Leprosy is a chronic infection caused by Mycobacterium leprae that primarily affects the skin and peripheral nerves. It was first identified and isolated in 1873 by Gerhard Hansen in Norway. While leprosy has affected humans for thousands of years, it remains endemic in some developing countries today. Treatment involves multidrug therapy with rifampicin, dapsone, and clofazimine over the course of months to years depending on the type of leprosy.

1. Leprosy
Dr. Kanwal Deep Singh Lyall
M.D. Microbiology

2. Leprosy
Gerhard Hansen ArmauerLeprosy patient

3. • Dard me kuch baat hai
• Ask the joy of pain from a leper

4. • Dates back to ancient Egypt in 4000 BC and
was discussed by Hippocrates in 460 BC.
• The earliest proven human case - 1-50 AD
• Mentioned in Bible
• Kushta in Sushta Samitha – 600 BC in India

5. • Hansen's disease
• Chronic infection caused Mycobacterium leprae
• Latin word Lepra, which means "scaly"
• Discovered by G. Hansen Armauer in Norway in
1873
• 1st bacterium to be identified as causing disease
in humans
• Non- cultivable

6. • Man alone gets leprosy and is reservoir of infection
• But in Americans – 9 banded armadillo
• Extremely slow generation time-12 to 13 days.
• Only bacillary diseases with predilection for nerves.
• Disease spectrum ranges from complete absence of
resistance to effective immunity.
• No satisfactory way of detecting past or unapparent
present infection.

7. Epidemiology
• One of the major health problems of
developing countries.
• Estimated prevalence is >1 case per 1000 of
population.
• High prevalence – India (60% of annual cases),
China, Myanmar, Indonesia, Brazil, Nigeria,
Madagascar, and Nepal.
• In India - Orissa and Bihar – highest prevalence

8. • Nasal droplets, contact with infected soil, &
even insect vectors
• Through upper resp. tract or skin
• Not highly contagious
• 95% population has innate immunity against it
• Not associated with AIDS (long incubation
period – 2 – 40 years)

9. Gen. Characteristics
• Obligate intracellular parasite,
• Usually present in parallel bundles of 50 or more
organisms bound by lipid like substances GLIA, called
GLOBI.
• The parallel rows of Globi present a cigar bundle
appearance. Seen inside the histiocytes.
• Bacteria divides by binary fission.

10. Morphology
• Slender, slightly curved or straight.
• Non motile, non sporing, gram +ve
• Acid fast bacilli , resist decolourisation with 5% H2SO4
• Bacteria are seen singly or in groups, intracellularly
and lying free outside the cell.

11. Antigenic structure
• Cell wall – 4 layers
1. Innermost – peptidogylcan – shape & rigidity
2. Lipoarabinomanan – B (LAM – B) – highly
immunogenic – serodiagnosis
3. Mycolic acid
4. Outermost – mycosides (has phenolic glycolipid 1
- PGL-1) – protects against enzymes and
suppresses CMI – prediliction to Schwann cells

12. Cultivation
• No genes for catabolic & respiratory pathways;
transport systems; purine, methionine, &
glutamine synthesis; & nitrogen regulation.
• Non-cultivable
• Non-confirmed reports of growth
• ICRC – ICRC bacillus
• Animals: Mouse, Armadillo, Chimpanzees,
Monkeys, etc.

13. Mouse
• Uses:
– to do susceptibility to chemotherapeutic agents
– determining the viability of organism
• Disadvantages:
– limited multiplication – insufficient yield
– Short life span – can not study pathogenesis

14. Armadillo
• Highly susceptible
• Long life span (12 – 15 yrs)
• Low body t°
• High yield
• Disadvantages :
– Only 40% susceptible
– High cost
– Wild armadillos – naturally infected

15. Pathogenesis
• Chronic granulomatous disease
• Humans – only source
• Localise primarily in skin, peripheral nerves &
nasal mucosa
• Has preference for low t°
• Long incubation & prolonged contact required
• Four types : Lepromatous, Tuberculoid,
Dimorphous, Intermediate

16. Lepromatous :
• Generalized form
• In people with low immunity
• More infectious
• Lepromin test is negative
• High level of Abs
• Nodular lesions, slow
thickening of peripheral
nerves
• Loss of sensation – trauma –
ulcers - 2° infections
• Continuous bacterimia
Tuberculoid
• Localized form
• In people with high immunity
• Lepromin test is positive
• Low level of Abs
• few non-elevated hypo- or
hyperpigmented macular
patches
• Initially peripherla nerve
involvement
• Later bigger nerves
• Nerves – thickened ,
hardened, tender

17. • Dimorphous :
– Clinically tuberculoid, but bacteriological &
immunologically lepromatous
– May shift to any extreme
• Intermediate :
– Unstable tissue reaction
– Neither tuberculoid, nor lepromatous
– Regress spontaneously or May shift to any extreme

18. Reversal (type 1) reactions. Erythematous, oedematous lesions.

19. Immune reactions
Type 1 (Downgrading &
reversal)
– Borderline leprosy patients→
CMI hypersensitivity →
tuberculoid shift
– Downgrading – pre Rx
(histological become
lepromatous)
– Reversal – post Rx
– Painful tender nerves, loss of
function, Swollen skin lesions,
New skin lesions
– Prednisolone 40 mg, reducing
over 3–6 months
Type 2 (Erythema nodosum leprosum)
– Lepromatous patients undergoing
treatment
– Bacilli die → release Ags → Ag-Ab
complexes
• Tender papules & nodules; may
ulcerate, painful tender nerves,
loss of function, iritis, orchitis,
myositis, lymphadenitis, Fever,
oedema
• Moderate: prednisolone 40mg od
• Severe: thalidomide 2 or
prednisolone 40–80 mg od,
reducing over 1–6 months

20. Ridley & Jopling’s classification
• Tuberculoid tuberculoid (TT)
• Borderline tuberculoid (BT)
• Borderline borderline (BB)
• Borderline lepromatous (BL)
• Lepromatous lepromatous (LL)
Tuberculoid
Lepromatous

22. Lepromin test
• Integral lepromin
• Bacillary lepromin
• 0.5 ml ID injection
• Early reaction of Fernandez: erythema &
induration within 24 - 48 hrs, remains 3 – 5
days
• Late reaction of Mitsuda: 1 -2 weeks after inj. ,
peak 4 weeks , nodule – ulecration – healing

23. Uses
1. Classification of leprosy: +ve in tuberculoid &
-ve in lepromatous
2. Assessment of prognosis : +ve = good
prognosis
3. Assessment of resistance : +ve = resistance
Field workers should be +ve

24. Laboratory diagnosis

25. Specimens
• From nasal mucosa, skin lesions, ear lobules
• Slit & scrape method
• Skin biopsy
• Nerve biopsy
• 6-7 sites sampled

26. Staining
• ZN stain (5% H2SO4)
• AFB arranged in parallel bundles within macrophages
(Lepra cell)
Grading
1 – 10 bacilli in 100 fields 1+
1 – 10 bacilli in 10 fields 2+
1 – 10 bacilli per field 3+
10 - 100 bacilli per field 4+
100 – 1000 bacilli per field 5+
> 1000 bacilli, clumps & Globi in every field 6+

27. Procedure : slit and scrape method
• Clean selected portion of skin with spirit
• Hold the skin pinched up & raised b/w thumb &
index finger of left hand
• Make an incision (5 mm long, 3 mm deep )
• Blade of scalpel turned at right angle to slit
• Bottom & sides of slit scraped
• Make smear → stain → examine

28. Interpretation
• LL : 6+ or 5+
• BT : 0 - 2+
• TT : 0
• Detects bacilli present at a conc. > 104/gm of skin
• In untreated patients earlobes yield the greatest
number.

29. Nasal scrapings
• Scrapings from nasal septum
• Nasal secretions collected by blowing nose into
polyethylene handkerchief
Interpretation :
• +ve in LL,BL type
• -ve in BB, BT, TT
• In patients of LL on chemotherapy: -ve earlier
than skin smears
• To decide whether patient is infectious or not

30. Skin and nerve biopsy
• Skin biopsy - active edge of patches
• Nerve biopsy - thickened nerve
Indications :
• When diagnosis is uncertain
• For accurate classification
• In TT or indeterminate when sensory impairment
is not marked, as in children
• To assess progress of treatment
• To differentiate between downgrading and
reversal reaction

31. Interpretation
• TT : Typical tubercles in dermis comprising of
epithelioid cells, langrhan giant cells and
surrounding zone of lymphocytes
• LL : Diffuse highly bacilliferous granuloma
(leproma) in dermis mainly consist of
macrophages.

32. • Live forms appear solid and uniformly stained.
• Dead or dying forms appear fragmented,
beaded and granular
• Bacteriological index
– BI = Total pluses / no. of smears examined
• Morphological index
– MI = % of uniformly stained bacilli out of total
bacilli counted

33. • Skin & nerve biopsy – histological
confirmation
• Animal inoculation
• Lepromin test
• Serological tests

34. Treatment
• Pucibacillary (TT,BT):
– Rifampicin 600 mg once a month +
– Dapsone 100 mg OD
• Multibacillary (BB, BL, LL)
– Rifampicin 600 mg once a month +
– Dapsone 100 mg OD +
– Clofazimine 50 mg OD
• Immunotherapy
• Vaccines
x 6 months
x 2 years or
skin smears –ve

35. Prevention
• Early diagnosis & treatment
• Surveillance of contacts
• Health education
• Vaccines

36. X