Diversity within sensu lato genospecies in Switzerland by gene sequence

Casati, Simona; Bernasconi, Marco Valerio; Gern, Lise; Piffaretti, Jean-Claude

doi:10.1016/j.femsle.2004.07.025

Cited by 11 publications

(15 citation statements)

References 22 publications

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“…Overall prevalence of infection by Borrelia (34.8%) was similar to that of another study conducted in the same area (32.7%) (Casati et al 2004). Infection prevalence in adults was higher (39.6%) than in nymphs (25.5%), as often described in Europe (Rauter and Hartung 2005) and Switzerland (Casati et al 2004, Jouda et al 2004.…”

Section: Discussionsupporting

confidence: 85%

“…Genospecies prevalence was in line with what had been observed in the same area: B. afzelii (33.8%), B. burgdorferi s.s. (10.3%), B. garinii (32.1%), B. myamotoi (3.1%), and B. valaisiana (20.2%) (Casati et al 2004, Jouda et al 2004, Morán Cadenas et al 2007b, Gern et al 2010. The Borrelia genospecies were similarly distributed among males and females.…”

Section: Discussionmentioning

confidence: 96%

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Survival of Ixodes ricinus (Acari: Ixodidae) Under Challenging Conditions of Temperature and Humidity Is Influenced by Borrelia burgdorferi sensu lato Infection

2010

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To determine whether Borrelia burgdorferi sensu lato (s.l.) inßuences tick survival under thermohygrometric stress, Ixodes ricinus (L.) (Acari: Ixodidae) questing ticks were tested under various relative humidities (13, 32, 51.5, 61, and 89% RH) at two different temperatures (12.5 and 25ЊC) and investigated for Borrelia infection. Survival rate of females was highest (77.6%), followed by males (51.6%), and nymphs (43.2%). The thermohygrometric factor that most importantly determined survival was saturation deÞcit (SD). As SD increased, tick survival rate decreased in all stages. Among the 1,500 ticks tested for B. burgdorferi s.l., 34.8% (n ϭ 522) were infected. Adult infection rate (39.6%) was higher than that of nymphs (25.5%). Infection load in real-time polymerase chain reaction ranged from 1 to 1.2 million spirochetes per tick. B. afzelii (39.7%), B. burgdorferi sensu stricto (12.1%), B. garinii (37.9%), B. myamotoi (3.6%), and B. valaisiana (23.8%) were recorded. B. garinii infected signiÞcantly less nymphs than adults whereas B. afzelii displayed the opposite trend. Survival rate of nymphal and adult I. ricinus was signiÞcantly enhanced by infection by B. burgdorferi s.l. ( 2 : nymph, P ϭ 0.008; adult, P ϭ 0.021). In adults, a negative effect of infection on tick survival was observed when spirochete load overcame a threshold estimated at 160,000 spirochetes per tick but not in nymphs. Moreover, ticks infected by B. afzelii survived better than other ticks (infected by other genospecies or not). The results here indicate that infection by B. burgdorferi s.l., and more speciÞcally infection by B. afzelii, confers survival advantages to I. ricinus under challenging thermohygrometric conditions.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 96%

Survival of Ixodes ricinus (Acari: Ixodidae) Under Challenging Conditions of Temperature and Humidity Is Influenced by Borrelia burgdorferi sensu lato Infection

2010

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“…In Europe, the most prevalent Borrelia species is either B. afzelii (7,29,35) or B. garinii (6,39). We observed marked differences in the prevalence levels of Borrelia species for both the geographic regions and the habitat categories, which may be related to the specific host preferences of the different Borrelia species.…”

Section: Discussionmentioning

confidence: 99%

Prevalence and Seasonality of Tick-Borne Pathogens in Questing Ixodes ricinus Ticks from Luxembourg

Reye

Hübschen

Sausy

et al. 2010

Appl Environ Microbiol

145

105

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In Europe, ixodid ticks are important arthropod vectors of human and animal pathogens, but comprehensive studies of the prevalence of all relevant pathogens in Central Europe are scarce. As a result of ecological changes, the incidences of tick-borne infections are expected to increase. In this study, 1,394 nymphal and adult Ixodes ricinus ticks sampled monthly during the active season from 33 ecologically distinct collection sites throughout Luxembourg were screened for all human tick-borne pathogens relevant in Central Europe. Species were identified by sequence analysis of detection PCR amplicons. Mean infection rates of ticks were 11.3% for Borrelia burgdorferi sensu lato, 5.1% for Rickettsia sp., 2.7% for Babesia sp., and 1.9% for Anaplasma phagocytophilum. No tick was found to be infected with Coxiella sp., Francisella tularensis subsp., or Tick-borne encephalitis virus (TBEV). A total of 3.2% of ticks were infected with more than one pathogen species, including mixed Borrelia infections (1.5%). Seasonal variations of tick infection rates were observed for Borrelia, Babesia, and Anaplasma, possibly reflecting a behavioral adaptation strategy of questing ticks. A positive correlation between the grade of urbanization and Borrelia infection rate of ticks was observed, suggesting an established urban zoonotic cycle. We also found Hepatozoon canis (0.1%) and Bartonella henselae (0.3%), which so far have not been found in questing Ixodes ricinus ticks in Central Europe.In Western Europe, the hard tick Ixodes ricinus is the main arthropod vector of various human and animal pathogens, causing several tens of thousands of severe infections in humans every year (25, 37). The most common tick-borne infection is Lyme borreliosis. This multisystemic disorder is caused by spirochetes of the Borrelia burgdorferi sensu lato complex, which is comprised of at least 12 species worldwide (45). Among the 6 European species, only Borrelia garinii, Borrelia afzelii, and Borrelia burgdorferi sensu stricto are known as human pathogens, whereas the significance of Borrelia valaisiana, Borrelia spielmanii, and Borrelia lusitaniae for human health is not clear (24). In a metaanalysis of 154 European studies, a mean of 13.7% of ticks were found to be infected with Borrelia spp., predominantly with B. afzelii and B. garinii. However, the prevalence of Borrelia species varies from 2 to 49% between different regions (43).Other tick-borne bacteria which cause disease in humans are Rickettsia sp., Anaplasma phagocytophilum, Bartonella henselae and Bartonella quintana, Coxiella burnetii, and Francisella tularensis subsp., all of which show only relatively low prevalence rates of 0.1 to 4.8% for European ticks (16,23,26,42,48,52). In addition, three species of the parasitic protozoan Babesia are known to infect humans, namely, B. divergens, B. microti, and the newly described Babesia sp. EU1 (5). Also, in Western Europe, Tick-borne encephalitis virus (TBEV) has a relatively low prevalence; however, this pathogen deserves special attention b...

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“…Interestingly, the homogeneity within the I. ricinus s.s. population contrasts with the extensive heterogeneity of B. burgdorferi s.l., which is harboured by the former (Casati et al, 2004). It has been hypothesised that the genetic diversity within the B. burgdorferi genospecies is driven mainly by the host, in particular by the sensitivity or resistance to its complement system (Kurtenbach et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Assessment of intraspecific mtDNA variability of European Ixodes ricinus sensu stricto (Acari: Ixodidae)

Casati

Bernasconi

Gern

et al. 2008

Infection, Genetics and Evolution

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The Ixodes ricinus complex is composed of 14 species distributed worldwide. Some members of this complex are involved in the transmission of a number of diseases to animals and humans, in particular Lyme borreliosis, tick-borne encephalitis, ehrlichiosis and babesiosis. While the phylogenetic relationships between species of the I. ricinus complex have been investigated in the past, still little is known about the genetic structure within the species I. ricinus sensu stricto. We have investigated the intraspecific variability among 26 I. ricinus s.s. ticks collected in various European countries, including Switzerland, Italy, Austria, Denmark, Sweden, and Finland by using five mitochondrial gene fragments corresponding to the control region, 12S rDNA, cytb, COI, and COII. The five genes considered here showed a low genetic variability (1.6-5%). Our results based on both statistical parsimony (applied to the COI + COII + cytb + 12S + CR data set, for a total of 3423 bp) and maximum parsimony (applied to the COI + COII + cytb + 12S data set, for a total of 2980 bp) did not provide any evidence for a correlation between the identified haplotypes and their geographic origin. Thus, the European I. ricinus s.s. ticks do not seem to show any phylogeography structure.

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Diversity within sensu lato genospecies in Switzerland by gene sequence

Cited by 11 publications

References 22 publications

Survival of Ixodes ricinus (Acari: Ixodidae) Under Challenging Conditions of Temperature and Humidity Is Influenced by Borrelia burgdorferi sensu lato Infection

Survival of Ixodes ricinus (Acari: Ixodidae) Under Challenging Conditions of Temperature and Humidity Is Influenced by Borrelia burgdorferi sensu lato Infection

Prevalence and Seasonality of Tick-Borne Pathogens in Questing Ixodes ricinus Ticks from Luxembourg

Assessment of intraspecific mtDNA variability of European Ixodes ricinus sensu stricto (Acari: Ixodidae)

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