Image from George Poinar, Jr, PhD/Oregon State University
Fossilized red blood cells
An amber specimen found in the Dominican Republic contained the first fossilized mammalian red blood cells (RBCs) and intraerythrocytic hemoparasites, according to an article published in the Journal of Medical Entomology.
The fossil contained an engorged tick and RBCs infected with parasites that resemble existing members of the Babesiidae and Theileriidae families of the order Piroplasmida.
It appears that 2 small holes in the back of the tick allowed blood to ooze out just as the tick became stuck in tree sap that later fossilized into amber.
“These 2 tiny holes indicate that something picked a tick off the mammal it was feeding on, puncturing it in the process and dropping it immediately into tree sap,” said study author George Poinar, Jr, PhD, of Oregon State University in Corvallis.
“This would be consistent with the grooming behavior of monkeys that we know lived at that time in this region. The fossilized blood cells, infected with these parasites, are simply amazing in their detail. This discovery provides the only known fossils of Babesia-type pathogens.”
Dr Poinar said the amber specimen came from mines located in the Cordillera Septentrional of the Dominican Republic. It may have originated anywhere from 15 to 45 million years ago.
The fossil contained an engorged nymphal tick of the genus Ambylomma. The parasites found in the RBCs were also found in the gut epithelial cells and body cavity of the tick.
“The life forms we find in amber can reveal so much about the history and evolution of diseases we still struggle with today,” Dr Poinar said. “This parasite, for instance, was clearly around millions of years before humans and appears to have evolved alongside primates, among other hosts.”
Part of what makes this fossil unique, Dr Poinar said, is the way in which the parasites and RBCs were preserved, almost as if they had been stained and otherwise treated in a lab.
The parasites were different enough in texture and density to stand out clearly within the RBCs during the natural embalming process for which amber is famous.
