Dam Influences on Liver Fluke Transmission: Fish Infection and Human Fish Consumption Behavior

Abstract

Infectious diseases associated with dams in many parts of the world suggest a strong possibility of similar occurrence in Southeast Asia, but little is known about the influences of dams on disease occurrences in Southeast Asia, where a wide range of water-related diseases are present. An important public health issue in Southeast Asia is opisthorchiasis, the infection from liver fluke spread by ingesting raw or undercooked freshwater fish. This study investigated the effects of the Ubolratana reservoir in Thailand on Opisthorchis viverrini infection through the analyses of fish species assemblage and fish host infection in the reservoir and rivers, human fish consumption behavior, and their interactions. Multivariate analyses for community ecology and surveys of human practices were used to examine human–environment interactions involved in O. viverrini transmission. The results showed that the reservoir and the rivers harbored different fish species of varied O. viverrini infection densities, with the reservoir having higher overall infection rates than the rivers. Although the preferred species for raw fish dishes was found with low infection, several high-infection species were commonly consumed. The reservoir might have implications for opisthorchiasis risk through the potential change of fish species assemblage and the supply of high O. viverrini–infected fish to most of the villages around it. This study underscored the need to consider human–environment interactions for understanding the risks of disease transmission.

在世界许多地方中, 与水坝有关的传染疾病, 指向与东南亚发生事件类似的强大可能性, 但有关水坝对于东南亚疾病发生的影响却鲜为人知, 而该处则是各种与水有关的疾病盛行之地。东南亚的一种重要的公共健康问题便是后睾吸虫症, 该疾病是透过生食或食用未经煮熟的活水鱼而导致肝吸虫扩散的传染病。本研究透过分析水库与河流中的鱼种集合和以鱼为宿主的传染病, 人类的鱼类消费行为, 以及两者之间的互动, 探讨泰国乌博拉塔纳水库对于泰国肝吸虫感染的影响。社区生态的多变项分析, 以及人类行为的调查, 被用来检视与泰国肝吸虫传播有关的人类—环境互动。研究结果显示, 水库与河流栖息着带有不尽相同的泰国肝吸虫传染密度的不同鱼种, 整体来说, 水库较河流而言拥有较高的感染率。尽管本研究发现, 受欢迎的生鱼料理种类拥有低度感染率, 但若干具有高度感染率的鱼种却被普遍消费。水库可能因鱼种集合的潜在改变, 以及供应高度感染泰国肝吸虫的鱼类至周遭的村落, 而对泰国肝吸虫风险具有意涵。本研究强调考量人类—环境互动以理解疾病传染风险的需要。

Las enfermedades infecciosas asociadas con represas en muchas partes del mundo sugieren una fuerte posibilidad de ocurrencia similar en Asia del Sudeste, aunque poco se sabe de las influencias que tienen estos embalses sobre enfermedades en esa región, donde existe una amplia gama de enfermedades relacionadas con el agua. Un asunto importante de salud pública en Asia del Sudeste es la opistorquiasis, infección de la duela hepática difundida por la ingesta de pescado de agua dulce crudo o mal cocido. Este estudio investigó los efectos del embalse de Ubolratana, en Tailandia, sobre la infección de Opisthorchis viverrini por medio de los análisis del ensamblaje de especies de peces y de la infección del pez huésped en el embalse y los ríos, comportamiento humano relacionado con el consumo de pescado, y sus interacciones. Se usaron análisis multivariados de ecología comunitaria y encuestas sobre prácticas humanas para examinar las interacciones humano-ambientales implicadas en la trasmisión de la O. viverrini. Los resultados indicaron que el embalse y los ríos albergaban diferentes especies de peces con diversas densidades de infección de O. viverrini, con el embalse registrando tasas de infección en general más altas que la de los ríos. Aunque se halló que la especie preferida para preparar los platos de pescado crudo registraba baja infección, varias especies de alta infección eran comúnmente consumidas. El embalse podría tener implicaciones de riesgo de opistorquiasis por el cambio potencial del ensamblaje de especies de peces y por la alta oferta de peces infectados con O. viverrini para la mayoría de las aldeas de los alrededores. Este estudio enfatiza la necesidad de considerar las interacciones humano–ambientales para entender el riesgo de trasmisión de la enfermedad.

Key Words:

• cyprinid fish
• disease ecology
• liver fluke
• one health
• Thailand

关键词：:

• 关键词：鲤科鱼类, 疾病生态学, 肝吸虫, 同一个健康, 泰国。

Palabras clave:

• peces ciprínidos, ecología de la enfermedad, duela hepática, una sola salud, Tailandia

Acknowledgments

The authors wish to thank Thaweesak Saraboon, Nonglak LaOprom, Nadda Kiatsopit, Kultida Kopolrat, Jutamas Namsanor, Nattaya Watwiengkam, Yikang Feng, and Cheekong Chim for assistance in field work or lab analysis.

Funding

This research was supported by the National University of Singapore (NUS) through the Academic Research Fund (Grant No. FY2012-FRC3-005; WBS: R109-000-151-112). Xueyuan Ong was also supported by the Faculty of Arts and Social Sciences and the Tropical Marine Science Institute of the NUS. Paiboon Sithithaworn was partially supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through health cluster (SHeP-GMS).

Additional information

Notes on contributors

Xueyuan Ong

XUEYUAN ONG is a PhD candidate in the Department of Geography at the National University of Singapore, Singapore 117570. E-mail: [email protected]. Her research interests include the study of coupled human–environment systems and disease ecology.

Yi-Chen Wang

YI-CHEN WANG is an Associate Professor in the Department of Geography at the National University of Singapore, Singapore 117570. E-mail: [email protected]. Her research interests are in biogeography, landscape ecology, and spatial epidemiology. Her current work focuses on examining the interplay of land use, water, parasitic hosts, and human behavior to comprehend the risk of liver fluke infection in Southeast Asia.

Paiboon Sithithaworn

PAIBOON SITHITHAWORN is an Associate Professor in the Department of Parasitology and the Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand. E-mail: [email protected]. His research interests include population genetics and epidemiology of the liver fluke in Southeast Asia.

Carl Grundy-Warr

CARL GRUNDY-WARR is a Senior Lecturer in the Department of Geography at the National University of Singapore, Singapore 117570. E-mail: [email protected]. His research interests include the geopolitics and political ecologies of the Mekong Basin and Greater Mekong subregion; geographies of food culture and public health in the Mekong Basin; and environmental politics within borderlands and maritime spaces of Asia.

Opal Pitaksakulrat

OPAL PITAKSAKULRAT is a Lecturer at the Faculty of Veterinary Science (Establishment Project), Prince of Songkla University, Songkhla 90110, Thailand. E-mail: [email protected]. Her research interests include systematics and population genetic structure of parasites.