uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Dissemination of Spotted Fever Rickettsia Agents in Europe by Migrating Birds
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Bacteriology. Department of Clinical Microbiology, Falu Hospital, Falun, Sweden.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
Department of Molecular Biology, Umeå University.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
Show others and affiliations
2010 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 1, e8572- p.Article in journal (Refereed) Published
Abstract [en]

Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp.IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases.

Place, publisher, year, edition, pages
2010. Vol. 5, no 1, e8572- p.
Keyword [en]
Ixodes, ticks, birds, infestation, rickettsia, spotted fever
National Category
Microbiology in the medical area
Identifiers
URN: urn:nbn:se:uu:diva-113683DOI: 10.1371/journal.pone.0008572ISI: 000273338500015PubMedID: 20052286OAI: oai:DiVA.org:uu-113683DiVA: diva2:291658
Available from: 2010-02-02 Created: 2010-02-02 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Epidemiological and Bacteriological Aspects of Spotted Fever Rickettsioses in Humans, Vectors and Mammals in Sweden
Open this publication in new window or tab >>Epidemiological and Bacteriological Aspects of Spotted Fever Rickettsioses in Humans, Vectors and Mammals in Sweden
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Rickettsiae are obligate intracellular gram-negative bacteria transmitted by arthropod vectors. Rickettsiae sometimes cause disease in humans, typically with high fever, headache and occasionally an eschar.

In Sweden, Rickettsia helvetica, belonging to the spotted fever group, is the only tick-transmitted rickettsia found free in nature. The pathogenic roll of R. helvetica has not been fully investigated, but it has been implicated in aneruptive fever and cardiac disease.

This thesis describes parts of the transmission pathways of rickettsiae in Sweden. Rickettsia infection rates in ticks collected from birds were analysed, and the birds’ role as disseminators and reservoirs was studied. We found that more than one in ten ticks was infected with rickettsia bacteria, predominantly R. helvetica, and that migrating birds contribute not only to long-distance dispersion of bacteria, but also to an inflow of novel and potentially pathogenic rickettsia species, in this case R. monacensis and R. sp. strain Davousti-like species, into Sweden.

Further, wild and domestic animals were found to have seroreactivity against R. helvetica, which shows that they are exposed and susceptible to rickettsia. Their role as reservoirs has not been determined, yet they may indirectly be involved in transmission of rickettsia to humans by infected ticks feeding on them.

The seroreactivity in humans was also studied. Patients investigated for suspected Borrelioses and blood donors had detectable antibodies against Rickettsia spp., with the highest prevalence detected in the suspected Borreliosis group. This shows that humans in Sweden are exposed to and develop an immune response against rickettsia. The suspicion that R. helvetica may cause severe symptoms was verified by a patient with subacute meningitis where the bacterium was shown for the first time to cause an invasive infection with CNS involvement and where the bacterium was isolated from the patient’s cerebrospinal fluid.

Growth characteristics and morphology of R. helvetica were studied to better understand invasiveness and virulence. The findings indicate that the invasiveness is comparable with other rickettsia, though R. helvetica seems to have a stable but slightly slower growth. 

Rickettsia helvetica is endemic in Sweden and therefore needs to be considered when investigating disease after a tick bite.

Abstract [sv]

Rickettsia är en liten, strikt intracellulär, gramnegativ bakterie som sprids med vektorer som fästingar, löss och loppor. Bakterien kan orsaka Rickettsios hos människa, en sjukdom där de vanligaste symtomen är hög feber, huvudvärk, muskelvärk och i vissa fall ett bettmärke (eschar). I Sverige är Rickettsia helvetica, som tillhör spotted fever gruppen (SFG), den enda fästingöverförda rickettsia bakterien som hittats allmänt i naturen. Patogeniciteten för R. helvetica är ofullständigt utredd, men ”aneruptive fever” och hjärtmuskelinflammation har rapporterats.

Avhandlingen beskriver delar av smittkedjan för SFG rickettsia i Sverige. Bakteriernas förekomst i fästingar plockade från fåglar har studerats, likaså det ekologiska tryck som flyttfåglars bärarskap av infekterade fästingar bidrar med när de korsar olika världsdelar. Mer än var tionde fästing var infekterad med rickettsia bakterier, i huvudsak R. helvetica. Det visade sig att flyttfåglar bidrar inte bara till långväga spridning av bakterier utan även till införsel av nya potentiellt patogena rickettsiaarter, i detta fall identifierades R. monacensis och en R. sp strain Davousti liknande art.

Vidare analyserades seroreaktivitet mot Rickettsia helvetica hos både tamdjur och vilda djur, vilket visade på antikroppsutveckling, som uttryck för smittexposition, i mer än vart femte djur. Djurens roll som reservoar för bakterien är inte klarlagd, men oavsett är djuren indirekt involverade i spridningen av bakterien till människa via infekterade fästingar som suger blod.

Seroreaktivitet hos människa har också studerats. Patienter, provtagna på grund av misstanke om borreliainfektion, samt blodgivare hade detekterbara antikroppar mot Rickettsiae, med högst prevalens i gruppen med misstänkt borreliainfektion. Fynden visar att människor i Sverige är exponerade för och utvecklar en immunreaktion mot rickettsia. Att R. helvetica skulle kunna ge allvarlig sjukdom verifieras av ett patientfall med subakut meningit där bakterien för första gången visats ge invasiv infektion med påverkan på nervsystemet (CNS engagemang) och där bakterien isolerats från patientens ryggmärgsvätska. 

Morfologi och tillväxtegenskaper för R. helvetica undersöktes för att bättre förstå bakteriens invasivitet och virulens. Fynden indikerar att invasiviteten är jämförbar med andra rickettsiaarter men R. helvetica verkar ha en stabil men något långsammare tillväxt.

Rickettsia helvetica är endemisk i Sverige och måste tas i beaktande vid sjukdomsutredning efter ett fästingbett.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 52 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 888
Keyword
Rickettsia helvetica, ticks, cultivation, serology, polymerase chain reaction (PCR), DNA sequencing, western blot, electron microscopy, meningitis, seroprevalence
National Category
Clinical Laboratory Medicine Microbiology Microbiology in the medical area
Identifiers
urn:nbn:se:uu:diva-197277 (URN)978-91-554-8639-6 (ISBN)
Public defence
2013-05-22, Hörsalen, Klinisk Mikrobiologi, Akademiska Sjukhuset, Dag Hammarskjöldsväg 17, Ing D1, Uppsala, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2013-04-26 Created: 2013-03-21 Last updated: 2013-08-30Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMedhttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0008572

Authority records BETA

Olsen, BjörnMejlon, HansNilsson, Kenneth

Search in DiVA

By author/editor
Olsen, BjörnMejlon, HansNilsson, Kenneth
By organisation
Clinical BacteriologyInfectious DiseasesMuseum of Evolution
In the same journal
PLoS ONE
Microbiology in the medical area

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 790 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf