leprosy

Question 1

case

Answer 1

A 25-year-old man presented with a single, slowly expanding, nonpainful scaly lesion on his chest for the past 2 months.
* The lesion was nonpruritic, and he had lost sensation at the site of the lesion. He was otherwise well.
* He is a recent immigrant.
* An acid-fast stain of scraping of the lesion
was positive.
* Lepromin test was positive

Question 2

Specimen Collection

Answer 2

Total six samples are collected; four from skin (forehead, cheek, chin and buttock), one from ear lobe and nasal mucosa by nasal blow/scraping.

Slit skin smear is the technique followed to collect the skin and ear lobe specimens. The edge of the lesion is the preferred site

Nasal specimens:
(1) Nasal blow: Early morning mucus material is collected by blowing the
patient’s nose on a clean cellophane sheet
(2) Nasal scraping: By using a mucosal scraper to scrape the nasal septum sufficiently to remove a piece of mucous membrane, which is transferred onto a slide and teased out into a uniform smear.

Biopsy from the thickened nerves and nodular lesions

Question 3

microscopy

Answer 3

Ziehl–Neelsen - 5% sulfuric acid for decolorization: Red acid-fast bacilli, arranged singly or in groups (cigar like bundles), bound together by lipid-like substance, the glia to form globi. The globi are present inside the foamy macrophages called
Virchow’s lepra cells or foamy cells.

Question 4

Grading of the Smear

Answer 4

The smears are graded, based on the number of bacilli per oil immersion field (OIF) as follows:
1–10 bacilli in 100 OIF =1+
1–10 bacilli in 10 OIF = 2+
1–10 bacilli per OIF = 3+
10–100 bacilli per OIF = 4+
100–1000 bacilli per OIF = 5+
>1000 bacilli or bacilli in clumps and globi in each OIF = 6+

Question 5

Mouse Foot Pad Cultivation

Answer 5

The specimen can be inoculated into foot pad of mice and keep at 20°C for 6–9 months.
➢ Nine banded armadillo

Question 6

Antibody Detection

Answer 6

➢ FLA-ABS (Fluorescent leprosy antibody absorption test
Detects M. leprae specific antibodies irrespective of duration and stage of the disease.
➢ ELISA detecting IgM antibodies to PGL-1 (phenolic glycolipid-1)

Question 7

Test for Detecting CMI (Lepromin Test)

Answer 7

Demonstrates the delayed hypersensitivity reaction against the lepra antigen.
➢ It also indicates an intact host’s CMI.
➢ It is not used for diagnosis of active infection.
➢ It is useful in classifying lesions of leprosy and also used as a prognostic indicator.