EPIDEMIOLOGY OF MYCOBACTERIUM LEPRAE INFECTION IN EASTERN ETHIOPIA: A COMMUNITY BASED STUDY

Abstract

Background: Leprosy or Hansen's disease is a chronic granulomatous infectious disease that remains the leading cause of physical disability. Reliance on the self-presentation of patients to the health services and lack of community knowledge regarding leprosy allow for a proportion of patients to remain hidden in the community. This results in a longer delay of presentation and disability. Although reports in Ethiopia have shown evidence of delayed diagnosis and an increasing trend of disability rate, the extent of hidden leprosy remains unexplored. Objective: To determine the prevalence of hidden leprosy in the general population and to assess barriers to early diagnosis; including community knowledge and attitude towards leprosy. Methods: A community-based cross-sectional survey was conducted between July and October 2019 in the Fedis district of eastern Ethiopia. The district contains 21 Kebeles with an estimated total population of 133,382. Health extension workers (HEWs) identified the leprosy suspects through house-to-house interviews and screening, covering six randomly selected Kebeles. The dermatologist performed a physical examination for all consented suspects and household contacts (HHCs). Medical laboratory technologists performed a bacteriological examination from a slit skin smear and assessed nasal DNA carriage using conventional PCR for all healthy HHCs and randomly selected healthy endemic controls (ECs). A structured questionnaire was used to collect data on participants' socio-demographic characteristics, the extent of case detection delay, and data on community knowledge and attitude towards leprosy. Logistic regression analysis was done using STATA version 16 statistical software. Results: Health extension workers visited 4798 households and identified 262 eligible study participants (214 with skin lesions suspected of leprosy and 48 household contacts) who were all investigated for leprosy. Fifteen study participants were confirmed to have leprosy, giving a detection rate of 5.7% (95%, CI: 3, 9). This yielded a total population-based xiv prevalence of hidden leprosy to be 9.3 per 10,000 population. There was no statistical difference in the detection rate between participants with and without a history of contact with a known leprosy case and their demographic characteristics (P> 0.05). Nasal swab analysis with PCR indicated that 11.4% (95% CI: 3, 24) of HHCs of untreated multibacillary (MB) patients were colonized by Mycobacterium leprae. All healthy ECs were negative for nasal swab DNA analysis. The positivity rate was significantly different among the study groups (P=0.022) and associated with disability grade within the patient group (P=0.003). Among 100 leprosy patients on MDT, the median delay in case detection was 12 months, with an inter-quartile range (IQR) of 10 to 36 months. Fear of stigma (AOR=3.85, 95% CI: 1.26, 11.77, P=0.01) and experiencing non-alarming painless symptoms (AOR=3.57, 95% CI: 1.24, 10.21, P=0.01) were significantly associated with a delay in case detection. Among 728 study participants, 40.8% (95% CI; 36, 44) expressed a positive attitude towards leprosy. Attending formal education (AOR= 2.72, 95% CI=1.76, 4.19, P < 0.001) and having a high level of knowledge (P = 0.001) were significantly associated with a positive attitude towards leprosy. Conclusions: A high number of leprosy cases remain undetected and hidden in the general population. A substantial proportion of HHCs of newly diagnosed patients carry M. leprae in their nostrils. Being asymptomatic and afraid of stigma are independent predictors of prolonged delay in case detection. Negative attitudes towards leprosy are reported in a considerable proportion of the community. Therefore, population-based active case finding survey is being prioritized, along with contact evaluation, in known hotspots. It is helpful to develop strategies that reduce the still existing stigma related to leprosy. The evidence from this study underscores the need for increased community knowledge on early signs and symptoms of leprosy and the imperative to generate a positive attitude towards leprosy in the community.