Two atypical cases of cystic echinococcosis (Echinococcus granulosus) in Alaska, 1999.

Before 1999, clinical experience demonstrated that the sylvatic (or Northern) biotype of Echinococcus granulosus seen in Alaska produced fewer complications and serious sequelae than infection with the pastoral (or European) biotype found in other parts of the world. Two cases of E. granulosus with severe sequelae occurred in Alaska in 1999. The adverse outcomes could have been rare complications that are part of the clinical spectrum of disease caused by sylvatic cystic echinococcus, an indication that the sylvatic biotype, especially when affecting the liver, has potential for severe clinical consequences, or perhaps in one case, infection with a more virulent biotype of E. granulosus contracted during visits to Washington State.