Giemsa stain

Principle

Giemsa is a Romanowsky stain combining azure dyes (basic) and eosin (acidic). Buffered at pH 7.2, it gives the colours needed to see malaria parasites, other blood parasites and cell detail.

Procedure (thin and thick films)

• Thin film: fix in methanol for about 30 s; do NOT fix a thick film.
• Stain with Giemsa diluted in buffered water (pH 7.2): about 3% for 30–45 minutes, or 10% for 10 minutes.
• Rinse gently with buffered water and air-dry upright.

Results

• Parasite chromatin: red; cytoplasm: blue
• Schüffner dots (P. vivax, P. ovale): pink stippling in red cells

Notes

• Thick films are for detecting parasites (more sensitive); thin films are for species identification and parasite counts.
• Wrong buffer pH is the most common cause of poor staining.