Prevalence and Intensity of Opisthorchis viverrini Metacercarial Infection in Fish from Phnom Penh, Takeo, and Kandal Provinces, Cambodia

Abstract

The prevalence and intensity of Opisthorchis viverrini metacercariae (OvMc) were investigated in fish from 3 southern administrative regions along the Mekong River in Cambodia, i.e., Phnom Penh, Takeo, and Kandal Provinces from 2017 to 2020. A total of 295 freshwater fish (24 species) were transported to our laboratory with ice and examined using the artificial digestion method. In Phnom Penh, among 4 fish species positive for OvMc, 9 (23.7%) of 38 specimens examined were infected, and their intensity of infection averaged 4.3 metacercariae per infected fish. In Takeo Province, among 10 fish species positive for OvMc, 24 (38.1%) out of 63 fish examined were infected, and their intensity of infection was av. 14.4 metacercariae per infected fish. In particular, all of 3 Osteochilus schlegelii fish examined were infected, and their infection intensity was high, 34.7 metacercariae per fish. In Kandal Province, among 6 fish species positive for OvMc, 46 (90.2%) out of 51 specimens examined were infected, and their infection intensity was 24.0 metacercaraie per infected fish. All fish of Systomus orphoides (n=17), Barbonymus altus (n=14), and Rasbora aurotaenia (n=2) were infected, and their intensity of infection averaged 37.7, 21.6, and 18.5 metacercariae per fish, respectively. Metacercariae of Haplochis yokogawai, Haplorchis taichui, and Centrocestus formosanus were detected in fish from Takeo and Kandal Provinces. From these results, it has been confirmed that a variety of fish species from Phnom Penh, Takeo, and Kandal Provinces are commonly infected with OvMc, and preventive measures to avoid human O. viverrini infection should be performed in Cambodia.

Intestinal parasitic infections and risk factors among the population in Cambodia

“…Three freshwater fish species are usually consumed of raw by villagers in Kratie Province; thus, they are thought to facilitate O. viverrini infections (Sohn et al, 2012). The prevalence of O. viverrini metacercariae (OvMc) in fish from 3 southern areas in Cambodia along the Mekong River has been reported, including that in Phnom Penh (23.7%), Takeo (38.1%), and Kandal (90.2%) Provinces, with 4, 10, and 6 fish species positive for OvMc, respectively (Sohn et al, 2021). Moreover, OvMc is most prevalent in workers and rural inhabitants of Lower Myanmar who consumed raw cyprinoid fish (Aung et al, 2017); scientific evidence has revealed that the consumption of raw freshwater fish is a major risk factor for human liver fluke infection (Chavengkun et al, 2016;Kaewpitoon et al, 2015).…”

“…A previous study reported on the prevalence of intestinal helminth infections among villages in Kratie Province, northeastern Cambodia, using fecal specimens and the Kato-Katz thick smear technique. The highest prevalence of Opisthorchis viverrini infections occurred in Roka Kandal A (10.4%), followed by Talous (5.9%); in both these villages, adult residents presented with a higher prevalence (19.4% and 9.0%, respectively) than schoolchildren (6.4% and 1.4%) (Sohn et al, 2021). Moreover, Strongyloides stercoralis and hookworm or soil-transmitted helminth were high prevalence in Preah Vihear Province, northeastern Cambodia.…”