Flått og flåttbårne sykdommer i Norge - med resultater fra lokale studier

Transkript

1 Flått og flåttbårne sykdommer i Norge - med resultater fra lokale studier Vivian Kjelland, Universitetet i Agder Fellesmøte for viltforvaltning i Aust-Agder 1.April

2 Lokale studier på flått og vilt Borrelia i norske flått Flått/Borrelia & hare Flått/Borrelia & rådyr/elg 2

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4 Forekomst av Borrelia i flått fra vegetasjon Forekomst av Borrelia i flått: Larver: 0.5% Nymfer: 24.5% Voksne: 26.9% Genotyper B. afzelii (61.6%) Overskrift Brødtekst B. garinii (23.4%) B. burgdorferi sensu stricto (10.6%) B. valaisiana (4.5%) 4

5 Abstract: From April to October 2007, host-seeking Ixodes ricinus ticks were collected from four locations in Southern Norway; Farsund, Mandal, Søgne and Tromøy, respectively. 210 larva, 1130 nymphs and 449 adults were investigated for infection with Borrelia burgdorferi sensu lato (s.l.) by real-time polymerase chain reaction (PCR) amplification of the 16S rrna gene. The total percentage of B. burgdorferi s.l. in nymphal and adult ticks was determined as 31.3% in Farsund, 25.2% in Mandal, 22.3% in Søgne and 22.1% in Tromøy, respectively. Larvae were pooled in groups of 10 before analysis, and Borrelia infection was detected in one of 21 pools of larvae. B. burgdorferi s.l. were genotyped by melting curve analysis after real-time PCR amplification of the hbb gene, or by direct sequencing of the PCR amplicon generated from the rrs (16S)-rrl (23S) intergenetic spacer. The most prevalent B. burgdorferi genospecies identified were B. afzelii (61.6%), followed by B. garinii (23.4%) and B. burgdorferi sensu stricto (10.6%). B. valaisiana (4.5%) was identified in Norwegian ticks for the first time. Mixed infections were observed in 0.3% of the infected ticks. A higher prevalence of B. burdorferi s.l. was found in present study than what has been shown in previous Nordic studies. Norsk sammendrag: I gjennomsnitt er omtrent 25 % av flåtten på Sørlandet infisert av Borrelia-bakterien, men det finnes store variasjoner både fra sted til sted og på ulike tidspunkt. Alle de kjente Borrelia-artene som forårsaker sykdom, B. afzelii, B. garinii, B. burgdorferi sensu stricto og B. valaisiana, ble påvist. Lenke til alle publikasjoner finner du her: 5

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7 Abstract: The mountain hare (Lepus timidus) population in southern Norway appears to be in decline. Necropsy and laboratory examinations of 36 hares found dead or diseased during in Vest- and Aust-Agder counties showed that disease and deaths were attributed to multiple causes, with no specific etiology emerging as a cause for population decline. To investigate whether Borrelia burgdorferi sensu lato (s.l.) infection is associated with mortality in mountain hares, tissues and ticks collected from hares were investigated for infection with the spirochete. Borrelia burgdorferi s.l. DNA was not detected in samples from internal organs, whereas Borrelia afzelii, B. burgdorferi sensu stricto (s.s.), and the not-yet-defined Borrelia sp. SV1 were found in skin samples from hares and in adult and nymphal Ixodes ricinus feeding on hares. Only B. burgdorferi s.s. and Borrelia sp. SV1 were detected in larvae feeding on hares. Our results indicate that disseminated Borrelia infection in hares rarely occurs and, presumably, does not play a central role in the suspected population decline. The results also suggest that the mountain hare to some degree functions as a transmission host for B. burgdorferi s.s. and Borrelia sp. SV1. Norsk sammendrag: Nedgang i harebestanden ser ikke ut til å skyldes Borrelia-infeksjon. Hare kan derimot være et mulig reservoir (det vil si en smittekilde for flåtten) for enkelte Borrelia-typer. I studien ble det påvist Borrelia sp. SV1 i hud hos hare samt i flått som sugde blod fra hare. Denne Borrelia-typen er senere navngitt Borrelia finlandensis, og ble i denne studien påvist for første gang i Norge. Lenke til alle publikasjoner finner du her: 7

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9 Abstract: As part of a larger survey, ears from 18 roe deer (Capreolus capreolus) and 52 moose (Alces alces) shot in the 2 southernmost counties in Norway were collected and examined for Ixodes ricinus ticks. Seventytwo adult ticks, 595 nymphs, and 267 larvae from the roe deer, and 182 adult ticks, 433 nymphs, and 70 larvae from the moose were investigated for infection with Borrelia burgdorferi sensu lato (s.l.). The results showed the presence of B. burgdorferi s.l. DNA in 2.9% of the nymphs collected from roe deer and in 4.4% of the nymphs and 6.0% of the adults collected from moose. The spirochetes were not detected in adult ticks from roe deer, or in larvae feeding on roe deer or moose. In comparison, the mean infection prevalences in questing I. ricinus collected from the same geographical area were 0.5% infection in larvae, 24.5% in nymphs, and 26.9% in adults. The most prevalent B. burgdorferi genospecies identified in ticks collected from roe deer was B. afzelii (76.5%), followed by B. garinii (17.6%), and B. burgdorferi sensu stricto (5.9%). Only B. afzelii (76.7%) and B. garinii (23.3%) were detected in ticks collected from moose. The present study indicates a lower prevalence of B. burgdorferi infection in I. ricinus ticks feeding on roe deer and moose compared to questing ticks. This is the first study to report B. burgdorferi s.l. prevalence in ticks removed from cervids in Norway. Norsk sammendrag: Sammenlignet med flått fra vegetasjonen er en lavere andel av flått som har sugd blod fra rådyr og elg infisert med Borrelia-bakterien. Det antas at disse dyrene har stoffer i blodet (kompliment-systemet) som dreper Borrelia-bakterien mens den er i magen til flåtten. Lenke til alle publikasjoner finner du her: 9

10 Vil du vite mer? Boken Fakta om flått omhandler flåttens anatomi, biologi, utbredelse, ulike flåttbårne sykdommer hos mennesker og dyr med mer. Boken ble utgitt i januar