A survey of Heterophyes nocens and Pygidiopsis summa metacercariae in mullets and gobies along the coastal areas of the Republic of Korea.

The infection status of mullets Mugil cephalus (n = 139) and gobies (n = 35) Acanthogobius flavimanus with metacercariae of Heterophyes nocens and Pygidiopsis summa was examined in 11 western, southern, and eastern coastal areas of the Republic of Korea, using a digestion technique. Heterophyid metacercariae were highly prevalent in mullets from western and southern coastal areas; Shinan-gun (100% for H. nocens and 100% for P. summa), Muan-gun (93% and 100%), Buan-gun (42% and 75%), Seocheon-gun (73% and 53%), Ganghwa-gun (47% and 100%), Sacheon-shi (47% and 77%), and Gangjin-gun (50% and 70%, respectively). Only 1 (10%) of 10 mullets from an eastern coastal area, i.e., Donghae-shi, was positive for P. summa metacercariae. Metacercarial densities were the highest in the trunk of mullets for H. nocens and the gill for P. summa. Gobies from Muan-gun were positive for H. nocens (40%) and P. summa metacercariae (40%), and gobies from Seocheon-gun revealed H. nocens metacercariae (20%). The metacercarial density was remarkably higher in mullets than in gobies. The results revealed that H. nocens and P. summa metacercariae are prevalent in mullets and gobies from coastal areas of the Republic of Korea, and the prevalence and intensity of infection vary according to geographical locality.

Prevalence of Heterophyes nocens and Pygydiopsis summa infections among residents of the western and southern coastal islands of the Republic of Korea.

To determine the distribution and prevalence of heterophyid fluke infections on coastal islands of the Republic of Korea, fecal specimens were collected from 4,179 people residing on 45 islands in the West (Yellow) and South Seas and examined using the formalin-ether and Kato-Katz techniques. Eggs of Heterophyes nocens were found in 459 (11.0%) residents of 42 islands, with an average number of eggs per gram (epg) of feces of 79.6. Eggs of Pygidiopsis summa were found in 49 (1.2%) on 12 islands, with an average epg of 253.0. The egg-positive rate for H. nocens was the highest on Chungdo (32.6%), followed by Imchado (27.3%); P. summa was most prevalent on Imchado (15.2%). The majority (78.9% [362 of 549] of those infected with H. nocens and 81.6% [40 of 49] of those infected with P. summa) of those infected were adults more than 40 years old. Adult flukes of these species were recovered from residents of Imchado by treatment with praziquantel and purgation. Our results indicate that H. nocens and P. summa are indigenous to the southern and western coastal islands of the Republic of Korea.