BACKGROUND: In general, studies on the diversity of strongylid nematodes in endangered host species are complicated as material obtained by non-invasive sampling methods has limited value for generic and species identification. While egg morphology barely allows assignment to family, the morphology of cultivated infective third stage larvae provides a better resolution at the generic level but cannot be used for exact species identification. Morphology-based taxonomic approaches greatly depend on the examination of adult worms that are usually not available. METHODS: Hookworm parasites in two European researchers, who participated in gorilla research in the Central African Republic, were expelled after anthelmintic treatment to the faeces, collected and morphologically examined. A male worm discharged naturally from a wild bonobo (Pan paniscus) in Congo was also examined for comparison. RESULTS: Two species of Necator were identified in researchers' faecal material: Necator americanus (Stiles, 1902) and N. gorillae Noda & Yamada, 1964; the latter species differed in having a smaller body, smaller buccal cavity and shorter spicules with spade-shaped membranes situated distally. Males of N. gorillae also possessed unusual cuticular thickenings on the dorsal side of the prebursal region of the body. These characters, shared with the male worm from the bonobo, correspond well to the description of N. gorillae described from gorillas in Congo. CONCLUSIONS: Based on the morphology of the hookworms recovered in this study and previous molecular analyses of larvae developed from both humans and western lowland gorillas (Gorilla gorilla gorilla) from this locality, we conclude that the researchers became infected with gorilla hookworms during their stay in the field. This is the first report of infection with a Necator species other than N. americanus in humans.

Biology Centre Institute of Parasitology Academy of Sciences of the Czech Republic Branisovska 31 370 05 Ceske Budejovice Czech Republic

Central European Institute for Technology University of Veterinary and Pharmaceutical Sciences Palackeho 1946 1 612 42 Brno Czech Republic

Department of Biology Faculty of Medicine Oita University Hasama Yufu Oita 879 5593 Japan

Department of Pathology and Parasitology Faculty of Veterinary Medicine University of Veterinary and Pharmaceutical Sciences Palackeho tr 1946 1 612 42 Brno Czech Republic

Department of Veterinary Science School of Veterinary Medicine Rakuno Gakuen University 582 Bunkyodai Midori Ebetsu Hokkaido 069 8501 Japan

Institute of Vertebrate Biology Academy of Sciences of the Czech Republic Kvetna 8 603 65 Brno Czech Republic

Liberec Zoo Lidove sady 425 1 460 01 Liberec Czech Republic

Primate Research Institute Kyoto University Inuyama Aichi 484 8506 Japan

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