Cystic echinococcosis in Iceland: a brief history and genetic analysis of a 46-year-old Echinococcus isolate collected prior to the eradication of this zoonotic disease

Cystic echinococcosis (CE) is considered the most severe parasitic disease that ever affected
the human population in Iceland. Before the start of eradication campaign in the 1860s,
Iceland was a country with very high prevalence of human CE, with approximately every
fifth person infected. Eradication of CE from Iceland by 1979 was a huge success story and
served as a leading example for other countries on how to combat such a severe One
Health problem. However, there is no genetic information on Echinococcus parasites before
eradication. Here, we reveal the genetic identity for one of the last Echinococcus isolates in
Iceland, obtained from a sheep 46 years ago (1977).We sequenced a large portion of the mitochondrial
genome (8141 bp) and identified the isolate as Echinococcus granulosus sensu stricto
genotype G1. As G1 is known to be highly infective genotype to humans, it may partly explain
why such a large proportion of human population in Iceland was infected at a time . The study
demonstrates that decades-old samples hold significant potential to uncover genetic identities
of parasites in the past.