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Spotted fever Rickettsia species in Hyalomma and Ixodes ticks infesting migratory birds in the European Mediterranean area
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Microbiology and Infectious Medicine, Clinical Bacteriology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
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2014 (English)In: Parasites & Vectors, ISSN 1756-3305, Vol. 7, 318- p.Article in journal (Refereed) Published
Abstract [en]

Background: A few billion birds migrate annually between their breeding grounds in Europe and their wintering grounds in Africa. Many bird species are tick-infested, and as a result of their innate migratory behavior, they contribute significantly to the geographic distribution of pathogens, including spotted fever rickettsiae. The aim of the present study was to characterize, in samples from two consecutive years, the potential role of migrant birds captured in Europe as disseminators of Rickettsia-infected ticks. Methods: Ticks were collected from a total of 14,789 birds during their seasonal migration northwards in spring 2009 and 2010 at bird observatories on two Mediterranean islands: Capri and Antikythira. All ticks were subjected to RNA extraction followed by cDNA synthesis and individually assayed with a real-time PCR targeting the citrate synthase (gltA) gene. For species identification of Rickettsia, multiple genes were sequenced. Results: Three hundred and ninety-eight (2.7%) of all captured birds were tick-infested; some birds carried more than one tick. A total number of 734 ticks were analysed of which 353 +/- 1 (48%) were Rickettsia-positive; 96% were infected with Rickettsia aeschlimannii and 4% with Rickettsia africae or unidentified Rickettsia species. The predominant tick taxon, Hyalomma marginatum sensu lato constituted 90% (n = 658) of the ticks collected. The remaining ticks were Ixodes frontalis, Amblyomma sp., Haemaphysalis sp., Rhipicephalus sp. and unidentified ixodids. Most ticks were nymphs (66%) followed by larvae (27%) and adult female ticks (0.5%). The majority (65%) of ticks was engorged and nearly all ticks contained visible blood. Conclusions: Migratory birds appear to have a great impact on the dissemination of Rickettsia-infected ticks, some of which may originate from distant locations. The potential ecological, medical and veterinary implications of such Rickettsia infections need further examination.

Place, publisher, year, edition, pages
2014. Vol. 7, 318- p.
Keyword [en]
Migratory birds, Spotted fever Rickettsia, Rickettsia aeschlimannii, Rickettsia africae, Transmission, Tick, Hyalomma marginatum, Hyalomma rufipes, Ixodes frontalis
National Category
Infectious Medicine Biological Sciences
URN: urn:nbn:se:uu:diva-231125DOI: 10.1186/1756-3305-7-318ISI: 000339579100001PubMedID: 25011617OAI: diva2:743650
Available from: 2014-09-04 Created: 2014-09-04 Last updated: 2016-04-12Bibliographically approved
In thesis
1. Studies of Spotted Fever Rickettsia - Distribution, Detection, Diagnosis and Clinical Context: With a Focus on Vectors and Patients in Sweden
Open this publication in new window or tab >>Studies of Spotted Fever Rickettsia - Distribution, Detection, Diagnosis and Clinical Context: With a Focus on Vectors and Patients in Sweden
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The spotted fever rickettsia, Rickettsia helvetica, is an endemic tick-borne bacteria in Sweden. It causes infections in humans, manifested as aneruptive fever, headache, arthralgia and myalgia, and sometimes an inoculation eschar or a rash. There have also been two known cases of human infections with R. felis in Sweden.

The present thesis starts by investigating dispersal of ticks and Rickettsia spp. by migrating birds flying from Africa to Europe. Almost 15,000 birds were searched and 734 ticks collected, mainly of the species Hyalomma marginatum complex. Almost half (48%) of the ticks were infected with Rickettsia spp., 96% of which was R. aeschlimannii, the remaining R. africae and undefined species.

The next study focused on questing ticks over a large area in Sweden and determining the prevalence of Rickettsia spp., Anaplasma spp. and Coxiella burnetii. Rickettsia spp. was found in 9.5-9.6% of the ticks and A. phagocytophilum in 0.7%; no C. burnetii was found.

The last three papers in the thesis focused on the clinical presentation of rickettsiosis, the symptoms associated with the infection in general and particularly in patients with neurological complications. A tick-exposed population in Sweden was investigated to gain a better understanding of symptoms due to rickettsioses, also in relation to co-infections with other tick-borne bacteria. Based on symptoms, it was not possible to distinguish what pathogen caused the infections. Most patients had erythema migrans, some had serological reactions to Rickettsia spp., Borrelia spp. or co-infections by Rickettsia spp., Borrelia spp. and/or Anaplasma spp. In the fourth and fifth papers, we found associations between antibodies against Rickettsia spp. and sudden deafness (in 10-24% of patients) and facial nerve paralysis (in 8.3-25% of patients). In three patients R. felis was detected in the cerebrospinal fluids.   

Briefly, the thesis helps to clarify our knowledge about tick dispersal, shows a narrower prevalence estimate of Rickettsia spp. in Swedish ticks, and illuminates symptoms of rickettsioses and co-infections with other tick-borne infections. It also shows that presence of erythema migrans may be explained by more than Lyme disease and indicates a possible association between rickettsiosis and sudden deafness and facial nerve paralysis.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 77 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1195
tick-borne infections, co-infections, ticks, Ixodes ricinus, zoonosis, Rickettsia helvetica, migrating birds, Bell’s pares, erythema migrans, Rickettsia aeschlimannii, sudden deafness, facial nerve paralysis, Hyalomma marginatum, Rickettsia africae, western blot, PCR, serology
National Category
Clinical Medicine Basic Medicine
Research subject
Clinical Bacteriology
urn:nbn:se:uu:diva-280667 (URN)978-91-554-9512-1 (ISBN)
Public defence
2016-05-04, Hörsalen, Klinisk Mikrobiologi, Akademiska sjukhuset, Ing D1, Dag Hammarskjöldsväg 17, Uppsala, 09:15 (Swedish)
Available from: 2016-04-11 Created: 2016-03-14 Last updated: 2016-04-12

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Wallmenius, KatarinaJaenson, Thomas G. T.Olsen, BjörnSalaneck, ErikNilsson, Kenneth
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