Leprosy

Question 1

Causative organism of leprosy?

Answer 1

Mycobacterium leprae

Question 2

Tell me about mycobacterium leprae

Answer 2

Bacillus, acid fast
Intracellular
Aerobic
Very slow growing
Survives in environment up to 45 days
Colonised 5% nasal mucosa in endemic area

Question 3

How is leprosy spread?

Answer 3

Droplets containing mycobacterium leprae

Question 4

Briefly outline pathophysiology of leprosy

Answer 4

Mycobacteriu leprae enter nasal mucosa via droplet

95% of hosts have effective immune response and clear bacteria

5% contract leprosy, m. leprae spread in blood to Schwann cells and macrophages in skin

Granulomas contain infection but cause tissue damage. Antibodies produced but no role in controlling bacteria

Question 5

What is incidence and epidemiology of leprosy?

Answer 5

> 200k cases / year
Mostly in India, Brazil, Bangladesh, Nepal, SSA

Question 6

How is leprosy classified?

Answer 6

Ridley-Jopling
TL: tuberculous leprosy
BT: borderline tuberculous
BB: borderline
BL: borderline lepromatous
LL: lepromatous leprosy

TL, BT = strong immune response
BL, LL = weak immune response

BL, BB, BL = unstable
TL, LL = stable

Question 7

What is the incubation period of tuberculous leprosy?

Answer 7

2-5 years

Question 8

What is the incubation period of lepromatous leprosy?

Answer 8

8-12 years

Question 9

What are the three cardinal signs of leprosy?

Answer 9

1. Anaesthetic hypopigmented / red skin lesion
2. Thickened peripheral nerve with reduced sensation / motor function in distribution
3. Acid fast bacilli on split skin smear

(Only one required for diagnosis)

Question 10

What’s the difference between paucibacillary TB and multibacillary TB?

Answer 10

Paucibacillary = <5 lesions

Multibacillary = >5 lesions

Question 11

How does tuberculous leprosy present?

Answer 11

Single / few skin plaques
Anaesthetic
Asymmetrical
Well defined
Hypopigmented

Question 12

How does borderline tuberculous leprosy present?

Answer 12

Several skin plaques
Anaesthetic
Asymmetrical
Ill defined

Question 13

How does borderline leprosy present?

Answer 13

Multiple plaques
Circinate (looks like large ring worm)
Asymmetrical
Anaesthetic

Question 14

How does borderline lepromatous leprosy present?

Answer 14

Multiple plaques
Symmetrical
May or may not be anaesthetic

Question 15

How does lepromatous leprosy present?

Answer 15

Multiple nodules
Symmetrical
Anaesthesia in glove and stocking distribution

Question 16

How do nerve lesions present in leprosy?

Answer 16

Occur at all stages (TL –> LL)
Thickened peripheral nerve + loss of motor function / sensation / autonomics (sweating) in distribution

Loss of sweating –> dry skin –> cracks, ulceration

Common sites: auricular, ulnar, radial, median, peroneal, lateral malleolus

Question 17

How do eye lesions present in leprosy?

Answer 17

Lagophthalmous –> corneal opacification –> blindness

Reduced corneal sensation

Acute –> chronic iritis

Cataracts

BL + LL most at risk, esp if facial skin lesions present

Question 18

How is leprosy diagnosed?

Answer 18

1 of 3 cardinal signs

AFB on ZN stain of split skin smear (grading 0 –> 6)

Skin lesion biopsy –> granuloma, nerve infiltration

PCR for m. leprae

Culture and sensitivity on mouse foot pad (takes 1yr lollll)

Question 19

What type of reactions can be seen in leprosy?

Answer 19

Type 1 = reversal reaction (type IV hypersensitivity)

Type 2 = erythema nodosum leprosum (type III immune complex deposition)

Neuritis

Question 20

Presentation and management of reversal reaction in leprosy

Answer 20

Occuring at any point
Delayed type IV hypersensitivity to m. leprae
All borderline types most at risk, plus recently pregnant women

Presentation = erythema and oedema of existing skin lesions plus new skin lesions occuring
New neuritis –> rapidly progressive nerve damage (motor / sensory)

Mx = continue therapy, add high dose weaning steroids. Permanent damage in 50% even in prompt treatment

Question 21

Presentation and management of erythema nodosum leprosum

Answer 21

Occurs at any stage
Type III immune complex deposition
BL and LL most at risk

Presentation = unwell. Painful erythematous nodules. Iritis, orchitis, arthritis, bony pain, renal impairment.

Mx = admit to hospital. High dose weaning steroids + thalidomide.
May relapse and remit across 5 years

Question 22

How is paucibacillary leprosy treated?

Answer 22

Paucibacillary = <5 lesions
6/12 treatment

Daily dapsone 100mg
Monthly rifampicin 600mg

Question 23

How is multibacillary leprosy treated?

Answer 23

Multibacillary = >5 lesions
12/12 treatment

Daily dapsone 100mg
Daily clofazimine 50mg
Monthly rifampicin 600mg
Monthly clofazimine 300mg

Question 24

How is leprosy managed in pregnancy and breast feeding?

Answer 24

All leprosy drugs are safe in pregnancy and breast feeding

(Dapsone, clofazimine, rifampicin)

Question 25

Side effects of rifampicin in leprosy protocol

Answer 25

Orange staining of body fluids few days after monthly dosing

No effect on liver enzymes

Question 26

Side effects of dapsone in leprosy protocol

Answer 26

Haemolytic anaemia, Hb drops ~20

Question 27

Clofazimine side effects in leprosy protocol

Answer 27

Brown discolouration of skin lesions –> highly stigmatising, sometimes permament
Reason for poor adherence

Question 28

How long are patients with leprosy infectious for once treatment started?

Answer 28

72 hours wow so fast

Question 29

Describe non pharmacological management of leprosy

Answer 29

Foot care: proper footwear, checking daily with mirror for new injuries, dressing and non weight bearing in ulcers

Skin care: soaking of dry skin in water and oil to prevent cracking

Psychological: not infective once on treatment >72 hours, high cure rate

Surgery: reconstructive, wound debridement, claw hand / foot drop, lagophthalmos

Question 30

How can leprosy be prevented?