Fecal flotations

David S. Lindsay lindsayd at vt.edu
Wed Mar 10 17:09:39 EST 1999


The recent postings on Cyclospora have me wondering why human medical
parasitologists do not use fecal flotation to diagnose intestinal
parasites. This has crossed my mind several times in the last 20 years.
(I am not an old cogger, I started when I was 22). Cyclospora, Isospora
belli, C. parvum, amoeba cysts, and Giardia cysts all float in sugar or
Zinc-sulfate solutions and the fecal flotation is a concentration
technique. Most nematode eggs also float in these solutions.

Is it to basic? I remember a case report of I. belli in an infant. The
problem went undiagnosed for several months and intestinal surgery was
done to control the condition. When the child died the infection was
diagnosed at autopsy. I keep thinking why didn't they do a fecal
flotation?

A fecal flotation using centrifugation takes about 20 minutes to conduct
and another 10 minutes to read. Therefor, time should not be a factor.

Any ideas on why this procedure is not done in human parasitology? Is
the fear of airbore pathogens a possible reason for not doing a
flotation. Capped centrifuge tubes would prevent airbore pathogens.
Fecal flotation with and without centrifugation is common in veterinary
parasitology.



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