CDC Morbidity and Mortality Weekly Report Tickborne Relapsing Fever — United States, 1990–2011 Jan 30, 2019 Tickborne relapsing fever (TBRF) is zoonoses… caused by spirochetes of the genus Borrelia and transmitted to humans by ticks of the genus Ornithodoros. TBRF is endemic in the western United States, predominately in mountainous regions. Clinical illness is characterized by recurrent bouts of fever, headache, and malaise. Although TBRF is usually a mild illness, severe sequelae and death can occur . This report summarizes the epidemiology of 504 TBRF cases reported from 12 western states during 1990–2011. Cases occurred most commonly among males and among persons aged 10‒14 and 40‒44 years. Most reported infections occurred among nonresident visitors to areas where TBRF is endemic. Clinicians and public health practitioners need to be familiar with current epidemiology and features of TBRF to adequately diagnose and treat patients and recognize that any TBRF case might indicate an ongoing source of potential exposure that needs to be investigated and eliminated.

CDC Emerging Infectious Diseases Detection of Tickborne Relapsing Fever Spirochete, Austin, Texas, USA Nov, 2018 In March 2017, a patient became febrile within 4 days after visiting a rustic conference center

Mafi, N. et al. Tick-Borne Relapsing Fever in the White Mountains, Arizona, USA, 2013–2018 Emerging Infectious Disease Journal Volume 25 Number 4 - April 2019 Tick-borne relapsing fever (TBRF) is a bacterial infection transmitted by tick bites. In the United States, TBRF most often occurs in western states and is usually transmitted by bites of Ornithodoros spp. ticks; Borrelia hermsii is thought to be the most common cause. …Tick-borne relapsing fever (TBRF) …occurs in several different parts of the world, including the western United States. TBRF typically manifests after a 7-day incubation period with recurring episodes of fever in association with headache, myalgias, and other nonspecific symptoms lasting for ≈3 days and separated by afebrile periods of ≈7 days’ duration. In the United States, transmission is associated with the bite of soft O. hermsi ticks. Ornithodoros spp. ticks usually feed at night on rodents, such as tree squirrels and chipmunks, but might choose to feed on human hosts, particularly when the rodent population has been cleared from the local habitat. Feeding is rapid, and most persons who are bitten are not aware of a tick bite. Cabins are a typical site to acquire infection. In addition, soft ticks can live up to 10 years; this long lifespan means that once a cabin or building is infested, it can remain a source of human infection for years unless steps are taken to find and remove rodent infestations and eradicate the ticks.

Parola, P. et al. Travel and tick-borne diseases: Lyme disease and beyond 2018 Tick-borne relapsing fevers (TBRF), transmitted by soft ticks … represent a major public health problem in some areas. TBRF are acute febrile illnesses followed by multiple recurrences of fever..., headache, and possible neurological complications. These infections … cannot be distinguished clinically from other acute undifferentiated febrile illnesses like malaria …. “Minimizing the risk of tick bites remains the most important measure to reduce the risk of TBD. This can be accomplished by wearing long pants that are tucked into boots and by applying tick repellents and acaricides. Inspecting for and removing attached ticks with tweezers or forceps as soon as possible following exposures to tick-infested areas is another important consideration. Finally, because most bacterial infections transmitted by ticks are susceptible to doxycycline, malaria prophylaxis with doxycycline might also provide protection against many TBD.”

Bouchard, C. et al. Canada Communicable Disease Report Increased risk of tick-borne diseases …. Apr 4, 2019 …Tick-borne diseases are likely to become more common in Canada. In addition to Lyme disease, four other tick-borne diseases (TBDs) have started to emerge and are likely to increase: Anaplasmosis, Babesiosis,Powassan virus, and Borrelia miyamotoi disease.

Gasmi, S. et al. PLoS One Evidence for increasing densities and geographic ranges of tick species of public health significance other than Ixodes scapularis in Québec, Canada.  Aug 22, 2018 The aims of this study were to determine (1) current diversity and abundance of ticks of public health significance other than I. scapularis, (2) sex and age of the human population bitten by these ticks (3), and the seasonal and geographic pattern of their occurrence.