Several different fixatives for preserving parasites exist, as well as different options for processing and staining. It is always best to follow the manufacturer's directions for processing and staining. Table 2 provides an overview of different preservatives.
Table 2. Fixatives to Preserve Parasites.Fixative | Concentration Possible | Permanent Stained Smear* | Immunoassays Possible (IA) ** | Comments |
5 or 10% Formalin | yes | no | yes | IAs:(e.g.EIA, FA) |
MIF (merthiolate-iodine-formalin) | yes | polychrome IV stain | no | |
SAF (sodium acetate-acetic acid-formalin) | yes | iron-hematoxylin best | yes | IAs:(e.g.EIA, FA) |
Schaudinn's (with or without PVA; with or without Hg) | rare | yes | no | |
Ecofriendly ECOFIX | rare | no | no | |
Universal Fixative, ecofriendly TOTAL-FIX | yes | yes | yes | contains no mercury, PVA or formalin |
*Stains: trichrome, iron hematoxylin, special stains/Coccidia and Microsporidia
**Mercury and PVA interfere with immunoassays (IAs)