Researchers have announced the discovery of evidence suggesting that Lyme disease is approximately 15 millions years old. The evidence, preserved in fossilized ticks that were embedded in amber, was found in the present-day Dominican Republic. The discovery, published in the journal Historical Biology in April, suggests that Lyme disease as well as various tick-borne diseases may have been causing illnesses in animals 12 million years before humans even appeared on Earth.
Four fossilized ticks were investigated by scientists, who discovered inside of them a large amount of cells resembling those of the Borrelia genus, which is a form of bacteria responsible for causing Lyme disease. Although bacteria was present on Earth 3.6 billion years ago, it is rare to find it preserved in the fossil record. In this case, because the ticks were entombed in amber, which is the hardened resin formed by trees and is able to preserve microscopic cells and soft tissue that would otherwise decay, the scientists were able to detect the bacteria. Amber has also allowed researchers to find microbes from a termite which were over 100 million years old as well as sperm from a 40-million-years-old springtail, which resembles an insect.
The S-shaped bacteria discovered by scientists in the body of the tick has been named Palaeoborrelia dominicana.
The lead author of the study which found the bacteria, entomologist and professor emeritus George Poinar, Jr. of Oregon State University, stated that in the countries of Asia, Europe and the U.S., ticks have become more significant in the spreading of diseases than mosquitos. Poinar believes that there are likely many illnesses and diseases throughout history for which doctors could provide no diagnosis, but were probably a result of ticks. Lyme disease itself, which afflicts thousands every year, was not even formally recognized as a disease until the 1970s.
Lyme disease affects the heart, joints and central nervous system and occurs worldwide. The U.S. reported 30,000 cases in 2009, even though many times the disease is misdiagnosed due to the symptoms, which include aches, fatigue, fever and rash, having a strong similarity to other diseases. As it takes hold in the body, it becomes a chronic illness that is very difficult to treat. Poinar thinks that due to the ancient origins of Lyme disease, the bacteria has evolved over time and developed a resistance to treatments meant to destroy it. However, when diagnosed early and correctly, Lyme disease is treated very successfully with antibiotics.
Cases of Lyme disease are growing in number each year, causing the U.S. government to consider the disease even more common than the West Nile virus or other diseases spread by insects. Because ticks that carry Lyme disease are found mainly on deer, the fast-growing deer population in the U.S. means that the deer tick population is also growing, which leads to more instances of tick-borne diseases.
The earliest confirmed human victim of Lyme disease was an ice mummy found in the Eastern Alps approximately 20 years ago. The mummy, named Otzi, was 5,300 years old. Upon studying their find, scientists discovered the Borrelia bacteria within his cells. Poinar believes that the man died in the full throes of Lyme disease.
By Jennifer Pfalz