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Eco-épidémiologie de la tique Ixodes ricinus et des pathogènes qu'elle transmet en Suisse

English title Eco-epidemiology of the tick Ixodes ricinus and of transmitted pathogens in Switzerland
Applicant Gern Lise
Number 127064
Funding scheme Project funding (Div. I-III)
Research institution Laboratoire d'Eco-épidémiologie Institut de Biologie Université de Neuchâtel
Institution of higher education University of Neuchatel - NE
Main discipline Zoology
Start/End 01.10.2009 - 30.09.2012
Approved amount 74'600.00
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All Disciplines (2)

Discipline
Zoology
Infectious Diseases

Keywords (7)

Ixodes ricinus; climate change; phenology; Borrelia burgdorferi; TBE virus; tick-borne pathogens; population genetic

Lay Summary (English)

Lead
Lay summary
Lyme borreliosis (LB) and Tick-borne encephalitis (TBE), both due to the bites of the tick Ixodes ricinus, are significant vector-borne diseases in humans in Switzerland. Risk of acquiring these diseases is primarily related to the frequency of contacts with infected ticks. Human activity is one of the factors influencing these contacts. However spatial and temporal variations of tick density are also important. Global climate change is suspected in having potential effects on distributions of tick-borne diseases. Increase in temperature may result in the extension of habitats suitable for ticks into higher altitudes. However assessing the relative importance of climate changes needs solid long-term data on ticks, which can then be statistically analysed and tested on biological models. Therefore, we will continue our study (1996-today) on the seasonal tick activity in relation with climatic data and on infection with Borrelia and we will statistically analyse these datasets. This should help to differentiate short-term fluctuations from long-term trends. These data will also be used to test and perfect an I. ricinus tick population model. TBE is a neurological disease due to a flavivirus. Recently, an increase of TBE cases and an emergence of new TBE foci were observed in Switzerland. We will study the role of migratory and local birds in the transport and the maintenance of TBE virus. We also intend to analyse the ticks for other tick-borne pathogens. LB is a systemic disease due to Borrelia burgdorferi and up to seven Borrelia species can infect the tick populations in Switzerland. The ospC gene of Borrelia is highly variable within each Borrelia species and can be used to define groups. A few ospC groups cause invasive forms of the disease in humans, other groups are not invasive or non pathogenic to humans. We are interested in studying the development of the Borrelia infection in the tick and the transmission processes to the host and from the host in relation with ospC groups. Recent studies suggested that Borrelia infection in I. ricinus ticks might also play a role in geographical dispersal of ticks. We will study population genetic in the context of tick dispersion in relation with their infection by Borrelia species. These projects should contribute to a better understanding of the eco-epidemiology of I. ricinus and tick-borne pathogens in relation with human risk to acquire the diseases.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Publications

Publication
Prevalence and genotyping of tick-borne encephalitis virus in questing Ixodes ricinus ticks in a new endemic area in Western Switzerland
Lommano Elena, Burri Caroline, Maeder Gilles, Guerne Maude, Bastic Viktoria, Patalas Eva, Gern Lise (2012), Prevalence and genotyping of tick-borne encephalitis virus in questing Ixodes ricinus ticks in a new endemic area in Western Switzerland, in Journal of medical Entomology, 49, 156-164.
Seasonality of Ixodes ricinus ticks on vegetation and on rodents and Borrelia burgdorferi sensu lato genospecies diversity in two lyme borreliosis-endemic areas in Switzerland.
Pérez David, Kneubühler Yvan, Rais Olivier, Gern Lise (2012), Seasonality of Ixodes ricinus ticks on vegetation and on rodents and Borrelia burgdorferi sensu lato genospecies diversity in two lyme borreliosis-endemic areas in Switzerland., in Vector borne and zoonotic diseases (Larchmont, N.Y.), 12(8), 633-44.
Infections and coinfections of questing Ixodes ricinus ticks by emerging zoonotic pathogens in Western Switzerland.
Lommano Elena, Bertaiola Luce, Dupasquier Christèle, Gern Lise (2012), Infections and coinfections of questing Ixodes ricinus ticks by emerging zoonotic pathogens in Western Switzerland., in Applied and environmental microbiology, 78(13), 4606-12.
Do the level of energy reserves, hydration status and Borrelia infection influence walking by Ixodes ricinus (Acari: Ixodidae) ticks?
Herrmann C, Gern L (2012), Do the level of energy reserves, hydration status and Borrelia infection influence walking by Ixodes ricinus (Acari: Ixodidae) ticks?, in Parasitology, 139(3), 330-7.
Serological evidence of tick-borne encephalitis virus infection in rodents captured at four sites in Switzerland.
Burri Caroline, Korva Misa, Bastic Viktoria, Knap Natasa, Avsic-Zupanc Tatjana, Gern Lise (2012), Serological evidence of tick-borne encephalitis virus infection in rodents captured at four sites in Switzerland., in Journal of medical entomology, 49(2), 436-9.
Pathogens of emerging tick-borne diseases, anaplasma phagocytophilum, rickettsia spp., and babesia spp., in ixodes ticks collected from rodents at four sites in Switzerland (Canton of Bern)
Burri Caroline, Dupasquier Christèle, Bastic Viktoria, Gern Lise (2011), Pathogens of emerging tick-borne diseases, anaplasma phagocytophilum, rickettsia spp., and babesia spp., in ixodes ticks collected from rodents at four sites in Switzerland (Canton of Bern), in Vector-Borne and Zoonotic Diseases, 11(7), 939-944.
Borrelia afzelii ospC genotype diversity in Ixodes ricinus questing ticks and ticks from rodents in two Lyme borreliosis endemic areas: contribution of co-feeding ticks.
Pérez David, Kneubühler Yvan, Rais Olivier, Jouda Fatima, Gern Lise (2011), Borrelia afzelii ospC genotype diversity in Ixodes ricinus questing ticks and ticks from rodents in two Lyme borreliosis endemic areas: contribution of co-feeding ticks., in Ticks and tick-borne diseases, 2(3), 137-42.
Prospective study on the incidence of infection by Borrelia burgdorferi sensu lato after a tick bite in a highly endemic area of Switzerland.
Huegli Delphine, Moret Jacqueline, Rais Olivier, Moosmann Yves, Erard Philippe, Malinverni Raffaele, Gern Lise (2011), Prospective study on the incidence of infection by Borrelia burgdorferi sensu lato after a tick bite in a highly endemic area of Switzerland., in Ticks and tick-borne diseases, 2(3), 129-36.
Microclimate and the zoonotic cycle of tick-borne encephalitis virus in Switzerland.
Burri C, Bastic V, Maeder G, Patalas E, Gern L (2011), Microclimate and the zoonotic cycle of tick-borne encephalitis virus in Switzerland., in Journal of medical entomology, 48(3), 615-27.
Prevalence of three zoonotic Babesia species in Ixodes ricinus (Linné, 1758) nymphs in a suburban forest in Switzerland.
Gigandet Luca, Stauffer Emilie, Douet Véronique, Rais Olivier, Moret Jacqueline, Gern Lise (2011), Prevalence of three zoonotic Babesia species in Ixodes ricinus (Linné, 1758) nymphs in a suburban forest in Switzerland., in Vector borne and zoonotic diseases (Larchmont, N.Y.), 11(4), 363-6.
Survival of Ixodes ricinus (Acari: Ixodidae) under challenging conditions of temperature and humidity is influenced by Borrelia burgdorferi sensu lato infection.
Herrmann Coralie, Gern Lise (2010), Survival of Ixodes ricinus (Acari: Ixodidae) under challenging conditions of temperature and humidity is influenced by Borrelia burgdorferi sensu lato infection., in Journal of medical entomology, 47(6), 1196-204.
[Diseases and pathogenic agents transmitted by ticks in Switzerland].
Gern L, Lienhard R, Péter O (2010), [Diseases and pathogenic agents transmitted by ticks in Switzerland]., in Revue médicale suisse, 6(266), 1906-9.
Diversity of Borrelia genospecies in Ixodes ricinus ticks in a Lyme borreliosis endemic area in Switzerland identified by using new probes for reverse line blotting.
Gern Lise, Douet Véronique, López Zully, Rais Olivier, Cadenas Francisca Morán (2010), Diversity of Borrelia genospecies in Ixodes ricinus ticks in a Lyme borreliosis endemic area in Switzerland identified by using new probes for reverse line blotting., in Ticks and tick-borne diseases, 1(1), 23-9.
Isolation of Borrelia burgdorferi sensu lato from the skin of the European badger (Meles meles) in Switzerland.
Gern Lise, Sell Katy (2009), Isolation of Borrelia burgdorferi sensu lato from the skin of the European badger (Meles meles) in Switzerland., in Vector borne and zoonotic diseases (Larchmont, N.Y.), 9(2), 207-8.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
II International Congress "Spirochetes Havana 2012" 23.04.2012 La Havana, Cuba
ESCMID 02.04.2012 Londres
Réunion du REID, Tiques et maladies à tiques 17.11.2011 Strasbourg
Seventh International Conference on Ticks and Tick-Borne Pathogens 28.08.2011 Zaragoza, Spain
XI International Jena Symposium on tick-borne diseases 24.03.2011 Weimar, german
Réunion annuelle de la Société Suisse de Médecine Tropicale et Parasitologie 28.10.2010 Spiez
12th International Conference on Lyme Borreliosis and other tick-borne Diseases. 26.09.2010 Ljubljana, Slovenia


Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Sus aux tiques Migros Magazine Italian-speaking Switzerland German-speaking Switzerland Western Switzerland 15.10.2012
Media relations: print media, online media Abeilles, tiques et pétunias En Direct no 238 International 17.09.2011
Talks/events/exhibitions Ah! Ces tiques…. Western Switzerland 24.02.2011
Media relations: print media, online media Befallene Zecken lieben es heiss St. Galler Tagblatt/Ausgabe St. Gallen und Gossau German-speaking Switzerland 15.04.2011
Talks/events/exhibitions Ecologie de la maladie de Lyme en Suisse International 15.02.2011
Media relations: print media, online media Eine Studie der Uni Neuenburg stellt fest, dass der Klimawandel zum l SR DSR 3 German-speaking Switzerland 15.04.2011
Media relations: print media, online media Elle a consacré toute sa vie aux tiques La Tribune de Genève Western Switzerland 10.07.2011
Media relations: print media, online media La chaleur développe les tiques 20 Minutes Western Switzerland 15.04.2011
Media relations: print media, online media Le réchauffement rend les tiques plus méchantes La Tribune de Genève Western Switzerland 15.04.2011
Media relations: radio, television Les petits matins de la RSR RSR Western Switzerland 05.05.2011
Media relations: print media, online media Les piqûres de tiques deviendront plus dangereuses Le Matin Western Switzerland 15.04.2011
Media relations: print media, online media Les tiques deviendront plus dangereuses Teletext TSI1, TSR1, SF1 Italian-speaking Switzerland Western Switzerland German-speaking Switzerland 15.04.2011
Talks/events/exhibitions Les tiques et les pathogènes qu’elles transmettent Western Switzerland 29.03.2011
Media relations: radio, television Les tiques sont de retour JT 19h30 TSR Western Switzerland 14.04.2011
Media relations: radio, television Mit Borreliose infizierte Zecken überleben Trockenperioden besser SR DSR 4 News German-speaking Switzerland 15.04.2011
Media relations: print media, online media Svizzera Riscaldamento del clima, in futuro zecche piu pericolose Corriere del Ticino Italian-speaking Switzerland 15.04.2011
Media relations: print media, online media Trockenheit hilft Zecken mit Borreliose-Erregern Der Bund German-speaking Switzerland 15.04.2011
Media relations: print media, online media Zeckengefahr so gross wie noche nie 20 Minuten German-speaking Switzerland 15.04.2011
Media relations: print media, online media Zeckenstiche werden gefährlicher Die Südostschweiz/ Ausgabe Graubünden German-speaking Switzerland 15.04.2011
Talks/events/exhibitions Actualités sur les tiques et les pathogènes qu’elles transmettent en Suisse Western Switzerland German-speaking Switzerland Italian-speaking Switzerland 14.12.2010
Media relations: radio, television Sunshine Report: Zecken vermehren sich mit warmen Wetter Radio Sunshine German-speaking Switzerland

Associated projects

Number Title Start Funding scheme
113936 Eco-epidemiology of the tick Ixodes ricinus and of transmitted pathogens in Switzerland 01.10.2006 Project funding (Div. I-III)
57098 Eco-epidemiology of ixodes ricinus and borrelia burgdorferi sensulato in Switzerland 01.10.1999 Project funding (Div. I-III)

Abstract

Lyme borreliosis (LB) and Tick-borne encephalitis (TBE), both due to the bites of the tick Ixodes ricinus, are significant vector-borne diseases in humans in Switzerland. Risk of acquiring these diseases is primarily related to the frequency of contacts with infected ticks. Human activity is one of the factors influencing these contacts. In addition, spatial and temporal variations of tick density are also important. Global climate change is suspected in having potential effects on distributions of tick-borne diseases. Increase in temperature may result in the extension of suitable habitats into higher altitudes. However assessing the relative importance of climate changes needs solid long-term data on ticks, which can then be statistically analysed and tested on biological models. Therefore, we will continue our long-term study (1996-today) on the seasonal tick activity in relation with climatic data and on infection with Borrelia. We intend to statistically analyse these long-term datasets. This should help to disentangle short-term fluctua-tions from long-term trends. These data will also be used to test and perfect an I. ricinus tick population model. TBE is a severe neurological disease caused by a flavivirus. Recently, an increase of TBE clinical cases (spike in 2006) and an emergence of new TBE foci were observed in Switzerland. Here, we will study the role of migratory and local birds in the transport and the maintenance of TBE virus and identify new TBE foci in the western part of Switzerland by detection of the virus in ticks by Real-Time PCR. We also intend to analyse ticks for other tick-borne pathogens using the Reverse Line Blot (RLB) technique.LB is a systemic disease due to Borrelia burgdorferi sensu lato (sl). Up to now, 15 Borrelia spe-cies have been described. In endemic areas in Switzerland, up to six Borrelia species may circulate bet-ween hosts and ticks. The ospC gene of B. burgdorferi sl is highly variable within each species and can be used to define groups. A few ospC groups cause invasive forms of the disease, other groups are not invasive or non pathogenic to humans. Intra-species differences also play roles in the development of the infection in the tick and in the transmission cycle. We are interested in studying these last points in relati-on with ospC groups. Recent studies suggested that Borrelia infection in I. ricinus ticks might also play a role in ge-ographical dispersal of ticks. In fact, studying population genetic of I. ricinus, it was observed that female ticks were more related to each other than males, meaning that males seemed more prone to dispersal than females. One explanation being that immature males would feed preferentially on hosts that move for long distance, like birds, whereas immature females would attach to rodents, which are less vagil. Since B. garinii and B. valaisiana are associated with birds, and B. afzelii and B. burgdorferi ss with ro-dents, it was hypothetised that male and female ticks may be differentially infected. It was shown that Borrelia species seems to play a role in local adaptation of I. ricinus. Since we have samples from ticks and Borrelia species collected on a long-term basis at high altitudes where they had not been observed before, we will study population genetic in the context of tick dispersion in relation with their infection by Borrelia species.The projects should contribute to a better understanding of the eco-epidemiology of I. ricinus and tick-borne pathogens in relation with human risk to acquire the diseases. Our long-term dataset on ticks in relation with climatic data and on their infection by Borrelia allow a statistical analysis and modelling of the situations, which are relevant to local human risk. This may also help to understand the exponential inc-rease of TBE incidence and appearance of new foci in parts of Switzerland.
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