Transmission of the Human Relapsing Fever Spirochete Borrelia persica by the Argasid Tick Ornithodoros tholozani Involves Blood Meals from Wildlife Animal Reservoirs and Mainly Transstadial Transfer

, transmitted by the argasid tick , causes human tick-borne relapsing fever in the Middle East and Central Asia. Infection is acquired often when visiting tick-infested caves and reported to be transmitted mainly transovarially between ticks, occasionally infecting humans. To study the epidemiology of this infection, ticks were trapped in 24 caves in 12 geographic zones covering all of Israel and identified morphologically. DNA was extracted from larvae, nymphs, and adult stages from each location and PCR followed by DNA sequencing was performed to identify infection, tick species, and tick blood meal sources. We collected 51,472 argasid ticks from 16 of 24 caves surveyed. We analyzed 2,774 ticks, and 72 (2.6%) from nine caves were PCR positive for Infection rates in male, female, and nymphal ticks (4.4%, 3%, and 3.2%, respectively) were higher than in larva ( 0.001), with only 3 (0.04%) positive larvae. Presence of blood meal was associated with infection in ticks ( 0.003), and blood meals of golden jackals, red foxes, and Cairo spiny mouse were associated with infection ( 0.043). PCR survey of 402 wild mammals revealed infection with the highest rates in social voles (22%), red foxes (16%), golden jackals (8%), and Cairo spiny mice (3%). In conclusion, although transovarial tick transmission of occurs at low levels, ticks apparently acquire infection mainly from wildlife canid and rodents and may eventually transmit relapsing fever borreliosis to humans who enter their habitat. is a spirochete that causes tick-borne relapsing fever in humans in an area that spans from India to the Mediterranean. Until now, it was thought that the soft tick vector of this infection, , is also its main reservoir and it transmits mostly transovarially between tick generations. This study showed that tick infection with is associated with feeding blood from wild jackals, foxes, and rodents and that transovarial transmission is minimal. Since ticks are found in isolated caves and ruins, it is assumed that wild canids who migrate over long distances have a major role in the transmission of between remote tick populations, and it is then maintained locally also by rodents and eventually transferred to humans during tick bites. Prevention of human infection could be achieved by restricting entrance of canines and humans to habitats with populations.