Human gnathostomiasis caused by Gnathostoma doloresi, with particular reference to the parasitological investigation of the causative agent

Abstract

Gnathostomiasis caused by Gnathostoma doloresi Tubangui was observed in a 46-year-old Japanese man, a clerk, who resided in the Fukuoka prefecture of Kyushu district, in southern Japan. The first symptom noted by the patient was epigastric pain, which occurred 3 days after he had consumed the raw flesh of a brook trout, Oncorhynchus masou masou (Brevoort), from a trout farm in neighbouring Kumamoto prefecture. Three days later, he developed creeping eruptions on his trunk. The eruptions spread and the patient was admitted to hospital 18 days after eating the trout. No nematode larvae were found in any of four skin biopsies collected on admission. However, vesicles appeared on the lower abdomen of the patient 20 days after he had eaten the trout, and a small nematode was removed from one of them. One day after the nematode had been excised, a cutaneous swelling suddenly occurred on the patient's lower left jowl and this persisted for a week. All the skin abnormalities gradually decreased from day 25 post-ingestion and had disappeared by day 30. The isolated nematode was identified as an advanced third-stage larva of G. doloresi, based on its morphology and the number of hooklets on its head-bulb.