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.