Acanthoparyphium tyosenense: The Discovery of Human Infection and Identification of Its Source

Abstract

Acanthoparyphium tyosenense Yamaguti, 1939 (Digenea: Echinostomatidae), was originally reported as an avian intestinal parasite; here, its presence is reported in 10 humans in the Republic of Korea. The patients were 9 adults aged 35-66 yr (males and females) and a young girl aged 7 yr residing in 2 coastal villages in Puan-gun, Chollabuk-do. The worms were recovered after treatment with praziquantel and purgation with magnesium salts. A total of 158 specimens (1-107 specimens/individual) was collected, together with varying numbers of other intestinal flukes. The patients had eaten various kinds of brackish water mollusks caught in an estuary near their villages. Five bivalves and a gastropod species suspected as sources of human infection were collected and examined. Two bivalves (Mactra veneriformis and Solen grandis) and the gastropod (Neverita bicolor) were found to be infected with the metacercariae of A. tyosenense; adult flukes were confirmed after the experimental infection of chicks. The results show that A. tyosenense infects humans and that brackish water mollusks are the source of human infection.

Tegumental ultrastructure of the juvenile and adult Himasthla alincia (Digenea: Echinostomatidae)

“…In Korea, the metacercariae of H. alincia were first found in several species of bivalves, during a survey of a western coastal area (unpublished data). These bivalves were also found to be infected with a number of metacercariae of Acanthoparyphium tyosenense (Chai et al, 2001;Han et al, 2003).…”

Foodborne Intestinal Flukes in Southeast Asia

“…Four species of brackish water bivalves, i.e., Mactra veneriformis, Solen grandis, Solen strictus, and Ruditapes philippinarum, and a species of brackish water gastropod, Neverita bicolor, have been verified to be the second intermediate hosts [7,9]. Chicks [7,11] and sea gulls Larus crassiostris [9] were reported to be the experimental definitive hosts. In chicks, worms grew quickly to become ovigerous adults in the jejunum within 5 days and survived at least up to 38 days [11].…”

“…The worms fully grew to have a peak number of uterine eggs during day 10 and day 15 after infection [11]. Ten human infections were first discovered in 2 coastal villages of Chollabuk-do Province, Republic of Korea [7]. The patients used to eat improperly cooked marine bivalves and gastropods.…”

“…Patients infected with E. ilocanum experienced intestinal colic and diarrhea [12]. Clinical symptoms in E. cinetorchis, E. japonicus, and A. tyosenense infections are not well known [5,7,56,92]. In 10 of 18 American tourists to Kenya and Tanzania who were echinostome egg positive in fecal examinations (adult flukes were not recovered), moderately severe abdominal cramps and loose or watery stools were encountered [381].…”

“…Cercaria yamagutii shed from marine gastropods, Tympanotonus microptera, Cerithidea cingulata, and Cerithidea largillierti, in Japan [10], is now considered to be the cercariae of A. tyosenense [9]. Four species of brackish water bivalves, i.e., Mactra veneriformis, Solen grandis, Solen strictus, and Ruditapes philippinarum, and a species of brackish water gastropod, Neverita bicolor, have been verified to be the second intermediate hosts [7,9]. Chicks [7,11] and sea gulls Larus crassiostris [9] were reported to be the experimental definitive hosts.…”