Pathogenic New World Relapsing Fever Borrelia in a Myotis Bat, Eastern China, 2015

Detection of Old and New World Relapsing Fever Borreliae in Ornithodoros Ticks Collected from Warthog Burrows in Zambia

Relapsing fever (RF) is an arthropod-borne disease caused by Borrelia spirochete, which is one of the major public health concerns in endemic regions including Africa. However, information on Borrelia spirochetes is limited in Zambia. Here, we investigate the Borrelia spirochetes harbored by Ornithodoros ticks in Zambian National Parks. We analyzed 182 DNA samples pooled from 886 Ornithodoros ticks. Of these, 43 tested positive, and their sequence revealed that the ticks harbored both Old and New World RF borreliae. This research presents the first evidence of Old-World RF borreliae in Zambia. The New World RF borreliae detected herein differed from the Candidatus Borrelia fainii previously reported in Zambia and were closely related to the pathogenic Borrelia sp. VS4 identified in Tanzania. Additionally, Borrelia theileri was recently reported in Zambia. Hence, at least four different Borrelia species occur in Zambia, and the organisms causing relapsing fever there might be more complex than previously thought. We empirically confirmed that real-time PCR with TaqMan minor groove binder probes accurately and simultaneously detected both Old and New World RF. In this manner, they could facilitate quantitative analyses of both types of RF borreliae. Subsequent investigations should endeavor to isolate the aforementioned Borrelia spp. and perform serosurveys on patients with RF.

Molecular evidence of Borrelia spp. in bats from Córdoba Department, northwest Colombia

BACKGROUND

The genus Borrelia is composed of two well-defined monophyletic groups, the Borrelia burgdorferi sensu lato complex (Bb) and the relapsing fever (RF) group borreliae. Recently, a third group, associated with reptiles and echidnas, has been described. In general, RF group borreliae use rodents as reservoir hosts; although neotropical bats may also be involved as important hosts, with scarce knowledge regarding this association. The objective of this study was to detect the presence of Borrelia spp. DNA in bats from the department of Córdoba in northwest Colombia.

METHODS

During September 2020 and June 2021, 205 bats were captured in six municipalities of Córdoba department, Colombia. Specimens were identified using taxonomic keys and DNA was extracted from spleen samples. A Borrelia-specific real-time PCR was performed for the 16S rRNA gene. Fragments of the 16S rRNA and flaB genes were amplified in the positive samples by conventional PCR. The detected amplicons were sequenced by the Sanger method. Phylogenetic reconstruction was performed in IQ-TREE with maximum likelihood based on the substitution model TPM3+F+I+G4 with bootstrap values deduced from 1000 replicates.

RESULTS

Overall, 10.2% (21/205) of the samples were found positive by qPCR; of these, 81% (17/21) and 66.6% (14/21) amplified 16S rRNA and flaB genes, respectively. qPCR-positive samples were then subjected to conventional nested and semi-nested PCR to amplify 16S rRNA and flaB gene fragments. Nine positive samples for both genes were sequenced, and seven and six sequences were of good quality for the 16S rRNA and flaB genes, respectively. The DNA of Borrelia spp. was detected in the insectivorous and fruit bats Artibeus lituratus, Carollia perspicillata, Glossophaga soricina, Phyllostomus discolor, and Uroderma sp. The 16S rRNA gene sequences showed 97.66-98.47% identity with "Borrelia sp. clone Omi3," "Borrelia sp. RT1S," and Borrelia sp. 2374; the closest identities for the flaB gene were 94.02-98.04% with "Borrelia sp. Macaregua." For the 16S rRNA gene, the phylogenetic analysis showed a grouping with "Candidatus Borrelia ivorensis" and "Ca. Borrelia africana," and for the flaB gene showed a grouping with Borrelia sp. Macaregua and Borrelia sp. Potiretama. The pathogenic role of the Borrelia detected in this study is unknown.

CONCLUSIONS

We describe the first molecular evidence of Borrelia spp. in the department of Córdoba, Colombia, highlighting that several bat species harbor Borrelia spirochetes.

Molecular detection and identification of relapsing fever Borrelia in ticks and wild small mammals in China

We identified relapsing fever (RF) Borrelia in 1.45% (145/10426) of the ticks and 1.40% (40/2850) of the wild mammals in a field investigation in China. Three RF Borrelia species, including human-pathogenic Borrelia miyamotoi, Borrelia persica and unclassified Babesia sp. were determined. Main species determined from ticks was B. miyamotoi (44.14%), followed by the unclassified Borrelia sp. (42.76%), and Borrelia theileri (13.10%). In wild mammals, main species found was B. persica (57.50%), followed by the unclassified Borrelia sp. (40.00%), and B. miyamotoi (2.50%). We determined B. theileri and B. persica in China for the first time. The coexistence of RF Borrelia species in one tick species in a given region was observed, with the most frequent coexistence seen for B. miyamotoi and the unclassified Borrelia sp. in Dermacentor silvarum, Haemaphysalis japonica, Haemaphysalis longicornis, and Ixodes persulcatuss respectively. The wide distribution and high variety of RF Borrelia in China pose a potential threat to public health.

Comparative genomics of the Western Hemisphere soft tick-borne relapsing fever borreliae highlights extensive plasmid diversity

Background

Tick-borne relapsing fever (TBRF) is a globally prevalent, yet under-studied vector-borne disease transmitted by soft and hard bodied ticks. While soft TBRF (sTBRF) spirochetes have been described for over a century, our understanding of the molecular mechanisms facilitating vector and host adaptation is poorly understood. This is due to the complexity of their small (~ 1.5 Mb) but fragmented genomes that typically consist of a linear chromosome and both linear and circular plasmids. A majority of sTBRF spirochete genomes’ plasmid sequences are either missing or are deposited as unassembled sequences. Consequently, our goal was to generate complete, plasmid-resolved genomes for a comparative analysis of sTBRF species of the Western Hemisphere.

Results

Utilizing a Borrelia specific pipeline, genomes of sTBRF spirochetes from the Western Hemisphere were sequenced and assembled using a combination of short- and long-read sequencing technologies. Included in the analysis were the two recently isolated species from Central and South America, Borrelia puertoricensis n. sp. and Borrelia venezuelensis, respectively. Plasmid analyses identified diverse sequences that clustered plasmids into 30 families; however, only three families were conserved and syntenic across all species. We also compared two species, B. venezuelensis and Borrelia turicatae, which were isolated ~ 6,800 km apart and from different tick vector species but were previously reported to be genetically similar.

Conclusions

To truly understand the biological differences observed between species of TBRF spirochetes, complete chromosome and plasmid sequences are needed. This comparative genomic analysis highlights high chromosomal synteny across the species yet diverse plasmid composition. This was particularly true for B. turicatae and B. venezuelensis, which had high average nucleotide identity yet extensive plasmid diversity. These findings are foundational for future endeavors to evaluate the role of plasmids in vector and host adaptation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08523-7.

Human-pathogenic relapsing fever Borrelia found in bats from Central China phylogenetically clustered together with relapsing fever borreliae reported in the New World

Bats can harbor zoonotic pathogens causing emerging infectious diseases, but their status as hosts for bacteria is limited. We aimed to investigate the distribution, prevalence and genetic diversity of Borrelia in bats and bat ticks in Hubei Province, China, which will give us a better understanding of the risk of Borrelia infection posed by bats and their ticks. During 2018-2020, 403 bats were captured from caves in Hubei Province, China, 2 bats were PCR-positive for Borrelia. Sequence analysis of rrs, flaB and glpQ genes of positive samples showed 99.55%-100% similarity to Candidatus Borrelia fainii, a novel human-pathogenic relapsing fever Borrelia species recently reported in Zambia, Africa and Eastern China, which was clustered together with relapsing fever Borrelia species traditionally reported only in the New World. Multilocus sequence typing (MLST) and pairwise genetic distances further confirmed the Borrelia species in the bats from Central China as Candidatus Borrelia fainii. No Borrelia DNA was detected in ticks collected from bats. The detection of this human-pathogenic relapsing fever Borrelia in bats suggests a wide distribution of this novel relapsing fever Borrelia species in China, which may pose a threat to public health in China.

Social Determinants of Health and Risk of SARS-CoV-2 Infection in Community-Dwelling Older Adults Living in a Rural Latin American Setting

High social risk, as measured by the social determinants of health (SDH), may increase the risk of SARS-CoV-2 infection. However, this association has not been studied in rural communities. Using the Atahualpa Project cohort, we aimed to assess the association between SDH and SARS-CoV-2 seropositivity in community-dwelling older adults living in rural Ecuador. SARS-CoV-2 antibodies were determined in 319 individuals aged ≥ 60 years that completed a validated field instrument to assess their social risk before the introduction of this novel pandemic. Multivariate models were fitted to assess the independent association between SDH-and each of their components-and SARS-CoV-2 seropositivity, after adjusting for relevant covariates. According to the Gijon scale, 102 (32%) individuals had a high social risk (≥ 10 points). A total of 141 (44%) individuals were seropositive to SARS-CoV-2. A fully-adjusted logistic regression model showed an independent) association between social risk and SARS-CoV-2 positivity (OR 1.15; 95% CI 1.04-1.27; p = 0.008). For every unit of the total SDH score, the odds of SARS-CoV-2 seropositivity increased 15% (95% CI 3.7-27%). In addition, multivariate models showed that the individual component of SDH more strongly associated with SARS-CoV-2 seropositivity was housing, which suggested that lack of basic home facilities may increase the risk of SARS-CoV-2 infection. Knowledge on the association between high social risk and SARS-CoV-2 infection is indispensable for the development of cost-effective preventive strategies for controlling modifiable factors that are in the path of SARS-CoV-2 infection among older adults living in underserved communities.