The impact of Pandemic COVID-19 on cases of Borreliosis infection in 2020

Borreliosis (Lyme borreliosis; Lyme disease) is a zoonotic disease caused by spirochetes from the genus Borrelia. In humans, the accidental host of ticks, the infection is transmitted by the bite of the tick - the spirochetes are present in the salivary glands of the tick. Any of the three forms of tick: larva, nymph and adult can be responsible for infection. The most common threats to humans are Borrelia burgdorferii sensu stricto, Borrelia garinii and Borrelia afzelii occurring mainly in Europe. Lyme disease is a complex, multi-stage disease and progresses in 3 stages. The targeted treatment of Lyme disease is based on the administration of antibiotics. The introduction of antibiotics in the early stages of Lyme borreliosis offers a good chance of a complete cure. Lyme disease is a major epidemiological problem in the world. In Europe, the average number of cases per year remains at 65,400. In Poland, the number of infections annually reaches several tens of thousands. According to the National Institute of Hygiene of Poland, which keeps statistics of epidemiological reports, a total of 83,495 people fell sick with Lyme disease in Poland between 2016 and 2019. Whereas in 2020, the number of cases of Lyme disease decreased to 12933. The reason for this is undoubtedly the COVID-19 pandemic, which has dominated health care and focused all the attention of medical workers. This review shows that Lyme borreliosis is a dangerous disease with a high risk of complications. A quick diagnosis is crucial in the therapeutic process. An algorithm should be developed in order to distinguish other diseases from Lyme disease and thus enable an early reaction and treatment.

Out of Asia? Vector switches leading to the expansion of Eurasian Lyme disease bacteria

Vector-borne pathogens exist in obligate transmission cycles between vector and reservoir host species. Host shifts can lead to geographic expansion and the emergence of new diseases. Three etiological agents of human Lyme borreliosis (Borrelia afzelii, Borrelia bavariensis, and Borrelia garinii) predominantly utilize two distinct tick species as vectors in Asia (Ixodes persulcatus) and Europe (Ixodes ricinus) but how and in which order they colonized each continent remains unknown. Here, by reconstructing the evolutionary history of 142 Eurasian isolates, we show that all three Borrelia genospecies evolved from an Asian origin, suggesting that successful expansion into Europe resulted through invading a novel vector. The pattern of gene flow between continents is different between genospecies and most likely conditioned by reservoir host association and their dispersal. Our results highlight that Eurasian Lyme borreliosis agents are all capable of geographic expansion through vector shifts, but potentially differ in their capacity as emergent pathogens.

Characteristics of spirochetemic patients with a solitary erythema migrans skin lesion in Europe

Neither pre-treatment characteristics, nor the outcome after antibiotic therapy, have been reported for spirochetemic European patients with Lyme borreliosis. In the present study, patients with a solitary erythema migrans (EM) who had a positive blood culture for either Borrelia afzelii (n = 116) or Borrelia garinii (n = 37) were compared with age- and sex-matched patients who had a negative blood culture, but were culture positive for the corresponding Borrelia species from skin. Collectively, spirochetemic patients significantly more often recalled a tick bite at the site of the EM skin lesion, had a shorter time interval from the bite to the onset of EM, had a shorter duration of the skin lesion prior to diagnosis, and had a smaller EM skin lesion that was more often homogeneous in appearance. Similar results were found for the subset of spirochetemic patients infected with B. afzelii but not for those infected with B. garinii. However, patients with B. garinii bacteremia had faster-spreading and larger EM skin lesions, and more often reported itching at the site of the lesion than patients with B. afzelii bacteremia. Treatment failures were rare (7/306 patients, 2.3%) and were not associated with having spirochetemia or with which Borrelia species was causing the infection.

Are Differences in Presentation of Early Lyme Borreliosis in Europe and North America a Consequence of a More Frequent Spirochetemia in American Patients?

To assess whether differences in presentation between US and European patients with early Lyme borreliosis are due to the lower rate of spirochetemia in Europe, we compared multiple variables for patients with erythema migrans (EM), restricting the analysis to subjects with a positive blood culture at the time of presentation: 93 US patients infected with Borrelia burgdorferi versus 183 European patients infected with Borrelia afzelii (No = 144) or Borrelia garinii (No = 39). Compared to spirochetemic Slovenian EM patients infected with B. afzelii, US patients with a positive blood culture significantly less often recalled a preceding tick bite at the site of the EM skin lesion, had a shorter duration of EM prior to diagnosis and more often had multiple EM lesions, regional lymphadenopathy, constitutional symptoms, an increased ESR value, a low blood lymphocyte count and detectable borrelia antibodies in acute and convalescent phase blood samples. Similar differences were observed when US patients were compared to Slovenian patients with B. garinii infection, but not all reached statistical significance. The findings are comparable to those previously reported for the corresponding skin culture positive patients and do not support the hypothesis that a higher frequency of spirochetemia at the time of presentation in US patients with EM, compared with European EM patients, is the reason for the observed differences.

Vitronectin binding protein, BOM1093, confers serum resistance on Borrelia miyamotoi

Borrelia miyamotoi, a member of the tick-borne relapsing fever spirochetes, shows a serum-resistant phenotype in vitro. This ability of B. miyamotoi may contribute to bacterial evasion of the host innate immune system. To investigate the molecular mechanism of serum-resistance, we constructed a membrane protein-encoding gene library of B. miyamotoi using Borrelia garinii strain HT59G, which shows a transformable and serum-susceptible phenotype. By screening the library, we found that bom1093 and bom1515 of B. miyamotoi provided a serum-resistant phenotype to the recipient B. garinii. These B. miyamotoi genes are predicted to encode P35-like antigen genes and are conserved among relapsing fever borreliae. Functional analysis revealed that BOM1093 bound to serum vitronectin and that the C-terminal region of BOM1093 was involved in the vitronectin-binding property. Importantly, the B. garinii transformant was not serum-resistant when the C terminus-truncated BOM1093 was expressed. We also observed that the depletion of vitronectin from human serum enhances the bactericidal activity of BOM1093 expressing B. garinii, and the survival rate of BOM1093 expressing B. garinii in vitronectin-depleted serum is enhanced by the addition of purified vitronectin. Our data suggests that B. miyamotoi utilize BOM1093-mediated binding to vitronectin as a mechanism of serum resistance.

The potential risk of exposure to Borrelia garinii, Anaplasma phagocytophilum and Babesia microti in the Wolinski National Park (north-western Poland)

Ixodes ricinus (Acari: Ixodida) is the main vector in Europe of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Babesia microti. Wolinski National Park (WNP) is situated by the Baltic Sea and is frequently visited by tourists. The aim of the study was to determine the potential risk of exposure to tick borne infection with B. burgdorferi s.l., A. phagocytophilum and B. microti on the areas of WNP. In total, 394 I. ricinus were tested. The pathogens in ticks were detected by PCR, nested PCR, RFLP and sequencing. Altogether, pathogens were detected in 12.69% of the studied ticks. B. burgdorferi s.l., was shown in 0.25% of the studied I. ricinus, while A. phagocytophilum and B. microti were detected in 1.01% and 10.65% of studied ticks, respectively. Co-infection by A. phagocytophilum and B. microti was shown in only one I. ricinus nymph. Analysis of B. burgdorferi s.l., genospecies showed that 0.25% of the studied ticks were infected with Borrelia garinii. The obtained results show the potentially high human risk of exposure to tick-borne infection with B. microti, and the low potential risk of infection with B. garinii and A. phagocytophilum on the studied areas of WNP.

Local Population Structure and Seasonal Variability of Borrelia garinii Genotypes in Ixodes ricinus Ticks, Slovakia

Lyme disease (LD) is the most common tick-borne human disease in Europe, and Borrelia garinii, which is associated with avian reservoirs, is one of the most genetically diverse and widespread human pathogenic genospecies from the B. burgdorferi sensu lato (s.l.) complex. The clinical manifestations of LD are known to vary between regions and depend on the genetic strain even within Borrelia genospecies. It is thus of importance to explore the genetic diversity of such pathogenic borreliae for the wide range of host and ecological contexts. In this study, multilocus sequence typing (MLST) was employed to investigate the local population structure of B. garinii in Ixodes ricinus ticks. The study took place in a natural wetland in Slovakia, temporally encompassing spring and autumn bird migration periods as well as the breeding period of resident birds. In total, we examined 369 and 255 ticks collected from 78 birds and local vegetation, respectively. B. burgdorferi s.l. was detected in 43.4% (160/369) of ticks recovered from birds and in 26.3% (67/255) of questing ticks, respectively. Considering the ticks from bird hosts, the highest prevalence was found for single infections with B. garinii (22.5%). Infection intensity of B. garinii in bird-feeding ticks was significantly higher than that in questing ticks. We identified ten B. garinii sequence types (STs) occurring exclusively in bird-feeding ticks, two STs occurring exclusively in questing ticks, and one ST (ST 244) occurring in both ticks from birds and questing ticks. Four B. garinii STs were detected for the first time herein. With the exception of ST 93, we detected different STs in spring and summer for bird-feeding ticks. Our results are consistent with previous studies of the low geographic structuring of B. garinii genotypes. However, our study reveals some consistency in local ST occurrence and a geographic signal for one of the clonal complexes.