Pattern of Leprosy in Post-Elimination Stage: A 20-Year Retrospective Study in The Largest Specialized Leprosy Hospital of Bangladesh

Background: Leprosy has affected humanity for over 4000 years. The global registered number of new leprosy cases in 2019 were 202256. Bangladesh has been achieved Elimination of leprosy in 1998, but a slow resurgence of the disease still continues in several parts of the country. Aims and objectives: Understanding the current magnitude of the disease is vital for the community, service providers and policy makers. The present study was undertaken to describe the pattern of the disease after leprosy has been declared eliminated. This will help for proper planning of patient-oriented leprosy services and judicial allocation of scarce resources. Materials and Methods: This descriptive study has been carried out using the registered record of patients attending the outpatient department (OPD) of leprosy hospital, Sylhet, Bangladesh during the period 2001-2020. Results: The new case detection pattern was declining. Of the 1835 new cases, males (76.95%) outnumbered females (23.05%). The PB and MB cases were 27.74% and 72.26% respectively. Leprosy reactions developed in 31.39% cases and 18.09% cases presented with grade 2 disabilities. Smear positive cases were 19.89%. Mode of case detection was mainly passive (98.75%). The new case detection of childhood leprosy (≤14 years) was declining. Majority of patients (40.27%) were from >40 age group. Borderline type (44.20%) was more common. Leprosy reactions and G2D were common in MB type of leprosy, 78.69% and 66.57% respectively. Conclusion : New case detection is declining but burden of leprosy in the community has not changed significantly. MB patients with grade 2 disabilities are still in upward trend. Although leprosy has been eliminated globally, the disease continues accompanying the significant cause of disabilities in Bangladesh. Community based surveillance could help to improve early detection, treatment, prevention of disabilities and stigma.


I. INTRODUCTION
Leprosy or Hansen's disease is a slowly progressive infectious disease caused by Mycobacterium leprae, which may be very mutilating if not diagnosed and treated early. Cutaneous lesions and involvement of the peripheral nerves are the cardinal signs of leprosy. Nerve damage in leprosy is associated with physical disabilities, psychological disturbances, economic dependence and social exclusion [1]. Leprosy has affected humanity for over 4000 years [2]. The global registered number of new leprosy cases in 2019 were 202256 [3]. Leprosy is unevenly distributed globally, with India, Brazil, and Indonesia accounting for 80% of the total number of new cases. Furthermore, within countries, it is focalized, with pockets of high endemicity existing often at sub-district level, despite relatively low country estimates [4]. Bangladesh is high endemic for leprosy since many decades, with known foci in the southeast (Cox's Bazar), central (around Dhaka capital) and northwest (around Rangpur, Nilphamari, and Saidpur city). In 2018 and 2019, around four thousand new cases were detected annually [5]. Bangladesh achieved elimination of leprosy at national level in December 1998 and sustained elimination level with gradual decreasing of prevalence rate (PR) [6], but a slow resurgence of the disease still continues in several parts of the country. Although there has been marked decline in the new case detection of leprosy in Bangladesh, understanding the current magnitude of the disease is vital for the community, service providers and policy makers. So, the present study was undertaken to describe the pattern of the disease after leprosy has been declared eliminated.

A. Study Design and Setting
This descriptive cross-sectional study has been carried out using the registered records of patients attending the outpatient department (OPD) of Leprosy Hospital, Sylhet, Bangladesh during the period 2001-2020.This hospital is the oldest (established on 1890 A.D.) and largest (80 bedded) specialized hospital in Bangladesh. The patients were mostly from Sylhet, Habiganj, Moulvibazar, Sunamganj districts. Multi Drug Therapy (MDT) is available in this hospital. We gathered the documents and searched for information about age, sex, clinical type of leprosy according to Ridley and Jopling classification, positivity of slit skin smear, disability status, leprosy reactions (LRs), World Health organization (WHO) classification for treatment.

B. Diagnostic Procedure
The diagnosis was based on clinical history, physical examination and laboratory investigations. Then the cases were categorized either as paucibacillary (PB) or multibacillary (MB) under direct supervision of leprosy specialist. Patients were classified as PB if they had ≤5 skin patches with or without one to two thickened major cutaneous nerves. Patients with ≥6 patches and/or >2 thickened nerves and those with infiltrations with or without papules or nodules and smear positive cases were classified as MB. Slit skin smear was done to see whether the case was smear positive or not.
Leprosy reactions were assessed as Type 1 (T1R) or Type 2 reaction (T2R). T1R was diagnosed if the patient had redness and swelling of existing lesions, nerve thickenings, and edema in the hands, feet or face.T2R or erythema nodosum leprosum was diagnosed when multiple small, tender, evanescent nodules with or without ulcerations associated with fever, asthenia, nerve thickening and pain, myalgia and lymphadenitis were developed. Neuritis was another category where reaction had not occurred within skin patches but within the nerves presenting as spontaneous pain or tenderness with Nerve Function Impairment (NFI).
Grade 1 Disability (G1D) was labeled which had only anesthesia, and Grade 2 Disability(G2D) was labeled when damage present in limbs or eyes.

C. Case Detection
The mode of case detection was categorized as an active and passive method. Active detection meant the household survey of leprosy cases by health workers of the National Leprosy Program (NLP) and passive detection meant the leprosy cases were referred by physicians or voluntary reporting by patients. The NLP workers usually make household survey of at least forty houses for contact tracing if a new case is detected. A new case is defined as one who had not been diagnosed earlier and had no history of treatment for leprosy.

IV. DISCUSSION
We studied total 1835 new cases treated in this hospital during the study period. In our study, new case detection was declining, 112 in 2001(6.10%) and 19 in 2020 (1.03%). Bulstra, [5] found 44 cases /100 000 population in 2000 and 10 cases /100 000 population in 2019. This achievement may be due to integration of all essential components of leprosy control into the primary healthcare system using Upazila Health Complexes as the peripheral service outlets. New case detection was declining may also be due to decreased fund flow, inadequate contact tracing, lack of community awareness and social stigma.
The male/female ratio showed a preponderance of males almost throughout the reference period; males were 76.95%, females were 23.05%. These findings were comparable to a Chinese study (71.6% male and 28.4% female) [7] and an Egyptian study (62% male and 32% female) [8]. Women's access to health services are influenced by availability of services, costs, and quality of care, social structure, and women's decision-making power [9].
The majority (40.27%) of patients were from >40 age group which was compatible with [10] who found majority (38.33%) of patients from >40 age group but not compatible with [11] who found majority (40.1%) of patients from 15-30 age group.
The new case detection of childhood leprosy was declining ,7 cases in 2001 (6.25%) and no case was found in 2020. This finding was supported by [12]  Childhood leprosy rate is an important marker of the ongoing active transmission in the community. Childhood leprosy still contributes to a significant proportion of the total case load denoting the continuing active horizontal transmission of leprosy [14].
MB was more common (72.26%) among new cases. It was comparable to Sankar A (81%)15, Thomas A (86.5%) [16]. In contrary, [5] found 74.3% PB cases. The higher proportion of MB cases alert the possible future increase in patients because of the continuous transmission of the disease.
Leprosy reaction was witnessed in 31.39% cases. Reaction was more common (78.69%) in MB patients. Reference [16] and [18] also observed reactions in 86.5% and 80.57% of MB cases respectively.
Grade 2 disability(G2D) was found in 18.09 % cases. It was also observed by [19] (17.1%) and [20] (13.48%). In contrary, [21] observed higher frequency of G2D (83.18%). As stated, the antagonism between the decrease in the detection rate and the increase in disabilities is a strong indication of difficulties in the active search for cases and the possibility of underreporting [17].

V. LIMITATION
The major limitation of the study is that all the case finding figures are derived from documented register of outdoor facility of our specialized hospital. Data from a single institution does not reflect the actual situation. Therefore, a multicenter study across the country in concurrence with large population-based survey is recommended.

VI. CONCLUSION
The study shows that new case detection is declining but burden of leprosy in the community has not changed significantly. Because MB (72.26%) patients with G2D (18.09%) are still in upward trend. Although leprosy has been eliminated globally, the disease continues accompanying with the significant cause of disabilities in Bangladesh. Updated reinforced new therapies to curb reactions and disabilities are mandatory. Community based surveillance could help to improve early detection, treatment, prevention of disabilities and stigma.