Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (723 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
An acute infection characterized by recurrent episodes of pyrexia alternating with asymptomatic intervals of apparent recovery. This condition is caused by spirochetes of the genus borrelia. It is transmitted by the bites of either the body louse (pediculus humanus corporis), for which humans are the reservoir, or by soft ticks of the genus ornithodoros, for which rodents and other animals are the principal reservoirs.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Fever, Relapsing; Relapsing Fevers; Borrelia hermsii Infection; Borrelia hermsii Infections; Infection, Borrelia hermsii; Tick-borne Relapsing Fever; Fever, Tick-borne Relapsing; Relapsing Fever, Tick-borne.
Where it fits in the MeSH classification
- Broader topics
- Borrelia Infections; Tick-Borne Diseases
Related concepts
- Pyrexia
- Spirochetes
- Borrelia
- Bites
- Pediculus
- Ornithodoros
Research landscape
PubMed indexes 1,164 records tagged with the MeSH heading “Relapsing Fever” (counts retrieved 2026-10-29). 169 of them (14.5%) were published from 2020 onward, and the busiest period so far is through 1999 with 593 records.
Reviews account for 116 records (10.0%) and meta-analyses for 1. Randomized controlled trials number 9 (0.8%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 593 |
| 2000-2009 | 158 |
| 2010-2019 | 244 |
| 2020 onward | 169 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 116 | 10.0% |
| Meta-analyses | 1 | 0.1% |
| Randomized controlled trials | 9 | 0.8% |
Method: PubMed query "Relapsing Fever"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in infectious diseases
Infectious disease evidence combines microbiology, epidemiology and clinical trials. Laboratory studies identify pathogens and how they cause harm; surveillance and outbreak investigations describe who is affected and how infection spreads; trials establish whether treatments and vaccines work. Results depend on place and time, because pathogens evolve and resistance patterns and population immunity change. Check when and where the data were collected, how cases were defined and how up to date the evidence is.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia | 2011 | Research article Design not recorded in structured metadata | 306 | cc by PMID 22000350 · DOI · PMC3310649 |
| Relapsing Fevers: Neglected Tick-Borne Diseases | 2018 | Review article Design not recorded in structured metadata | 132 | cc by PMID 29670860 · DOI · PMC5893795 |
| Vector interactions and molecular adaptations of lyme disease and relapsing fever spirochetes associated with transmission by ticks | 2002 | Review article Design not recorded in structured metadata | 127 | cc by PMID 11897061 · DOI · PMC2732444 |
| Prevalence, distribution, and phylogenetics of the tick-borne relapsing fever spirochete Borrelia turicatae in the soft tick Ornithodoros turicata americanus in Florida | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42371983 · DOI · PMC13327513 |
Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Borrelia miyamotoi is distantly related to B.
- Closing excerpt
- miyamotoi infection may cause relapsing fever and Lyme disease-like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (138 words)
Borrelia miyamotoi is distantly related to B. burgdorferi and transmitted by the same hard-body tick species. We report 46 cases of B. miyamotoi infection in humans and compare the frequency and clinical manifestations of this infection with those caused by B. garinii and B. burgdorferi infection. All 46 patients lived in Russia and had influenza-like illness with fever as high as 39.5°C; relapsing febrile illness occurred in 5 (11%) and erythema migrans in 4 (9%). In Russia, the rate of B. miyamotoi infection in Ixodes persulcatus ticks was 1%-16%, similar to rates in I. ricinus ticks in western Europe and I. scapularis ticks in the United States. B. miyamotoi infection may cause relapsing fever and Lyme disease-like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 22000350 · DOI · PMC3310649
Relapsing Fevers: Neglected Tick-Borne Diseases [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Relapsing fever still remains a neglected disease and little is known on its reservoir, tick vector and physiopathology in the vertebrate host.
- Closing excerpt
- miyamotoi.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (136 words)
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.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29670860 · DOI · PMC5893795
Vector interactions and molecular adaptations of lyme disease and relapsing fever spirochetes associated with transmission by ticks [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Pathogenic spirochetes in the genus Borrelia are transmitted primarily by two families of ticks.
- Closing excerpt
- hermsii change their outer surface during their alternating infections in ticks and mammals, which in turn suggests biological functions for a few surface-exposed lipoproteins.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (157 words)
Pathogenic spirochetes in the genus Borrelia are transmitted primarily by two families of ticks. The Lyme disease spirochete, Borrelia burgdorferi, is transmitted by the slow-feeding ixodid tick Ixodes scapularis, whereas the relapsing fever spirochete, B. hermsii, is transmitted by Ornithodoros hermsi, a fast-feeding argasid tick. Lyme disease spirochetes are generally restricted to the midgut in unfed I. scapularis. When nymphal ticks feed, the bacteria pass through the hemocoel to the salivary glands and are transmitted to a new host in the saliva after 2 days. Relapsing fever spirochetes infect the midgut in unfed O. hermsi but persist in other sites including the salivary glands. Thus, relapsing fever spirochetes are efficiently transmitted in saliva by these fast-feeding ticks within minutes of their attachment to a mammalian host. We describe how B. burgdorferi and B. hermsii change their outer surface during their alternating infections in ticks and mammals, which in turn suggests biological functions for a few surface-exposed lipoproteins.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 11897061 · DOI · PMC2732444
Prevalence, distribution, and phylogenetics of the tick-borne relapsing fever spirochete Borrelia turicatae in the soft tick Ornithodoros turicata americanus in Florida [4]
Abstract reading summary — source excerpts
- Opening excerpt
- In the southwestern United States, the occurrence and potential for disease spread of Tick-Borne Relapsing Fever (TBRF) has been studied.
- Closing excerpt
- By understanding the occurrence and phylogenetics of Borrelia turicatae in the state, we can better comprehend and mitigate the risk of this neglected vector-borne disease for humans and companion animals in Florida.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (292 words)
In the southwestern United States, the occurrence and potential for disease spread of Tick-Borne Relapsing Fever (TBRF) has been studied. In Florida, Borrelia pathogens that cause TBRF have only been found in two domestic dogs (Canis lupus familiaris), yet the soft tick vector, Ornithodoros turicata americanus, is commonly found throughout the state. The goal of our study was to provide the first large-scale investigation of this disease system in the southeastern US. Our objectives were to: 1) describe the occurrence and prevalence of Borrelia spp. in ticks found throughout their distribution; and 2) phylogenetically describe the pathogen species compared to other isolates of B. turicatae. We pooled ticks by sample location and extracted DNA from over 3,000 ticks systematically collected throughout Florida. Conventional PCR was used with a genus-wide IGS primer to detect any Borrelia spp. present in the ticks. We discovered a low but detectable prevalence (7/745; 0.94%) of the pathogen within localized foci, which could present an epidemiological risk to humans and companion animals in those areas. We Sanger sequenced the 7 pools that were positive for Borrelia spp. and created a phylogenetic tree with our samples and 27 previously described isolates. Our tree showed clustering of our samples into two distinct clades, one that fit with Texas isolates and one that was entirely distinct. We hypothesized that a combination of biogeographic and host influences may be the driving force behind the history of Borrelia turicatae in Florida. Future research is needed to improve our understanding of the drivers of pathogen occurrence and the phylogeography of this species. By understanding the occurrence and phylogenetics of Borrelia turicatae in the state, we can better comprehend and mitigate the risk of this neglected vector-borne disease for humans and companion animals in Florida.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42371983 · DOI · PMC13327513
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Biology of Borrelia species [5]
- Research article The body louse as a vector of reemerging human diseases [6]
- Research article Borrelia miyamotoi infection in nature and in humans [7]
- Research article Tick-borne relapsing fever [8]
- Research article Antigenic variation of a relapsing fever Borrelia species [9]
- Research article Neuroborreliosis during relapsing fever: review of the clinical manifestations, pathology, and treatment of infections in humans and experimental animals [10]
References
- Platonov AE, Karan LS, Kolyasnikova NM, Makhneva NA, Toporkova MG, Maleev VV, et al.. Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia. . 2011. PMID 22000350 · DOI · PMC3310649
- Talagrand-Reboul E, Boyer PH, Bergström S, Vial L, Boulanger N. Relapsing Fevers: Neglected Tick-Borne Diseases. . 2018. PMID 29670860 · DOI · PMC5893795
- Schwan TG, Piesman J. Vector interactions and molecular adaptations of lyme disease and relapsing fever spirochetes associated with transmission by ticks. . 2002. PMID 11897061 · DOI · PMC2732444
- Canino N, Torhorst CW, Botero-Cañola S, Wilson KN, Wisely SM. Prevalence, distribution, and phylogenetics of the tick-borne relapsing fever spirochete Borrelia turicatae in the soft tick Ornithodoros turicata americanus in Florida. . 2026. PMID 42371983 · DOI · PMC13327513
- Barbour AG, Hayes SF. Biology of Borrelia species. Microbiol Rev. 1986. PMID 3540570 · DOI · PMC373079
- Raoult D, Roux V. The body louse as a vector of reemerging human diseases. Clin Infect Dis. 1999. PMID 10589908 · DOI
- Krause PJ, Fish D, Narasimhan S, Barbour AG. Borrelia miyamotoi infection in nature and in humans. Clin Microbiol Infect. 2015. PMID 25700888 · DOI · PMC4470780
- Dworkin MS, Schwan TG, Anderson DE, Borchardt SM. Tick-borne relapsing fever. Infect Dis Clin North Am. 2008. PMID 18755384 · DOI · PMC3725823
- Barbour AG. Antigenic variation of a relapsing fever Borrelia species. Annu Rev Microbiol. 1990. PMID 2252381 · DOI
- Cadavid D, Barbour AG. Neuroborreliosis during relapsing fever: review of the clinical manifestations, pathology, and treatment of infections in humans and experimental animals. Clin Infect Dis. 1998. PMID 9455525 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-29.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.