isolation 69.6%, and self-esteem 59.1%. Composite indices showed that 89.9% experienced at least one socio-economic impact and 95.8% at least one psychological impact. The two burden dimensions were statistically independent (ρ = .026, p = .311). Socio-economic impact did not differ across chiefdoms (F(4,1495) = 1.91, p = .106) and psychological impact did not differ by sex (t(1498) = 0.26, p = .796); no specific impact was associated with chiefdom, sex or education (all effect sizes trivial). Qualitative themes described a productivity poverty cycle, stigma experienced as “social death,” and an unrecognized gendered caregiving load.

**Conclusions:** Onchocerciasis imposes a near-universal, uniformly distributed dual burden in Bo District that is invisible to parasitological surveillance. Because the burden is community-wide rather than concentrated in identifiable subgroups, morbidity-management, stigma-reduction, and psychosocial support should be delivered population-wide and integrated into primary healthcare and MDA delivery rather than targeted at demographic risk groups.