Explore the vast range of titles available.

We conducted a molecular survey for Borrelia spp. in Ornithodoros ticks previously reported as biting humans. We collected specimens in natural ecosystems and inside human dwellings in 6 states in Brazil. Phylogenetic analyses unveiled the occurrence of 4 putatively new species of relapsing fever group borreliae.

Lyme disease (LD) is caused by a group of tick-borne bacteria of the genus Borrelia termed Lyme disease Borreliae (LDB). The detection of serum antibodies to specific LDB antigens is widely used to support diagnosis of LD. Recent findings highlight a need for serological tests that can differentiate LD from tick-borne relapsing fever (TBRF) caused by a separate group of Borrelia species termed relapsing fever Borreliae. This is because LD and TBRF share some clinical symptoms and can occur in overlapping locations. The development of serological tests for TBRF is at an early stage compared with LD. This article reviews the application of line immunoblots (IBs), where recombinant proteins applied as lines on nitrocellulose membrane strips are used to detect antibodies in patient sera, for the diagnosis and differentiation of LD and TBRF.

Borreliae of the relapsing fever group (RFG) are heterogenous and can be divided mainly into three groups according to vectors, namely the soft-tick-borne relapsing fever (STBRF) Borreliae, the hard-tick-borne relapsing fever (HTBRF) Borreliae, the louse-borne relapsing fever (LBRF) Borreliae, and the avian relapsing fever ones. With respect to the geographical distribution, the STBRF Borreliae are further subdivided into Old World and New World strains. Except for the Avian relapsing fever group Borreliae, which cause avian spirochetosis, all the others share infectivity in humans. They are indeed the etiological agent of both endemic and epidemic forms of relapsing fever, causing high spirochaetemia and fever. Vectors are primarily soft ticks of Ornithodoros spp. in the STBRF group; hard ticks, notably Ixodes sp., Amblyomma sp., Dermacentor sp., and Rhipicephalus sp., in the HTBRF group; and the louse pediculus humanus humanus in the TBRF one. A recent hypothesis was supported for a common ancestor of RFG Borreliae, transmitted at the beginning by hard-body ticks. Accordingly, STBRF Borreliae switched to use soft-bodied ticks as a vector, which was followed by the use of lice by Borrelia recurrentis. There are also new candidate species of Borreliae, at present unclassified, which are also described in this review.

Lyme borreliosis (LB) is more common in the Northern Hemisphere. It is endemic mainly in North America, where the vectors are Ixodes scapularis and Ixodes pacificus, and in Eurasia, where the vectors are Ixodes ricinus and Ixodes persulcatus. Both tick-borne diseases and LB are influenced by climate change. Africa and South America are crossed by the equator and are situated in both the Northern and Southern Hemispheres. In Africa, the LB is present on the Mediterranean and the Indian Ocean coasts. Borrelia lusitaniae is prevalent in countries bordering the Mediterranean Sea, such as Tunisia, Morocco, Algeria, and Egypt. Ticks were detected in the Ixodes Ricinus, which are carried by migratory birds and the Ixodes inopinatus and captured by the Psammodromus algirus lizards. The Borreliae Lyme Group (LG) and, in particular, Borrelia garinii, have been reported in countries bordering the Indian Ocean, such as Kenya, Tanzania, and Mozambique, transported by migratory birds from North African countries, where the vector was identified as Hyalomma rufipes ticks. This review aims to document the presence of Borreliae LG and LB in Africa.

Bacteria in the genus Borrelia are primarily spread by ticks and cause either Lyme borreliosis or relapsing fever. Substantial work has demonstrated the degree to which rodents and songbirds can contribute to the enzootic cycles and dispersal of these human diseases, but comparatively less attention has been paid to the role of wild bats, particularly in temperate regions. We here report human-relevant findings from a two-year, seasonal survey of migratory Mexican free-tailed bats ( Tadarida brasiliensis ) in Oklahoma, USA. We tested nearly 400 bats and identified Borrelia puertoricensis , a relapsing fever species that could infect humans. Importantly, this represents the first detection of Borrelia puertoricensis in bats and only the second detection in wild vertebrate hosts, expanding the known host range of this emerging tick-borne pathogen. Given the known migratory routes of Mexican free-tailed bats, our results have implications for the role that bats may play in tick-borne pathogen dispersal in North America.

Background/Objectives: Lyme disease is caused by some species of tick-borne bacteria of the genus Borrelia, termed Lyme disease Borreliae (LDB). Borrelia burgdorferi is the LDB species principally responsible for Lyme disease in the US. The outer surface protein A (OspA) of LDB attaches the bacteria to the gut of Ixodes tick vectors. OspA expression is downregulated when B. burgdorferi is transmitted from ticks to mammalian hosts. Vaccination with OspA elicits antibody-mediated protective immunity in animals and humans against LDB infection. The possible presence of serum antibodies against OspA in persons with PCR-confirmed LDB infections in blood was investigated in this study. Methods: Ninety-one archived sera from patients with LDB infections in blood demonstrated by a sensitive PCR assay were tested for reactivity with OspA from multiple LDB species in line immunoblots. Results: In total, 14 of the 91 sera (15.4%) had either IgG or IgM antibodies to OspA from one or more LDB species. Conclusions: The results show for the first time that serum antibodies to OspA are formed when LDB are present in human blood. However, the factors that governed the expression of OspA by LDB in patients could not be ascertained. It will be useful to determine whether the observed levels of serum antibodies to OspA in infected persons can protect against subsequent tick-borne infection and whether OspA used in conjunction with other LDB antigens can improve the serological diagnosis of Lyme disease.

Lyme disease, initially described as Lyme arthritis, was reported before nucleic-acid based detection technologies were available. The most widely used diagnostic tests for Lyme disease are based on the serologic detection of antibodies produced against antigens derived from a single strain of Borrelia burgdorferi. The poor diagnostic accuracy of serological tests early in the infection process has been noted most recently in the 2018 Report to Congress issued by the U.S. Department of Health and Human Services Tick-Borne Disease Working Group. Clinical Lyme disease may be caused by a diversity of borreliae, including those classified as relapsing fever species, in the United States and in Europe. It is widely accepted that antibiotic treatment of Lyme disease is most successful during this critical early stage of infection. While genomic sequencing is recognized as an irrefutable direct detection method for laboratory diagnosis of Lyme borreliosis, development of a molecular diagnostic tool for all clinical forms of borreliosis is challenging because a “core genome” shared by all pathogenic borreliae has not yet been identified. After a diligent search of the GenBank database, we identified two highly conserved segments of DNA sequence among the borrelial 16S rRNA genes. We further developed a pair of Borrelia genus-specific PCR primers for amplification of a segment of borrelial 16S rRNA gene as a “core genome” to be used as the template for routine Sanger sequencing-based metagenomic direct detection test. This study presented examples of base-calling DNA sequencing electropherograms routinely generated in a clinical diagnostic laboratory on DNA extracts of human blood specimens and ticks collected from human skin bites and from the environment. Since some of the tick samples tested were collected in Ireland, borrelial species or strains not known to exist in the United States were also detected by analysis of this 16S rRNA “core genome”. We recommend that hospital laboratories located in Lyme disease endemic areas begin to use a “core genome” sequencing test to routinely diagnose spirochetemia caused by various species of borreliae for timely management of patients at the early stage of infection.

Tick-borne relapsing fever (TBRF) is caused by spirochete bacteria of the genus Borrelia termed relapsing fever Borreliae (RFB). TBRF shares symptoms with Lyme disease (LD) caused by related Lyme disease Borreliae (LDB). TBRF and LD are transmitted by ticks and occur in overlapping localities worldwide. Serological detection of antibodies used for laboratory confirmation of LD is not established for TBRF. A line immunoblot assay using recombinant proteins from different RFB species, termed TBRF IB, was developed and its diagnostic utility investigated. The TBRF IBs were able to differentiate between antibodies to RFB and LDB and had estimated sensitivity, specificity, and positive and negative predictive values of 70.5%, 99.5%, 97.3%, and 93.4%, respectively, based on results with reference sera from patients known to be positive and negative for TBRF. The use of TBRF IBs and analogous immunoblots for LD to test sera of patients from Australia, Ukraine, and the USA with LD symptoms revealed infection with TBRF alone, LD alone, and both TBRF and LD. Diagnosis by clinical criteria alone can, therefore, underestimate the incidence of TBRF. TBRF IBs will be useful for laboratory confirmation of TBRF and understanding its epidemiology worldwide.