Echinococcus granulosus is a small, three-segmented tapeworm about 8mm long found worldwide. The adults are parasites in the small intestine of carnivores, dogs, wolves and jackals where they lay eggs. They usually cause little or no damage in dog, but the eggs passes out with the faeces and when eaten by intermediate host, mainly sheep, cattle, horses, pigs or humans. A larva hatches from the egg, penetrates the gut, and migrates to various tissues, especially liver, spleen, muscle, and brain. The larva of Echinococcus develops into a spherical fluid-filled cyst called a hydatid cyst. This cyst can reach 150mm in diameter, contains numerous secondary cysts (germinal epithelium) or broad capsules in which thousands of future larvae (called protoscolices) develop usually in the liver and lungs. If the hydatid cyst ruptures, the brood capsules can spill out of the cyst, metastasize to other sites, and develop into a hydatid cyst and is responsible for hydatid disease (hydatidosis). Thus, ingestion of a single egg can give rise to several hydatid cysts, each containing several brood capsules (Oxford Concise Veterinary Dictionary. 2002) (Brooks, Carroll, Butel. (2007).
2- Literature Review
The hydatid control program in Tasmania
I. The origin of Echinococcus granulosus in Tasmania
Gemmell (1990), Jenkins (2005) and Jenkins (2004) mentioned that Echinococcus granulosus introduced in Australia about 200 years ago during European settlement, with domestic animals and dogs and it is the only member of Genus Echinococcus that transpire in Australia. According to Thompson and McManus 2002 (As cited by Jenkins & Macpherson 2003) claimed E. granulosus was introduced during the 18oos and the early 1900 in Australia. In Tasmania it was introduced by merino sheep in 1804 and it was the common sheep strain that is found in wild life and domestic animals (Jenkins & Macpherson 2003). According to my understanding this merino sheep may from...
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