Factors associated with Mycobacterium Leprea occurrence among people with leprosy in Kwale County, Kenya

Background: Leprosy, an infection caused by Mycobacterium Leprea, remains an important problem globally. In 2020, approximately 22.9 per million population cases were reported to WHO. India contributed 60% of these cases. In Africa, the prevalence of leprosy is 0.21 per 10,000 population. Although there is no effective vaccine to prevent leprosy, about 85% of the world's population have natural immunity. Kenya has maintained the global target of leprosy elimination at the national level. However, the country reported a 6-fold increase in leprosy cases over 10 years (2011-2021), with Kwale County contributing 20.3%.

Objectives: To determine Social-demographic, clinical, behavioral, socioeconomic, and environmental factors associated with leprosy disease in Kwale County.

Methods: A case-control study design was conducted in Kwale among people with leprosy. A case was defined as any person presenting with hypopigmented skin lesions, loss of sensation, and manifestation of leprosy bacilli with or without positive skin, including a person recently discharged from treatment . A control was any person living in Kwale from the same village as the case, of the same age group, and sex, with no report of leprosy within the kinship. The study listed 65 cases extracted from the leprosy registers and traced them to their respective villages where consent was sought. The cases and controls were interviewed using a questionnaire. Univariate analysis for continuous and categorical variables.Variables with a p-value of<0.2 in the bivariate analysis were subjected to unconditional multivariate binary logistic regression. Stepwise backward elimination was used to develop the final model. Variables with a p-value of <0.05 in the multivariate model were regarded as independently associated with increased Mycobacterium Leprea occurrence.

Results: A total of 65 cases and 195 controls were enrolled. The mean age among the cases and controls was 55 years (SD±16 years) and 54 years (SD±15 years) respectively. Age group ≥50 years contributed 44 (68.2%) and 0-14 years contributed 1(1.5%). The proportion of males among the cases was 39 (60.0%) and controls 108 (55.6%). The majority of the cases 59 (90.8%) were Multibacillary type of leprosy, and 38 (58.5%) presented with disability grade II. The median delay in case detection was 45 months (IQR 12-69 months). A low frequency of changing bed linen (cOR=2.69, 95% CI 1.02-3.9); and food scarcity (cOR=2.55, 95% CI 1.25–5.24) were 2 times likely to increase Mycobacterium Leprea occurrence. In multivariate analysis, household crowding (≥5 members) increased Mycobacterium Leprea occurrence risk by 6 times (aOR=6.99, 95% CI 2.71–18.06). Family contact (aOR=4.33, 95% CI 2.18–8.58), Social contact (aOR=2.24, 95% CI 1.16–4.32), and absence of BCG scar (aOR=2.24, 95% CI 1.11–4.53) were independently linked to Mycobacterium Leprea occurrence.

Conclusion: Crowded households of ≥ 5 members, family, and social contacts, and absence of BCG scar were associated with leprosy.