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Unilocular or Cystic Hydatid Disease (E. Granulosus)

Geographic Distribution

As already noted, hydatid disease is an unusual parasitic disease in that it occurs much more commonly in the temperate than in the tropical zones of the world. The causative parasite of unilocular cystic hydatid disease, E. granulosus, is found in sheep-raising areas such as Australia, New Zealand, Tasmania, Iceland, England, Spain, Italy, Greece and other countries in Central, Eastern and southern Europe, Egypt, North, East and southern Africa, Israel, the Arab countries of the Middle East, Russia, North China, the Philippines, and Japan (Fig.3.1). In South America, it is especially prevalent in Uruguay, Argentina, and Chile. The disease occurs also in Canada and rarely in parts of the western United States and the lower Mississippi Valley. More than 1,000 patients have been reported in the U.S., but most of these were immigrants from countries where the disease is endemic.

Fig. 3.1 Geographic distribution of hydatid disease [(black areas) E. granulosus and (crosses) E. multilocularis]. Note that both forms of hydatidosis are not truly tropical diseases, since they occur in more temperate zones. The highest frequency of cystic hydatid disease (E. granulosus) is in South America, North Africa, the Mediterranean littoral, Eastern Europe, and the Middle and Far East. The disease has been partially controlled in some areas which previously had a high incidence, such as Australasia, Greenland, and Cyprus.

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