Research Article: Uncooked fish consumption among those at risk of Opisthorchis viverrini infection in central Thailand

Date Published: January 31, 2019

Publisher: Public Library of Science

Author(s): Picha Suwannahitatorn, Joanne Webster, Steven Riley, Mathirut Mungthin, Christl A. Donnelly, Brecht Devleesschauwer.


In contrast to northern and northeastern Thailand, central Thailand was believed not to be endemic for Opisthorchis viverrini (OV). Fieldwork conducted in a rural area of central Thailand revealed that the prevalence and incidence were relatively high compared with regional average data. We hypothesized that the behavioural-psycho-social background of the study population might play an important role in the high burden of the infection. As a result, a qualitative study was conducted to highlight potential social determinants of the infection dynamics to gain greater understanding of the risk behaviours and their contexts. A qualitative study using focus group discussion and in-depth interviews was conducted in Na-ngam Village, Chachoengsao Province from 2012–14. Framework analysis was used to explore associations between infection and thematic content. Social influence showed a strong impact on infection dynamics of OV infection. Our results revealed that Koi pla (chopped raw fish salad) remains a popular dish in the community, as the dish itself represents northeastern culture. The cultural norm had been transferred from ancestors to their descendants. Some elders complained that discontinuing the consumption of Koi pla went against old traditions with respect to cultural norms and socialization. In contrast, modern education teaches about hygiene including OV infection risks, and accordingly teenagers and young adults were reported to modify their lifestyles including their eating habits. Children are a potential key to pass knowledge to their parents and school-based education programs can serve as a practical hub for knowledge dissemination. However, health education alone might not lead to behavioural change in other age groups. Therefore, more efforts are needed to support the transformation.

Partial Text

Opisthorchis viverrini (OV), a human liver fluke, is a pathologically and economically important food-borne trematode. [1–3] OV infection is endemic in Southeast Asia along the Mekong Basin [4–7] including Thailand, Lao PDR and Cambodia, where an estimated nine million people are infected [8–10]. Transmission to humans (and other animals) occurs through the consumption of uncooked cyprinoid or white-scale freshwater fish containing infective stage metacercariae [11,12]. After infection, OV survives in the bile duct in the absence of treatment [13–15]. Many studies have demonstrated that chronic infection is strongly related to a bile duct cancer, cholangiocarcinoma (CCA) [16–19]. The International Agency for Research on Cancer has declared that OV is a group 1 agent, carcinogenic to humans [8]. Thailand has the highest CCA incidence in the world, with estimates ranging from 93.8 to 317.6 /100,000 person-years [13,18,20–22]. However, OV infection is acknowledged as a neglected and underestimated disease globally [9,10,23].

The research protocol of this study was approved by the Ethics Committee of the Royal Thai Army Medical Department (approval code S045h/54). Study participants or parents of participants under 18 years of age agreed to join the study after reading the data sheet provided in Thai and provided their written informed consent.

A total of 35 study participants were enrolled. FGD sessions were categorized in four groups; local health volunteers, never infected, newly infected and previously infected groups (Table 3). Participants in the re-infected group were too few to form a group discussion, so they were allocated to in-depth interviews to provide information about the recurrence of the disease.

The study provided more insight about OV infection dynamics emphasized on uncooked fish consumption behaviors in a behavioral-psycho-social aspect. However, assumption was mainly made by data obtained from FGD in 35 participants with majority of female participants (77.1%), and in-depth interviews in 5 participants. Therefore, strong conclusion should be aware to reflect the whole picture of rural Thai community, and would be discussed in relation to the data obtained from this study. Additionally, microscopic-based stool examinations could not differentiate eggs of O. viverrini from those of minute intestinal flukes in terms of morphological appearance. The issue has been described in previous cohort study in Na-yao area, the adjacent community, from 2007 to 09 [32] and molecular study [36] showed that minute intestinal flukes were not detected by PCR.

Social influence plays an important role in shaping the dynamics of OV infection. The interaction of knowledge and culture transfer across generations provided insights into behavioral-psycho-social dynamics in affected communities. Koi pla was considered a tasty dish, which many people considered an important factor in its continued consumption. To some the dish itself represents northeastern culture. The elderly generation recently migrated from northeastern Thailand, so traditional beliefs were transferred from their ancestors to their descendants. They still preserved their traditional lifestyle even though they had migrated. However, the younger generation was more likely to absorb modern culture and become more urbanized. In rural settings, community leaders are important keys in the social structure. As the local administration is managed by the central and regional authority, governmental staff might not be aware of local cultural norms. Community leaders could bridge this gap and help facilitate the government’s strategies.




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