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. 2011 May;18(2):185-8.
doi: 10.1051/parasite/2011182185.

Zoonotic onchocerciasis in Hiroshima, Japan, and molecular analysis of a paraffin section of the agent for a reliable identification

M Fukuda  1 , Y Otsuka, S Uni, T Boda, H Daisaku, H Hasegawa, H Takaoka, O Bain
Affiliations

Zoonotic onchocerciasis in Hiroshima, Japan, and molecular analysis of a paraffin section of the agent for a reliable identification

M Fukuda et al. Parasite. 2011 May.

Abstract
in English, French

Japan is a country of high specific diversity of Onchocerca with eight species, the adults of two not yet known. Onchocerca dewittei japonica, a common filarial parasite of wild boar, had been proved to be the agent of five zoonotic onchocerciasis in Kyushu island with morphological and molecular studies. The sixth case, at Hiroshima in the main island, was identified to the same Onchocerca species, based on adult characters observed on histological sections. To consolidate the identification, mitochondrial cytochrome c oxidase subunit 1 (CO1) gene analysis was attempted with the formalin-fixed, paraffin-embedded parasite specimen. The sequence (196 bp) of a CO1 gene fragment of the parasite successfully PCR-amplified agreed well with those of O. dewittei japonica registered in GenBank, confirming the morphological identification. Moreover a comparison with the CO1 gene sequences of six other Onchocerca species in GenBank excluded the possibility that Onchocerca sp. from wild boar and Onchocerca sp. type A from cattle in Japan, were the causative agents in this case. Mitochondrial DNA analysis proved to be a valuable tool to support the morphological method for the discrimination of zoonotic Onchocerca species in a histological specimen.

Le Japon est une région de grande diversité du genre Onchocerca avec huit espèces, dont deux identifiées par les microfilaires, les adultes étant encore inconnus. Il a été démontré par les analyses morphologiques et moléculaires qu’Onchocerca dewittei japonica, filaire fréquente du cochon sauvage, est l’agent des cinq cas d’onchocercose zoonotique dans l’île de Kyushu. Le sixième cas, à Hiroshima, île principale, a été identifié à la même espèce d’onchocerque d’après les caractères de l’adulte observés sur coupes histologiques. Afin de vérifier cette identification, l’analyse du gène mitochondrial de la sous-unité 1 de la cytochrome c oxydase (CO1) a été effectuée avec une coupe du specimen fixé au formol et inclus en paraffine. La séquence (196 bp) d’un fragment du gène CO1 du parasite, amplifié par PCR, est semblable à celles d’O. dewittei japonica enregistrées dans GenBank, confirmant l’identification morphologique. En outre, la comparaison avec les séquences du gène CO1 de six autres espèces d’Onchocerca déposées dans cette base de données exclut comme agents possibles Onchocerca sp. du sanglier et Onchocerca sp. type A du bétail au Japon. L’analyse de l’ADN mitochondrial est donc un outil valable qui complète la méthode morphologique de discrimination des espèces zoonotiques d’onchocerques sur coupes histologiques.

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Figures

Fig 1.
Fig 1.
Histological section of a nodule showing the worm and surrounding tissue excised from the patient. Morphological characteristics of the female worm identified as Onchocerca dewittei japonica showing the salient transverse ridges (arrows), lateral chords (*), uteri (U), and intestine (I). The section is stained with hematoxylin and eosin. Bar, micrometers.
See this image and copyright information in PMC

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