Risk factors for Clonorchis sinensis infection transmission in humans in northern Vietnam: A descriptive and social network analysis study

Abstract

Clonorchis sinensis is major fish-borne trematode, endemic in North Vietnam. Risk factors described so far include individual eating behaviors and environmental factors. Here, additional to conventional risk factors, we report on socially influenced liver fluke transmission in endemic communities. A cross-sectional study on risk factors and fish sharing networks was conducted in 4 villages of Gia Thinh Commune, Ninh Binh Province. A total of 510 residents in 272 households were recruited for risk factor analysis while 220 households, 28 fishermen and 10 fish-sellers were enrolled for social network study. Fecal examination for C. sinensis eggs was performed. Average C. sinensis infection rate at Gia Thinh commune was 16.5% (range 2% to 34.4%). Higher infection rates were significantly associated with males, lower educational levels, eating raw fish, and location of the villages. Social network analysis (SNA) showed a strong positive correlation between ego network size (number of households in fish sharing network) and quantity of raw fish consumed (r=0.603, P< 0.05). The infection rate in people who ate raw-fish caught from a nearby river was significantly higher than those who consumed fish taken from farmed ponds (P<0.05). The amount of raw-fish meal consumed per resident/year was significantly higher in villages that had a strong network of sharing raw-fish food (P<0.001). This study reports for the first time on fish-food sharing among neighbors, proximity to water bodies, frequency of eating raw fish from natural water bodies and low education were key risk factors in C. sinensis infection transmission in northern Vietnam.

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

“…A similar finding was observed in Ninh Binh province [20]. Moreover, 17.3% of respondents had never heard about liver fluke, a higher percentage than earlier observed in Thanh Hoa province [18] (6.3%), but lower than estimated in Ninh Binh province [20] (69.0%). Although the knowledge score was not retained in the final multivariable model, health education campaigns should be implemented to raise awareness on risk factors and disease prevention, especially as a significant proportion of the population has misconceptions about disease transmission and prevention.…”

“…Indeed, according to the results in the present study, the habit of eating raw fish in the last year increased the risk of C. sinensis infection by 8 times. Raw fish consumption thus represents the key risk factor for C. sinensis infection, as was demonstrated in other studies in Vietnam (and other Asian countries) [5,[19][20][21]29], but was now confirmed in a multivariable model. Interestingly, a high proportion of participants (20.7%) who declared to have never consumed raw fish were also infected with C. sinensis.…”

“…Dang et al reporting a prevalence of 26.1% in Ninh Binh province, found that infection was significantly associated with raw fish consumption (univariable analysis, no other factors investigated) [19]. In a more recent cross-sectional study in Ninh Binh province (reported prevalence 16.5%), C. sinensis infection was significantly associated with raw or undercooked fish consumption, as well as with gender, education and village location (all univariable analyses) [20].…”

“…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].…”

High prevalence of Clonorchis sinensis infections and coinfection with hepatitis virus in riverside villages in northeast China

“…In our findings, a greater proportion of men have this unhealthy eating habit than women, as do farmers compared to people in other occupations, which is similar to other studies 21,22 . In the present study, alcohol consumption was significantly associated with an increased risk of C. sinensis infection in the multivariate analysis, and this result was consistent with another report 23 since the local residents drank alcohol while eating raw fish and shrimp. Additionally, more males (50.3%) drank while eating raw fish in comparison with females (5%, P = 0.000); thus, this outcome could have resulted from the influence of gender.…”