ABSTRACTTicks are important disease vectors that can cause considerable economic losses by affecting animal health and productivity, especially in tropical and subtropical regions. In this study, we investigated the prevalence and diversity of bacterial and protozoan tick-borne pathogens in ticks collected from the vegetation and cattle in Nigeria by PCR. The infection rates of questing ticks were 3.1% forRickettsiaspecies, 0.1% forCoxiella burnetiiand 0.4% forBorreliaspecies. Other pathogens, such asBabesia,Theileria,Anaplasma, andEhrlichiaspecies, were not detected in ticks from the vegetation. Feeding ticks collected from cattle displayed infection rates of 12.5% forRickettsiaspecies, 14% forCoxiella burnetii, 5.9% forAnaplasmaspecies, 5.1% forEhrlichiaspecies, and 2.9% forTheileria mutans. BabesiaandBorreliaspecies were not detected in ticks collected from cattle. Mixed infections were found only in feeding ticks and mainlyRickettsiaspecies andCoxiella burnetiiwere involved. The diversity of tick-borne pathogens in Nigeria was higher in feeding than in questing ticks, suggesting that cattle serve as reservoirs for at least some of the pathogens studied, in particularC. burnetii. The total estimated herd infection rates of 20.6% for aRickettsia africae-like species, 27% forCoxiella burnetii, and 8.5% forAnaplasma marginale/centralesuggest that these pathogens may have considerable implications for human and animal health.

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...

Worldwide, ticks are important vectors of human and animal pathogens. Besides Lyme Borreliosis, a variety of other bacterial and protozoal tick-borne infections are of medical interest in Europe. In this study, 553 questing and feeding Ixodes ricinus (n = 327) and Dermacentor reticulatus ticks (n = 226) were analysed by PCR for Borrelia, Rickettsia, Anaplasma, Coxiella, Francisella and Babesia species. Overall, the pathogen prevalence in ticks was 30.6% for I. ricinus and 45.6% for D. reticulatus. The majority of infections were caused by members of the spotted-fever group rickettsiae (24.4%), 9.4% of ticks were positive for Borrelia burgdorferi sensu lato, with Borrelia afzelii being the most frequently detected species (40.4%). Pathogens with low prevalence rates in ticks were Anaplasma phagocytophilum (2.2%), Coxiella burnetii (0.9%), Francisella tularensis subspecies (0.7%), Bartonella henselae (0.7%), Babesia microti (0.5%) and Babesia venatorum (0.4%). On a regional level, hotspots of pathogens were identified for A. phagocytophilum (12.5–17.2%), F. tularensis ssp. (5.5%) and C. burnetii (9.1%), suggesting established zoonotic cycles of these pathogens at least at these sites. Our survey revealed a high burden of tick-borne pathogens in questing and feeding I. ricinus and D. reticulatus ticks collected in different regions in Belarus, indicating a potential risk for humans and animals. Identified hotspots of infected ticks should be included in future surveillance studies, especially when F. tularensis ssp. and C. burnetii are involved.

In vertebrate reproductive endocrinology sex steroids play a pivotal role via binding to receptors. However, information on the origin and relevance of sex steroids in invertebrates is limited. This review highlights current literature on steroid receptors in aquatic invertebrates and reports on some new findings. It has been shown that invertebrates of the deuterostome clade, such as Acrania and Echinodermata, respond to estrogens and androgens and, at least in Branchiostoma, an estrogen receptor has been cloned. Within the protostomes, most findings are related to aquatic molluscs. Sex steroid receptor-like proteins are abundant in gastropods, bivalves and cephalopods and also sex hormone signalling shows partial similarity to the deuterostomes. In ecdysozoans, however, the impact of sex steroids is still a matter of debate even though there is evidence on the presence of estrogen receptor-like proteins in Crustacea and on physiological effects of estrogens in both Nematoda and Crustacea. Recent findings suggest the presence of an estrogen receptor alpha-like protein of unclear physiological role in Gammarus fossarum (Crustacea). Binding studies revealed the crustacean Hyalella azteca to possess specific binding sites only for androgens but not for estrogens suggesting a possible limitation to functional androgen receptors in this species. Further studies have to be conducted to shed more light into the discussion about the controversy about sex steroid receptors in invertebrates.

We report on the identification of two new Francisella-like endosymbionts (FLEs) found in three different tick species from Bulgaria. The FLEs were characterized by 16S rRNA and tul4 gene sequencing and seem to lack the molecular marker RD1. These two new taxa seem to be facultative secondary endosymbionts of ticks.