Geographical distribution of Metagonimus yokogawai and M. miyatai in Shizuoka Prefecture, Japan, and their site preferences in the sweetfish, Plecoglossus altivelis, and hamsters

Foodborne Intestinal Flukes in Southeast Asia

“…Subsequently, high prevalences were reported among people residing around the Daechong Reservoir and its upper reaches [209], the upper reaches of the Namhan River [210], the Hantaan River basin [211], and the western inland of Gangwon-do [212]. In Japan, small rivers of Shizuoka Prefecture, Japan, were found to be endemic areas of this fluke [213]. Freshwater snails, Semisulcospira globus [209], Semisulcospira libertina, or Semisulcospira dolorosa [214], are the first intermediate host.…”

“…In Japan, the prevalence rate became negligible after the 1970s, except in some areas surrounding the Hamana Lake [227]. In fish hosts, however, small rivers of Shizuoka prefecture were prevalent with M. yokogawai metacercariae [213]. In Russia, the endemic areas include the Amur and Ussuri valleys of Khabarovsk territory where the prevalence in ethnic minority groups was between 20% and 70% [6].…”

<i>Metagonimus yokogawai</i> (Trematoda: Heterophyidae): From Discovery to Designation of a Neotype

“…3-5 [1] (original specimens of Heterophyes yokogawai ) were obtained from the stools of 3 men, who perhaps had eaten sweetfish from the nearby river, one of the most famous fishing spots of sweetfish then, (2) metacercariae of M. yokogawai and Loxotrema ovatum were found in sweetfish from the river [2,9-16,26], and (3) metacercariae of M. yokogawai are found encysted mainly in the body muscles of sweetfish [23,27]. …”

“…Saito [22] recovered metacercariae from sweetfish exposed to the cercariae identified as M. yokogawai : 48.1% of them from the body muscles and 39.3% from the scales. In this exposure experiment, cercariae of M. miyatai today [23] (see below) should have been mixed in the cercariae of M. yokogawai used, because metacercariae of M. yokogawai and those of M. miyatai are found encysted mainly in the body muscles and under (or in) the scales, respectively [23,27]. Neither Saito [22] nor Saito et al [23] paid attention to this unexpected, taxonomically important finding that the metacercariae of M. miyatai today were also experimentally recovered from the scales of sweetfish.…”

“…The 3 men used to eat sweetfish raw or undercooked [1]. Sweetfish is usually infected with metacercariae of M. yokogawai (mainly in the body muscles) and M. miyatai (mainly under or in the scales) in at least Japan and Korea [23,27]. M. miyatai is also infective to man [23].…”