Zoonotic Trematode Metacercariae in Fish from Phnom Penh and Pursat, Cambodia

Abstract

A survey was performed to investigate the infection status of freshwater fish with zoonotic trematode metacercariae in Phnom Penh and Pursat Province, Cambodia. All collected fish with ice were transferred to our laboratory and examined using the artificial digestion method. In fish from Phnom Penh, 2 kinds of metacercariae (Opisthorchis viverrini and Haplorchis yokogawai) were detected. O. viverrini metacercariae were positive in 37 (50.0%) of 74 fish in 11 species (average no. metacercariae/fish, 18.6). H. yokogawai metacercariae were detected in 23 (57.5%) of 40 fish in 5 species (average no. metacercariae/fish, 21.0). In fish from Pursat Province, 5 kinds of metacercariae (O. viverrini, H. yokogawai, Haplorchis pumilio, Centrocestus formosanus, and Procerovum sp.) were detected; O. viverrini metacercariae (n=3) in 2 fish species (Henicorhynchus lineatus and Puntioplites falcifer), H. yokogawai metacercariae (n=51) in 1 species (P. falcifer), H. pumilio metacercariae (n=476) in 2 species (H. lineatus and Pristolepis fasciata), C. formosanus metacercariae (n=1) in 1 species (H. lineatus), and Procerovum sp. metacercariae (n=63) in 1 species (Anabas testudineus). From the above results, it has been confirmed that various freshwater fish play the role of a second intermediate host for zoonotic trematodes (O. viverrini, H. yokogawai, H. pumilio, C. formosanus, and Procerovum sp.) in Cambodia.

Diagnosis of Centrocestus formosanus Infection in Zebrafish (Danio rerio) in Italy: A Window to a New Globalization-Derived Invasive Microorganism

“…The occurrence of C. formosanus infection in zebrafish in Italy underlines the necessity to focus the attention on this invasive parasite, since this is the second case reported in the Italian peninsula [32]. Although its origin and distribution were initially restricted to Asia [4,[9][10][11][12][13]24,31], C. formosanus has been subsequently reported in other countries, including Europe [16][17][18][19][20][21][22]25,26,29,48]. Actually, to the authors' knowledge, this is the fourth case of C. formosanus infection in freshwater fish imported in Europe [19,32,40], confirming the introduction of this parasite in the European area, as well as the possible underestimation of this infection.…”

“…In particular, given the huge numbers of the ornamental fish industry in Europe (approximately 300 million fish, more than 2500 species, of which 60% are of freshwater origin), the importation of ornamental freshwater fish, from countries where C. formosanus is endemic, plays a crucial role in spreading this parasite [35,36,51]. Indeed, Asian countries are the major traders and most of the suppliers of freshwater fish to Europe are involved with C. formosanus infections [4,5,[10][11][12]35,36,51].…”

“…Digenetic trematode infections in animals and humans have attracted much attention from different disciplines, in particular veterinary medicine. Specifically, fish-borne zoonotic trematodes represent a concerning health issue in many Asian countries [2][3][4][5][6]. Indeed, 20 years ago, the World Health Organization estimated that more than 18 million people infected with fish-borne trematodes, and more than half a billion people at risk of infection worldwide [7,8].…”

“…Within fish-borne trematodes, Centrocestus formosanus is a small heterophyid fluke, described for the first time in Taiwan [9] and widely distributed in Asia [4,5,[10][11][12][13][14][15]. Since the 1950s, several authors have reported this species in new continents, although its occurrence could still be underestimated [16][17][18][19][20][21][22].…”

“…Subsequently, free-swimming cercariae encyst in second intermediate fish hosts, specifically in the gills, where they develop into metacercariae. Piscivorous birds and mammals, ingesting the infected fish, complete the cycle [4,15,16,18,19,23]. Analogously, human infections can occur through consumption of raw or improperly cooked fish, containing metacercariae [12,15,24].…”