5. PATHOGENESIS
Infection occurs by inhalation of bacteria
into the respiratory system along with that,
the organism also enters into the body
from small abrasions present on the skin.
6. Most of the damage done is by entering
the nerves, mainly spinal nerves and
cause damage to them.
It leads to loss of sensation of touch, pain,
temperature.
7. It leads to white patches on the skin which
arise due to loss of pigmentation from skin.
If this disease starts
deteriorating , nodes appear on the skin which
contains bundles of bacteria, slowly it
disseminates into the complete body and
causes formation of “ granuloma” .
8. This granuloma is different from tubercle
granuloma due to absence of central
necrosis.
9. Clinically 4 types of leprosy are
1 Lepromatous leprosy
2 Tuberculoid type
3 Dimorphic leprosy
4 Inditerminate leprosy
10. 1. LEPROMATOUS LEPROSY
Lepromatous leprosy is a skin condition
consisting of pale macules.
The macules will appear on face, hand, feet,
ear lobes, and less commonly on the trunk.
In the macules a large number of bacilli will
be present
11. 2. TUBERCULOID TYPE
In the tuberculoid form of the disease the skin
lesions appear as light red or purplish spots.
Tuberculoid leprosy is the more benign type,
even though it is accompanied by nerve
involvement, which leads to numbness (usually
of the extremities), contractures, and
ulceration.
12. 3. DIMORPHIC LEPROSY/BORDER LINE
Borderline leprosy is a cutaneous skin condition
with numerous skin lesions that are red irregularly
shaped plaques.
In this type lesions produced possess characteristics
of both lepromatous and tuberculoid lesions.
This lesions clinically resembles lesions of
tuberculoid leprosy but bacteriologically resembles
lesion of lepromatous type.
13. 4. INDITERMINATE LEPROSY
In this type, the lesions produced often
resemble maculo-anesthetic patches which are
neither characteristic of lepromatous or
tuberculoid type.
In some cases these lesions heal
spontaneously while in others it may progress to
lepromatous or tuberculoid type.
14. How to diagnose leprosy
Examine skin
Check for patches
Test for sensation
Count the number of patches
Look for damage to nerves
Dr.T.V.Rao MD
14
15. DIAGNOSIS OF LEPROSY
Diagnosis must therefore be made by
doing a biopsy, in which a small piece of
skin is taken to analyse for the leprosy
bacterium.
Early diagnosis is very important because
it can prevent permanent deformities and
disability.
Dr.T.V.Rao MD
15
16. LAB DIAGNOSIS
OVERVIEW :
1. Specimens
2. Acid fast staining
3. Skin and nerve biopsy
4. Animal inoculation
5. Lepromin test
20. 2. ACID FAST STAINING
Ziehl-Neelson method
Decolourising agent = 5% sulphuric acid
Lepra cells confirm the diagnosis
of lepromatous leprosy
The living bacilli will stain uniformly and
appear as solid while dead bacilli appear as
granular and fragmented.
21.
22. i. BACTERIOLOGICAL INDEX (B.I) :
Number of total bacilli in a tissue.
Higher the B.I , severe the infection
23.
24.
25.
26. Percentage of uniformly stained bacilli
out of the total number of bacilli
counted.
For assessing the progress of patients
with leprossy.
ii. MORPHOLOGICAL INDEX(M.I) :
27. For histological confirmation
of tuberculoid bacilli ( as they
cannot be demonstrated in
direct smear)
Skin biopsy is also useful in
diagnosis and accurate
classification of leprosy lesion.
3. SKIN AND NERVE BIOPSY
28. 4. ANIMAL INOCULATION
Nine banded armadillo
Injection of ground tissue from lepromatous
nodules or nasal scrapings from leprosy patient into
the foot pad of armadillo.
Typical granuloma at the site of inoculation within
6 months.
29. 5. LEPROMIN TEST
Delayed type of hypersensitive reaction.
First described by Mitsuda in 1919.
Lepromins used as antigen
31. 1) Early reaction or
Fernandez reaction
2) Late reaction or
Mitsuda reaction
BIPHASIC RESPONSE:
32. Early reaction
or Fernandez
Erythema &
induration of 10-
30mm in diameter
Develops in 24-48 hrs &
usually remains for 3-5
days
Late reaction
or Mitsuda
Appears 3-4 weeks
after the injection,
reaching a peak in 4
weeks.
Appears in the form of
nodule that may ulcerate.
Takes few weeks to heal.
