Prevalence, Species Distribution, and Related Factors of Fish-Borne Trematode Infection in Ninh Binh Province, Vietnam

Abstract

Background. Clonorchis sinensis/Opisthorchis viverrini and minute intestinal flukes (MIF) such as Haplorchis pumilio and H. taichui are fish-borne trematodes (FBT) that may coexist in regions where local people have a habit of eating raw fish like Vietnam. Responses to FBT should be verified according to the data on the distribution of these flukes. This study aims to explore the prevalence of different species of FBT and related factors among local people in a northern province of Vietnam. Methods. A cross-sectional study was conducted in Kim Son and Yen Khanh districts, Ninh Binh province, between March 2016 and March 2017. Four hundred people aged 15 years or older were interviewed and gave stool samples. The FBT eggs in faecal samples were enumerated by modified formalin-ether technique and identified by sequencing of the second internal transcribed spacer (ITS2) region. Result. Among the 400 persons, 19.5% were infected with FBT. On univariate analysis, eating raw fish was the main risk factor (odds ratios (OR)) of 6.769 (95% confidence interval (CI) of 2.655–17.259) followed by being of male gender (3.994 (CI95% 2.117–7.536)) and drinking alcohol (2.680 (CI95% 1.440–4.986)), respectively. There was no risk of increased infection among those living at home without hygienic latrines, those living close to rivers or having ponds, or those raising cats or dogs. By multivariate analysis, FBT infection was only related to the consumption of raw fish and gender. Seventy stool samples with a sufficient amount of faecal matter were subjected to DNA extraction, 42.85% of them yielded DNA production, and all were of Clonorchis sinensis. Conclusion. Results of the study showed the high prevalence of infection of fish-borne trematode, mostly C. sinensis among humans in Ninh Binh province. The prevention of FBT should be strengthened with programs detailed according to the distribution of FBT in different endemic areas.

Prevalence and risk factors associated with Clonorchis sinensis infections in rural communities in northern Vietnam

“…This finding could be explained by recall or emotional bias for raw fish consumption (i.e having forgotten past consumption, or feeling ashamed to admit). An alternatively hypothesis might be the cross-contamination of food by kitchen utensils by metacercariae as reported in other studies [ 19 – 21 , 29 , 30 ], supported by the fact that a large number of people (57%) in this study used the same knife or cutting board for preparing raw and cooked food dishes.…”

“…Differences in prevalence of C . sinensis by gender have been described elsewhere in the region [ 2 , 3 , 6 , 36 ], including in Vietnam [ 18 – 20 , 30 ]. Consumption of raw fish in Vietnam is often associated with social gatherings, to which mainly men participate and during which alcohol use is high [ 22 ].…”

“…We found a clear relationship between gender and C. sinensis infection, as well as between gender and raw fish consumption. Differences in prevalence of C. sinensis by gender have been described elsewhere in the region [2,3,6,36], including in Vietnam [18][19][20]30]. Consumption of raw fish in Vietnam is often associated with social gatherings, to which mainly men participate and during which alcohol use is high [22].…”

Zoonotic diseases of fish and their prevention and control

“…Cleaning and sterilizing ponds effectively lowers the number of intermediate hosts of some nematode species to disrupt the lifecycle. Ponds that have not been cleaned and sterilized before refilling are at increased risk of retaining large numbers of intermediate hosts (Clausen et al 2012 ; Hedegaard et al 2012 ; Tran et al 2019 ).…”

“…In recent years, with the increase in the world population and the consumption of seafood, demand for seafood has increased. Since seafoods are one of the sources of protein for people, the fisheries and aquaculture industry have also shown sustainable growth worldwide; however, they are not risk-free (Shamsi 2019 ; Tran et al 2019 ). In addition to food poisoning from seafood, there is also the transmission of aquatic pathogens to humans.…”