Molecular detection and phylogenetic analysis of Borrelia miyamotoi strains from ticks collected in the capital region of Finland

Borrelia miyamotoi is an emerging pathogen that shares high similarity with relapsing fever Borrelia, but has an atypical clinical presentation. Within the framework of tick-borne disease surveillance in Finland, human serum samples suspected for tick-borne encephalitis (n=974) and questing ticks (n=739) were collected from the capital region in Finland to determine the prevalence of B. miyamotoi. All tested human samples were negative and 5 (0.68 %) Ixodes ricinus ticks were positive for B. miyamotoi. Partial sequencing of the flagellin (flaB) gene of 3 positive samples and 27 B. miyamotoi-positive tick samples obtained from previous studies across Finland were amplified, sequenced, and included in the phylogenetic analysis.The phylogenetic tree revealed that most B. miyamotoi strains isolated from ticks in Finland share high similarity with other European strains, including strains related to human infection. Possible disease transmission may occur during exposure to tick bites. A single strain collected from an I. persulcatus tick in Pajujärvi grouped with an outlier of B. miyamotoi strains isolated from Russia and Far East Asian countries. Further studies should investigate the pathogen’s role in human infection in Finland.Another important finding is the occurrence of I. persulcatus ticks (8%) collected by crowdsourcing from the coastal southern part of Finland. This suggests a regular introduction and a possible wide expansion of this tick species in the country. This could be associated with transmission of new pathogens.</p

Recent establishment of tick-borne encephalitis foci with distinct viral lineages in the Helsinki area, Finland

Number of tick-borne encephalitis (TBE) cases has increased and new foci have emerged in Finland during the last decade. We evaluated risk for locally acquired TBE in the capital region inhabited by 1.2 million people. We screened ticks and small mammals from probable places of TBE virus (TBEV) transmission and places without reported circulation. The TBEV positive samples were sequenced and subjected to phylogenetic analysis. Within the study period 2007-2017, there was a clear increase of both all TBE cases and locally acquired cases in the Helsinki area. The surveillance of ticks and small mammals for TBEV confirmed four distinct TBEV foci in the Helsinki area. All detected TBEV strains were of the European subtype. TBEV genome sequences indicated that distinct TBEV lineages circulate in each focus. Molecular clock analysis suggested that the virus lineages were introduced to these foci decades ago. In conclusion, TBE has emerged in the mainland of Helsinki area during the last decade, with at least four distinct virus lineages independently introduced into the region previously. Although the overall annual TBE incidence is below the threshold for recommending general vaccinations, the situation requires further surveillance to detect and prevent possible further emergence of local TBE clusters.Peer reviewe

En demografisk studie : prevalensen av TBEV i Esbo och på Drumsö i Helsingfors, Finland

Antalet smittfall av fästingburet encefalitvirus (TBEV) har ökat och nya riskområden för TBEV har identifierats årligen i Finland under det senaste årtiondet. Som resultat av ökat intresse hos lokala invånare att utreda över nyintroducerade TBEV riskområden initierades detta projekt år 2016 i samarbete med Helsingfors universitets virologiska avdelning och det privatägda företaget Skärgårdsdoktorn Ab, att samla fästingar från Drumsö och senare testa dessa på TBEV (RNA). Senare kom projektet också att innefatta Esbo. Materialet samlades under åren 2016 - 2017 och bestod av fästingar samlade lokalt både direkt från naturen, samt fästingar som låtits hämtas in utav privatpersoner till utgivna lokalisationer. Det slutliga materialet bestod av 754st fästingar varav 666st härstammade från Esbo och 88st härstammade från Drumsö i Helsingfors. Laboratorieanalyserna gjordes i Helsingfors universitets virologiska avdelnings utrymmen. Utav enstaka fästingar isolerades RNA och DNA lösning i separata provrör i en manuell laboratorieprocess, och senare genomgick dessa lösningar automatiserade TBEV (RNA) respektive Borrelia Burgdorferi tester. Denna rapport behandlar endast TBEV testerna och deras resultat. I de slutliga TBEV testerna hittades 7st TBEV RNA positiva fästingar, av vilka alla härstammade från 3 olika regioner i Esbo; Esbogård, Tomtekulla och Larsvik. Av dessa områden var Larsvik det ända varifrån det inte tidigare rapporterats några TBEV smittor. Resultaten i denna studie är i linje med tidigare kända uppgifter över TBEV demografi i den finska huvudstadsregionen och antyder för potentialen även till ytterligare spridning till övriga lokalisationer inom detta område

Molecular detection and phylogenetic analysis of Borrelia miyamotoi strains from ticks collected in the capital region of Finland.

Borrelia miyamotoi is an emerging pathogen that shares high similarity with relapsing fever Borrelia, but has an atypical clinical presentation. Within the framework of tick-borne disease surveillance in Finland, human serum samples suspected for tick-borne encephalitis (n=974) and questing ticks (n=739) were collected from the capital region in Finland to determine the prevalence of B. miyamotoi. All tested human samples were negative and 5 (0.68 %) Ixodes ricinus ticks were positive for B. miyamotoi. Partial sequencing of the flagellin (flaB) gene of 3 positive samples and 27 B. miyamotoi-positive tick samples obtained from previous studies across Finland were amplified, sequenced, and included in the phylogenetic analysis. The phylogenetic tree revealed that most B. miyamotoi strains isolated from ticks in Finland share high similarity with other European strains, including strains related to human infection. Possible disease transmission may occur during exposure to tick bites. A single strain collected from an I. persulcatus tick in Pajujarvi grouped with an outlier of B. miyamotoi strains isolated from Russia and Far East Asian countries. Further studies should investigate the pathogen's role in human infection in Finland. Another important finding is the occurrence of I. persulcatus ticks (8%) collected by crowdsourcing from the coastal southern part of Finland. This suggests a regular introduction and a possible wide expansion of this tick species in the country. This could be associated with transmission of new pathogens.Peer reviewe