versión impresa ISSN 0365-9402
Bol. chil. parasitol. v.54 n.3-4 Santiago jul. 1999
The control of hydatidosis
Cystic hydatidosis, caused by the larval stage of Echinococcus granulosus, which is wide spread through over the worldhas been a permanent preocupation for the medical profession and health authorities for centuries.
The greatest prevalence of hydatidosis in human and animals is found in countries of the temperate zones including southern South America, the entire Mediterranean littoral, the southern and central parts of the former Soviet Union, Central Asia, China and parts of Africa. The highest prevalence rates are found arnong populations involved with sheep raising.
Although hydatidosis has been considered as highly susceptible to control meausres, its eradication requires long term programs and a lot of resources which are not always available in many countries.
Control programs have had the aim to reduce or eliminate the infection in man and animals. The desired outcome is a satisfactory decrease in prevalence in age groups under 20 years.
Several geographicallyisolated countries as Iceland, Cyprus and New Zealand have procedures in place to eradicate the parasite. Others, such as Tasmania and the Falkland Islands are satisfied with the degree of control obtained. In constrast, countries forming part of large continentsUruguay, Chile, Argentina, Algeria, Morocco, Spain, Greece and Sardinia and that have seriously attempted hydatidosis control, for various reasons have not alwalys achieved the satisfactory level of control. In many endemic areas effective control has not been achiveved or even attemplted. Appart from eventual political instability, the major difficulties seem to be: movement of definitive and intermediate hosts across borders, difficulty in gaining access to definitive hosts, the need in some countries to feed dogs on viscera of dead livestock and the need to hold regularly anthelmintic treatment of all dogs for more than 20 years, as it has ocurred in New Zealand for 23 year. Recent information demostrates that this country is close to declare the eradication of the parasitose from its territoy. Two promising control programs are in progress at present in the southern extreme of Chile and Argentina.
The ideal basic items to fulfill in an echinococcosis/hydatidosis control program are control of canine population, regular dog treatment with praziquantel, slaughter control, safe destruction of infected viscera and offals and constant health education at all community levels.
According to D.D. Heath a vaccine to prevent intermediate hosts becoming infected with E. granulosus is now a feasible addition to control programs.