Intestinal parasites at Mahale Parasitological studies of chimpanzees in Mahale have been conducted since the late 1970s, mainly on K and M groups in the Kasoje area. Kawabata and Nishida (1991) first reported on the parasite fauna, and recorded protozoans, cestodes, trematodes, and nematodes from chimpanzee feces. Parasite fauna and prevalence varied according to the chimpanzee study site (Ashford et al., 2000). The prevalence depends on the habitat environment, climate, food resources, group size, home range, and behavior. Among chimpanzee habitats in Tanzania, Mahale and Gombe consist of semi-deciduous forest. Both are located on the shores of Lake Tanganyika, but more than 100 km apart. The habitat at Ugalla is woodland, and is located inland from the lake, between two national parks. These three areas are separated mostly by human habitations. The estimated chimpanzee population size at Ugalla is smaller than that at Mahale, and fewer than 700 chimpanzees have been estimated to reside outside the national parks (Yoshikawa et al., 2008). Parasite species recorded in chimpanzee fecal samples in Mahale are listed in Table 47.1. The prevalence of parasites among chimpanzees differs by parasite species: chimpanzees show higher prevalences of Oesophagostomum spp., Strongyloides sp., Probstmayria gombensis, Troglodytella abrassarti, and Troglocorys cava, but lower prevalences of Trichuris spp., Bertiella sp., Dicrocoeliidae gen sp., and Entamoeba sp., as determined by microscopic analysis of fecal specimens. Spirurida nematode infection was not observed in chimpanzees despite infection of other primate species at Mahale (Kooriyama et al., 2012). Modes of infection are also important (see Table 47.2). These are divided into two types, with or without an intermediate host, which affects parasite prevalence in combination with other factors. The parasite species and their characteristics are summarized below. Parasite examination Several studies used microscopy to identify parasite species morphologically. However, the preparation methods for microscopic examination varied: direct smear methods (Kawabata and Nishida, 1991), McMasters floatation and formalin-ether concentration method, combined with EPG calculation (Huffman et al., 1997), saturated NaCl floatation method (Nigi et al., 1998), formalin-ether concentration and Harada-Mori culture methods (Hasegawa et al., 2010), and formalin-ether concentration method (Kooriyama et al., 2012). For the examination of protozoans, basic iodine staining or polyvinyl alcohol fixation techniques for feces smeared on slide glass is recommended. Microscopic fecal examinations can yield lower prevalences of parasite eggs, such as Bertiella sp., because such cestodes normally do not liberate eggs in the host intestine but pass their senile proglottids in feces.