[Three recent cases of ascariasis in northern Kyushu]

Ascariasis is considered to be one of the rare infectious diseases in Japan, but recently it has been slightly increasing. This paper reports three ascariasis cases who seemed to be infected recently in the Kitakyushu area, Japan. Case 1: A 59-year-old woman in Kitakyushu City passed a round worm after continuous abdominal pain. The patient was discharged from the hospital because of no further abnormal intestinal symptoms and findings. Case 2: An 85-year-old woman in Nakama City, who suffered from cerebral infarction, vomited a round worm before hospitalization. Many ascarid eggs were detected after admission, and after treatment with pyrantel pamoate (Combantrin) two round worms were passed and egg detection became negative. Case 3: A 77-year-old man in Saikawa Town vomited 3 round worms after gastrectomy due to early gastric cancer. Many unfertilized eggs were also detected from the stool together with hook worm eggs, but no eggs were found after administration of pyrantel pamoate. Morphological examination was made by a scanning electron microscope on the denticles on the dentigerous lip ridges of the worms to differentiate from possible infection with a pig parasite, Ascaris suum. The three cases were diagnosed as ascariasis due to human Ascaris lumbricoides based on the following evidences that the expelled worms had 1) less pointed tips of the denticles and shallower or wider interdenticle notches, and 2) far more denticles of smaller size along the dentigerous ridges, compared with Ascaris suum. The necessity of differentiating pig- from human-ascarids, when considering human infection with Ascaris suum, is discussed.