Disability and quality of life assessment using WHODAS-12 items 2.0 and EQ-5D-5L in a rural area endemic for loiasis in the Republic of Congo: a population-based cross-sectional study (the MorLo project)

Background: Loa loa filariasis, a parasitic infection endemic to Central Africa, is a common cause of medical consultation in this region. Methods: To evaluate the quality of life (QoL) of individuals living in loiasis-endemic areas, we enrolled 991 subjects (one-third being microfilaremic) from the general population of a rural area in the Republic of Congo. QoL and disability were assessed using WHODAS 2.0 12-items and EQ-5D-5L questionnaires. We collected data on the number of eye worm (Ew) and Calabar swellings episodes experienced throughout their lives, as well as individual L. loa microfilarial densities and information on infections with soil-transmitted helminthiasis. Principal findings: Individuals with a history of Ew had a nearly doubled risk of experiencing moderate disability (score >25/100) (adjusted Odds-Ratio=1.77 (95%CI [1.05-2.99], p=0.033), compared to those without such a history. Those with more than 10 episodes of Ew during their lifetime had a 28% increase in overall disability as measured by WHODAS. No other variable related to loiasis (Calabar swelling frequency, L. loa microfilarial density and positivity to L. loa antibody rapid test) was associated with the various scores. Additionally, infection with Trichuris trichiura was associated to worse anxiety score (adjusted incidence risk ratio=1.22 (95% CI [1.06-1.39], p=0.004)). . Conclusions: The impact of loiasis on daily QoL appears to be primarily due to adult worms rather than microfilarial density. Adult worms would mainly affect daily activities through peripheral symptoms, such as joint-related discomfort (with notable mobility impairment), while microfilariae would primarily induce organ dysfunction. Further studies are needed to better understand the respective clinical impacts of adult worms and L. loa microfilariae. Team projects: https://www.ntd-researchgroup.com/morlo Fundings: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 949221)