Hydatid cysts. These cysts are formed in the body by the larvae of the Echinococcus tapeworm. The small adult worms live in the lining of the small intestine of (usually) dogs,and release eggs that are excreted in the dogs' faeces. The eggs can then be eaten by a herbivore (such as sheep),in which they hatch and the embryos enter the bloodstream before settling in an organ,usually the liver,but sometimes the lungs (as here),kidneys or brain. The embryos then develop into these cysts,which contain thousands of developing larvae. If the host is eaten by a predator,the cycle begins again. The presence of the growing cysts disrupts blood vessels,nerves and organs,and can be fatal |