Tickborne relapsing fever in Israel

Tick-Borne Relapsing Fever Infection from a Bunker, a Case Report on a "One Health" Approach

Background: Tick-borne relapsing fever (TBRF) caused by Borrelia persica is an endemic disease in Israel and highly prevalent in military personnel. Prevention among the Israel Defense Force soldiers is based on increased awareness mainly in hyperendemic areas and selective postexposure prophylaxis with doxycycline. In this study, we report the presence of a suspected outbreak of TBRF in four soldiers who spent 30 h inside a deserted bunker. Materials and Methods: Clinical data on TBRF suspected cases were retrieved from clinical records, soft ticks were collected using carbon dioxide (CO2) traps and their DNA was extracted and analysed by PCR and nucleotide sequencing. Environmental conditions such as relative humidity, air temperature, wind speed, and type of soil, as well as presence or absence of animal traces inside the bunkers were documented. Results: TBRF-like clinical symptoms in the patients included: tick bite scars, fever (37.5-39.2°C), rash, tachycardia, hypotension, myalgia, cough, headache, cervical lymphadenopathy and nausea. Microscopic search for B. persica in blood smears was performed in three patients and was negative. Out of the 255 Ornithodoros tholozani ticks collected from the bunker, 198 were analyzed and 2 (1%) were infected with B. persica. To determine if tick infestation in military bunkers is a common phenomenon, we surveyed nine additional military bunkers located in four different geographical areas for the presence of soft ticks. Only one additional bunker was infested with two O. tholozani ticks, both negative for B. persica. Presence of earth that probably helped sustain a relatively big tick population was observed on the floor in the highly infested bunker. Environmental treatment with lambda-cyhalothrin at 9.7% was performed and showed efficacy with no ticks recovered in the infested bunker 124 days after intervention. Conclusion: This study shows that military bunkers may harbor soft ticks infected with B. persica and entrance into bunkers should be considered as a risk for acquiring this infection like entrance into natural caves and archeological ruins.

Prevalence of Lyme Disease and Relapsing Fever Borrelia spp. in Vectors, Animals, and Humans within a One Health Approach in Mediterranean Countries

The genus Borrelia has been divided into Borreliella spp., which can cause Lyme Disease (LD), and Borrelia spp., which can cause Relapsing Fever (RF). The distribution of genus Borrelia has broadened due to factors such as climate change, alterations in land use, and enhanced human and animal mobility. Consequently, there is an increasing necessity for a One Health strategy to identify the key components in the Borrelia transmission cycle by monitoring the human-animal-environment interactions. The aim of this study is to summarize all accessible data to increase our understanding and provide a comprehensive overview of Borrelia distribution in the Mediterranean region. Databases including PubMed, Google Scholar, and Google were searched to determine the presence of Borreliella and Borrelia spp. in vectors, animals, and humans in countries around the Mediterranean Sea. A total of 3026 were identified and screened and after exclusion of papers that did not fulfill the including criteria, 429 were used. After examination of the available literature, it was revealed that various species associated with LD and RF are prevalent in vectors, animals, and humans in Mediterranean countries and should be monitored in order to effectively manage and prevent potential infections.

Borrelia persica infection in wild carnivores in Israel: molecular characterization and new potential reservoirs

BACKGROUND

Borrelia persica causes tick-borne relapsing fever in Israel, the eastern Mediterranean basin, and Asia. Relapsing fever is associated with severe illness and potentially death in humans and animals. Since B. persica infection has rarely been described in wild animals, the aim of this study was to evaluate the prevalence of infection with B. persica in wild carnivores in Israel.

METHODS

Spleen and blood clot samples from wild carnivores, which underwent necropsy, were tested for the presence of Borrelia DNA by real-time polymerase chain reaction (PCR). PCR products were sequenced, and the spirochete loads were quantified using a specific quantitative PCR (qPCR).

RESULTS

A total of 140 samples from 74 wild carnivores were analyzed for the presence of Borrelia DNA. Six out of the 74 (8.1%) animals were found positive for B. persica by PCR and sequencing of the flagellin B gene, of which 4/74 (5.4%) were also positive by PCR for the glycerophosphodiester phosphodiesterase (glpQ) gene. Positive samples were obtained from three European badgers, and one striped hyena, golden jackal, and red fox each. All B. persica-positive animals were young males (P < 0.0001). Quantifiable results were obtained from 3/5 spleen and 4/5 blood samples. The spirochete loads in the blood were significantly higher than those found in the spleen (P = 0.034).

CONCLUSIONS

The prevalence of B. persica infection found in wild carnivores brought for necropsy was unexpectedly high, suggesting that this infection is widespread in some wild animal species in Israel. This is the first report of B. persica infection in the European badger and striped hyena. These carnivores have a wide geographical range of activity, and the results of this survey raise the possibility that they may serve as reservoir hosts for B. persica.

CD55 Facilitates Immune Evasion by Borrelia crocidurae, an Agent of Relapsing Fever

Relapsing fever, caused by diverse Borrelia spirochetes, is prevalent in many parts of the world and causes significant morbidity and mortality. To investigate the pathoetiology of relapsing fever, we performed a high-throughput screen of Borrelia-binding host factors using a library of human extracellular and secretory proteins and identified CD55 as a novel host binding partner of Borrelia crocidurae and Borrelia persica, two agents of relapsing fever in Africa and Eurasia. CD55 is present on the surface of erythrocytes, carries the Cromer blood group antigens, and protects cells from complement-mediated lysis. Using flow cytometry, we confirmed that both human and murine CD55 bound to B. crocidurae and B. persica. Given the expression of CD55 on erythrocytes, we investigated the role of CD55 in pathological B. crocidurae-induced erythrocyte aggregation (rosettes), which enables spirochete immune evasion. We showed that rosette formation was partially dependent on host cell CD55 expression. Pharmacologically, soluble recombinant CD55 inhibited erythrocyte rosette formation. Finally, CD55-deficient mice infected with B. crocidurae had a lower pathogen load and elevated proinflammatory cytokine and complement factor C5a levels. In summary, our results indicate that CD55 is a host factor that is manipulated by the causative agents of relapsing fever for immune evasion. IMPORTANCE Borrelia species are causative agents of Lyme disease and relapsing fever infections in humans. B. crocidurae causes one of the most prevalent relapsing fever infections in parts of West Africa. In the endemic regions, B. crocidurae is present in ~17% of the ticks and ~11% of the rodents that serve as reservoirs. In Senegal, ~7% of patients with acute febrile illness were found to be infected with B. crocidurae. There is little information on host-pathogen interactions and how B. crocidurae manipulates host immunity. In this study, we used a high-throughput screen to identify host proteins that interact with relapsing fever-causing Borrelia species. We identified CD55 as one of the host proteins that bind to B. crocidurae and B. persica, the two causes of relapsing fever in Africa and Eurasia. We show that the interaction of B. crocidurae with CD55, present on the surface of erythrocytes, is key to immune evasion and successful infection in vivo. Our study further shows the role of CD55 in complement regulation, regulation of inflammatory cytokine levels, and innate immunity during relapsing fever infection. Overall, this study sheds light on host-pathogen interactions during relapsing fever infection in vivo.

Infection and seroprevalence of Borrelia persica in domestic cats and dogs in Israel

Background

Relapsing fever borreliosis is an infectious disease caused by bacteria of the genus Borrelia, inflicting recurrent episodes of fever and spirochetemia in humans. Borrelia persica, the causative agent of relapsing fever in Israel, is prevalent over a broad geographic area that extends from India to Egypt. It is transmitted by the soft tick Ornithodoros tholozani and causes disease in humans as well as domestic cats and dogs. The goal of this study was to survey domestic dogs and cats in Israel for infection with B. persica.

Methods

Blood, sera and demographic and clinical data were collected from dogs and cats brought for veterinary care in central Israel. PCR followed by DNA sequencing was used to detect B. persica DNA in blood samples, and an enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies reactive with B. persica antigens in sera from the same animals. This is the first serological survey of B. persica in dogs and the first survey for antibodies reactive with a relapsing fever Borrelia sp. in cats globally.

Results

Four of the 208 dogs (1.9%) and three of 103 cats (2.9%) sampled were positive by PCR for B. persica DNA, and 24 dogs (11.5%) and 18 cats (17.5%) were seropositive for B. persica antigen by ELISA. The ratio between PCR-positivity and seropositivity in both the dog and cat populations was 1:6. All four PCR-positive dogs and two of three PCR-positive cats were seronegative, suggesting a probable recent infection. Thrombocytopenia showed significant association with seropositivity in dogs (P = 0.003). In cats, anemia had a significant association with seropositivity (P = 0.0001), and thrombocytopenia was associated with the combined prevalence of seropositivity or PCR-positivity (P = 0.022).

Conclusions

Borrelia persica infection is more prevalent and widespread in domestic canine and feline populations in Israel than previously thought. Dogs and cats may play a role as reservoirs and sentinels for human infection. Precautions should be taken to prevent transfusion-transmitted infection between blood donor and recipient animals.

Graphic Abstract

Tickborne Relapsing Fever, Jerusalem, Israel, 2004-2018

To compare tickborne relapsing fever (TBRF) in children and adults in Jerusalem, Israel, we collected data from the medical records of all 92 patients with TBRF during 2004–2018. The 30 children with TBRF had more episodes of fever and lower inflammatory markers than adult patients.

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

Borrelia persica, transmitted by the argasid tick Ornithodoros tholozani, 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 Borrelia infection, tick species, and tick blood meal sources. We collected 51,472 argasid ticks from 16 of 24 caves surveyed. We analyzed 2,774 O. tholozani ticks, and 72 (2.6%) from nine caves were PCR positive for B. persica Infection rates in male, female, and nymphal ticks (4.4%, 3%, and 3.2%, respectively) were higher than in larva (P < 0.001), with only 3 (0.04%) positive larvae. Presence of blood meal was associated with B. persica infection in ticks (P = 0.003), and blood meals of golden jackals, red foxes, and Cairo spiny mouse were associated with infection (P ≤ 0.043). PCR survey of 402 wild mammals revealed B. persica 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 B. persica 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.IMPORTANCE Borrelia persica 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, Ornithodoros tholozani, is also its main reservoir and it transmits B. persica mostly transovarially between tick generations. This study showed that tick infection with B. persica is associated with feeding blood from wild jackals, foxes, and rodents and that transovarial transmission is minimal. Since O. tholozani 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 B. persica 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 O. tholozani populations.

Single Dose of Doxycycline for the Prevention of Tick-borne Relapsing Fever

The current postexposure prophylaxis regimen for tick-borne relapsing fever (TBRF) consists of 5 days' doxycycline. In this observational study of 77 spelunkers at high risk for TBRF, a single dose of 100 mg doxycycline taken up to 72 hours after exposure to ticks was 100% effective in preventing the disease.

Relapsing Fevers: Neglected Tick-Borne Diseases

Relapsing fever still remains a neglected disease and little is known on its reservoir, tick vector and physiopathology in the vertebrate host. The disease occurs in temperate as well as tropical countries. Relapsing fever borreliae are spirochaetes, members of the Borreliaceae family which also contain Lyme disease spirochaetes. They are mainly transmitted by Ornithodoros soft ticks, but some species are vectored by ixodid ticks. Traditionally a Borrelia species is associated with a specific vector in a particular geographical area. However, new species are regularly described, and taxonomical uncertainties deserve further investigations to better understand Borrelia vector/host adaptation. The medical importance of Borrelia miyamotoi, transmitted by Ixodes spp., has recently spawned new interest in this bacterial group. In this review, recent data on tick-host-pathogen interactions for tick-borne relapsing fevers is presented, with special focus on B. miyamotoi.

Borrelia persica infection in rock hyraxes

Tick-borne relapsing fever (TBRF) is an acute infectious disease caused by arthropod-borne spirochetes of the genus Borrelia and characterized by recurrent episodes of fever. Borrelia persica, the causative agent of this disease in Israel, is transmitted by the argasid tick Ornithodoros tholozani. There is little information about the maintenance and possible vertebrate reservoirs of B. persica in nature, but the tick O. tholozani is known to feed on animals that enter its habitat in caves, rock crevices and shady environments. The rock hyrax (Procavia capensis) is commonly found in such habitats and may therefore serve as a reservoir host for O. tholozani. Blood and spleen samples from rock hyraxes were collected from twelve locations in Israel and the West Bank during 2009-2014 to test if these animals may be infected with B. persica. Real-time PCR targeting a segment of the flagellin (flaB) gene was initially used to detect B. persica. Positive samples were further analyzed by PCR, using a segment of the glycerophosphodiester phosphodiesterase (GlpQ) gene for additional confirmation. Borrelia species were identified by nucleotide sequence analysis and the copy number of Borrelia was quantified in blood and spleen samples based on the number of Borrelia 16S rRNA gene copies. A total of 112 hyraxes were examined, with both blood and spleen samples tested from 108 animals. Nine hyraxes were infected with B. persica, with a prevalence of 8%. Of these, two animals were positive for both blood and spleen samples, three only for blood and four only for the spleen. The number of DNA copies of Borrelia 16S rRNA was significantly higher in blood (5 × 10⁶ to 9.2 × 10⁸/ml blood) compared to spleen (2.1 × 10⁴ to 1.0 × 10⁶/ml). We conclude that rock hyraxes are possible reservoirs for B. persica because they have long lifespans and gregarious habits, share habitats with vector ticks, and are naturally infected with this spirochete. Further studies should be conducted in the future to evaluate the competence of hyraxes as reservoirs for B. persica infection.

Epidemiological Study of Endemic Relapsing Fever in Hamadan Province, West of Iran

BACKGROUND

Endemic relapsing fever remains under diagnosed in our area according to a low index of suspicion among clinicians, as well as its difficult diagnosis. The goal of this study was to present the epidemiological aspects of the disease in western Iran.

METHODS

In this analytical-descriptive cross-sectional study, the epidemiological and clinical aspects of relapsing fever were investigated in Hamadan Province, western Iran from 1999 to 2013. A confirmed patient was defined as a person who had both febrile illness and detected spirochetes by Wright-Giemsa or dark-field microscopy in a peripheral blood smear. For the statistical analysis, the statistical software SPSS was used.

RESULTS

During the study period, 276 cases of relapsing fever were recorded that 146 were male. Due to the age group distributions, most of the patients aged less than 20 yr. Patients noticed from April through March, most cases were reported in September (53 cases, 19.2%). Considering time trend of the mentioned disease between 1999 and 2013 showed an increasing trend of disease from 1999 to 2003 (from 2.5% to 21.0%), while the prevalence of disease had a decreasing trend after than from 21.0% in 2003.

CONCLUSION

The rate of endemic relapsing fever is similar in both male and female genders, but its prevalence reduced by increase of age. The trend of the changes in prevalence of the mentioned disease has shown to be downward in recent years probably due to improving health policies especially among children and adolescents and particularly in rural areas.

Borrelia persica infection in dogs and cats: clinical manifestations, clinicopathological findings and genetic characterization

Background

Relapsing fever (RF) is an acute infectious disease caused by arthropod-borne spirochetes of the genus Borrelia. The disease is characterized by recurrent episodes of fever that concur with spirochetemia. The RF borrelioses include louse-borne RF caused by Borrelia recurrentis and tick-borne endemic RF transmitted by argasid soft ticks and caused by several Borrelia spp. such as B. crocidurae, B. coriaceae, B. duttoni, B. hermsii, B. hispanica and B. persica. Human infection with B. persica is transmitted by the soft tick Ornithodoros tholozani and has been reported from Iran, Israel, Egypt, India, and Central Asia.

Methods

During 2003–2015, five cats and five dogs from northern, central and southern Israel were presented for veterinary care and detected with borrelia spirochetemia by blood smear microscopy. The causative infective agent in these animals was identified and characterized by PCR from blood and sequencing of parts of the flagellin (flab), 16S rRNA and glycerophosphodiester phosphodiestrase (GlpQ) genes.

Results

All animals were infected with B. persica genetically identical to the causative agent of human RF. Phylogenetic analysis indicated that DNA sequences from these pet carnivores clustered together with B. persica genotypes I and II from humans and O. tholozani ticks and distinctly from other RF Borrelia spp. The main clinical findings in cats included lethargy, anorexia, anemia in 5/5 cats and thrombocytopenia in 4/5. All dogs were lethargic and anorectic, 4/5 were febrile and anemic and 3/5 were thrombocytopenic. Three dogs were co-infected with Babesia spp. The animals were all treated with antibiotics and the survival rate of both dogs and cats was 80 %. The cat and dog that succumbed to disease died one day after the initiation of antibiotic treatment, while survival in the others was followed by the rapid disappearance of spirochetemia.

Conclusions

This is the first report of disease due to B. persica infection in cats and the first case series in dogs. Infection was associated with anemia and thrombocytopenia. Fever was more frequently observed in dogs than cats. Domestic canines and felines suffer from clinical disease due to B. persica infection and may also serve as sentinels for human infection.

Molecular characterization of Borrelia persica, the agent of tick borne relapsing fever in Israel and the Palestinian Authority

The identification of the Tick Borne Relapsing Fever (TBRF) agent in Israel and the Palestinian Authority relies on the morphology and the association of Borrelia persica with its vector Ornithodoros tholozani. Molecular based data on B. persica are very scarce as the organism is still non-cultivable. In this study, we were able to sequence three complete 16S rRNA genes, 12 partial flaB genes, 18 partial glpQ genes, 16 rrs-ileT intergenic spacers (IGS) from nine ticks and ten human blood samples originating from the West Bank and Israel. In one sample we sequenced 7231 contiguous base pairs that covered completely the region from the 5'end of the 16S rRNA gene to the 5'end of the 23S rRNA gene comprising the whole 16S rRNA (rrs), and the following genes: Ala tRNA (alaT), Ile tRNA (ileT), adenylosuccinate lyase (purB), adenylosuccinate synthetase (purA), methylpurine-DNA glycosylase (mag), hypoxanthine-guanine phosphoribosyltransferase (hpt), an hydrolase (HAD superfamily) and a 135 bp 5' fragment of the 23S rRNA (rrlA) genes. Phylogenic sequence analysis defined all the Borrelia isolates from O. tholozani and from human TBRF cases in Israel and the West Bank as B. persica that clustered between the African and the New World TBRF species. Gene organization of the intergenic spacer between the 16S rRNA and the 23S rRNA was similar to that of other TBRF Borrelia species and different from the Lyme disease Borrelia species. Variants of B. persica were found among the different genes of the different isolates even in the same sampling area.

Post exposure prophylaxis of tick-borne relapsing fever

Tick-borne relapsing fever (TBRF) is endemic to Israel. Since 2004, the Israel Defence Forces (IDF) has mandated the prophylaxis of tick-bitten subjects with a five-day doxycycline course. We examined the safety and effectiveness of this policy in preventing TBRF. We analyzed the records from January 2004 to January 2007, and identified all reported events of tick bites or TBRF cases. Data were available on 27 events in which 816 soldiers have undergone physical examination following exposure, and seven TBRF cases were recorded in this group-an attack rate of 0.86% compared with the expected rate of 5.34% from previous army data (relative risk [RR] = 0.16). Of those screened, 128 (15.7%) had tick-bite and were intended for prophylaxis, of which four TBRF cases occurred-3.13% attack rate compared with an expected rate of 38.4% in these bitten individuals without prophylaxis (RR = 0.08, number needed to treat = 3). In all cases in which screening and prophylaxis were provided within 48 h of tick bite, complete prevention of TBRF was achieved. No cases of Jarisch-Herxheimer reaction (JHR) was recorded. Tick-bite screening and prophylactic treatment with doxycycline in endemic areas is a practical, safe, and highly effective policy for preventing TBRF.

Relapsing fever borreliosis in Eurasia--forgotten, but certainly not gone!

Tick-borne relapsing fever (TBRF) has been reported in Eurasia and attributed mainly to Borrelia persica, although other entities have also been described. Ornithodoros tholozani is the most important tick vector, found in India and Kashmir, the southern countries of the former USSR, Iran, Iraq, Syria, Jordan, Turkey, Israel, Egypt, and Cyprus. It inhabits caves, ruins, and burrows of rodents and small mammals. In the northern countries, O. tholozani also lives in houses and cowsheds. In Israel, 30-60% of caves were found to be infested. PCR studies of Borrelia infection of O. tholozani ticks collected in caves showed very variable rates, ranging from less than 2% to 40%. The number of human cases reported varies among countries, from eight cases per year in Israel to 72 cases per year in Iran. The incubation period is 5-9 days. The fever attacks last from several hours to 4 days, and are accompanied by chills, headache, nausea and vomiting, sweating, abdominal pain, arthralgia, and cough; complications are rare. Other described Borrelia species are Borrelia caucasica, Borrelia latyschewii, Borrelia microtii, and Borrelia baltazardi. The classic taxonomy based on the co-speciation concept is very complex and very confusing. For this reason, 16S rRNA and flaB genes were used for taxonomic clarification. Sequencing of Israeli TBRF flaB genes, from human and tick samples, has demonstrated a third cluster corresponding to the Eurasia strains, in addition to both New World and Old World clusters. Thin and thick blood smears remain the most frequently used methods for laboratory diagnosis, with a sensitivity of 80%. PCR-based diagnosis is the most sensitive method, and has the advantage of allowing species identification.

Alkhurma hemorrhagic fever virus in Ornithodoros savignyi ticks

Evidence for the tickborne nature of Alkhurma hemorrhagic fever virus (AHFV) is indirect because AHFV has not been detected in arthropods. One Ornithodoros savignyi tick from Saudi Arabia contained AHFV RNA. This is the first direct evidence that AHFV is a tickborne flavivirus and confirms the association between human AHFV cases and tickbite history.

Molecular characterization of tickborne relapsing fever Borrelia, Israel

Blood samples from 18 tickborne relapsing fever (TBRF) patients and Ornithodoros tholozani specimens were tested with a Borrelia fla B-PCR. Results were positive for all patients and 2%–40% of ticks. A 7–amino acid gap characterized all 9 sequenced flagellin gene amplicons. By phylogenetic analysis, Israel TBRF Borrelia sequences clustered separately from American and African groups.

Possibilities for relapsing fever reemergence

Increasing globalization may pave the way for reemergence of relapsing fever.

Relapsing fever Borrelia infections have attracted little attention in recent years; however, where endemic, these infections still result in considerable illness and death. Despite the marked antimicrobial drug susceptibility of these organisms, therapy is often delayed through lack of clinical suspicion. With increasing travel, infections may be imported, through exotic relapsing fever infection or through resurgence of infected disease vectors. Although louseborne relapsing fever is now geographically limited, it was once of global importance. The possibility for reemergence was recently highlighted by the probable reemergence of louseborne relapsing fever in homeless persons from France. Host limitations enforced through louseborne transmission are less applicable for the tickborne forms of relapsing fever. Although the latter have reduced potential for epidemic spread, they have the ability to infect diverse hosts, thus establishing reservoirs of infection and presenting greater challenges for their control.

Detection of relapsing fever in human blood samples from Israel using PCR targeting the glycerophosphodiester phosphodiesterase (GlpQ) gene

Relapsing fever caused by Borrelia persica is an acute tick-borne disease infecting people in the Middle East. A PCR test targeting the glycerophosphodiester phosphodiesterase (GlpQ) gene was used to detect infection in the blood of suspected relapsing fever patients. The assay detected infection in all 19 patients from Israel who were spirochetemic by blood smear examination and in two additional patients with clinical relapsing fever who were negative by smear examination. Patients were positive by PCR of blood only at the febrile stage and not during the incubation period prior to the appearance of clinical symptoms. Of 52 tick-bitten subjects who were tested and followed-up after being bitten by ticks, 10 developed symptoms of relapsing fever and all became positive by PCR following an earlier negative test. Partial sequencing of the 16S rRNA gene supported by phylogenetic analysis indicated that infection was caused by B. persica or a closely related species. A phylogenetic analysis of the GlpQ sequence showed that it was different yet closely related to other relapsing fever Borrelia spp. present in the Old World. The GlpQ PCR was positive also with the relapsing fever spirochetes B. recurrentis and B. crocidure but not with the Lyme disease agent B. burgdorferi DNA. A second modified GlpQ PCR was able to discriminate between probable B. persica and B. recurrentis and B. crocidurae infection. This study describes the first molecular assay for the diagnosis of relapsing fever caused by B. persica.