leprosy

1. Epidemiology of Leprosy &
Contagious Disease
Dr. Khem R Sharma
Assistant Professor
School of Public Health & Community Medicine

2. Introduction
• Leprosy (Hansen's disease) is a chronic infectious disease caused by
M. Ieprae that mainly affects the peripheral nerves.
• It also affects the skin, muscles, eyes, bones, testes and internal
organs
• In Nepal, leprosy is known since ancient times as kustha rog and
attributed to punishment or curse from God

3. Disease is divine
punishment
Curse of God
Due to sin
Incurable
Highly
contagious
Nepalese Societal Beliefs Towards Leprosy

4. • Modern-day leprosy dates from 1873 when Hansen of Norway
discovered M. leprae.
• After a long period without any cure, introduction of sulphone drugs
in the treatment of leprosy in 1943 marked the beginning of the era
of case-finding and domiciliary treatment.
• The decade of 1980s has witnessed a change in the strategy of
leprosy control from mono-therapy to multidrug therapy, due to
widespread emergence of dapsone-resistant strains.

5. Epidemiology
• In 1991, WHO Member States resolved to decrease the level of
leprosy in the world by over 90 per cent
• Elimination of leprosy as a public health problem is defined as a
prevalence rate of less than one case per 10 000 persons.
• This has now been accomplished, and the overall target for the global
elimination of leprosy as a public health problem has been attained
• According to WHO, global registered prevalence of leprosy at the end
of 2015 was 176 176 cases (0.2 cases per 10 000 people)

6. India
Brazil
Indonesia

7. • In mid 2003, Nepal with overall leprosy prevalence rate of 3.04/10000
ranked 4th globally.
• But the GoN undertook the initiative to decrease it below 1 per
10,000 population and finally succeeded in 2010.
• Current prevalence is below 1/10000 and now major target for 2020
is to reduce grade II disability below 1 per million populations

8. Agent Factors
• Agent: Mycobacterium Leprae
• acid-fast and occur in the human host both intracellularly and
extracellularly.
• Numerous antigens (more than 20) have been detected in M. leprae,
some of these are shared by those of pathogenic and non-pathogenic
mycobacteria, e.g.. BCG, M. smegmatis, M. tuberculosis
• M. Ieprae has not yet been conclusively shown to grow inartificial
medium which is why progress in research has lagged behind than
that of many other diseases.

9. • SOURCE OF INFECTION
• Currently all patients with "active leprosy" are considered infectious.
• Recently new evidence has surfaced that natural infections with M.
Ieprae are present in wild animals like armadillos and chimpanzees
though it is not yet known if leprosy in wild animals is a threat to
public health.
• PORTAL OF EXIT
• Lepromatous cases harbour millions of M. Ieprae in their nasal
mucosa which are discharged when they sneeze or blow the nose.
• ulcerated or broken skin of bacteriological +ve cases

10. • INFECTIVITY
• highly infectious disease with low pathogenicity
• ATTACK RATES
• among household contacts of lepromatous cases, 4.4% to 12% -in
expected to show signs of leprosy within 5 years.

11. Host factors
• lncidence rates generally rise to a peak between 10 and 20 years of
age and then fall
• A high prevalence of infection among children means that the disease
is active and spreading.
• incidence and prevalence of leprosy appear to be higher in males
than in females in most regions of the world probably due to their
greater mobility and increased opportunities for contact in many
populations.

12. • only a few persons exposed to infection develop the disease. A large
proportion of early lesions that occur in leprosy heal spontaneously.
• Cell-mediated immunity (CMI) is responsible for resistance to
infection with M. leprae, ln lepromatous leprosy and there is a
complete breakdown of CMI; in these cases the lepromin test is
negative

13. Environmental factors
• the presence of infectious cases in that environment. overcrowding
and lack of ventilation within households have been implicated in
transmission of Leprosy.
• There is evidence that humidity favours the survival of M. Ieprae in
the environment

14. Social pathology
• Leprosy is called social disease
• Social factors are poverty, poor housing, overcrowding, lack of education,
lack of personal hygiene …
• Fear, Guilt & unfounded prejudices……
• Social stigma is due to “deformity”
• Social ostracism – Hide infection & delay in treatment ---- affect the control
program
• Psychological factors

15. Modes of transmission
1. leprosy may be transmitted via aerosols containing M. leprae
(droplet infection) supported by the fact that:
• Inability of the organisms to be found on the surface of the skin
• demonstration of a large number oforganisms in nasal discharge
• the high proportion of intact bacilli in the nasal secretions
2. Ieprosy is transmitted from person-to-person by close contact
between an infectious patient and a healthy but susceptible person

16. Incubation period
• Range 9 months to 20 years
• Average:
4 years tuberculoid leprosy
8 years lepromatous cases

17. Signs and Symptoms
Early signs and symptoms of leprosy are
very subtle and occur slowly (usually
over years).
 First symptoms :
 Numbness and loss of temperature
sensation (cannot sense very hot or
cold temperatures)
 As the disease progresses :
 The sensations of touch, then pain,
and eventually deep pressure are
decreased or lost.
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18. Long-term developing sequence of events :
• Relatively painless ulcers,
skin lesions of
hypopigmented macules
(flat, pale areas of skin), and
eye damage (dryness, reduced
blinking)
• Late stage: large ulcerations,
loss of digits, and facial
disfigurement. (for example,
hands, feet, face, and knees).
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19. 19

20. Leprosy
- It is characterized by one or more of the following cardinal features :-
a) Hypopigmented patches
b) Partial or total loss of cutaneous sensation in the affected areas
c) Presence of thickened Nerve.
d) Presence of acid-fast bacilli in the skin or nasal smear.

21. Signs of advanced disease :
• Presence of Nodules or Lumps in the skin of the face &
ears
• Plantar ulcers
• Loss of fingers or toes
• Nasal Depression
• Foot Drop & others.
Leprosy….

22. Classification
Ridley & Jopling Classification
Based on Host Immunity
TT BL LL
BT BB BL
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Other Classifications
Indian: T,B,L, Pure neuritic
Madrid: Indeterminate, T,B,L

23. Classification
WHO Classification
Based on Bacterial Load
Paucibacillary
1-5 skin lesions
Multibacillary
>6 skin lesions
Slit Skin Smear
Positive
Negative
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Indeterminate Leprosy (IL)
Tuberculoid Leprosy (TL)
Borderline Tuberculoid (BT)
Borderline Borderline (BB)
Borderline Lepromatous(BL)
Lepromatous Leprosy (LL)
BI≥2
BI<2

24. Diagnosis
1. Clinical Examination
2. Bacteriological Examination: skin smears, Nasal blows/smears &
scrapping's
3. Foot pad culture: only certain way to identify M. leprae is to
inoculate the material into the foot-pads of mice and demonstrate
multiplication.
4. Histamine Test: very reliable method for detecting peripheral nerve
damage due to leprosy at an early stage.
5. Biopsy

25. 6. Immunological Tests
For detecting CMI Fernandez(early)
1. Lepromin Test Mitsuda(late)
• The early reaction is induced by the soluble constituents of the
leprosy bacilli; and the late reaction by the bacillary component of the
antigen. It indicates cell-mediated immunity.
2. LTT/LMIT
For Humoral responses: FLA-ABS, Monoclonal antibodies, ELISA

26. Bacterial index (BI)
• indicates the density of leprosy bacilli in smears and includes both
living (solid-staining) and dead (fragmented or granular) bacilli.
• only objective way of monitoring the benefit of treatment.
0 - No bacilli in any of the 100 oil-immersion fields
1+ - 1-10 bacilli. on average, in 100 oil-immersion fields
2+ -10 bacilli on average, in 10 oil-immersion fields
3+ - 1-10 bacilli, on average, in each oil-immersion field
4+ - 10-100 bacilli, on average, in each oil-immersion field
5+ - 100-1000 bacilli, on average, in each oil-immersion field
6+ - More than 1000 bacilli on average, in each oil immersion field

27. Morphological index
• During microscopy examination it is possible to count the number of
solid (completely) staining organisms and irregularly staining bacilli.
• widely believed that only solid-staining organisms are viable.
• The percentage of solid staining bacilli in a stained smear is referred
to as morphological index (MI).
• This is an indicator of the patient's response to treatment with drugs,
during the first few months and helps to signal drug resistance.

28. Leprosy Control
• The main principles of leprosy control is based on timely detection of
new cases and their treatment with effective chemotherapy in the
form of multidrug therapy and social support.
• The control Measures include:
(A) Medical measures
(B) Social support
(C) Program management
(D) Evaluation

29. (A) Medical Measures
-Estimation of the problem
-Early case Detection
-Records
-Multi drug Therapy (MDT)
prevalence
a) Contact
survey
< 1 per 1000 popn
b) Group
survey
1 per 1000 popn or more
c) Mass
survey
1 per 1000 popn Hyper endemic area

30. • Objectives :-
- To interrupt transmission of the infection in the community by drugs
- To ensure early detection & treatment of cases to prevent
deformities
- To prevent drug Resistance

31. (A) Multibacillary:
- Ritampcin – 600 mg once monthly
- Dapsone – 100 mg Daily- self
- Clofamizine – 300 mg once monthly
(supervised)
- 50 mg daily – self
- Clofamizine if unacceptable
- Ethionamide or protionamide -250-375 mg daily –selfadministered
Duration- one years

32. Paucibacillary:
- Ritampcin – 600 mg once monthly supervised
- Dapsone -100 mg daily- self
Duration – six months
Surveillance :-
- Paucibacillary –Examine once in a year for 2 years after
completion of Rx
- Multibacillary :- once in a year for minimum of 5 yrs after
completion of Rx.
Leprosy……

33. Immunoproplyaxis :
- BCG has protective effect
- Uganda (80%), Myanmar (30%), India (23%)
Chemoprophylaxis:-
For the contacts of Leprosy
• 1-4 mg/kg body wt- Dapsone- per week for child contacts – 35-53%,
protection
• Given for 3 yrs or until the Index case becomes bacteriologically
negative.
Leprosy……

34. Deformities:
- 25% pts. develop deformities.
- Gloves , foot wears etc. prevent deformities
Rehabilitation :
-Physical, Mental, Social & Vocational.
- Preventive Rehabilitation – preventing deformities
- Health Education : pt. & family – General public

35. B. Social support
- Socio- economic problem of the pt. should be identified
& solved.
- Social stigma & support.
C. Program Management
- Long term activity
- Proper planning & Management are essential
D. Evaluation
Operational Indicators : case finding & Rx Relapse &
deformities
Epidemiological Indicators :- Incidence & Prevalence.

36. January 27 - World Leprosy Day