Oct. 17, 2014

By Medical Discovery News

Some diseases are older than others. AIDS, for instance, is a recent phenomenon, while malaria has plagued humans for millennia. Recently, scientists examining ticks fossilized in amber found they were infected with bacteria similar to those that cause Lyme disease, a spirochete named Borrelia burgdorferi. Lyme disease is a bacterial infection caused by the bite of an infected tick. The discovery of an ancient Borrelia-like bacterium, now named Palaeoborrelia dominicana, shows that tick-borne diseases have been around for millions of years.

Lyme disease was identified in the early 1970s when mysterious cases of rheumatoid arthritis struck children in Lyme, Conn., and two other nearby towns. The first symptom is a rash called erythema migrans, which begins with a small red spot where the tick bite occurred. Over the next few days or weeks, the rash gets larger, forming a circular or oval red rash much like a bull’s eye. This rash can stay small or can cover the entire back. But not everyone with Lyme disease gets this rash, and the other symptoms, including fever, headaches, stiff neck, body aches, and fatigue, are common to many other ailments. Some people develop symptoms of arthritis, nervous system problems, or even cardiac issues.

Lyme disease can be difficult to diagnose. Sometimes, people write off their initial symptoms as the flu or another common illness, and experience symptoms for months or even years before finding the true cause. To diagnose Lyme disease, doctors measure the levels of antibodies the body produces in response to Borrelia infection. Lyme patients are treated with antibiotics, but if the bacteria have been in the body for a long period of time, it can take a long time to cure. The sooner diagnosis and treatment begin, the more quickly and completely patients will recover. Even after treatment for Lyme disease, people can still experience muscle or joint aches and nervous system symptoms.

Scientists from Oregon State University have studied 15- to 20-million-year-old amber found in the Dominican Republic. Despite existing for millions of years, bacteria are rarely found in fossils. However, free-flowing tree resin traps and preserves material such as seeds, leaves, feathers, and insects in great detail. Amber is then formed from the fossilization of the resin over millions of years as it turns into a semi-precious stone. This is the oldest fossil evidence of ticks containing such bacteria.

Four ticks from the Dominican amber were examined and found to have large populations of spirochetes that resemble the Borrelia bacteria, such as those that cause Lyme disease today. The oldest reported case of Lyme disease was Oetzi, a well-preserved natural mummy who lived 5,000 years ago and was discovered by hikers in the Alps. In other studies, fossils have revealed bacteria such as Rickettsia, which cause modern diseases like Spotted Fevers and Typhus, found in ticks from about 100 million years ago. Evidence suggests that even dinosaurs may have been infected with Rickettsia, showing these microbes likely infected other creatures before humans were added to the mix. Millions of years of co-evolution resulted in highly adapted pathogens that scientists and physicians still struggle to understand and treat.

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