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PubMed1978

Tick-borne relapsing fever in the Eastern United States.

Tick-borne relapsing fever is endemic in the western part of the United States, but it has not been reported east of the Mississippi River. Sporadic cases have been reported in the eastern part of the United States, but travel to the West during the incubation period appeared to provide the source of infection. In the fall of 1975, a case of relapsing fever was diagnosed in Cincinnati in a child who had not traveled outside of Ohio, indicating the presence of Borrelia in this area. Serial serological studies indicated that B turicatae was the species involved. The occurrence of this case suggests that relapsing fever may exist in the eastern part of the United States, but its presence may not be appreciated because of the rarity of the disease and the difficulty in confirming the diagnosis.

Anti-Bacterial Agents↗

PubMed1991

Molecular biology of antigenic variation in Lyme borreliosis and relapsing fever: a comparative analysis.

Lyme borreliosis and relapsing fever are human diseases caused by different members of the genus Borrelia. Antigenic variation has been a well-known feature of the pathogenesis of relapsing fever for decades. More recently it has been recognized that Borrelia burgdorferi, the agent of Lyme borreliosis, also can vary its surface antigens. In this review the biology and molecular biology of antigenic variation of the pathogens in these two disorders are compared.

Antigenic Variation↗

PubMed2005

Horizontally acquired genes for purine salvage in Borrelia spp. causing relapsing fever.

Unlike Borrelia burgdorferi, the relapsing fever agent Borrelia hermsii and the related Borrelia miyamotoi had purA and purB genes of the purine salvage pathway. These were located among the rRNA genes. Phylogenetic analysis indicated that these genes had a different evolutionary history than those of orthologs in other spirochetes.

Adenylosuccinate Lyase↗

PubMed2006

Postexposure treatment with doxycycline for the prevention of tick-borne relapsing fever.

BACKGROUND: Tick-borne relapsing fever (TBRF) is an acute febrile illness. In Israel, TBRF is caused by Borrelia persica and is transmitted by Ornithodoros tholozani ticks. We examined the safety and efficacy of postexposure treatment to prevent TBRF. METHODS: In a double-blind, placebo-controlled trial, 93 healthy subjects with suspected tick exposure (52 with signs of tick bites and 41 close contacts--those without signs but with a similar risk of contact with ticks) were randomly assigned to receive either doxycycline (Dexxon, in a dose of 200 mg the first day and then 100 mg per day for four days) or placebo after presumed exposure to TBRF. Cases of TBRF were defined by fever and a positive blood smear. Serologic analysis for cross-reactivity to Borrelia burgdorferi and polymerase chain reaction (PCR) for the borrelia glpQ gene were also performed. RESULTS: After randomization, 47 subjects (26 with signs of tick bites and 21 close contacts) received doxycycline. Forty-six other subjects (26 with signs of tick bites and 20 close contacts) received placebo. All 10 cases of TBRF identified by a positive blood smear were in the placebo group of subjects with signs of a tick bite (P<0.001). These findings suggested a 100 percent efficacy of preemptive treatment (95 percent confidence interval, 46 to 100 percent). PCR for the borrelia glpQ gene was negative at baseline for all subjects and subsequently positive in all subjects with fever and a positive blood smear. Seroconversion was detected in eight of nine cases of TBRF. PCR and serum samples were negative for all of the other subjects tested. No major treatment-associated adverse effects were identified. CONCLUSIONS: Treatment with doxycycline is safe and efficacious in preventing TBRF after suspected exposure to ticks in a high-risk environment. (ClinicalTrials.gov number, NCT00237016 [ClinicalTrials.gov].).

Adult↗

PubMed2002

Tick-borne relapsing fever caused by Borrelia turicatae.

Tick-borne relapsing fever manifests as relapsing episodes of fever with significant morbidity and mortality. We report a case of Borrelia turicatae disease in a 13-year-old male youth with outdoor exposures in Texas. After multiple clinic visits the diagnosis was made, and treatment was initiated. The patient did well without long term sequelae.

Adolescent↗

PubMed1991

Can protracted relapsing fever resemble Lyme disease?

We report the case of a Protestant missionary who contracted tick-borne relapsing fever in 1979 while serving in the Sudan. Despite tetracycline treatment, his acute illness ran a protracted course, with migratory polyarthralgias lasting approximately 10 months. Symptoms recurred in 1984 and have persisted. At regular intervals, the patient has experienced recurrent episodes of fever, generalized fatigue, bilateral upper and lower extremity muscle weakness, and asymetric large joint polyarthralgia. Indirect fluorescent antibody testing of sera demonstrated titers of 1:16 for B. burgdorferi and 1:64 for B. hermsii, and immunoblotting confirmed past exposure to relapsing fever, but not Lyme disease. It is hypothesized that this individual's chronic symptoms have been related to relapsing fever, and that in certain situations or in select individuals, relapsing fever can be capable of producing a chronic clinical picture analogous to Lyme disease.

Adult↗

PubMed1998

Cloning and molecular characterization of a multicopy, linear plasmid-carried, repeat motif-containing gene from Borrelia turicatae, a causative agent of relapsing fever.

Borrelia turicatae is one of several spirochete species that can cause relapsing fever. Here, we describe the identification and characterization of a gene from B. turicatae and other relapsing-fever spirochetes that exhibits homology with the rep+ and ORF-E gene families of the Lyme disease spirochetes. This gene, which we have designated repA, encodes a putative protein of 30.2 kDa with an isoelectric point of 4.69. The central region of RepA harbors a series of amino acid repeat motifs which exhibit homology with casein kinase 2 phosphorylation sites. Through Southern hybridization analyses, we demonstrate that repA (or a closely related sequence) is multicopy in the relapsing-fever spirochetes and is carried on variably sized linear plasmids in both Borrelia parkeri and B. turicatae. Transcriptional analyses demonstrate that repA is expressed, albeit at low levels, during in vitro cultivation of B. turicatae. Transcriptional start site analysis revealed that repA is preceded by a consensus ribosomal binding site and an appropriately spaced promoter element. The sequence conservation, unique features, and multicopy status of repA and its homologs suggest that RepA may play an important genus-wide role in the biology of the Borrelia.

Amino Acid Sequence↗

PubMed2006

Relapsing fever spirochaetes produce a serine protease that provides resistance to oxidative stress and killing by neutrophils.

The spirochaetes that cause tick-borne relapsing fever and Lyme disease are closely related human pathogens, yet they differ significantly in their ecology and pathogenicity. Genome sequencing of two species of relapsing fever spirochaetes, Borrelia hermsii and Borrelia turicatae, identified a chromosomal open reading frame, designated bhpA, not present in the Lyme disease spirochaete Borrelia burgdorferi. The predicted amino acid sequence of bhpA was homologous with the HtrA serine proteases, which are involved with stress responses and virulence in other bacteria. B. hermsii produced an active serine protease that was recognized by BhpA antibodies and the recombinant BhpA protein-degraded beta-casein. bhpA was transcribed in vitro at all growth temperatures and transcription levels were slightly elevated at higher temperatures. These results correlated with the synthesis of BhpA during B. hermsii infection in mice. With the exception of Borrelia recurrentis, the bhpA gene, protein and enzymatic activity were found in all relapsing fever spirochaetes, but not in Lyme disease or related spirochaetes. Heterologous expression of bhpA in B. burgdorferi increased the spirochaete's resistance to both oxidative stress and killing by human neutrophils. Therefore, we propose that bhpA encodes a unique and functional serine protease in relapsing fever spirochaetes. This periplasmic enzyme may prevent the accumulation of proteins damaged by the innate immune response and contribute to the ability of the relapsing fever spirochaetes to achieve high cell densities in blood.

Animals↗

PubMedDate not supplied

[Current status of the foci and morbidity of tick-borne relapsing fever in Uzbekistan].

The contemporary state of settlement nidi of tick-borne relapsing fever is discussed on the material collected in the Namanganskaya and Andizhanskaya regions of Uzbek SSR. Despite the control measures and rise of the sanitary culture of population the conditions are still preserved for the maintenance of nidi. As in ancient estates, classical nidi of tick-borne relapsing fever, so in modern ones there are preserved conditions for existence of flourishing populations of vectors, i.e. favourable habitats and the availability of hosts. The analysis of factors is given affecting the contemporary level of sick-rate with tick-borne relapsing fever. Within the limits of the distribution area of the vector a higher sick-rate should be expected than it is registered.

Animals↗

PubMed2000

The relapsing fever spirochete Borrelia hermsii contains multiple, antigen-encoding circular plasmids that are homologous to the cp32 plasmids of Lyme disease spirochetes.

Borrelia hermsii, an agent of tick-borne relapsing fever, was found to contain multiple circular plasmids approximately 30 kb in size. Sequencing of a DNA library constructed from circular plasmid fragments enabled assembly of a composite DNA sequence that is homologous to the cp32 plasmid family of the Lyme disease spirochete, B. burgdorferi. Analysis of another relapsing fever bacterium, B. parkeri, indicated that it contains linear homologs of the B. hermsii and B. burgdorferi cp32 plasmids. The B. hermsii cp32 plasmids encode homologs of the B. burgdorferi Mlp and Bdr antigenic proteins and BlyA/BlyB putative hemolysins, but homologs of B. burgdorferi erp genes were absent. Immunoblot analyses demonstrated that relapsing fever patients produced antibodies to Mlp proteins, indicating that those proteins are synthesized by the spirochetes during human infection. Conservation of cp32-encoded genes in different Borrelia species suggests that their protein products serve functions essential to both relapsing fever and Lyme disease spirochetes. Relapsing fever borreliae replicate to high levels in the blood of infected animals, permitting direct detection and possible functional studies of Mlp, Bdr, BlyA/BlyB, and other cp32-encoded proteins in vivo.

Amino Acid Sequence↗

PubMed1980

Tick-borne relapsing fever in the Pacific Northwest: an underdiagnosed illness?

Some 30 cases of tick-borne relapsing fever due to Borrelia are known to have occurred between 1965 and 1978 in the Pacific Northwest. This disease was found more frequently in young men with a history of wilderness exposure during the summer months. Recurrent fever was the most common symptom with temperatures reaching higher than 39.5 degrees C (103.1 degrees F) in all cases, and many patients had three or more febrile episodes. Splenomegaly was the second most common finding reported. Diagnosis of relapsing fever was made in 20 cases by identifying spirochetes on peripheral blood smears. In ten remaining cases the diagnosis was made on clinical and epidemiologic grounds.Information regarding therapy was available in 21 cases. Ten patients received a tetracycline drug and all had a prompt response without relapse. Two of the patients died, a 68-year-old woman with possible myocardial involvement and a newborn infant with infection acquired in utero and meningeal involvement. The diagnosis was often delayed in spite of outpatient evaluation and admittance to hospital, probably because borreliosis was not considered in the differential diagnosis. Because tick-borne relapsing fever is eventually a self-limited disease in most patients, it is probably not recognized often enough. Awareness of this disease and examination of the peripheral blood smear for spirochetes will lead to earlier diagnosis. Prompt initiation of tetracycline therapy should reduce morbidity associated with borreliosis.

Adult↗

PubMed2005

Relapsing fever spirochetes contain chromosomal genes with unique direct tandemly repeated sequences.

Genome sequencing of the relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae identified three open reading frames (ORFs) on the chromosomes that contained internal, tandemly repeated amino acid sequences that were absent in the Lyme disease spirochete Borrelia burgdorferi. The predicted amino acid sequences of these genes (BH0209, BH0512, and BH0553) have hydrophobic N termini, indicating that these proteins may be secreted. B. hermsii transcribed the three ORFs in vitro, and the BH0512- and BH0553-encoded proteins (PBH-512 and PBH-553) were produced in vitro and in experimentally infected mice. PBH-512 and PBH-553 were on the spirochete's outer surface, and antiserum to these proteins reduced the adherence of B. hermsii to red blood cells. PCR analyses of 28 isolates of B. hermsii and 8 isolates of B. turicatae demonstrated polymorphism in each gene correlated with the number of repeats. Serum samples from relapsing fever patients reacted with recombinant PBH-512 and PBH-553, suggesting that these proteins are produced during human infection. These polymorphic proteins may be involved in the pathogenicity of these relapsing fever spirochetes and provide a mechanism for antigenic heterogeneity within their populations.

Amino Acid Sequence↗

PubMed2005

Cardiac apoptosis in severe relapsing fever borreliosis.

Previous studies revealed that the heart suffers significant injury during experimental Lyme and relapsing fever borreliosis when the immune response is impaired (D. Cadavid, Y. Bai, E. Hodzic, K. Narayan, S. W. Barthold, and A. R. Pachner, Lab. Investig. 84:1439-1450, 2004; D. Cadavid, T. O'Neill, H. Schaefer, and A. R. Pachner, Lab. Investig. 80:1043-1054, 2000; and D. Cadavid, D. D. Thomas, R. Crawley, and A. G. Barbour, J. Exp. Med. 179:631-642, 1994). To investigate cardiac injury in borrelia carditis, we used antibody-deficient mice persistently infected with isogenic serotypes of the relapsing fever agent Borrelia turicatae. We studied infection in hearts 1 to 2 months after inoculation by TaqMan reverse transcription-PCR and immunohistochemistry (IHC) and inflammation by hematoxylin and eosin and trichrome staining, IHC, and in situ hybridization (ISH). We studied apoptosis by terminal transferase-mediated DNA nick end labeling assay and measured expression of apoptotic molecules by RNase protection assay, immunofluorescence, and immunoblot. All antibody-deficient mice, but none of the immunocompetent controls, developed persistent infection of the heart. Antibody-deficient mice infected with serotype 2 had more severe cardiac infection and injury than serotype 1-infected mice. The injury was more severe around the base of the heart and pericardium, corresponding to sites of marked infiltration by activated macrophages and upregulation of interleukin-6 (IL-6). Infected hearts showed evidence of apoptosis of macrophages and cardiomyocytes as well as significant upregulation of caspases, most notably caspase-1. We conclude that persistent infection with relapsing fever borrelias causes significant loss of cardiomyocytes associated with prominent infiltration by activated macrophages, upregulation of IL-6, induction of caspase-1, and apoptosis.

Animals↗

PubMed2005

Tick-borne relapsing fever during pregnancy: a case report.

BACKGROUND: Tick-borne relapsing fever (TBRF) is uncommon. Vertical transmission in the gravid woman may result in spontaneous abortion, preterm delivery or perinatal mortality. We report a case in a pregnant woman who experienced a Jarisch-Herxheimer reaction (J-HR). CASE: A 24-year-old woman at 23 weeks' gestation had a relapsing fever of unknown origin and nonspecific complaints. Her peripheral blood smear demonstrated spirochetes consistent with TBRF caused by Borrelia. Treatment with antibiotics precipitated J-HR. Supportive measures and appropriate antibiotic therapy resulted in a clinical cure and normal term delivery. CONCLUSION: The diagnosis of TBRF should be considered in individuals with recurrent fevers, especially those who have been in mountainous regions where Borrelia hermsii exists. Individuals receiving antimicrobials should be closely monitored for a J-HR.

Adult↗

PubMed1999

Erythrocyte-aggregating relapsing fever spirochete Borrelia crocidurae induces formation of microemboli.

The African relapsing fever spirochete Borrelia crocidurae forms aggregates with erythrocytes, resulting in a delayed immune response. Mice were infected with B. crocidurae and monitored during 50 days after infection. Spirochetes were observed extravascularly at day 2 after infection. Two days later, inflammatory responses, cell death, and tissue damage were evident. The pathologic responses in lungs and kidneys were similar, whereas the symptoms in the brains were delayed, with a less pronounced inflammatory response. Microemboli were found in the blood vessels, possibly a result of the erythrocyte aggregation. The B. crocidurae invasion emerged more rapidly than has been described for Lyme disease-causing Borrelia species. In addition to erythrocyte rosetting, the presence of extravascular B. crocidurae indicates a novel route for these bacteria to propagate and cause damage in the mammalian host. The histopathologic findings in this study may explain the clinical manifestations of human relapsing fever.

Animals↗

PubMed2004

Identification and characterization of a linear-plasmid-encoded factor H-binding protein (FhbA) of the relapsing fever spirochete Borrelia hermsii.

In North America, tick-borne relapsing fever (TBRF) is caused by the spirochete species Borrelia hermsii, Borrelia parkeri, and Borrelia turicatae. We previously demonstrated that some isolates of B. hermsii and B. parkeri are capable of binding factor H and that cell-bound factor H can participate in the factor I-mediated cleavage of C3b. Isolates that bound factor H expressed a factor H-binding protein (FHBP) that we estimated to be approximately 19 to 20 kDa in size and thus, pending further characterization, temporarily designated FHBP19. Until this report, none of the FHBPs of the TBRF spirochetes had been characterized. Here we have recovered the gene encoding the FHBP of B. hermsii YOR from a lambda ZAP II library and determined its sequence. The gene encodes a full-length protein of 22.7 kDa, which after processing is predicted to be 20.5 kDa. This protein, which we redesignate factor H-binding protein A (FhbA), is unique to B. hermsii. Two-dimensional pulsed-field gel electrophoresis and hybridization analyses revealed that the B. hermsii gene encoding FhbA is a single genetic locus that maps to a linear plasmid of approximately 220 kb. The general properties of FhbA were also assessed. The protein was found to be surface exposed and lipidated. Analysis of the antibody response to FhbA in infected mice revealed that it is antigenic during infection, indicating expression during infection. The identification and characterization of FhbA provides further insight into the molecular mechanisms of pathogenesis of the relapsing fever spirochetes.

Amino Acid Sequence↗

PubMed1993

Epidemic of louse-borne relapsing fever in Ethiopia.

During summer 1991 an outbreak of louse-borne relapsing fever occurred simultaneously in two transit camps established for prisoners of war being returned from Eritrea at the end of the Ethiopian civil war. Only antibiotic treatment was given at the Bahr Dar camp where the frequency of cases increased for 20 days. Vector control by delousing in addition to antibiotics was given at Mekele camp where the frequency of cases fell over a similar period. This difference was significant (p < 0.001). Furthermore, there was a significant correlation between the decreasing proportion of camp inhabitants that had not been deloused at Mekele camp each day and the numbers of patients with fever (r = 0.89, p < 0.001). Taken together, these results confirm that effective control of an epidemic of louse-borne relapsing fever is dependent on efficient vector control in addition to antibiotic treatment.

Adolescent↗

PubMed2006

Molecular divergences of the Ornithodoros sonrai soft tick species, a vector of human relapsing fever in West Africa.

The soft tick Ornithodoros sonrai is recognized as the only vector of Borrelia crocidurae causing human relapsing fever in West Africa. Its determination has been exclusively based on morphological features, geographical distribution and vector competence. Some ambiguities persist in its systematics and may cause misunderstanding about West African human relapsing fevers epidemiology. By amplifying and aligning 16S and 18S rDNA genes in O. sonrai specimens collected from 14 distinct sites in Senegal and Mauritania, we showed the existence of four genetically different subgroups that were morphologically and ecologically identified as belonging to the same species. Within O. sonrai, intraspecific polymorphism was high (pairwise divergence from 0.2% to 16.4%). In all cases, these four subgroups formed a monophyletic clade sharing a common ancestor with East African soft ticks that transmit Borrelia duttoni human relapsing fever. From amplification of the flagellin gene of B. crocidurae we verified that all subgroups of O. sonrai were infected by B. crocidurae and may constitute vectors for this pathogen. All flagellin sequences were identical, refuting the hypothesis suggesting parallel evolution between O. sonrai and B. crocidurae. However, differences in infection rates were significant, suggesting different vector competences between subgroups of O. sonrai.

Africa, Western↗