Background The alpha-Gal syndrome (AGS) is characterized by a delayed allergic response to mammalian meat and by-products. Numerous studies have confirmed that hard ticks are the source of α-Gal sensitization. However, the source of the α-Gal carrying sensitizing molecules remains controversial as α-Gal could either originate from endogenous production or residual host blood proteins. Objective To study the kinetics of host blood protein degradation in fully engorged Ixodes ricinus larvae upon prolonged starvation after moulting into nymphs. Method 1200 I. ricinus larvae were fed on BALB/c mice under laboratory conditions. Fully engorged larvae moulted into nymphs and underwent starvation for 0, 10, and 20 weeks. Protein extracts from nymphs and larvae were analysed with LC-MS/MS mass spectrometry. Results Although 1200 larvae were fed on mice, only 249 engorged and 197 (79.12%) of the engorged larvae survived and moulted into nymphs. Overall, the global tick protein profile was similar for all stages except immediately after moulting (0 week). Peptides originating from 22 host-derived mouse proteins were detected, out of which 9 proteins were detected across all time-points post-moulting (serum albumin, hemoglobin subunits, cytosolic carboxypeptidase 2, protein KRI1 homolog, serine protease inhibitors 1c and 3k, and SH3 domain-containing protein 21). A sequence coverage of 76% was observed for mouse serum albumin, and more than 85% for hemoglobin subunits, suggesting the persistence of largely preserved host-derived mouse protein structures at all stages. Conclusion Under controlled conditions, mouse blood proteins survive moulting and are passed onto the next developmental stage in I. ricinus ticks, from larvae to nymphs. These proteins are detectable up to five months post-moulting.
Borrelia (B.) garinii, a causative agent of Lyme borreliosis, is maintained by diverse avian hosts in the marine and terrestrial transmission cycles. Data regarding survivability of B. garinii towards complement of individual seabird species is scarce. In this study, we aimed to gain insight into host association of B. garinii by examining the susceptibility to sera of marine and terrestrial birds. Four B. garinii strains isolated from seabird-associated Ixodes uriae, the Ixodes ricinus isolate B. garinii 20047 and the human isolates B. garinii G1, B. bavariensis PBi, and B. afzelii FEM1 were assessed. Serum was collected from gull (Ichthyaetus audouinii, Larus michahellis) and shearwater juveniles (Calonectris borealis) at Berlenga Island and Deserta Island (Algrave) in Portugal. Serum from common blackbirds (Turdus merula), Japanese quail (Coturnix japonica), and human donors were investigated as well. All B. garinii isolates, independent of their biological origin resisted complement-mediated killing by the bird sera analyzed whereas B. afzelii FEM1 was efficiently killed. Of note, B. bavariensis PBi remained unaffected by Japanese quail serum while being killed by all other avian sera, suggesting a broader host range for this particular Borrelia species. Following incubation with serum from Japanese quail, complement deposition assessment revealed no binding of complement C3 to the surface of B. bavariensis PBi. In contrast, B. afzelii cells were completely covered with C3 after serum challenge. Our data expand previous findings and provide further insight into the role of host innate immunity in shaping reservoir host association of B. garinii.
Lyme disease, caused primarily by the bite of a nymphal blacklegged tick (Ixodes scapularis) infected with Borrelia burgdorferi sensu stricto (Bbss), is the most common vector-borne disease in the United States. Counties reporting high Lyme disease incidence (LDI) continue to expand beyond historic foci in the Northeast and Upper Midwest. Identifying areas of expansion aids in targeting efforts to improve Lyme disease awareness in affected communities. Tick surveillance is conducted to track changes in acarological risk for tickborne diseases; the density of host-seeking Bbss-infected I. scapularis nymphs (DIN) is considered the most predictive metric for human LDI. We aimed to identify a threshold in DIN that accurately separated high (≥10 average annual cases/100,000 and ≥3 cases/year; 2022–2023) from low LDI counties in the eastern US. Using previously reported model-derived DIN, we identified 0.98 Bbss-infected nymphs per 1000 m2 as the threshold. Based on this threshold, we classified 18% of eastern counties (487/2695), primarily in the Northeast and Upper Midwest, with both high LDI and elevated acarological risk and 72% (1935/2695) with both low LDI and acarological risk. Another 8% of counties (220/2695), primarily in Michigan, Illinois, Indiana, and Ohio, were predicted to pose elevated acarological risk, but reported low LDI and may reflect areas of emergence that could benefit from expanded tick surveillance and public health outreach. The remaining 2% of counties (53/2695), mainly along the Appalachian Mountains, reported high LDI, but were misclassified as low acarological risk, highlighting the need for additional tick surveillance to improve acarological risk assessments.
Lyme borreliosis (LB) and hard tick-borne relapsing fever caused by Borrelia miyamotoi are emerging tick-borne infections, yet in Kazakhstan routine LB diagnosis relies on single-tier enzyme immunoassay (EIA) without confirmatory testing, and B. miyamotoi is absent from national diagnostic protocols. In 2024–2026, 1300 participants were enrolled in the Ixodes persulcatus-endemic Almaty and Jetisu regions and the non-endemic Zhambyl and Turkistan regions, across diverse clinical and tick-exposure groups. All sera were screened for IgM and IgG to both pathogens by multi-antigen protein arrays, with subsets tested by the LymeBest ELISA and the Anti-Borrelia EUROLINE-WB immunoblot. In addition, 503 ticks removed from participants were tested for borrelial DNA by PCR. Seroreactivity to B. burgdorferi sensu lato (s.l.) was rare (4/1300, 0.3%), whereas B. miyamotoi seroreactivity was more frequent (31/1300, 2.4%) and concentrated in tick-exposed groups. In ticks the pattern was the opposite: B. burgdorferi s.l. DNA was detected in 37/503 ticks (7.4%; 45.3% in I. persulcatus) and B. miyamotoi DNA in 7/64 I. persulcatus (10.9%), with four ticks co-infected, the single B. miyamotoi strain typed by eight-locus MLST matched a sequence type reported from Japan, Mongolia and China. Of the 28 participants bitten by Borrelia DNA-positive ticks who provided follow-up sera, three (10.7%) seroconverted, one to B. burgdorferi s.l. and two to B. miyamotoi. One of the latter, PCR-positive for B. miyamotoi DNA in baseline blood, is, to our knowledge, the first molecularly confirmed case of B. miyamotoi infection in Kazakhstan. The LymeBest ELISA agreed poorly with the other two assays: none of its 27 positive baseline results was confirmed by immunoblot or protein array. In contrast, immunoblot confirmed two of the four baseline samples seroreactive to B. burgdorferi s.l. by protein array, as well as the B. burgdorferi s.l. seroconversion. These findings support two-tier serological testing for LB and dedicated B. miyamotoi diagnostics in Kazakhstan.
Tick-borne rickettsioses are emerging and re-emerging zoonotic diseases worldwide that are caused by Gram-negative bacteria of the genus Rickettsia. Ticks act as both reservoirs and vectors for these bacteria, thereby increasing opportunities for the spillover of infections that they cause. This study aims to bridge the knowledge gap regarding the occurrence of zoonotic Rickettsia species in the Republic of Guinea. Ticks were manually collected from dogs, cattle, goats, and sheep. Morphological identification of 1213 ixodid ticks revealed five genera. Screening of individual DNA for Rickettsia spp. showed a prevalence of 39% (469/1213; 95% CI [36%–41%]). The main tick genera positive for Rickettsia spp. were Amblyomma spp. 83.7% (300/358), Rhipicephalus spp. 22% (165/744), Hyalomma spp. 7.3% (3/41), and Haemaphysalis spp. 3% (2/69). Molecular analysis of positive tick genera confirmed nine species. Subsequent specific qPCR assays and sequencing identified five Rickettsia species, including Rickettsia africae (36%), Rickettsia aeschlimannii (0.5%), Rickettsia massiliae (1%), Rickettsia conorii (0.2%), and a new genotype named Rickettsia sp. "guineensis" (0.1%). Additionally, two strains of Rickettsia africae were isolated from Amblyomma variegatum by cell culture techniques using XTC-2 cells and S2 cells. The present study highlights the need for further surveillance involving humans and other animals to better assess the public and veterinary health risks posed by zoonotic Rickettsia species.
