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Gern, Lise

Nom
Gern, Lise
Affiliation principale
Fonction
Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/303

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  • Publication
    Métadonnées seulement
    Reservoir role of lizard Psammodromus algirus in transmission cycle of Borrelia burgdorferi sensu lato (Spirochaetaceae) in Tunisia
    (2006)
    Dsouli, Najla
    ;
    Younsi-Kabachii, Hend
    ;
    Postic, Danièle
    ;
    Nouira, Said
    ;
    Gern, Lise 
    ;
    Bouattour, Ali
    To investigate the reservoir role of the lizard Psammodromus algirus for the Lyme disease spirochete, 199 lizards were trapped from April to October 2003 in El Jouza, northwestern Tunisia. In this site, the infection rate of free-living Ixodes ricinus (L.) by Borrelia was evaluated by immunofluorescence as 34.6% for adult ticks and 12.5% for nymphs. Eighty percent of P. algirus (117/146) captured during this study were infested by I. ricinus, the predominant tick species collected from lizards. The intensity of tick infestation of this host by larvae and nymphs ranged from 0.14 to 7.07 and from 1.5 to 6.58, respectively. These immature stages of I. ricinus were found on lizards in spring and the beginning of summer, with a peak of intensity during June (10.16 immature ticks by lizard). Tissue cultures from lizards and xenodiagnosis with larval L ricinus were used to assess the infection and the ability, respectively, of infected lizards to transmit Borrelia to naive ticks. Seventeen percent of xenodiagnostic ticks (40/229) acquired B. lusitaniae while feeding on P. algirus. Therefore, we demonstrated the ability of the lizards to sustain Borrelia infection and to infect attached ticks, and we proved that P. algirus is a reservoir host competent to transmit B. lusitaniae.
  • Publication
    Métadonnées seulement
    Prevalence of Borrelia burgdorferi sensu lato in ticks collected from migratory birds in Switzerland
    (2006)
    Poupon, Marie-Angèle
    ;
    Lommano, Elena 
    ;
    Humair, Pierre-François
    ;
    Douet, Véronique 
    ;
    Rais, Olivier 
    ;
    Schaad, Michael
    ;
    Jenni, Lukas
    ;
    Gern, Lise 
    The prevalence of ticks infected by Borrelia burgdorferi sensu lato on birds during their migrations was studied in Switzerland. A total of 1,270 birds captured at two sites were examined for tick infestation. Ixodes ricinus was the dominant tick species. Prevalences of tick infestation were 6% and 18.2% for birds migrating northward and southward, respectively. Borrelia valaisiana was the species detected most frequently in ticks, followed by Borrelia garinii and Borrelia lusitaniae. Among birds infested by infected ticks, 23% (6/26) were infested by B. lusitaniae-infected larvae. Migratory birds appear to be reservoir hosts for B. lusitaniae.
  • Publication
    Métadonnées seulement
    Characterization of Borrelia lusitaniae isolates collected in Tunisia and Morocco
    (2005)
    Younsi, Hend
    ;
    Sarih, M'Hammed
    ;
    Jouda, Fatima
    ;
    Godfroid, Edmond
    ;
    Gern, Lise 
    ;
    Bouattour, Ali
    ;
    Baranton, Guy
    ;
    Postic, Danièle
    Borrelia lusitaniae is a species within the complex Borrelia burgdorferi sensu lato and is infrequently isolated in Europe. In contrast, this species is by far the most predominant in North Africa and in Portugal. In this study, we analyzed the genetic diversity, at several loci, of a large population of isolates from free-living Ixodes ricinus ticks collected in Tunisia and Morocco. We found a moderate diversity of the whole genome by using pulsed-field gel electrophoresis as well as in the ospA gene sequences, compared to a high level of strain homogeneity in the small noncoding ribosomal spacer. In contrast, a high diversity of this locus has been previously reported for Portuguese isolates. We hypothesize that B. lusitaniae strains isolated in North Africa constitute a clone of Portuguese origin.
  • Publication
    Métadonnées seulement
    Detection and identification of Ehrlichia spp. in ticks collected in Tunisia and Morocco
    (2005)
    Sarih, M'Hammed
    ;
    M'Ghirbi, Youmna
    ;
    Bouattour, Ali
    ;
    Gern, Lise 
    ;
    Baranton, Guy
    ;
    Postic, Danièle
    A broad-range 16S rRNA gene PCR assay followed by partial sequencing of the 16S rRNA gene was used for the detection of members of the family Anaplasmataceae in ticks in North Africa. A total of 418 questing Ixodes ricinus ticks collected in Tunisia and Morocco, as well as 188 Rhipicephalus ticks from dogs and 52 Hyalomma ticks from bovines in Tunisia, were included in this study. Of 324 adult L ricinus ticks, 16.3% were positive for Ehrlichia spp., whereas only 3.4 and 2.8% of nymphs and larvae, respectively, were positive. A large heterogeneity was observed in the nucleotide sequences. Partial sequences identical to that of the agent of human granulocytic ehrlichiosis (HGE) were detected in L ricinus and Hyalomma detritum, whereas partial sequences identical to that of Anaplasma platys were detected in Rhipicephalus sanguineus. However, variants of Anaplasma, provisionally designated Anaplasma-like, were predominant in the L ricinus tick population in Maghreb. Otherwise, two variants of the genus Ehrlichia were detected in L ricinus and H. detritum. Surprisingly, a variant of Wolbachia pipientis was evidenced from L ricinus in Morocco. These results emphasized the potential risk of tick bites for human and animal populations in North Africa.
  • Publication
    Métadonnées seulement
    Apodemus species mice are reservoir hosts of Borrelia garinii OspA serotype 4 in Switzerland
    (2002)
    Hügli, Delphine
    ;
    Hu, Chang Min
    ;
    Humair, Pierre-François
    ;
    Wilske, Bettina
    ;
    Gern, Lise 
    Among Borrelia burgdorferi sensu lato isolates, seven outer surface protein A (OspA) serotypes have been described: serotypes 1 and 2 correspond to B. burgdorferi sensu stricto and Borrelia afzelii, respectively, and serotypes 3 to 7 correspond to Borrelia garinii. In Europe, serotype 4 has never been isolated from Ixodes ricinus ticks until recently, although this serotype has been frequently isolated from cerebrospinal fluid from patients. In Europe, B. afzelii and B. burgdorferi sensu stricto were found associated with rodents and B. garinii was found associated with birds. In this study, the reservoir role of Apodemus mice for B. garinii OspA serotype 4 was demonstrated by xenodiagnosis. Apodemus mice are the first identified reservoir hosts for B. garinii OspA serotype 4.