Use of a non-mercury containing fixative for diagnosis of giardiasis

In the present study, methanol was used instead of Schaudinn's fluid for preparation of permanently stained faecal smears. The efficacy of this method to detect Giardia lamblia trophozoites and cysts were compared to merthiolate iodine formalin (MIF) direct smear method and MIF concentration (MIFC) technique. Fresh faecal samples were collected from school students with gastrointestinal symptoms. In 50 Giardia positive faecal samples, trophozoites were detected alone in 9 samples and in association with cysts in 24 ones. A paired comparison of the frequency of detection of trophozoites and cysts by various methods was performed using McNemar statistical test. The results revealed that trichrome staining of methanol fixed smears was the most sensitive technique for trophozoite detection followed by MIF direct smear method (p < 0.05). For cysts, trichrome staining and MIFC had nearly equal sensitivity and were more sensitive than MIF direct smear method but with no statistically significant difference.