Toyin Ajayi, May 2001
Metagonimiasis is an infectious parasitic disease that is associated with eating undercooked fish. It is found mostly in the Far East, but also in Siberia, Manchuria, the Balkan states, Israel and Spain.
Also known as Yokogawai's fluke, the infection was first identified in 1912 (or 1913; sources differ), by scientists Katsurada and Yokogawai, who discovered the eggs in the feces of patients suffering from persistent diarrhea and stomach cramps.
The symptoms are caused by an intestinal worm of the Trematode family. The scientists originally named the parasite Heterophyes yokogawai because of its great similarity to the intestinal trematode Heterophyes heterophyes. However, following further research by Yokogawa on human subjects and experimental dogs that showed the two parasites to be morphologically different, they later renamed the fluke Metagonimus yokogawai.
Public Health Implications
Metagonimiasis is transmitted through eating undercooked fish caught in water polluted with infected fecal matter. By nature of its mode of transmission, M. yokogawai tends to be more a disease of rural and underprivileged populations. Because of this, public health measures that rely on mass screening and drug therapy of infected people are likely to encounter difficulties with funding and delivery.
A 1984 study entitled "Socio-economic and Cultural Aspects of Human Trematode Infections in Korea" linked general increases in socio-economic conditions and environmental practices to a reduction in the prevalence of water-dependent intestinal flukes (including metagonimiasis) in several rural Korean communities. The researcher found that establishing sanitary waste disposal systems and encouraging thorough cooking practices had a great effect on the transmission of parasitic intestinal infections, even in the absence of mass chemotherapy programs. This study shows how, with metagonimiasis as with many other infectious diseases, socio-economic and sanitary conditions are inextricably bound to the prevalence and transmission of infection.
In addition, the Food Safety Unit division of the World Health Organisation also stresses the impact of behavioral changes on reducing the transmission of intestinal parasites. The board recommends the use of widespread educational campaigns, with emphasis on thorough cooking of fish rather than attempting large-scale diagnostic and treatment campaigns. It is important to address cultural norms of food preparation in this context as well; traditional methods of smoking or pickling fish are not sufficient to kill the parasite.
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Perry-Castaņeda Library Map Collection - http://www.lib.utexas.edu/Libs/PCL/Map_collection/world_maps/World_2000.jpg
Rim, Han-Jong; Chu, Dong-Sun; Lee,Joon-Sang; Joo, Kyoung-Hwan; Won, Chang-Yong. "Anthelmintic Effects of Various Drugs against Metagonimiasis". Korean Journal of Parasitology. 16(2): 117-122. Dec, 1978.
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Useful Web Links:
http://www.hsc.wvu.edu/som/micro/317VIEW/lecture4/sld020.htm (page is untitled)
Healthy Me! Drug Database - http://www.ahealthyme.com/topic/topic100588584
Identification and Diagnosis of Parasites of Public Health Concern (Centers for Disease Control) - http://www.dpd.cdc.gov/dpdx/HTML/Metagonimiasis.htm