Page 132 - LECTURE NOTES

5.7. Laboratory Diagnosis of Cutaneous Leishmaniasis

- Cutaneous leishmaniasis in Ethiopia is caused by the following Leishmania

species: L. tropica, L. major, and L.aethiopica

Laboratory diagnosis is based on detecting amastigotes in smears taken from
infected ulcers or nodules.

5.7.1. Collection and examination of slit skin smears for amastigotes
Material for examination should be taken from the inflamed raised swollen edge of an

ulcer or nodule. Its base or center, which usually contains only necrotic tissue should be
taken to avoided because it can contaminate the specimen with blood and is low yield

for amastigotes.

Note: Secondary bacterial contamination makes it difficult to find parasites and

therefore if bacterial infection is present, delay examination for leishmania
amastigotes until antimicrobial treatment has been completed and the bacterial

infection has cleared.

Method

1. Cleanse the area with a swab soaked in 70% v/v alcohol. Allow drying
completely.

2. Firmly squeeze the edge of the lesion between the finger and thumb to
drain the area of blood (protective rubber glove should be worn)

3. Using a sterile scalpel blade, make a small cut in to the dermis and blot

any blood. Scrape the cut surface in an out ward direction to obtain
tissue juice and cells.

4. 4.Spread the material on a clean slide using a circular motion and
working outwards to avoid damaging parasites in those parts of the

smear that have started to dry.
ƒ The smear must be thinly spread and not left as thick ‘dab’ smear.

Parasites are difficult to find in thick smears.

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