An epidemiological study of metagonimiasis along the upper reaches of the Namhan River.

An epidemiological study of Metagonimus infection was undertaken along the upper reaches of the Namhan River, with special consideration on the species (type) of the worms collected from humans. Eggs of Metagonimus spp. were detected from 15 (9.7%) of 154 people examined in Umsong-gun, and from each infected person (5 cases) 6,015-24,060 worms (mean 13,233) were recovered after treatment with praziquantel (10 mg/kg). Eggs were also detected from 37 (48.1%) of 77 people in Yongwol-gun, from whom (27 cases) 1-4,965 worms (means 1,215) were collected. The worm from Umsong-gun consisted of both Metagonimus Miyata type and Metagonimus takahashii, whereas those from Yongwol-gun consisted of only Metagonimus Miyata type. When the uterine eggs of the two kinds and M. yokogawai (obtained from people in Tamjin River basin) were morphologically compared, it was suggested that the egg size should be a good indicator for discrimination of the species or type. The source of human infection was proved to be fresh water fishes; 49 of 52 Zacco platypus examined, 6 of 8 Hemibarbus longirostris, 13 of 15 Pseudogobio esocinus, 4 of 6 Odontobutis obscura interrupta, and 17 of 18 Carassius carassius were found infected with Metagonimus metacercariae. From the results, it is concluded that the upper reaches of the Namhan River are endemic foci of Metagonimus Miyata type and M. takahashii.