|Photo of Indian rhino by Krish Dulal|
The eggs had the characteristic look of schistosome eggs - an ovoid with a hook at one end (see below). But they were not just any blood fluke eggs, they looked very similar to the eggs of B. nairi - the elephant blood fluke. When the researchers sequenced specific marker section of the fluke eggs' DNA, they found that it matched the known sequences for B. nairi, showing that what is usually thought of as just an elephant parasite can also find a home in the Indian rhinoceros. Furthermore, the B. nairi eggs they recovered from the rhino dung were completely viable, showing that the rhino is a natural and commonly used host for this parasite and that they did not end up there by accident
|Image of Bivitellobilharzia nairi egg from here|
So there is more than one way for two (or more) different species to end up with the same parasite. You can either share a recent common ancestry, or you can share the same habitat which gives the parasite ample opportunities to cross the evolutionary gulf between different hosts.
Devkota, R., Brant, S.V., Thapa, A. & Loker, E.S. (2014) Sharing schistosomes: the elephant schistosome Bivitellobilharzia nairi also infects the greater one-horned rhinoceros (Rhinoceros unicornis) in Chitwan National Park, Nepal. Journal of Helminthology 88: 32–40