Public Health and Prevention

Different small public health initiatives have been undertaken in endemic countries to stem the spread of Clonorchiasis.  Most initiatives have had to do with educating the populace on the dangers of eating undercooked and raw river fish.  Officials of the United States government during World War I became concerned about the possible spread of Clonorchiasis in the US when infected Chinese immigrants arrived.  They took measures to test for the disease, and placed restrictions on immigration of infected individuals until 1937, when it was found that native snails could not serve as intermediate hosts. A mass treatment program undertaken in South Korea in 1984 resulted in a reduction of the prevalence of Clonorchiasis from 13.3% in 1984 to 0.9% in 1990.

Over the period 1969–1995, the Korea Association for Parasite Eradication conducted a parasite control program that focused on the mass treatment of school children throughout the Republic of Korea. Repeated countrywide surveys revealed that the program had no significant effect on the prevalence of clonorchaisis.  The report suggests that appropriate legislation and overall government support may be necessary to succeed in eradicating clonorchiasis. (Korea Association of Health)

The easiest way to prevent infection with Clonorchiasis is to avoid eating raw or undercooked fresh water fish.  Intensive health education campaigns to persuade the populace of endemic areas, where it is a cultural norm to eat fish prepared in these ways, to reform their eating habits is important if the disease is to be eradicated. (David Grove)  

Additionally, “night soil” (fertilizer contaminated with human feces) is used in many regions to fertilize fish ponds to increase fish production.  This practice stimulates snail growth and increases the number of secondary hosts.  Public education campaigns could be used to decrease this practice in combination with the construction and implementation of sanitary disposal mechanisms for human feces. 

Measures have been taken to control the snail population but were not successful.  In the People’s Republic of China, the slaughter of animals who are reservoirs for the disease (dogs and cats) has probably reduced transmission of the disease in that area.

The WHO has a protocol on how to safely prepare foods to prevent infection with Clonorchiasis.  (WHO)  Additionally, they include Clonorchiasis amongst their list of “neglected zoonoses in neglected populations.”  They state that these diseases have a high financial burden on the individual, the family, the community and the country by impeding social and economic development.  People of low SES and other vulnerable groups in society are unevenly burdened with these diseases, and are the least capable of obtaining health care.  Public health initiatives and future prevention must be a joint effort between workers in education, environment and agriculture.

Information for this section was obtained from Tropical Medicine Central Resource: Chapter 21 and from A History of Human Helminthology.


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