Adult hookworms (Necator spp.) collected from researchers working with wild western lowland gorillas

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

A century of taxonomic uncertainty: re-description of two species of tapeworms (Diphyllobothriidea) from Arctic seals

Diphyllobothriid tapeworms are well-known parasites of mammals including humans. Most species are known for centuries, but the validity of many species and their classification are still poorly understood. Based on new collections and re-observation of museum material, we focus on widely distributed taxa infecting several species of seals (Phocinae) in Arctic and sub-Arctic waters. The existence of two morphologically similar diphyllobothriid species, Diphyllobothrium lanceolatum and Diphyllobothrium schistochilos, is revealed through detailed analyses of morphological and morphometric data as well as supported by genetic data published recently. Both species show a striking similarity in their body shape, which historically resulted in numerous misidentifications and erroneous records in the literature. Despite previous attempts to unequivocally recognize the species identity of these congeners, D. lanceolatum can be differentiated from D. schistochilos by the presence of a triangular scolex with a posterior velum, a rapid maturation of the strobila and the pointed or slightly rounded appearance of the last proglottid. In addition to the re-descriptions of both species, we provide novel information on their host spectrum and biogeographic distributio