Dominican amber, dating back 15 million years ago, provides the oldest evidence ever found of Borrelia – a kind of bacteria that causes Lyme disease (a stealthy bacterial illness that is spread by tick bites and was only recognized about 40 years ago).

“In the United States, Europe and Asia, ticks are a more important insect vector of disease than mosquitos. They can carry bacteria that cause a wide range of diseases, affect many different animal species, and often are not even understood or recognized by doctors,” said Prof George Poinar, Jr., a paleoentomologist with the Oregon State University’s College of Science and the author of a paper published in the journal Historical Biology.

“It’s likely that many ailments in human history for which doctors had no explanation have been caused by tick-borne disease.”

Lyme disease is a perfect example. It can cause problems with joints, the heart and central nervous system, but researchers didn’t even know it existed until 1975.

But the discovery of an ancient Borrelia-like bacterium, Palaeoborrelia dominicana, shows these problems with tick-borne disease have been around for millions of years.

Prof Poinar found spirochetes-like cells of Palaeoborrelia dominicana in a series of four ticks (Amblyomma sp.) preserved in 15-million-year-old amber from the Dominican Republic. This is the oldest fossil evidence of ticks associated with such bacteria.

“Ticks and the bacteria they carry are very opportunistic. They are very efficient at maintaining populations of microbes in their tissues, and can infect mammals, birds, reptiles and other animals,” he said.

In 30 years of studying diseases revealed in the fossil record, the scientist has documented the ancient presence of such diseases as malaria, leishmania, and others.

Evidence suggests that even dinosaurs could have been infected with Rickettsial-like bacteria – microorganisms that can cause various types of spotted fever.

“Humans have probably been getting diseases, including Lyme disease, from tick-borne bacteria as long as there have been humans,” Dr Poinar concluded.

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George Poinar Jr. Spirochete-like cells in a Dominican amber Ambylomma tick (Arachnida: Ixodidae). Historical Biology: An International Journal of Paleobiology, published online April 22, 2014; doi: 10.1080/08912963.2014.897699