Lyme disease is a tick-borne, bacterial disease which causes emotional and physical debilitation, leads to chronic arthritis -- even in children and young people -- and, in many cases, to heart problems. The disease has 3 phases in most patients: first, for several weeks, a skin rash with a red border around the tick bite; second, several days of fever accompanied by digestive problems and meningitis; and third, visual loss, arthritis or carditis.
The incidence of Lyme disease has increased markedly over the past decades. It has spread from North America through Europe, Asia and Australia following the spread of the Ixodes tick. Since 2014, its progress is an official marker of climate change in the USA.
Classical Lyme disease is caused by the spirochete Borrelia burgdorferi, named after its discoverer, Willy Burgdorfer. A spirochete is a spiral shaped bacterium. Other diseases caused by spirochetes include relapsing fever and syphilis. The ailment is named after the town of Old Lyme in Connecticut where it was first found in 1975. It commenced on the east coast of the USA and has spread to almost all states. Lyme disease is most commonly transmitted by a tick bite (usually painless). The tick vectors include the deer ticks Ixodes scapularis and I. dammini, the Pacific tick Ixodes pacificus and the larger Lone Star tick Amblyomme americanum. In the UK the vector is the sheep tick.
Most cases are cured if treated early with two to four weeks of antibiotics. Patients are often co-infected with other illnesses from the same tick bite. Blood tests may not be as accurate if the patient has been infected for a long time. The medical community is divided about whether Lyme disease persists as a chronic infection and disagrees over the benefits of long-term antibiotic treatment. Recent research shows the bacteria can morph into persistent forms that evade antibiotics.
In 1988, more than 5,000 cases were officially recorded in the USA, but this was officially declared a "dangerous underestimate". More than 16,000 cases of Lyme disease were reported in 1999, making it the most common illness transmitted by insects, ticks or spiders in the USA. Most cases are concentrated in about 115 counties in the eastern and north-central United States where animals (chiefly mice and deer) have high infection rates with the disease-causing bacteria, increasing the likelihood that a tick bite will transmit the infection to humans.
A 1994 study did not find evidence of classical Lyme disease in Australian ticks. Many of the co-infections associated with the disease are known to exist in Australia and can cause symptoms that are like Lyme disease. Similarly, in 2015, Murdoch University tick researchers were unable to find classical Lyme disease in 656 ticks they had examined. However, the study found bacteria associated with Lyme co-infections and several new species of bacteria. Among these was a small fragment of relapsing fever Borrelia, a genetic cousin to Lyme disease, which may cause similar symptoms. There is currently no commercial test available for RF Borrelia.