DR BAVITHRAN D
COMMUNITY MEDICINE
EPIDEMIOLOGY OF
LEPROSY

Leprosy (Hansen's disease) is a chronic infectious disease caused by Mycobacterium
leprae . It affects mainly the peripheral nerves. It also affects the skin, muscles, eyes,
bones, testes and internal organs. The disease manifests itself in two polar forms, namely
the lepromatous leprosy and tuberculoid leprosy, lying at the two ends of a long spectrum
of the disease. Between these two polar types occur the borderline and indeterminate
forms depending upon the host response to infection.
LEPROSY / HANSEN’S DISEASE

Leprosy is clinically characterised by one or more of the following cardinal features :
1. hypo-pigmented patches
2. partial or total loss of cutaneous sensation in the affected areas (the earliest sensation to be
affected is usually light touch)
3. presence of thickened nerves, and
4. presence of acid-fast bacilli in the skin or nasal smears. The signs of advanced disease are
striking: presence of nodules or lumps especially in the skin of the face and ears;

PROBLEM STATEMENT - WORLD
1991 -WHO Member states resolved to decrease the level of
leprosy in the world by over 90%. This has now been accomplished
and the overall target for global elimination of leprosy as a public
health problem has been attained.
The fall in prevalence rate is largely explained by an improvement
in management of cases, very low rates of relapse, high cure rates,
absence of drug resistance and shorter duration of treatment with
MDT

PROBLEM STATEMENT- INDIA
1981- 57 Cases / 10000 Population
2005- <1 Cases / 10000 Population
India achieved the goal of leprosy elimination at the
national level.
Annual new case detection Rate (ANCDR) 8.69 /
LAKH POPULATION

DR BAVITHRAN D
A. AGENT- Mycobacterium leprae
B. SOURCE OF INFECTION- Multibacillary cases ( L and BL)/ all “active leprosy” patients are
considered infectious.
C. PORTAL OF EXIT- Nose, harbours in nasal mucosa, discharged by sneeze or blow, exit from
ulcerated wounds
D. INFECTIVITY- Highly infectious diseases with low pathogenicity.
E. ATTACK RATES-4.4 to 12 % of household contacts are expected to show signs of leprosy within
5 years.
DETERMINANTS OF LEPROSY
AGENT FACTORS

DR BAVITHRAN D
A. AGE 20- 30
B. SEX Males > Females
C. MIGRATION Rural > Urban
D. PREVALENCE Balance between inflow and outflow
E. INACTIVATION OF DISEASE
F. IMMUNITY
G. GENETIC FACTORS
DETERMINANTS OF LEPROSY
HOST FACTORS

DR BAVITHRAN D
Humidity favours survival of M leprae in environment. It will remain viable in dried nasal
secretions for at least 9 days, and in moist soil for 46 days
Over crowding and lack of ventilation within households
DETERMINANTS OF LEPROSY
ENVIRONMENTAL FACTORS

MODES OF TRANSMISSION
DROPLET INFECTION
CONTACT TRANSMISSION
FOMITES
INCUBATION PERIOD - 3 TO 5 YEARS,SYMPTOMS CAN TAKE UPTO 20 YEARS TO APPEAR

A. Medical measures
1. estimation of the problem
2. early case detection multidrug therapy
3. surveillance
4. immunoprophylaxis
5. chemoprophylaxis
6. deformities
7. rehabilitation
8. health education
B. Social support
C. Programme management
D. Evaluation
LEPROSY CONTROL

RIFAMPICIN+
DAPSONE+CLOFAZIMINE

DISABILIT
Y

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