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. When a person is bitten by a Lyme-carrying tick, the tick feeds for roughly 36 hours and transmits the infecting organism Borrelia burgdorferi.
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.
Lyme disease is the fastest growing, vector-borne infectious disease in the United States. 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. However, diagnosing Lyme is difficult. By 2018, The Centers for Disease Control and Prevention (CDC) estimated roughly 300,000 people are diagnosed with Lyme disease in the U.S. each year. 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.