An Onchocerca species of wild boar found in the subcutaneous nodule of a resident of Oita, Japan

Histological examination and dissection of a subcutaneous nodule removed from the right infraclavicular region of a 69-year-old woman from Oita, Kyushu, Japan, revealed a young female of Onchocerca dewittei japonica, a common parasite of wild boar in the Oita region. Distinctive morphologic characteristics of this Onchocerca species include the thick cuticle with very prominent and straight transverse ridges overlapping at the lateral sides, the lack of inner striae (scalloping) of the inner cuticle layer, the dorso-ventral symmetry, and the thick somatic muscles. Jointed with previous reports in the past decade, this case confirms the occasional transmission of the parasite from wild boar to humans in Oita.