Wiwanitkit Viroj, Nithiuthai Suwannee, Suwansaksri Jamsai
Department of Laboratory Medicine, Chulalongkorn University, Bangkok, Thailand.
MedGenMed. 2002 Mar 6;4(1):8.
Fish-borne trematode is a worldwide problem, with the number of people infected by liver flukes alone estimated at 21 million. In addition to the major liver flukes, Opisthorchis viverrini and Clonorchis sinensis, several types of intestinal flukes also use cyprinoid fish as the intermediate host. Traditional ingestion of undercooked and uncooked fish preparations is a major factor in pathogen acquisition.
To examine the motility of Haplorchinae spp metacercariae in matched minnows using a number of preparation methods that mimic traditional practices.
Several freshly killed freshwater fish, Cyclocheilichthys armatus, were purchased from the local market and sent to the authors' laboratory to be examined under a stereoscopic microscope for active Haplorchinae spp metacercariae. A total of 10 fish were infected with many active metacercariae and used in the preparation of uncooked fish dishes. Five different raw fish dishes that mimic traditional meals (2 fishes/dish) were prepared using the following methods: 1) left to dry at room temperature; 2) frozen at -20 Celsius; 3) refrigerated at 4 Celsius; 4) marinated in saline (5% sodium chloride solution); and 5) marinated in 5% acetic acid solution to mimic traditional vinegar. The motility of the metacercariae in each of these dishes was examined under a stereoscopic microscope. Motility was estimated as the level of activity or degeneration of the metacercariae at the start of the experiment and then every 30 minutes until all the parasites appeared degenerate (and therefore, presumably not viable).
Degeneration of the parasites was slowed by cooling: degeneration of all metacercariae took approximately 5 hours in the refrigerated or frozen fish, compared with 3 hours in all other dishes left at room temperature.
The study substantiates the epidemiologic data demonstrating transmission of these types of pathogens despite freezing, pickling, and salting. Although the tradition of eating uncooked fish is deeply rooted in Thailand, constant efforts need to be made to discourage this practice.
食源性吸虫是一个全球性问题，仅肝吸虫感染人数估计就达2100万。除了主要的肝吸虫，如麝猫后睾吸虫和华支睾吸虫外，几种肠吸虫也以鲤科鱼类作为中间宿主。传统上食用未煮熟和生的鱼类制品是感染病原体的主要因素。
使用多种模拟传统做法的制备方法，研究单睾科吸虫囊蚴在配对的米诺鱼中的活力。
从当地市场购买了几条刚杀死的淡水鱼（圆唇鱼），送到作者实验室，在立体显微镜下检查是否有活动的单睾科吸虫囊蚴。总共10条鱼感染了许多活动的囊蚴，并用于制作生鱼菜肴。使用以下方法制作了5种模拟传统餐食的不同生鱼菜肴（每盘2条鱼）：1）室温下晾干；2）-20摄氏度冷冻；3）4摄氏度冷藏；4）用盐水（5%氯化钠溶液）腌制；5）用5%醋酸溶液腌制以模拟传统醋渍。在立体显微镜下检查每盘菜肴中囊蚴的活力。活力评估为实验开始时囊蚴的活动水平或退化程度，然后每30分钟评估一次，直到所有寄生虫出现退化（因此，推测不再存活）。
冷却减缓了寄生虫的退化：冷藏或冷冻鱼中所有囊蚴的退化大约需要5小时，而室温下的所有其他菜肴中则需要3小时。
该研究证实了流行病学数据，表明尽管经过冷冻、腌制和盐渍，这些类型的病原体仍可传播。尽管在泰国食用生鱼的传统根深蒂固，但仍需不断努力劝阻这种做法。
