Medical Entomology and Zoology

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A survey of the helminth infection in brown rats (Rattus norvegicus) captured in 2017 at Chuo Ward, Tokyo, was carried out. Of the 20 rats examined, 13 (65%) were infected with helminths. The prevalence of helminths was as follows: Capillaria hepatica (35%), cysticerci of Taenia taeniaeformis (20%), Nippostrongylus brasiliensis (20%), Orientostrongylus ezoensis (20%), Heterakis spumosa (20%), Dioctophyma renale (15%), Vampirolepis nana (5%). The helminths were identified based on morphological features, and molecular analyses of the nuclear 18S ribosomal DNA, ITS region, and mitochondrial 12S ribosomal DNA sequences. From the standpoint of public health, it should be noted that 4 helminth species, namely C. hepatica, T. taeniaeformis, D. renale, V. nana were capable of infecting humans. In addition, C. hepatica and V. nana can be accidentally transmitted to humans by direct ingestion of embryonated eggs from rat feces. This is the third confirmed report of D. renale from R. norvegicus in Japan. A total of 11 worms were recovered from the abdominal cavities of 3 brown rats. In this rare case, we describe the morphological features of the adult worms and eggs and determined the 18S ribosomal DNA sequence of D. renale.

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A live bird-parasitic fly, Carnus hemapterus Nitzsch, was retrieved from the external ear canal of a 74-year-old Japanese woman in Yokohama City. Her chief complaint included odd sensation and recurring pain in the right ear. Otoscopic examinations revealed many red spots inside the ear canal, suggesting sucking by the fly. To the best of our knowledge, this is the first case of invasion by this fly species into the human ear canal outside Hokkaido.

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