Comparison of three microscopic techniques for diagnosis of Cyclospora cayetanensis.

Cyclospora cayetanensis oocysts in the feces of humans from Kathmandu, Nepal were identified on the basis of their size and other morphological characteristics. We compared the detection of C. cayetanensis oocysts in the feces using three microscopic techniques such as formalin-ether sedimentation, sucrose centrifugal floatation, and direct smear. Standard procedures were used for the formalin-ether sedimentation and the sucrose centrifugal floatation techniques using 0.5 g of feces, however, the direct smear technique was performed using 10 microl of fecal suspension (0.005 g of feces) and observed under the fluorescent microscope. Of the 403 samples examined, 21 samples were positive for oocysts by all three techniques. Therefore, in these 21 samples, the number of oocysts recovered by the three techniques were compared. The highest number of oocyst was obtained by the sucrose centrifugal floatation technique. In contrast, the formalin-ether sedimentation technique was found to be the least reliable concentration technique for the detection of Cyclospora in human feces. Surprisingly, the direct smear technique was found to be an effective and rapid technique for diagnosis of C. cayetanensis making it a technique of choice for routine epidemiological investigation of the prevalence of this infection in human populations.

Epidemiological survey of intestinal parasitic infections of diarrhoeal patients in Nepal and Lao PDR.

Intestinal parasitological survey was conducted to clarify the distribution of intestinal parasites in Nepal and Lao Peoples' Democratic Republic (Lao PDR) from 2001 to 2003. A total of 401 diarrheal fecal specimens were collected from patients aged one to 75 years (250 from Nepal and 151 from Lao PDR). The specimens were examined using the formalin-ether sedimentation (FES) and sucrose centrifugal flotation (SCF) techniques. Nine species (3 Nematoda, 1 Cestoda, and 5 Protozoa) of parasites were recovered from Nepal, whereas seven species (3 Nematoda, 1 Trematoda, and 3 Protozoa) from Lao PDR. Of the parasites detected, (14.4%) was the most common in Nepal, and was Opisthorchis viverrini (29.8%) in Lao PDR. Infection rates were markedly different among age groups in both countries; higher rates were observed in age groups of 10-29 years than in 0-9 years group. Scanning electron microscopic observation revealed that trematoda eggs recovered from Lao PDR were identified as O. viverrini, which could not be done by a light microscope.