Prevalence and antelmintic efficacy studies on gastrointestinal parasites of semi captive orangutans at Orang Utan Island (OUI), Bukit Merah, Perak

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A total of 338 faecal samples are collected from 16 semi-captive orang utans (5 adults,5 sub-adults,6 juveniles) from December 2010 to October 2011. They are screened for gastrointestinal parasites using method of direct smear, faecal flotation, faecal sedimentation, faecal culture and McMaster technique. The aimed are to study the gastrointestinal parasites prevalence for semicaptive orang utans and the parasitic infection with the seasonal trend. For the nematodes, Strongyloides spp. prevalence was significantly higher throughout the study period compared to trichostrongylids and Trichuris spp. One protozoan found and classified as cysts and trophozoites of Balantidium spp. Sub-adult orang utans gave the highest prevalence for Strongyloides spp. larvae, while juveniles gave the highest for Strongyloides spp. eggs. However, the occurences of trichostrongylids
and Trichuris spp. were at low prevalence throughout the study. For the protozoa, subadults gave the highest prevalence for Balantidium spp. cysts and juveniles for the trophozoites. The seasonal difference occurred only in juvenile orang utans where the number of total eggs per gram was significantly higher during the wet season compared to the dry season. Anthelmintics efficacy test was also done to the parasitic infections of the orang utans. The percent efficacy tested that Ivermectin with 98.9%, Albendazole with 99.3% and Mebendazole with 23.2% of
percent eggs reduction. However, orang utans tested with Ivermectin had the lowest mean epg at 25 eggs per gram until the fourth week. Also, two species of nematodes are identified until the species level using the 18s rDNA for Strongyloides spp. and ITS-
2 rDNA for Oesophagostomum spp. Sequencing results revealed that the larvae culture had 100% similarity of Strongyloides fuelleborni and 99% similarity of Oesophagostomum cf. aculeatum.