Dicrocoelium dendriticum found in a Bronze Age cemetery in western Iran in the pre-Persepolis period: The oldest Asian palaeofinding in the present human infection hottest spot region.

Dicrocoeliasis of animals and humans is caused by trematode species of the genus Dicrocoelium, mainly Dicrocoelium dendriticum in ruminants of the Holarctic region. D. dendriticum may be considered an old parasite, probably related to the appearance and diversification of Eurasian ovicaprines, occurred 14.7-14.5 million years ago. The oldest palaeoparasitological findings of Dicrocoelium in domestic animals and humans date from more than 5000 years BC in Europe. Eggs of D. dendriticum have been found in a burial of a Bronze Age cemetery (2600-2200 BC) close to Yasuj city, southwestern Iran. This is the oldest finding of D. dendriticum in the Near East, where present human infection reports are more numerous than in other world regions where human dicrocoeliasis is rare and sporadic. This palaeofinding in the Zagros mountainous chain area is of interest by its location close to Persepolis, suggesting a narrow relationship between humans and herbivorous animals in these highlands. Domestic ruminant populations of these highlands were following a repeated contact with those of the western flat lowlands of the Fertile Crescent thanks to annual altitudinal transhumance migrations of the nomadic pastoral tribes with their herds living throughout Zagros Mountains in the several millennium period BC. It is concluded that D. dendriticum spread together with sheep and goats westward throughout Europe from the Fertile Crescent during the 8000-6000 year BC period and somewhat later southward into Africa, both spreads facilitated by the low specificity of that trematode species regarding the snail and ant intermediate hosts.