Swiss Army Survey in Switzerland to determine the prevalence of Francisella tularensis, members of the Ehrlichia phagocytophila genogroup, Borrelia burgdorferi sensu lato, and tick-borne encephalitis virus in ticks

Tularemia on the rise in Switzerland? A one health approach is needed!

In the last 10 years, an increase in tularemia cases has been observed in both humans and animals in Switzerland. In these, infection with Francisella tularensis, the causative agent of the zoonotic disease tularemia, can occur through arthropod vectors or contact to infected animals or exposure to contaminated environmental sources. Currently, we are only able to postulate potential aetiologies: (i) behavioral changes of humans with more exposure to endemic habitats of infected arthropod vectors; (ii) an increased rate of tularemia infected ticks; (iii) increasing number and geographical regions of tick biotopes; (iv) increasing and/or more diverse reservoir populations; (v) increasing presence of bacteria in the environment; (vi) raised awareness and increased testing among physicians; (vii) improved laboratory techniques including molecular testing. To approach these questions, a one-health strategy is necessary. A functioning collaboration between public health, human medicine, and diagnostic and veterinary units for the control of tularemia must be established. Furthermore, the public should be included within citizen-supported-science-projects.

Serological and molecular detection as well as typing of Leptospira spp. in foxes, raccoons, and other wild carnivores in North-Eastern Germany, 2021-2022

Leptospirosis is a worldwide zoonosis caused by pathogenic Leptospira spp. While the latter are reported from various mammal hosts such as humans, dogs, or rodents, less is known about their presence in wild carnivores. We therefore investigated the presence of Leptospira spp. in foxes, raccoons, badgers, raccoon dogs, and martens in North-Eastern Germany. Kidney, urine, and blood specimens obtained from legally hunted or road-killed animals were tested by real-time PCR and by serogroup specific antibody detection for the presence of Leptospira spp. Additionally, kidney and urine specimens were tested by real-time PCR for the presence of Brucella spp. and Francisella tularensis, with all being negative for these two zoonotic pathogens. Leptospira spp. were detected by PCR in 12.6 % (n = 21/166) and serologically in 26.2 % (n = 53/202) of tissue and serum samples, respectively. Antibodies to 15 different serogroups were identified with Javanica (n = 25) and Bataviae (n = 12) being predominant. A high sero-prevalence of 34.0 % and 18.6 % in foxes and raccoons, respectively, and the presence of ST17 associated with human and animal leptospirosis indicates a reservoir and the zoonotic potential of these wild animals.

Hazard potential of Swiss Ixodes ricinus ticks: Virome composition and presence of selected bacterial and protozoan pathogens

Ticks play an important role in transmitting many different emerging zoonotic pathogens that pose a significant threat to human and animal health. In Switzerland and abroad, the number of tick-borne diseases, in particular tick-borne encephalitis (TBE), has been increasing over the last few years. Thus, it remains essential to investigate the pathogen spectrum of ticks to rapidly detect emerging pathogens and initiate the necessary measures. To assess the risk of tick-borne diseases in different regions of Switzerland, we collected a total of 10'286 ticks from rural and urban areas in ten cantons in 2021 and 2022. Ticks were pooled according to species, developmental stage, gender, and collection site, and analyzed using next generation sequencing (NGS) and quantitative polymerase chain reaction (qPCR). The metagenomic analysis revealed for the first time the presence of Alongshan virus (ALSV) in Swiss ticks. Interestingly, the pool-prevalence of ALSV was higher than that of tick-borne encephalitis virus (TBEV). Furthermore, several TBEV foci have been identified and pool prevalence of selected non-viral pathogens determined.

Ticks and Chlamydia-Related Bacteria in Swiss Zoological Gardens Compared to in Contiguous and Distant Control Areas

Ticks are vectors of numerous agents of medical importance and may be infected by various Chlamydia-related bacteria, such as members of Parachlamydiaceae and Rhabdochlamydiaceae families, which are sharing the same biphasic life cycle with the pathogenic Chlamydia. However, the veterinary importance of ticks and of their internalized pathogens remains poorly studied. Thus, we wondered (i) whether the prevalence of ticks was higher in zoological gardens than in control areas with similar altitude, vegetation, humidity and temperature, and (ii) whether the presence of Chlamydia-related bacteria in ticks may vary according to the environment in which the ticks are collected. A total of 212 Ixodes ricinus ticks were collected, and all were tested for the presence of DNA from any member of the Chlamydiae phylum using a pan-Chlamydiae quantitative PCR (qPCR). We observed a higher prevalence of ticks outside animal enclosures in both zoos, compared to in enclosures. Tick prevalence was also higher outside zoos, compared to in enclosures. With 30% (3/10) of infected ticks, the zoological gardens presented a prevalence of infected ticks that was higher than that in contiguous areas (13.15%, 10/76), and higher than the control distant areas (8.65%, 9/104). In conclusion, zoological gardens in Switzerland appear to contain fewer ticks than areas outside zoological gardens. However, ticks from zoos more often contain Chlamydia-like organisms than ticks from contiguous or distant control areas.

Canine Tick-Borne Encephalitis: Clinical Features, Survival Rate and Neurological Sequelae: A Retrospective Study of 54 Cases (1999-2016)

Tick-borne encephalitis (TBE) is one of the most important infectious diseases of the central nervous system in dogs from endemic areas. While in humans survival rate and long-term outcomes are well described, these data are lacking in veterinary literature. The aim of the present paper is to characterize the clinical aspects of TBE and to investigate fatality rate, long-term outcome and the long-term neurological sequelae in a population of dogs infected with TBE. We performed a retrospective analysis of 54 dogs diagnosed with TBE at the veterinary hospital of the University of Zurich between 1999 and 2016. Medical data such as signalment, clinical presentation, results of diagnostic procedures, treatment and outcome were collected and analyzed. Statistical analysis including a cox proportional hazard model using a backward stepwise regression approach was performed. In 62% of the TBE cases unspecific signs were described before the onset of neurological signs, resembling a biphasic appearance that is well known in human TBE. Case fatality rate was 33% and all dogs died within the first 4 months after diagnosis. Long-term neurological sequalae were detected in 17% of the TBE cases. For each day of clinical signs before hospital entry the odds of sequalae increased by a factor of 1.88 (CI 1.04–3.15). Older dogs and dogs presented with seizure activity had an increased hazard risk of death (Hazard ration = 1.2, p = 0.03; and 9.38, p = 0.001, respectively). In conclusion, despite TBE being a life-threatening disease with severe clinical signs, the survival rate in our study was 67%. However, long-term sequalae can be of concern especially in dogs with longer clinical course.

Clinical Presentation and Laboratory Diagnostic Work-Up of a Horse with Tick-Borne Encephalitis in Switzerland

Tick-borne encephalitis is an important viral tick-borne zoonosis in Europe and Asia. The disease is induced by tick-borne encephalitis virus (TBEV). This report describes a 16-year-old Warmblood gelding presenting with sudden onset of lethargy, ataxia, and muscle fasciculations on the nostrils, the lips, and the eye lids as the most important clinical findings. The horse further had a mild facial nerve paralysis with drooping of the right upper and lower lip. Diagnosis was based on paired serum samples using TBEV-ELISAs revealing high serum IgM in the first sample with normal IgM in the second sample and an increase in serum IgG and neutralizing antibodies, indicating acute and recent infection. TBEV was confirmed by a virus-neutralization test, revealing a fivefold increase in antibodies 32 days after of the onset of clinical signs. Although the specific PCR on cerebrospinal fluid (CSF) was negative, TBEV-specific IgG and IgM were identified in the CSF of the horse. Treatment consisted of anti-inflammatory and anti-oxidative treatment and the horse recovered with a mild drooping of the right nostril as the only remaining clinical sign. TBEV infection is a potential differential diagnosis of neurological disease in horses living in endemic areas and this is the first report to describe the diagnostic criteria in a horse as recommended in humans with suspected TBEV infection.

Tularemia Outbreaks in Spain from 2007 to 2020 in Humans and Domestic and Wild Animals

In this study, tularemia outbreaks associated with humans and several domestic and wild animals (Iberian hares, wild rabbits, voles, mice, grey shrews, sheep, dogs, foxes, wolves, ticks, and river crayfish) are reported in Spain from 2007 to 2020. Special attention was paid to the outbreaks in humans in 2007–2009 and 2014–2015, when the most important waves occurred. Moreover, positive rates of tularemia in lagomorphs were detected in 2007–2010, followed by negative results in 2011–2013, before again returning to positive rates in 2014 and in 2017 and in 2019–2020. Lagomorphs role in spreading Francisella tularensis in the epidemiological chain could not be discarded. F. tularensis is described for the first time infecting the shrew Crocidura russula worldwide, and it is also reported for the first time infecting wild rabbits (Oryctolagus cuniculus) in Spain. Serological positives higher than 0.4% were seen for sheep only from 2007–2009 and again in 2019, while serological rates greater than 1% were revealed in dogs in 2007–2008 and in wild canids in 2016. F. tularensis were detected in ticks in 2009, 2014–2015, 2017, and 2019. Lastly, negative results were achieved for river crayfish and also in environmental water samples from 2007 to 2020.

First European report of Francisella tularensis subsp. holarctica isolation from a domestic cat

Francisella tularensis subsp. holarctica is a select agent causing life-threatening tularemia. It has been isolated from humans and animals, mainly lagomorphs and rodents, rarely other wild carnivore species. Increasing numbers of human tularemia cases have been reported during the last 5 years in Switzerland. Here we report the first isolation of Francisella tularensis subsp. holarctica from a domestic cat in Europe and compare its genome sequence with other Swiss isolates. The cat isolate shows a close phylogenetic relationship with a contemporary hare isolate from close geographic proximity, indicating a possible epidemiological link.

Prevalence of Anaplasma phagocytophilum and Coxiella burnetii in Ixodes ricinus ticks in Switzerland: an underestimated epidemiologic risk

Ticks are vectors of several microorganisms responsible for infectious diseases in human and animals, such as Anaplasma phagocytophilum and Coxiella burnetii. In this study, we investigated the prevalence of these two bacteria in 62 889 Ixodes ricinus ticks in selected regions covering all Switzerland. A high prevalence of 11.9% of A. phagocytophilum DNA was observed by real-time PCR on 8534 pools of ticks. This pool prevalence corresponds to an estimated prevalence of 1.71% in individual tick. A total of 144 of the 171 collection sites (84.2%) were positive for the presence of A. phagocytophilum, and these sites were homogenously distributed throughout Switzerland. Such prevalence and geographical distribution underline the risk of human and animal exposure to A. phagocytophilum and highlight the need to assess the epidemiology and clinical diagnosis of human and animal anaplasmosis in Switzerland. However, DNA of C. burnetii was never found in any tick pool. This absence suggests a very low role of I. ricinus ticks as vector and reservoir of C. burnetii in Switzerland, and it supports previous reports demonstrating the role of sheep and goats in the epidemiology of Q fever. However, considering its pathogenic potential, it is necessary to keep monitoring for the possible reemergence of this bacterium in ticks in the future.

A Novel Francisella-Like Endosymbiont in Haemaphysalis longicornis and Hyalomma asiaticum, China

Francisella tularensis causes a highly infectious zoonotic disease tularemia. Both Haemaphysalis longicornis and Hyalomma asiaticum are widely distributed in China, but the presence of Francisella and Francisella-like endosymbionts (FLEs) in the two tick species is poorly understood. Therefore, a total of 627 H. longicornis (471 adults and 156 nymphs) and 88 Hy. asiaticum ticks (adults) were collected, of which 88 were from Bole of Xinjiang, 236 from Liaoyang, and 176 from Shenyang of Liaoning, and 215 from Wuhan of Hubei. Notably, five H. longicornis pools from Liaoyang of Liaoning province might have harbored F. tularensis, showing a minimum prevalence of 2.12% (5/236). This study should alert the health department and veterinarians working within the region to prevent and control the emergence of tularemia. After the screening of 16S rRNA and tul4 genes, the results revealed that FLEs were detected in Hy. asiaticum ticks in Bole and in H. longicornis ticks in Liaoyang and Shenyang. Their infection rate was 100% (88/88), 3.39% (8/236 is a minimum), and 8.52% (15/176), respectively. Phylogenetic analyses indicated that the sequence named bole in Hy. Asiaticum from Bole, the sequence named liaoyang1 in H. longicornis from Liaoyang, and the sequence named shanyang1 in H. longicornis from Shenyang shared consistent 16S rRNA sequence, and the difference between Chinese FLEs and the known FLEs was obvious. These findings suggest that this FLE species might be a potentially novel FLE circulating in H. longicornis and Hy. asiaticum from China.

Population Genomics of Francisella tularensis subsp. holarctica and its Implication on the Eco-Epidemiology of Tularemia in Switzerland

Whole genome sequencing (WGS) methods provide new possibilities in the field of molecular epidemiology. This is particularly true for monomorphic organisms where the discriminatory power of traditional methods (e.g., restriction enzyme length polymorphism typing, multi locus sequence typing etc.) is inadequate to elucidate complex disease transmission patterns, as well as resolving the phylogeny at high resolution on a micro-geographic scale. In this study, we present insights into the population structure of Francisella tularensis subsp. holarctica, the causative agent of tularemia in Switzerland. A total of 59 Fth isolates were obtained from castor bean ticks (Ixodes ricinus), animals and humans and a high resolution phylogeny was inferred using WGS methods. The majority of the Fth population in Switzerland belongs to the west European B.11 clade and shows an extraordinary genetic diversity underlining the old evolutionary history of the pathogen in the alpine region. Moreover, a new B.11 subclade was identified which was not described so far. The combined analysis of the epidemiological data of human tularemia cases with the whole genome sequences of the 59 isolates provide evidence that ticks play a pivotal role in transmitting Fth to humans and other vertebrates in Switzerland. This is further underlined by the correlation of disease risk estimates with climatic and ecological factors influencing the survival of ticks.

Prevalence of tick-borne pathogens in questing Ixodes ricinus ticks in urban and suburban areas of Switzerland

Background

Throughout Europe, Ixodes ricinus transmits numerous pathogens. Its widespread distribution is not limited to rural but also includes urbanized areas. To date, comprehensive data on pathogen carrier rates of I. ricinus ticks in urban areas of Switzerland is lacking.

Results

Ixodes ricinus ticks sampled at 18 (sub-) urban collection sites throughout Switzerland showed carrier rates of 0% for tick-borne encephalitis virus, 18.0% for Borrelia burgdorferi (sensu lato), 2.5% for Borrelia miyamotoi, 13.5% for Rickettsia spp., 1.4% for Anaplasma phagocytophilum, 6.2% for "Candidatus Neoehrlichia mikurensis", and 0.8% for Babesia venatorum (Babesia sp., EU1). Site-specific prevalence at collection sites with n > 45 ticks (n = 9) significantly differed for B. burgdorferi (s.l.), Rickettsia spp., and "Ca. N. mikurensis", but were not related to the habitat type. Three hundred fifty eight out of 1078 I. ricinus ticks (33.2%) tested positive for at least one pathogen. Thereof, about 20% (71/358) were carrying two or three different potentially disease-causing agents. Using next generation sequencing, we could detect true pathogens, tick symbionts and organisms of environmental or human origin in ten selected samples.

Conclusions

Our data document the presence of pathogens in the (sub-) urban I. ricinus tick population in Switzerland, with carrier rates as high as those in rural regions. Carriage of multiple pathogens was repeatedly observed, demonstrating the risk of acquiring multiple infections as a consequence of a tick bite.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2500-2) contains supplementary material, which is available to authorized users.

Ten years of R&D and full automation in molecular diagnosis

A 10-year experience of our automated molecular diagnostic platform that carries out 91 different real-time PCR is described. Progresses and future perspectives in molecular diagnostic microbiology are reviewed: why automation is important; how our platform was implemented; how homemade PCRs were developed; the advantages/disadvantages of homemade PCRs, including the critical aspects of troubleshooting and the need to further reduce the turnaround time for specific samples, at least for defined clinical settings such as emergencies. The future of molecular diagnosis depends on automation, and in a novel perspective, it is time now to fully acknowledge the true contribution of molecular diagnostic and to reconsider the indication for PCR, by also using these tests as first-line assays.

Evaluation of a microfluidic chip system for preparation of bacterial DNA from swabs, air, and surface water samples

The detection of bacterial pathogens from complex sample matrices by PCR requires efficient DNA extraction. In this study, a protocol for extraction and purification of DNA from swabs, air, and water samples using a microfluidic chip system was established. The optimized protocol includes a combination of thermal, chemical and enzymatic lysis followed by chip-based DNA purification using magnetic particles. The procedure was tested using Gram-positive Bacillus thuringiensis Berliner var. kurstaki as a model organism for Bacillus anthracis and the attenuated live vaccine strain of Francisella tularensis subsp. holarctica as Gram-negative bacterium. The detection limits corresponded to 10³ genome equivalents per milliliter (GE/ml) for surface water samples spiked with F. tularensis and 10² GE/ml for B. thuringiensis. In air, 10 GE of F. tularensis per 10 L and 1 GE of B. thuringiensis per 10 L were detectable. For swab samples obtained from artificially contaminated surfaces the detection limits were 4 × 10³ GE/cm² for F. tularensis and 4 × 10² GE/cm² for B. thuringiensis. Suitability of the chip-assisted procedure for DNA preparation of real samples was demonstrated using livestock samples. The presence of thermophilic Campylobacter spp. DNA could be confirmed in air samples collected on pig and broiler farms.

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A microfluidic chip system for magnetic bead-based DNA preparation was evaluated.

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Bacterial DNA was recovered from swabs, air, and surface water.

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A universal protocol was used for Gram-positive and Gram-negative bacteria.

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10 GE of F. tularensis and 1 GE of B. thuringiensis per 10 l air were detectable.

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Thermophilic Campylobacter DNA was detected in air samples of pig and broiler farms.

Francisella Tularensis Clades B.FTN002-00 and B.13 Are Associated With Distinct Pathology in the European Brown Hare (Lepus europaeus)

Tularemia is a severe disease caused by Francisella tularensis This bacterium has a major pathogenic potential in countless animal species as well as in humans. Despite the relatively significant body of literature available on this microorganism, many questions are still open concerning its biological cycle in the environment, the pathology and pathogenesis of the disease, the possible routes of infection in animals, and the pathologic and ecological relevance of the distinct phylogenetic clusters of F. tularensis In order to address these questions, we have thoroughly characterized the pathology and microbiology of terminally ill European brown hares (Lepus europaeus) infected with F. tularensis subsp. holarctica, collected in Switzerland from 2012 to 2014. F tularensis isolates were typed by defining their phylogenetic clusters. We showed that the pathology associated with F. tularensis subsp. holarctica belonging to the clade B.FTNF002-00 is different from that previously reported to be associated with the clade B.13. In particular, strains of the clade B.FTNF002-00 were almost invariably associated with splenitis and hepatitis and not with the polyserositis affecting pleura, pericardium, and kidney reported in the literature for infections caused by the clade B.13. We describe findings suggesting that the ports of entry for the bacteria might be the respiratory and digestive routes.

Long-Lasting Fever and Lymphadenitis: Think about F. tularensis

We report the case of glandular tularemia that developed in a man supposedly infected by a tick bite in Western Switzerland. Francisella tularensis (F. tularensis) was identified. In Europe tularemia most commonly manifests itself as ulcero-glandular or glandular disease; the diagnosis of tularemia may be delayed in glandular form where skin or mucous lesion is absent, particularly in areas which are assumed to have a low incidence of the disease.

The high prevalence and diversity of Chlamydiales DNA within Ixodes ricinus ticks suggest a role for ticks as reservoirs and vectors of Chlamydia-related bacteria

The Chlamydiales order is composed of nine families of strictly intracellular bacteria. Among them, Chlamydia trachomatis, C. pneumoniae, and C. psittaci are established human pathogens, whereas Waddlia chondrophila and Parachlamydia acanthamoebae have emerged as new pathogens in humans. However, despite their medical importance, their biodiversity and ecology remain to be studied. Even if arthropods and, particularly, ticks are well known to be vectors of numerous infectious agents such as viruses and bacteria, virtually nothing is known about ticks and chlamydia. This study investigated the prevalence of Chlamydiae in ticks. Specifically, 62,889 Ixodes ricinus ticks, consolidated into 8,534 pools, were sampled in 172 collection sites throughout Switzerland and were investigated using pan-Chlamydiales quantitative PCR (qPCR) for the presence of Chlamydiales DNA. Among the pools, 543 (6.4%) gave positive results and the estimated prevalence in individual ticks was 0.89%. Among those pools with positive results, we obtained 16S rRNA sequences for 359 samples, allowing classification of Chlamydiales DNA at the family level. A high level of biodiversity was observed, since six of the nine families belonging to the Chlamydiales order were detected. Those most common were Parachlamydiaceae (33.1%) and Rhabdochlamydiaceae (29.2%). "Unclassified Chlamydiales" (31.8%) were also often detected. Thanks to the huge amount of Chlamydiales DNA recovered from ticks, this report opens up new perspectives on further work focusing on whole-genome sequencing to increase our knowledge about Chlamydiales biodiversity. This report of an epidemiological study also demonstrates the presence of Chlamydia-related bacteria within Ixodes ricinus ticks and suggests a role for ticks in the transmission of and as a reservoir for these emerging pathogenic Chlamydia-related bacteria.

The status of tularemia in Europe in a one-health context: a review

The bacterium Francisella tularensis causes the vector-borne zoonotic disease tularemia, and may infect a wide range of hosts including invertebrates, mammals and birds. Transmission to humans occurs through contact with infected animals or contaminated environments, or through arthropod vectors. Tularemia has a broad geographical distribution, and there is evidence which suggests local emergence or re-emergence of this disease in Europe. This review was developed to provide an update on the geographical distribution of F. tularensis in humans, wildlife, domestic animals and vector species, to identify potential public health hazards, and to characterize the epidemiology of tularemia in Europe. Information was collated on cases in humans, domestic animals and wildlife, and on reports of detection of the bacterium in arthropod vectors, from 38 European countries for the period 1992-2012. Multiple international databases on human and animal health were consulted, as well as published reports in the literature. Tularemia is a disease of complex epidemiology that is challenging to understand and therefore to control. Many aspects of this disease remain poorly understood. Better understanding is needed of the epidemiological role of animal hosts, potential vectors, mechanisms of maintenance in the different ecosystems, and routes of transmission of the disease.

Prevalence and phylogenetic analysis of tick-borne encephalitis virus (TBEV) in field-collected ticks (Ixodes ricinus) in southern Switzerland

BACKGROUND

Tick-borne encephalitis is the most common tick-borne viral infection in Europe with 3,000 human cases reported each year. In Western Europe, the castor bean tick, Ixodes ricinus, is the principal vector of the tick-borne encephalitis virus (TBEV). TBEV appears to be spreading geographically and was recently detected for the first time in Canton Valais in the southern part of Switzerland. The purpose of the present study was to survey the I. ricinus tick populations of Canton Valais for TBEV.

METHODS

We collected a total of 19,331 I. ricinus ticks at 45 different sites in Canton Valais between 2010 and 2013. Ticks were processed in pools and tested for TBEV using reverse transcription quantitative PCR. The NS5 gene and the envelope gene of the TBEV isolates were partially sequenced for phylogenetic analysis.

RESULTS

TBEV was detected in tick populations at six of the 45 sites. These six sites were all located in a 33 km transect along the Rhône River. TBEV was detected in two sites for three of the four years of the study showing the temporal persistence of the pathogen. Prevalence of TBEV in the six positive sites ranged from 0.16% to 11.11%. Phylogenetic analysis found that all TBEV isolates from Canton Valais belonged to the European subtype. Genetic analysis found two distinct lineages of TBEV suggesting that Canton Valais experienced two independent colonization events.

CONCLUSIONS

TBEV appears to be well established at certain locations in Canton Valais.

Pathogen infection and exposure, and ectoparasites of the federally endangered Amargosa vole (Microtus californicus scirpensis), California, USA

Abstract We surveyed pathogens and ectoparasites among federally endangered Amargosa voles (Microtus californicus scirpensis) and sympatric rodents in Tecopa Hot Springs, Inyo County, California, December 2011-November 2012. We aimed to assess disease and detect possible spillover from or connectivity with other hosts within and outside the Amargosa ecosystem. We assessed 71 individual voles and 38 individual sympatric rodents for current infection with seven vector-borne zoonotic pathogens and past exposure to five pathogens. Thirteen percent of Amargosa voles were PCR positive for Toxoplasma gondii, a zoonotic protozoan that may alter host behavior or cause mortality. Additionally, we found antibodies against Borrelia burgdorferi sensu lato (SL) spp. in 21% of voles, against Anaplasma phagocytophilum in 2.6%, Rickettsia spp. in 13%, relapsing fever Borrelia (3.9%), and T. gondii (7.9%). Sympatric rodents also had active infections with Borrelia SL spp. (15%). Of the ectoparasites collected, the tick Ixodes minor is of particular interest because the study area is well outside of the species' reported range and because I. minor ticks infest migratory birds as well as rodents, showing a potential mechanism for pathogens to be imported from outside the Amargosa ecosystem.

Characterisation of a new group of Francisella tularensis subsp. holarctica in Switzerland with altered antimicrobial susceptibilities, 1996 to 2013

Molecular analysis of Francisella tularensis subsp. holarctica isolates from humans and animals revealed the presence of two subgroups belonging to the phylogenetic groups B.FTNF002-00 and B.13 in Switzerland. This finding suggests a broader spread of this group in Europe than previously reported. Until recently, only strains belonging to the Western European cluster (group B.FTNF002-00) had been isolated from tularaemia cases in Switzerland. The endemic strains belonging to group B.FTNF002-00 are sensitive to erythromycin, in contrast to the strains of the newly detected group B.13 that are resistant to this antibiotic. All the strains tested were susceptible to ciprofloxacin, streptomycin, gentamicin, nalidixic acid and chloramphenicol but showed reduced susceptibility to tetracycline when tested in a growth medium supplemented with divalent cations. The data show a previously undetected spread of group B.13 westwards in Europe, associated with changes in the antibiotic resistance profile relevant to treatment of tularaemia.

Serological investigation of wild boars (Sus scrofa) and red foxes (Vulpes vulpes) as indicator animals for circulation of Francisella tularensis in Germany

Tularemia outbreaks in humans have recently been reported in many European countries, but data on the occurrence in the animal population are scarce. In North America, seroconversion of omnivores and carnivores was used as indicator for the presence of tularemia, for the European fauna, however, data are barely available. Therefore, the suitability of wild boars (Sus scrofa) and red foxes (Vulpes vulpes) as indicators for the circulation of F. tularensis in Germany was evaluated. Serum samples from 566 wild boars and 457 red foxes were collected between 1995 and 2012 in three federal states in Central Germany (Hesse, Saxony-Anhalt, and Thuringia). The overall rate of seropositive animals was 1.1% in wild boars and 7.4% in red foxes. In conclusion, serological examination of red foxes is recommended, because they can be reliably used as indicator animals for the presence of F. tularensis in the environment.

Anaplasma phagocytophilum--a widespread multi-host pathogen with highly adaptive strategies

The bacterium Anaplasma phagocytophilum has for decades been known to cause the disease tick-borne fever (TBF) in domestic ruminants in Ixodes ricinus-infested areas in northern Europe. In recent years, the bacterium has been found associated with Ixodes-tick species more or less worldwide on the northern hemisphere. A. phagocytophilum has a broad host range and may cause severe disease in several mammalian species, including humans. However, the clinical symptoms vary from subclinical to fatal conditions, and considerable underreporting of clinical incidents is suspected in both human and veterinary medicine. Several variants of A. phagocytophilum have been genetically characterized. Identification and stratification into phylogenetic subfamilies has been based on cell culturing, experimental infections, PCR, and sequencing techniques. However, few genome sequences have been completed so far, thus observations on biological, ecological, and pathological differences between genotypes of the bacterium, have yet to be elucidated by molecular and experimental infection studies. The natural transmission cycles of various A. phagocytophilum variants, the involvement of their respective hosts and vectors involved, in particular the zoonotic potential, have to be unraveled. A. phagocytophilum is able to persist between seasons of tick activity in several mammalian species and movement of hosts and infected ticks on migrating animals or birds may spread the bacterium. In the present review, we focus on the ecology and epidemiology of A. phagocytophilum, especially the role of wildlife in contribution to the spread and sustainability of the infection in domestic livestock and humans.

Francisella tularensis infection in a stone marten (Martes foina) without classic pathological lesions consistent with tularemia

The current report describes the isolation and typing of a strain of Francisella tularensis, the causative agent of tularemia, from the spleen of a stone marten (Martes foina) showing no classic lesions consistent with the disease. The identification of this bacterium, belonging to the World Health Organization risk 3 category and considered to have a low infectious dose, could be performed only because of an ongoing project screening F. tularensis in the environment sensu lato. The findings described herein should alert diagnostic laboratories of the possible presence of F. tularensis in clinical samples in countries where tularemia is endemic even in cases with no consistent anamnesis and from unsuspected animal species.

Presence of an emerging subclone of Francisella tularensis holarctica in Ixodes ricinus ticks from south-western Germany

The zoonotic disease tularaemia is caused by the bacterial pathogen Francisella tularensis. Although the causative agent is known for 100 years, knowledge of its enzootic cycles is still rudimentary. Apart from tabanids and mosquitoes, hard ticks have been described as important vectors and potential reservoirs for F. tularensis. Available data on the incidence of human tularaemia indicate an increase in cases in the federal state of Baden-Wuerttemberg. To determine whether ticks are involved in the reported increase in F. tularensis infections in humans and wildlife in this south-western part of Germany, 916 Ixodes ricinus and 211 adult Dermacentor marginatus and D. reticulatus ticks were collected in two different locations. Screening for the presence of F. tularensis was performed by real-time PCR of the 16S rRNA gene. Of the 95 pools of I. ricinus ticks (representing 916 individual ticks), 8 tick pools (8.4%) were positive in this PCR. 30-bp deletion PCR confirmed that the F. tularensis subspecies holarctica was present. FtM24 VNTR analysis revealed that they belong to the emerging Franco-Iberian subclone group of F. tularensis holarctica. Of the 211 ticks of the genus Dermacentor, 35 randomly chosen DNAs were subjected to 16S rRNA gene screening PCR; 20 of these (57%) gave positive signals. For cluster analysis, the lpnA gene region of all Francisella-positive I. ricinus pools and 6 Dermacentor ticks with a positive reaction in the screening PCR was amplified and sequenced. In the resulting neighbour-joining tree, all Francisella-positive I. ricinus samples clustered with sequences of F. tularensis, whilst all Dermacentor tick samples clustered with FLE (Francisella-like endosymbiont) sequences. This study shows that I. ricinus ticks may serve as vectors and/or reservoirs of F. tularensis in Germany and supports the hypothesis that the state of Baden-Wuerttemberg represents an emerging endemic focus of tularaemia.

Prevalence and genotyping of tick-borne encephalitis virus in questing Ixodes ricinus ticks in a new endemic area in western Switzerland

Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE) and causes neurological disease in humans in Eurasia. TBEV is transmitted by ticks of the genus Ixodes. Currently 10,000-12,000 clinical cases are reported annually in approximately 30 TBE endemic countries. Since 1990 the epidemiology of TBE is characterized by a global increase of clinical cases and an expansion of risk areas. Similar trends are also observed in Switzerland but few studies confirmed the emergence of new TBE foci by detecting viral RNA in field-collected ticks. In this study, free-living Ixodes ricinus (L.) ticks from one nonendemic and three new TBE endemic regions located in the Western part of Switzerland were screened during four consecutive years (2007-2010) for the presence of TBEV. A total of 9,868 I. ricinus ticks (6,665 nymphs and 3,203 adults) were examined in pools for TBEV by real-time reverse transcription polymerase chain reaction. Our results confirmed the presence of viral RNA in 0.1% (6/6120) of questing ticks collected in one new endemic region. Among TBE endemic sites, the minimal infection rate per 100 ticks tested ranged from 0.21 (1/477) to 0.95 (1/105). Four positive samples were sequenced and phylogenetic analysis of the NS5 gene showed that all TBEV nucleotide sequences belonged to the European subtype and were split into two distinct lineages originating probably independently from two distinct foci located North-East and East of the study region.

PCR detection of Anaplasma phagocytophilum in goat flocks in an area endemic for tick-borne fever in Switzerland

Central Switzerland is a highly endemic region for tick-borne fever (TBF) in cattle, however, little is known about A. phagocytophilum in goats. In the present study, 72 animals from six goat flocks (373 EDTA blood-samples) in Central Switzerland were analysed for A. phagocytophilum DNA. A real-time PCR targeting the msp2 gene of A. phagocytophilum was performed and in positive samples the partial 16S rRNA, groEL and msp4 gene were amplified for sequence analysis. Four DNA extracts were positive. Different sequence types on basis of the amplified genes were found. For comparison, sequences of A. phagocytophilum from 12 cattle (originating from Switzerland and Southern Germany) were analysed. The 16S rRNA gene sequences from cattle were all identical amongst each other, but the groEL and msp4 gene differed depending on the origin of the cattle samples and differed from the variants from goats. This study clearly provides molecular evidence for the presence of different types of A. phagocytophilum in goat flocks in Switzerland, a fact which deserves more thorough attention in clinical studies.

Diversity and coexistence of tick-borne pathogens in central Germany

In total, 1000 Ixodes ricinus L. ticks were collected from a small recreational forest area in central Germany (Thuringia) and investigated for the presence of Borrelia spp., Babesia spp., Anaplasma spp., Rickettsia spp., Coxiella burnetii, and Francisella tularensis. Overall, 43.6% of the ticks were infected with at least one pathogen. In 8.4% of ticks double infections were detected, and 1.6% harbored more than two pathogens. In this study, we present data on the coexistence of established and emerging pathogens in questing nymphs and adult ticks in a recreational area in central Germany, indicating the need for further studies for a reliable risk assessment.

Microclimate and the zoonotic cycle of tick-borne encephalitis virus in Switzerland

The focal distribution of tick-borne encephalitis virus (TBEV; Flaviviridae, Flavivirus) appears to depend mainly on cofeeding transmission between infected Ixodes ricinus L. nymphs and uninfected larvae. To better understand the role of cofeeding ticks in the transmission of TBEV, we investigated tick infestation of rodents and the influence of microclimate on the seasonality of questing I. ricinus ticks. A 3-yr study was carried out at four sites, including two confirmed TBEV foci. Free-living ticks and rodents were collected monthly, and microclimatic data were recorded. A decrease in questing nymph density was observed in 2007, associated with low relative humidity and high temperatures in spring. One site, Thun, did not show this decrease, probably because of microclimatic conditions in spring that favored the questing nymph population. During the same year, the proportion of rodents carrying cofeeding ticks was lower at sites where the questing nymph density decreased, although the proportion of infested hosts was similar among years. TBEV was detected in 0.1% of questing ticks, and in 8.6 and 50.0% of larval ticks feeding on two rodents. TBEV was detected at all but one site, where the proportion of hosts with cofeeding ticks was the lowest. The proportion of hosts with cofeeding ticks seemed to be one of the factors that distinguished a TBEV focus from a non-TBEV focus. The enzootic cycle of TBEV might be disrupted when dry and hot springs occur during consecutive years.

Coexistence of pathogens in host-seeking and feeding ticks within a single natural habitat in Central Germany

The importance of established and emerging tick-borne pathogens in Central and Northern Europe is steadily increasing. In 2007, we collected Ixodes ricinus ticks feeding on birds (n = 211) and rodents (n = 273), as well as host-seeking stages (n = 196), in a habitat in central Germany. In order to find out more about their natural transmission cycles, the ticks were tested for the presence of Lyme disease borreliae, Anaplasma phagocytophilum, spotted fever group (SFG) rickettsiae, Francisella tularensis, and babesiae. Altogether, 20.1% of the 680 ticks examined carried at least one pathogen. Bird-feeding ticks were more frequently infected with Borrelia spp. (15.2%) and A. phagocytophilum (3.2%) than rodent-feeding ticks (2.6%; 1.1%) or questing ticks (5.1%; 0%). Babesia spp. showed higher prevalence rates in ticks parasitizing birds (13.2%) and host-seeking ticks (10.7%), whereas ticks from small mammals were less frequently infected (6.6%). SFG rickettsiae and F. tularensis were also found in ticks collected off birds (2.1%; 1.2%), rodents (1.8%; 1.5%), and vegetation (4.1%; 1.6%). Various combinations of coinfections occurred in 10.9% of all positive ticks, indicating interaction of transmission cycles. Our results suggest that birds not only are important reservoirs for several pathogens but also act as vehicles for infected ticks and might therefore play a key role in the dispersal of tick-borne diseases.

The past and present threat of vector-borne diseases in deployed troops

From time immemorial, vector-borne diseases have severely reduced the fighting capacity of armies and caused suspension or cancellation of military operations. Since World War I, infectious diseases have no longer been the main causes of morbidity and mortality among soldiers. However, most recent conflicts involving Western armies have occurred overseas, increasing the risk of vector-borne disease for the soldiers and for the displaced populations. The threat of vector-borne disease has changed with the progress in hygiene and disease control within the military: some diseases have lost their military significance (e.g. plague, yellow fever, and epidemic typhus); others remain of concern (e.g. malaria and dengue fever); and new potential threats have appeared (e.g. West Nile encephalitis and chikungunya fever). For this reason, vector control and personal protection strategies are always major requirements in ensuring the operational readiness of armed forces. Scientific progress has allowed a reduction in the impact of arthropod-borne diseases on military forces, but the threat is always present, and a failure in the context of vector control or in the application of personal protection measures could allow these diseases to have the same devastating impact on human health and military readiness as they did in the past.

High-throughput procedure for tick surveys of tick-borne encephalitis virus and its application in a national surveillance study in Switzerland

Tick-borne encephalitis (TBE), a viral infection of the central nervous system, is endemic in many Eurasian countries. In Switzerland, TBE risk areas have been characterized by geographic mapping of clinical cases. Since mass vaccination should significantly decrease the number of TBE cases, alternative methods for exposure risk assessment are required. We established a new PCR-based test for the detection of TBE virus (TBEV) in ticks. The protocol involves an automated, high-throughput nucleic acid extraction method (QIAsymphony SP system) and a one-step duplex real-time reverse transcription-PCR (RT-PCR) assay for the detection of European subtype TBEV, including an internal process control. High usability, reproducibility, and equivalent performance for virus concentrations down to 5 x 10(3) viral genome equivalents/microl favor the automated protocol compared to the modified guanidinium thiocyanate-phenol-chloroform extraction procedure. The real-time RT-PCR allows fast, sensitive (limit of detection, 10 RNA copies/microl), and specific (no false-positive test results for other TBEV subtypes, other flaviviruses, or other tick-transmitted pathogens) detection of European subtype TBEV. The new detection method was applied in a national surveillance study, in which 62,343 Ixodes ricinus ticks were screened for the presence of TBE virus. A total of 38 foci of endemicity could be identified, with a mean virus prevalence of 0.46%. The foci do not fully agree with those defined by disease mapping. Therefore, the proposed molecular test procedure constitutes a prerequisite for an appropriate TBE surveillance. Our data are a unique complement of human TBE disease case mapping in Switzerland.

Development and application of a universal Hemoplasma screening assay based on the SYBR green PCR principle

Hemotropic mycoplasmas (hemoplasmas) are the causative agents of infectious anemia in several mammalian species. Their zoonotic potential has recently been substantiated by the identification of a feline hemoplasma isolate in an immunocompromised human patient. Although species-specific diagnostic molecular methods have been developed, their application as screening tools is limited due to the species diversity of hemoplasmas. The goals of this study were to develop a universal hemoplasma screening assay with broad specificity based on the SYBR green PCR principle, to compare the assay with hemoplasma-specific TaqMan PCR, and to analyze potential tick vectors and human blood samples to address the zoonotic potential. The newly developed PCR assay based on the 16S rRNA gene amplified feline, canine, bovine, porcine, camelid, and murine hemoplasmas, as well as Mycoplasma penetrans and Mycoplasma pneumoniae. The lower detection limit for feline and canine hemoplasmas was 1 to 10 copies/PCR. The assay exhibited 98.2% diagnostic sensitivity and 92.1% diagnostic specificity for feline hemoplasmas. All 1,950 Ixodes ticks were PCR negative, suggesting that Ixodes ticks are not relevant vectors for the above-mentioned hemoplasma species in Switzerland. None of the 414 blood samples derived from anemic or immunocompromised human patients revealed a clear positive result. The SYBR green PCR assay described here is a suitable tool to screen for known and so-far-undiscovered hemoplasma species. Positive results should be confirmed by specific TaqMan PCR or sequencing.

Molecular Investigations of Rickettsia helvetica infection in dogs, foxes, humans, and Ixodes ticks

Rickettsia helvetica, a tick-borne member of the spotted-fever-group rickettsiae, is a suspected pathogen in humans; however, its role in animals is unknown. The aims of this study were to establish a R. helvetica-specific real-time TaqMan PCR assay and apply it to the analysis of tick vectors (to determine potential exposure risk) and blood samples from Canidae and humans (to determine prevalence of infection). The newly designed 23S rRNA gene assay for R. helvetica was more sensitive than a published citrate synthase gene (gltA) assay for several rickettsiae. Blood samples from 884 dogs, 58 foxes, and 214 human patients and 2,073 ticks (Ixodes spp.) collected from either vegetation or animals were analyzed. Although the maximal likelihood estimate of prevalence was 12% in unfed ticks and 36% in ticks collected from animals, none of the 1,156 blood samples tested PCR positive. Ticks from cats were more frequently PCR positive than ticks from dogs. Sequencing of the 23S rRNA and/or the gltA gene of 17 tick pools confirmed the presence of R. helvetica. Additionally, Rickettsia monacensis, which has not been previously found in Switzerland, was identified. In conclusion, R. helvetica was frequently detected in the tick population but not in blood samples. Nevertheless, due to the broad host range of Ixodes ticks and the high rate of infestation with this agent (i.e., R. helvetica was 13 times more frequent in unfed ticks than the tick-borne encephalitis virus), many mammals may be exposed to R. helvetica. The PCR assay described here represents an important tool for studying this topic.

Molecular characterization of two different strains of haemotropic mycoplasmas from a sheep flock with fatal haemolytic anaemia and concomitant Anaplasma ovis infection

After the first outbreak of fatal Mycoplasma ovis infection (eperythrozoonosis) in a sheep flock in Hungary (1997), a second wave of the disease was noted in 2006, with different seasonal pattern and affected age group, as well as increased mortality (5.5%). The aim of the present study was to molecularly characterize the causative agent and to reveal underlying factors of the second wave of the disease. Remarkably, among the 33 sheep examined, 17 were infected with two strains of haemotropic mycoplasmas. Cloning and sequencing isolates of the latter showed that one of the strains was 99.4-99.8% identical to M. ovis (AF338268), while the second was only 96.8-97.9% identical and contained a 17-bp deletion. Different isolates of both strains were demonstrated in the same animal. When analyzing possible risk factors for fatal disease outcome, we found that among sheep born prior to the 1997 outbreak significantly more animals survived the second outbreak than succumbed to disease. In addition, locally born sheep were less frequently diseased than sheep introduced into the flock from other places. This suggests an immunoprotective effect in some animals. Concurrent infection with Anaplasma ovis was detected in 24 of the 33 evaluated sheep. In conclusion, this is the first study to demonstrate the existence of and characterize two genetically distinct ovine haemotropic mycoplasma strains in a sheep flock with fatal haemolytic anaemia.

Rapid diagnosis and quantification of Francisella tularensis in organs of naturally infected common squirrel monkeys (Saimiri sciureus)

Francisella tularensis, a small Gram-negative facultative intracellular bacterium, is the causative agent of tularaemia, a severe zoonotic disease transmitted to humans mostly by vectors such as ticks, flies and mosquitoes. The disease is endemic in many parts of the northern hemisphere. Among animals, the most affected species belong to rodents and lagomorphs, in particular hares. However, in the recent years, many cases of tularaemia among small monkeys in zoos were reported. We have developed a real-time PCR that allows to quantify F. tularensis in tissue samples. Using this method, we identified the spleen and the kidney as the most heavily infected organ containing up to 400 F. tularensis bacteria per simian host cell in two common squirrel monkeys (Saimiri sciureus) from a zoo that died of tularaemia. In other organs such as the brain, F. tularensis was detected at much lower titres. The strain that caused the infection was identified as F. tularensis subsp. holarctica biovar I, which is susceptible to erythromycin. The high number of F. tularensis present in soft organs such as spleen, liver and kidney represents a high risk for persons handling such carcasses and explains the transmission of the disease to a pathologist during post-mortem analysis. Herein, we show that real-time PCR allows a reliable and rapid diagnosis of F. tularensis directly from tissue samples of infected animals, which is crucial in order to attempt accurate prophylactic measures, especially in cases where humans or other animals have been exposed to this highly contagious pathogen.

Increased prevalence of Borrelia burgdorferi infections in Bernese Mountain Dogs: a possible breed predisposition

Background

Glomerulonephritis in dogs has been associated with B. burgdorferi infections. In Bernese Mountain Dogs with glomerulonephritis antibodies against B. burgdorferi have been found in most dogs, raising the question if the breed is predisposed to infections with B. burgdorferi. The aim of this study was to determine the prevalence of antibodies against B. burgdorferi sensu lato in a well defined population of Bernese Mountain Dogs and to compare this prevalence with data from dogs of other breeds.

Results

160 Bernese Mountain Dogs and 62 control dogs (large breed dogs with long hair) were included. All dogs were considered healthy according to a questionnaire filled out by the owner, complete blood count, chemistry panel, urinalysis and urine culture. Bernese Mountain Dogs and control dogs were kept in similar environments. Seroprevalence of B. burgdorferi was assessed by ELISA and Western blot and was 58% in Bernese Mountain Dogs compared to 15% in control dogs. This difference was significant. Neither antibodies against leptospires nor vaccination or hair coat color influenced the results.

Conclusion

The cause of the considerably higher prevalence of antibodies against B. burgdorferi in Bernese Mountain Dogs and it's consequences are not known. A breed predisposition can be suspected.

Real-time PCR investigation of potential vectors, reservoirs, and shedding patterns of feline hemotropic mycoplasmas

Three hemotropic mycoplasmas have been identified in pet cats: Mycoplasma haemofelis, "Candidatus Mycoplasma haemominutum," and "Candidatus Mycoplasma turicensis." The way in which these agents are transmitted is largely unknown. Thus, this study aimed to investigate fleas, ticks, and rodents as well as saliva and feces from infected cats for the presence of hemotropic mycoplasmas, to gain insight into potential transmission routes for these agents. DNA was extracted from arthropods and from rodent blood or tissue samples from Switzerland and from salivary and fecal swabs from two experimentally infected and six naturally infected cats. All samples were analyzed with real-time PCR, and some positive samples were confirmed by sequencing. Feline hemotropic mycoplasmas were detected in cat fleas and in a few Ixodes sp. and Rhipicephalus sp. ticks collected from animals but not in ticks collected from vegetation or from rodent samples, although the latter were frequently Mycoplasma coccoides PCR positive. When shedding patterns of feline hemotropic mycoplasmas were investigated, "Ca. Mycoplasma turicensis" DNA was detected in saliva and feces at the early but not at the late phase of infection. M. haemofelis and "Ca. Mycoplasma haemominutum" DNA was not amplified from saliva and feces of naturally infected cats, despite high hemotropic mycoplasma blood loads. Our results suggest that besides an ostensibly indirect transmission by fleas, direct transmission through saliva and feces at the early phase of infection could play a role in the epizootiology of feline hemotropic mycoplasmas. Neither the investigated tick nor the rodent population seems to represent a major reservoir for feline hemotropic mycoplasmas in Switzerland.

Anaplasma phagocytophilum in Dogs in Germany

A total number of 111 dogs were included in the present prospective study investigating the prevalence of Anaplasma phagocytophilum in dogs in Germany. Dogs were divided into two groups. Dogs of group 1 (n = 49) showed clinical and/or haematological signs seen in infections with A. phagocytophilum, whereas those of group 2 (n = 62) did not have any evidence of anaplasmosis. For each dog, an A. phagocytophilum 16S rRNA-nested polymerase chain reaction (PCR) of ethylenediaminetetraacetic acid (EDTA)-anticoagulated whole blood analysis, a microscopic evaluation of a buffy coat and a serum indirect fluorescent antibody test (IFAT) were performed. Forty-eight seroreactive dogs were identified altogether, which amounts to an overall point prevalence of 43.2%. There was no significant difference between the seroreactivity to A. phagocytophilum antigens among group 1 (44.9%) and 2 (41.9%) (P > 0.5). Seven dogs (6.3%) had positive PCR results. All of them were seroreactive. Six belonged to group 1. Morulae in neutrophilic granulocytes were found in two dogs of group 1 but in none of group 2. Both dogs were seroreactive. Very high antibody titres (> or =1:1024) were detected significantly more frequently in dogs with clinical signs attributable to infection with A. phagocytophilum (group 1) than in those without (group 2) (P < 0.001). There was no significant correlation of overall positives or antibody titres to age, breed, sex, or whether the dogs were family or working dogs. Dogs with high tick infestation were significantly more often seroreactive to A. phagocytophilum than those with no or low tick infestation (P = 0.007). In conclusion, there seems to be a high risk of infection with A. phagocytophilum in Germany. Results of this study suggest that severe illness solely caused by A. phagocytophilum may be possible although definitive evidence does not exist. Very high antibody titres (>1:1024) may be associated with clinical anaplasmosis.

DISTRIBUTION AND HABITAT CHARACTERISTICS OF MANAYUNKIA SPECIOSA AND INFECTION PREVALENCE WITH THE PARASITE CERATOMYXA SHASTA IN THE KLAMATH RIVER, OREGON–CALIFORNIA

A survey for Manayunkia speciosa, the freshwater polychaete host for the myxozoan parasite Ceratomyxa shasta, was conducted from 2003 to 2005 as part of an integrated study of the epizootiology of ceratomyxosis in Klamath River salmonids. Substrata samples (n = 257) were collected in a variety of habitats from Klamath Lake to the mouth of the Klamath River to document occurrence and relative abundance of the polychaete by habitat type and to estimate the prevalence of C. shasta within selected polychaete populations. Populations of M. specios a were identified throughout the Klamath River within pools (51.6%), eddy-pools (47.0%), and runs (40.0%). Large populations of M. speciosa were consistently found at the inflow to the main-stem reservoirs where densities were correlated with distance from the inflow into the reservoir. Using polymerase chain reaction assay and composite samples, 12 of 71 populations identified were tested for C. shasta, revealing a mean infection prevalence of 0.27%. An area of elevated infection prevalence (4.9 and 8.3%) was identified with 2 populations below a barrier to salmonid migration, which explains the high infectious spore densities demonstrated in concurrent studies and observations of C. shasta-induced mortality in Klamath River fall Chinook salmon (Oncorhynchus tshawytscha).

Diagnostic procedures in tularaemia with special focus on molecular and immunological techniques

Tularaemia is a severe bacterial zoonosis caused by the highly infectious agent Francisella tularensis. It is endemic in countries of the northern hemisphere ranging from North America to Europe, Asia and Japan. Very recently, Francisella-like strains causing disease in humans were described from tropical northern Australia. In the last decade, efforts have been made to develop sensitive and specific immunological and molecular techniques for the laboratory diagnosis of tularaemia and also for the definite identification of members of the species F. tularensis and its four subspecies. Screening for the keyword 'Francisella' a Medline search over the last decade was performed and articles describing diagnostic methods for tularaemia and its causative agent were selected. Besides classical microbiological techniques (cultivation, biochemical profiling, susceptibility testing) several new immunological and molecular approaches to identify F. tularensis have been introduced employing highly specific antibodies and various polymerase chain reaction (PCR)-based methods. Whereas direct antigen detection by enzyme-linked immunosorbent assay (ELISA) or immunofluorescence might allow early presumptive diagnosis of tularaemia, these methods--like all PCR techniques--still await further evaluation. Therefore, diagnosis of tularaemia still relies mainly on the demonstration of specific antibodies in the host. ELISA and immunoblot methods started to replace the standard tube or micro-agglutination assays. However, the diagnostic value of antibody detection in the very early clinical phase of tularaemia is limited. Francisella tularensis is regarded as a 'highest priority' biological agent (category 'A' according to the CDC, Atlanta, GA, USA), thus rapid and reliable diagnosis of tularaemia is required not only for a timely onset of therapy, the handling of outbreak investigations but also for the surveillance of endemic foci. Only very recently, evaluated test kits for serological diagnosis of human tularaemia became available, while the introduction of standardized molecular techniques for detection and typing is still missing.

Tularemia in Denmark: identification of a Francisella tularensis subsp. holarctica strain by real-time PCR and high-resolution typing by multiple-locus variable-number tandem repeat analysis

We report ulceroglandular tularemia affecting an 8-year-old boy and the first recovery of Francisella tularensis in Denmark. A novel real-time PCR assay was used to identify the strain as F. tularensis subsp. holarctica (type B). Multiple-locus variable-number tandem repeat analysis demonstrated a close genetic relationship to strains from Norway.

The importance of tick-borne encephalitis virus RNA detection for early differential diagnosis of tick-borne encephalitis

BACKGROUND

Tick-borne encephalitis virus (TBEV) is one of the most important causes of human viral infections of the central nervous system in Europe. Currently, the diagnosis of TBE is based on the demonstration of specific antibodies in patient's serum, which appear only several weeks after the infection.

OBJECTIVE

To determine how successfully can viral RNA be detected by RT-PCR in the samples of body fluids of patients with TBE prior to and after the appearance of antibodies.

STUDY DESIGN

Serum, whole blood and CSF samples from 34 patients with a serologically confirmed TBE were collected. Samples were tested for the presence of TBEV RNA by using RT-PCR method.

RESULTS

Viral RNA was detected in all blood and serum samples collected before the development of antibodies. After the appearance of IgM antibodies, the number of positive samples dropped by at least one third. After the development of IgG antibodies, only 3% of serum and 16% of blood samples tested positive for viral RNA. Samples of cerebrospinal fluid were shown to be inappropriate for the molecular diagnosis of TBE using this assay, since only one sample (10%) that was collected in the sero-negative phase of disease was found positive by the PCR assay.

CONCLUSIONS

RT-PCR is an efficient method for an early detection of TBEV in blood and serum samples collected prior to the appearance of antibodies. This method can be of valuable use for a differential diagnosis of TBEV infection in patients with febrile illness after a tick bite, particularly in regions where more than one tick-transmitted diseases are endemic.

Concomitant or consecutive infection with Coxiella burnetii and tickborne diseases

BACKGROUND

Q fever is a worldwide zoonosis caused by Coxiella burnetii, which can be isolated from ticks. Reports of people with both Q fever and other tickborne diseases are rare. In this study, we describe 6 patients with Q fever who were infected with 1 of the following tickborne pathogens: Rickettsia conorii (2 patients), Rickettsia slovaca (2), Rickettsia africae (1), and Francisella tularensis (1).

METHODS

Diagnoses were made on the basis of results of microimmunofluorescence assays for detection of C. burnetii, R. conorii, R. slovaca, R. africae, and F. tularensis antigens. Cross-adsorption studies and Western blots were used to confirm dual infections.

RESULTS

Among the 6 cases presented, 3 were probably due to a concomitant infection after a tick bite, whereas the remaining 3 were more likely consecutive infections.

CONCLUSIONS

Because acute Q fever is often asymptomatic, we recommend that patients infected with the tickborne pathogens mentioned above also undergo routine testing for concurrent infections with C. burnetii.