Page 129 - LECTURE NOTES

- The fluid obtained from fresh vesicles may contain enough viruses for culture

- Direct smears are prepared by scraping cells form the base of the lesions
- The cells are smeared on a slide, fixed and stained with Giemsa or Wright stains

to identify multi cellularar cells with inclusion bodies, or procedures of specific
antibodies conjugated to fluoresce or to immunoperoxidase methods may also be

used.

Collection and processing of specimens for viral Diagnosis

- Select a freshly erupted vesicle, preferably containing clear fluid
- Carefully puncture the vesicle and collect the fluid on a cotton wool swab

- Rub the base of the lesion with the same swab

- Break off the head of swab into viral transport medium (VTM) and transport to
laboratory as soon as possible

- The date of request, the date and time of collection and finally brief clinical information
and provisional diagnosis should be stated with the sample.

- Scrapings may also be taken from the base or side of the lesion with a small curetting
spoon or fine scalpel;

- The harvested cells can then be smeared on slides for immuno fluorescence (IF)

examination and the curette is agitated in virus transport medium to provide samples for
culture-amplified EIA.

- The epithelial cells most likely to contain inclusions and antigens are those taken from
the advancing edge of the lesion.

Diagnostic Methods of Viruses

Tests can be grouped into 3 categories
1. Direct examination of specimen

A. Light microscopy histological appearance e.g. inclusion bodies
B. Antigen detection immunofluoreicence, ELISA etc

C. Molecular techniques for the direct detection of viral genomes
D. Electron microscopy (not applicable in health centers)

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