High diversity of ankA sequences of Anaplasma phagocytophilum among Ixodes ricinus ticks in Germany

Diversity of Anaplasma phagocytophilum Strains from Roe Deer (Capreolus capreolus) and Red Deer (Cervus elaphus) in Poland

BACKGROUND

The Gram-negative bacterium Anaplasma phagocytophilum is an intracellular pathogen and an etiological agent of human and animal anaplasmosis. Its natural reservoir comprises free-ranging ungulates, including roe deer (Capreolus capreolus) and red deer (Cervus elaphus). These two species of deer also constitute the largest group of game animals in Poland. The aim of the study was to genotype and perform a phylogenetic analysis of A. phagocytophilum strains from roe deer and red deer.

METHODS

Samples were subjected to PCR amplification, sequencing, and phylogenetic analysis of strain-specific genetic markers (groEL, ankA).

RESULTS

Five haplotypes of the groEL gene from A. phagocytophilum and seven haplotypes of ankA were obtained. The phylogenetic analysis classified the groEL into ecotypes I and II. Sequences of the ankA gene were classified into clusters I, II, and III.

CONCLUSIONS

Strains of A. phagocytophilum from red deer were in the same ecotype and cluster as strains isolated from humans. Strains of A. phagocytophilum from roe deer represented ecotypes (I, II) and clusters (II, III) that were different from those isolated from red deer, and these strains did not show similarity to bacteria from humans. However, roe deer can harbor nonspecific strains of A. phagocytophilum more characteristic to red deer. It appears that the genetic variants from red deer can be pathogenic to humans, but the significance of the variants from roe deer requires more study.

Strains of Anaplasma phagocytophilum from horses in Ohio are related to isolates from humans in the northeastern USA

IMPORTANCE

The tick-borne obligatory intracellular bacterium Anaplasma phagocytophilum infects humans as well as domesticated and wild animals, causing a febrile disease collectively called granulocytic anaplasmosis. The epidemiology and the host species specificity and zoonotic potential of A. phagocytophilum strains remain unclear. In this study, ankA (encoding ankyrin A) and p44 gene sequences of A. phagocytophilum were determined in clinical specimens from horses in Ohio and compared with those found in A. phagocytophilum strains from various hosts and geographic regions. With increasing numbers of seropositive horses, the study points out the unrecognized prevalence and uncharacterized strains of A. phagocytophilum infection in horses and the importance of A. phagocytophilum molecular testing for the prevention of equine and human granulocytic anaplasmosis.

Host-pathogen associations revealed by genotyping of European strains of Anaplasma phagocytophilum to describe natural endemic cycles

BACKGROUND

The zoonotic intracellular alpha-proteobacterium Anaplasma phagocytophilum is a tick-transmitted pathogen. The associations between vertebrate reservoirs and vectors are described as wide-ranging, and it was previously shown that the pathogenicity of A. phagocytophilum differs depending on the combination of pathogen variant and infected host species. This leads to the question of whether there are variations in particular gene loci associated with different virulence. Therefore, this study aims at clarifying existing host-variant combinations and detecting possible reservoir hosts. To understand these interactions, a complex toolset for molecular epidemiology, phylogeny and network theory was applied.

METHODS

Sequences of up to four gene loci (msp4, msp2, groEL and 16S rRNA) were evaluated for different isolates from variable host species, including, for example, dogs, cattle and deer. Variant typing was conducted for each gene locus individually, and combinations of different gene loci were analysed to gain more detailed information about the genetic plasticity of A. phagocytophilum. Results were displayed as minimum spanning nets and correlation nets.

RESULTS

The highest diversity of variants for all gene loci was observed in roe deer. In cattle, a reduced number of variants for 16S rRNA [only 16S-20(W) and 16S-22(Y)] but multiple variants of msp4 and groEL were found. For dogs, two msp4 variants [m4-20 and m4-2(B/C)] were found to be linked to different variants of the other three gene loci, creating two main combinations of gene loci variants. Cattle are placed centrally in the minimum spanning net analyses, indicating a crucial role in the transmission cycles by possibly bridging the vector-wildlife cycle to infections of humans and domestic animals. The minimum spanning nets confirmed previously described epidemiological cycles of the bacterium in Europe, showing separation of variants originating from wildlife animals only and a set of variants shared by wild and domestic animals.

CONCLUSIONS

In this comprehensive study of 1280 sequences, we found a high number of gene variants only occurring in specific hosts. Additionally, different hosts show unique but also shared variant combinations. The use of our four gene loci expand the knowledge of host-pathogen interactions and may be a starting point to predict future spread and infection risks of A. phagocytophilum in Europe.

Presence of Anaplasma phagocytophilum Ecotype I in UK Ruminants and Associated Zoonotic Risk

Anaplasma phagocytophilum is the causative agent of tick-borne fever in sheep, pasture fever in cattle, and granulocytic anaplasmosis in humans. The increasing prevalence and transboundary spread of A. phagocytophilum in livestock, ticks, and wildlife in the UK poses a potential zoonotic risk that has yet to be estimated. Several ecotypes of A. phagocytophilum show variable zoonotic potential. To evaluate the possible risk associated with the transmission of A. phagocytophilum from ruminants to humans, the ecotype was determined by sequencing the groEL gene from 71 positive blood and tissue samples from UK ruminants. Thirty-four groEL sequences were obtained, fourteen of which were identified in multiple samples. Of the 13 nucleotide polymorphisms identified through pairwise comparison, all corresponded to synonymous substitutions. The subsequent phylogenetic estimation of the relationship with other European/world isolates indicated that all the groEL sequences clustered with other ecotype I sequences. The presence of ecotype I closely reflects that observed in ruminants in continental Europe and suggests a lower risk of zoonotic transmission from this reservoir.

The Biological and Ecological Features of Northbound Migratory Birds, Ticks, and Tick-Borne Microorganisms in the African-Western Palearctic

Identifying the species that act as hosts, vectors, and vehicles of vector-borne pathogens is vital for revealing the transmission cycles, dispersal mechanisms, and establishment of vector-borne pathogens in nature. Ticks are common vectors for pathogens causing human and animal diseases, and they transmit a greater variety of pathogenic agents than any other arthropod vector group. Ticks depend on the movements by their vertebrate hosts for their dispersal, and tick species with long feeding periods are more likely to be transported over long distances. Wild birds are commonly parasitized by ticks, and their migration patterns enable the long-distance range expansion of ticks. The African-Palearctic migration system is one of the world's largest migrations systems. African-Western Palearctic birds create natural links between the African, European, and Asian continents when they migrate biannually between breeding grounds in the Palearctic and wintering grounds in Africa and thereby connect different biomes. Climate is an important geographical determinant of ticks, and with global warming, the distribution range and abundance of ticks in the Western Palearctic may increase. The introduction of exotic ticks and their microorganisms into the Western Palearctic via avian vehicles might therefore pose a greater risk for the public and animal health in the future.

Prevalence and Genotyping of Anaplasma phagocytophilum Strains from Wild Animals, European Bison (Bison bonasus) and Eurasian Moose (Alces alces) in Poland

Simple Summary

The populations of bison and moose, the largest wild ruminants in Poland, are growing every year. These animals return to Polish forests after many years of risk of extinction or, as in the case of European bison, are reintroduced step by step. Unfortunately, they are still rare and require close health surveillance and monitoring. One serious threat to their health and life is the bacterial parasite Anaplasma phagocytophilum. Moose and bison can also be sources of pathogenic bacteria for humans, which can be transferred through tick bites. In line with the World Health Organization (WHO) “OneHealth” program, indicating that animal health affects human health and vice versa, the following study examines the occurrence of Anaplasma phagocytophilum bacteria in European bison and Eurasian moose populations using molecular biology tools. Our results provide useful data regarding Anaplasma phagocytophilum that could be used in future strategies for the diagnosis and treatment of people and animals.

Abstract

Wild large ungulates, like European bison (Bison bonasus) and Eurasian moose (Alces alces), form an important part of the circulation of Anaplasma phagocytophilum, a Gram-negative, intracellular, tick-transmitted bacterium, in the natural environment. Bison and moose tissue samples were subjected to 16S rDNA, groEL and ankA partial gene marker amplification with specific primers using various variants of PCR. Out of 42 examined individuals, Anaplasma sp. were detected in 4/13 Eurasian moose (31%) and 7/29 European bison (24%). In addition, 12 groEL and 5 ankA partial gene positive samples were obtained from the examined animals. The phylogenetic analysis of the groEL partial gene classified samples from European bison to ecotype I, and samples from Eurasian moose to ecotype I and II; the analysis of the ankA partial gene assigned the samples to clusters I and IV. This study extends knowledge about A. phagocytophilum in wild large ungulates in Poland. This is the first report about the occurrence of Anaplasma sp. in one of the largest populations of free living European bison in the world. Our findings confirm that strains of A. phagocytophilum from Bison bonasus and Alces alces may constitute a natural reservoir of pathogenic HGA Anaplasma strains.

Genetic diversity of Anaplasma bacteria: Twenty years later

The genus Anaplasma (family Anaplasmataceae, order Rickettsiales) includes obligate intracellular alphaproteobacteria that multiply within membrane-bound vacuoles and are transmitted by Ixodidae ticks to vertebrate hosts. Since the last reclassification of Anaplasmataceae twenty years ago, two new Anaplasma species have been identified. To date, the genus includes eight Anaplasma species (A. phagocytophilum, A. marginale, A. centrale, A. ovis, A. bovis, A. platys, A. odocoilei, and A. capra) and a large number of unclassified genovariants that cannot be assigned to known species. Members of the genus can cause infection in humans and a wide range of domestic animals with different degrees of severity. Long-term persistence which, in some cases, is manifested as cyclic bacteremia has been demonstrated for several Anaplasma species. Zoonotic potential has been shown for A. phagocytophilum, the agent of human granulocytic anaplasmosis, and for some other Anaplasma spp. that suggests a broader medical relevance of this genus. Genetic diversity of Anaplasma spp. has been intensively studied in recent years, and it has been shown that some Anaplasma spp. can be considered as a complex of genetically distinct lineages differing by geography, vectors, and host tropism. The aim of this review was to summarize the current knowledge concerning the natural history, pathogenic properties, and genetic diversity of Anaplasma spp. and some unclassified genovariants with particular attention to their genetic characteristics. The high genetic variability of Anaplasma spp. prompted us to conduct a detailed phylogenetic analysis for different Anaplasma species and unclassified genovariants, which were included in this review. The genotyping of unclassified genovariants has led to the identification of at least four distinct clades that might be considered in future as new candidate species.

Wentzel J, Wills-Berriman S, Boni LD, Weyer J, Rossouw J, Oosthuizen MC. Anaplasma phagocytophilum and Other Anaplasma spp. in Various Hosts in the Mnisi Community, Mpumalanga Province, South Africa

DNA samples from 74 patients with non-malarial acute febrile illness (AFI), 282 rodents, 100 cattle, 56 dogs and 160 Rhipicephalus sanguineus ticks were screened for the presence of Anaplasma phagocytophilum DNA using a quantitative PCR (qPCR) assay targeting the msp2 gene. The test detected both A. phagocytophilum and Anaplasma sp. SA/ZAM dog DNA. Microbiome sequencing confirmed the presence of low levels of A. phagocytophilum DNA in the blood of rodents, dogs and cattle, while high levels of A. platys and Anaplasma sp. SA/ZAM dog were detected in dogs. Directed sequencing of the 16S rRNA and gltA genes in selected samples revealed the presence of A. phagocytophilum DNA in humans, dogs and rodents and highlighted its importance as a possible contributing cause of AFI in South Africa. A number of recently described Anaplasma species and A. platys were also detected in the study. Phylogenetic analyses grouped Anaplasma sp. SA/ZAM dog into a distinct clade, with sufficient divergence from other Anaplasma species to warrant classification as a separate species. Until appropriate type-material can be deposited and the species is formally described, we will refer to this novel organism as Anaplasma sp. SA dog.

The absence of the drhm gene is not a marker for human-pathogenicity in European Anaplasma phagocytophilum strains

BACKGROUND

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks of the Ixodes ricinus complex and causes febrile illness in humans and animals. The geographical distribution of A. phagocytophilum spans the Americas, Europe, Africa and Asia. However, human disease predominantly occurs in North America but is infrequently reported from Europe and Asia. In North American strains, the absence of the drhm gene has been proposed as marker for pathogenicity in humans whereas no information on the presence or absence of the drhm gene was available for A. phagocytophilum strains circulating in Europe. Therefore, we tested 511 European and 21 North American strains for the presence of drhm and compared the results to two other typing methods: multilocus sequence typing (MLST) and ankA-based typing.

RESULTS

Altogether, 99% (478/484) of the analyzable European and 19% (4/21) of the North American samples from different hosts were drhm-positive. Regarding the strains from human granulocytic anaplasmosis cases, 100% (35/35) of European origin were drhm-positive and 100% (14/14) of North American origin were drhm-negative. Human strains from North America and Europe were both part of MLST cluster 1. North American strains from humans belonged to ankA gene clusters 11 and 12 whereas European strains from humans were found in ankA gene cluster 1. However, the North American ankA gene clusters 11 and 12 were highly identical at the nucleotide level to the European cluster 1 with 97.4% and 95.2% of identity, respectively.

CONCLUSIONS

The absence of the drhm gene in A. phagocytophilum does not seem to be associated with pathogenicity for humans per se, because all 35 European strains of human origin were drhm-positive. The epidemiological differences between North America and Europe concerning the incidence of human A. phagocytophilum infection are not explained by strain divergence based on MLST and ankA gene-based typing.

Phylogeographical diversity of Anaplasma phagocytophilum in the Asian part of Russia based on multilocus sequence typing and analysis of the ankA gene

Anaplasma phagocytophilum is a tick-transmitted bacterium that replicates in neutrophil granulocytes and elicits febrile disease in humans and animals; it is widely distributed in the Americas, Europe, Africa, and Asia. A. phagocytophilum is commonly regarded as a single species, but several genetic variants with distinct host distribution and geographical origin have been described. In a previous study, we used multilocus sequence typing (MLST) to characterize 25 A. phagocytophilum strains from Ixodes spp. ticks collected in the Asian part of Russia. The obtained concatenated sequences formed two separate clades reflecting their Asiatic origin and/or the vector species. As one of the clades was related to A. phagocytophilum strains from European voles and shrews, we here extended our analysis to seven samples from the northern red-backed vole Myodes rutilus and included 38 additional strains of Asiatic origin from Ixodes persulcatus, I. pavlovskyi, and their hybrids. Further, the ankA gene was sequenced in 59 A. phagocytophilum strains from ticks and voles. The Russian strains belonged to the two new MLST clusters 5 (38/70) and 6 (32/70), previously referred to as clades within clusters 1 and 3, respectively. The total number of sequence types (STs) found was 27 including 12 new STs. The ankA sequences were unique and formed two new clusters: cluster 8 (34/59) and cluster 10 (25/59). The concordance between MLST and ankA-based typing was 100%. This means that at least two distinct genetic groups of A. phagocytophilum circulate in the Asian Part of Russia whose reservoir hosts and transmission cycles have to be further elucidated.

A review on the eco-epidemiology and clinical management of human granulocytic anaplasmosis and its agent in Europe

Anaplasma phagocytophilum is the agent of tick-borne fever, equine, canine and human granulocytic anaplasmosis. The common route of A. phagocytophilum transmission is through a tick bite, the main vector in Europe being Ixodes ricinus. Despite the apparently ubiquitous presence of the pathogen A. phagocytophilum in ticks and various wild and domestic animals from Europe, up to date published clinical cases of human granulocytic anaplasmosis (HGA) remain rare compared to the worldwide status. It is unclear if this reflects the epidemiological dynamics of the human infection in Europe or if the disease is underdiagnosed or underreported. Epidemiologic studies in Europe have suggested an increased occupational risk of infection for forestry workers, hunters, veterinarians, and farmers with a tick-bite history and living in endemic areas. Although the overall genetic diversity of A. phagocytophilum in Europe is higher than in the USA, the strains responsible for the human infections are related on both continents. However, the study of the genetic variability and assessment of the difference of pathogenicity and infectivity between strains to various hosts has been insufficiently explored to date. Most of the European HGA cases presented as a mild infection, common clinical signs being pyrexia, headache, myalgia and arthralgia. The diagnosis of HGA in the USA was recommended to be based on clinical signs and the patient’s history and later confirmed using specialized laboratory tests. However, in Europe since the majority of cases are presenting as mild infection, laboratory tests may be performed before the treatment in order to avoid antibiotic overuse. The drug of choice for HGA is doxycycline and because of potential for serious complication the treatment should be instituted on clinical suspicion alone.

Genetic characterization of Anaplasma phagocytophilum strains from goats (Capra aegagrus hircus) and water buffalo (Bubalus bubalis) by 16S rRNA gene, ankA gene and multilocus sequence typing

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks and causes tick-borne fever in domestic ruminants such as sheep, cattle and goats. However, in contrast to sheep and cattle little is known about the clinical course of infection in goats. We report here on three cases of symptomatic infection with A. phagocytophilum in two goats (Capra aegagrus hircus) and one water buffalo (Bubalus bubalis). The animals showed symptoms and laboratory findings similar to sheep and cattle. To our knowledge, this is the first report on the symptomatic infection of water buffalos with A. phagocytophilum. The infecting strains were genetically characterized by 16S rRNA gene, ankA gene and multilocus sequence typing (MLST). Four other strains from asymptomatically infected goats were also included. The ankA sequences from five goats were part of the formerly described ankA gene clusters I and IV that are known to contain A. phagocytophilum strains from sheep and cattle. However, the sequences from one goat and from the water buffalo belonged to ankA gene cluster II that was formerly described to be restricted to roe deer. A similar observation was made for MLST as three goats clustered with sequences from sheep and cattle, whereas three other goats and the water buffalo were found to be part of the roe deer cluster. However, since most of the strains from sheep and cattle were distinct from the roe deer strains, roe deer might not represent major reservoir hosts for tick-borne fever in domestic ruminants. When differing parts of the 16S rRNA gene were used for typing the results were conflicting. This shows that the use of a standardized typing method such as MLST is highly desirable to generate easily comparable results.

Simultaneous infection of cattle with different Anaplasma phagocytophilum variants

Anaplasma phagocytophilum is a tick-transmitted Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It causes tick-borne fever in cattle and sheep. We report here the case of a 5-year-old cow from Germany with clinically overt granulocytic anaplasmosis presenting with fever, lower limb oedema and drop in milk-yield. The herd encompassed 10 animals, 8 other animals showed subclinical infection. The strains from the 9 A. phagocytophilum positive cows were molecularly characterized using ankA gene-based and multilocus sequence typing (MLST). Seven of 9 (78%) animals were infected simultaneously with different ankA variants belonging to ankA clusters I and IV. MLST analysis also revealed the presence of multiple strain types. This could be due to co-transmission or superinfection. Hosts harboring diverse A. phagocytophilum strains might enable the emergence of new ankA variants and/or MLST sequence types via bacterial recombination.

Tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran: A systematic review

BACKGROUND

Tick-borne zoonoses in the Order Rickettsiales and Legionellales cause infections that often manifest as undifferentiated fevers that are not easy to distinguish from other causes of acute febrile illnesses clinically. This is partly attributed to difficulty in laboratory confirmation since convalescent sera, specific diagnostic reagents, and the required expertise may not be readily available. As a result, a number of tick-borne zoonoses are underappreciated resulting in unnecessary morbidity, mortality and huge economic loses. In Iran, a significant proportion of human infectious diseases are tick-borne, with anecdotal evidence suggesting that tick-borne zoonoses are widespread but underreported in the country. Epidemiological review is therefore necessary to aid in the effective control and prevention of tick-borne zonooses in Iran. The aim of this review is to provide an in-depth and comprehensive overview of anaplasmosis, ehrlichiosis, spotted fever group rickettsioses and coxiellosis in Iran.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, all relevant publications on tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran were searched using a number of search terms. The search was confined to authentic resources from repositories of popular data bases among them PubMed, Web of Science, Google Scholar, Science Direct, SpringerLink and SCOPUS. The search items included peer reviewed journals, books and book chapters published between 1996 and 2017.

RESULTS

A total of 1 205 scientific publications and reports were sourced, of which 63 met the search criteria and were reviewed. Of the 63 articles reviewed, 36 (57.1%) reported on coxiellosis, 15 (23.8%) on anaplasmosis, 11 (17.5%) on ehrlichiosis and 1(1.6%) on spotted fever group rickettsiae in a large scale study involving four countries, among them Iran. The existence of tick-borne pathogens in the Order Rickettsiales and Legionellales was confirmed by molecular, serological and microscopic techniques conducted on samples obtained from sheep, cattle, goats, camels, poultry, animal products (milk and eggs), dogs, ticks and even human subjects in different parts of the country; pointing to a countrywide distribution.

DISCUSSION

Based on the review, coxiellosis, anaplasmosis, ehrlichiosis, and SFG rickettsiae can be categorized as emerging tick-borne zoonotic diseases in Iran given the presence of their causiative agents (C. burnetii, A. phagocytophilum, A. marginale, A. bovis, A. ovis, A. central, E. canis, E. ewingii, E. chaffeensis and R. conorii) collectively reported in a variety of domestic animals, animal products, arthropods and human beings drawn from 22 provinces in Iran.

CONCLUSION

Given the asymptomatic nature of some of these zoonoses, there is a high likelihood of silent transmission to humans in many parts of the country, which should be considered a public health concern. Presently, information on the transmission intensity of tick-borne zoonoses caused by pathogens in the Order Rickettsiales and Legionellales to humans and its public health impact in Iran is scanty.

Evaluation of potential predictor variables for PCR assay diagnosis of Anaplasma phagocytophilum infection in equids in Northern California

OBJECTIVE To identify clinical or clinicopathologic variables that can be used to predict a positive PCR assay result for Anaplasma phagocytophilum infection in equids. ANIMALS 162 equids. PROCEDURES Medical records were reviewed to identify equids that underwent testing for evidence of A phagocytophilum infection by PCR assay between June 1, 2007, and December 31, 2015. For each equid that tested positive (case equid), 2 time-matched equids that tested negative for the organism (control equids) were identified. Data collected included age, sex, breed, geographic location (residence at the time of testing), physical examination findings, and CBC and plasma biochemical analysis results. Potential predictor variables were analyzed by stepwise logistic regression followed by classification and regression tree analysis. Generalized additive models were used to evaluate identified predictors of a positive test result for A phagocytophilum. RESULTS Total lymphocyte count, plasma total bilirubin concentration, plasma sodium concentration, and geographic latitude were linear predictors of a positive PCR assay result for A phagocytophilum. Plasma creatine kinase activity was a nonlinear predictor of a positive result. CONCLUSIONS AND CLINICAL RELEVANCE Assessment of predictors identified in this study may help veterinarians identify equids that could benefit from early treatment for anaplasmosis while definitive test results are pending. This information may also help to prevent unnecessary administration of oxytetracycline to equids that are unlikely to test positive for the disease.

Molecular identification of tick-borne pathogens in asymptomatic individuals with human immunodeficiency virus type 1 (HIV-1) infection: a retrospective study

Background

The studies on the occurrence and diversity of tick-borne infections in HIV-infected individuals have been few, and the subject has been relatively neglected when compared with other common infections associated with HIV. In HIV-positive patients in whom a serological diagnostics is complicated due to reduced positive predictive value, a method where the microorganism is detected directly is of great value. Therefore, we performed a molecular study to ascertain the prevalence and incidence of tick-borne infections in HIV-infected persons in Poland, an endemic area for Ixodes ricinus ticks.

Methods

Genomic DNA was isolated from whole blood of tested patients. Detection of tick-borne pathogens was performed by amplification and sequencing of different loci. Molecular and phylogenetic analyses of obtained nucleotide sequences were performed. Serum samples were analyzed for antibodies against tick-borne pathogens by using commercial tests in all patients.

Results

Among 148 studied blood samples from HIV-infected patients, two cases (1.4%) of infection with tick-borne pathogen were reported. No symptoms of tick-borne infection were observed in these cases. In one case a patient was infected with Anaplasma phagocytophilum – the agent of human granulocytic anaplasmosis (HGA) and in the other with Borrelia garinii.

Conclusions

Our study revealed the first case of HIV positive patient infected with A. phagocytophilum. Asymptomatic tick-borne infection can occur in HIV-positive patients. The detailed history of tick bites, especially in endemic tick areas, should be considered as part of anamnesis in routine clinical care of HIV-positive patients.

Epidemiology, genetic variants and clinical course of natural infections with Anaplasma phagocytophilum in a dairy cattle herd

Background

Anaplasma phagocytophilum is an obligate intracellular, tick-transmitted bacterium that causes granulocytic anaplasmosis in humans and several mammalian species including domestic ruminants where it is called tick-borne fever (TBF). Different genetic variants exist but their impact with regard to putative differences in host associations and pathogenicity are not yet completely understood.

Methods

Natural infections with A. phagocytophilum in a dairy cattle herd in Germany were investigated over one pasture season by using serology, haematology, blood chemistry and polymerase chain reaction (PCR). Sequence analysis of partial 16S rRNA, groEL, msp2 and msp4 genes of A. phagocytophilum was carried out in order to trace possible genetic variants and their relations between cattle, roe deer (Capreolus capreolus) and ticks (Ixodes ricinus) in this area.

Results

In total 533 samples from 58 cattle, 310 ticks, three roe deer and one wild boar were examined. Our results show (i) typical clinical symptoms of TBF in first-time infected heifers, such as high fever, reduced milk yield, lower limb oedema and typical haematological and biochemical findings such as severe leukopenia, erythropenia, neutropenia, lymphocytopenia, monocytopenia, a significant increase in creatinine and bilirubin and a significant decrease in serum albumin, γ-GT, GLDH, magnesium and calcium; (ii) a high overall prevalence of A. phagocytophilum infections in this herd as 78.9% (15/19) of the naïve heifers were real-time PCR-positive and 75.9% (44/58) of the entire herd seroconverted; and (iii) a high level of sequence variation in the analysed genes with five variants of the 16S rRNA gene, two variants of the groEL gene, three variants of the msp2 gene and four variants in the msp4 gene with certain combinations of these variants.

Conclusions

In cattle particular combinations of the genetic variants of A. phagocytophilum occurred, whereas three roe deer showed different variants altogether. This is indicative for a sympatric circulation of variants in this small geographical region (< 1 km²). Both re- and superinfections with A. phagocytophilum were observed in five cattle showing that infection does not result in sterile immunity. For prevention of clinical cases we suggest pasturing of young, not pregnant heifers to reduce economical losses.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2570-1) contains supplementary material, which is available to authorized users.

Molecular Survey on Rickettsia spp., Anaplasma phagocytophilum, Borrelia burgdorferi Sensu Lato, and Babesia spp. in Ixodes ricinus Ticks Infesting Dogs in Central Italy

Dogs are a common feeding hosts for Ixodes ricinus and may act as reservoir hosts for zoonotic tick-borne pathogens (TBPs) and as carriers of infected ticks into human settings. The aim of this work was to evaluate the presence of several selected TBPs of significant public health concern by molecular methods in I. ricinus recovered from dogs living in urban and suburban settings in central Italy. A total of 212 I. ricinus specimens were collected from the coat of domestic dogs. DNA was extracted from each specimen individually and tested for Rickettsia spp., Borrelia burgdorferi sensu lato, Babesia spp., and Anaplasma phagocytophilum, using real-time and conventional PCR protocols, followed by sequencing. Sixty-one ticks (28.8%) tested positive for TBPs; 57 samples were infected by one pathogen, while four showed coinfections. Rickettsia spp. was detected in 39 specimens (18.4%), of which 32 were identified as Rickettsia monacensis and seven as Rickettsia helvetica. Twenty-two samples (10.4%) tested positive for A. phagocytophilum; Borrelia lusitaniae and Borrelia afzelii were detected in two specimens and one specimen, respectively. One tick (0.5%) was found to be positive for Babesia venatorum (EU1). Our findings reveal the significant exposure of dogs to TBPs of public health concern and provide data on the role of dogs in the circulation of I. ricinus-borne pathogens in central Italy.

Detecting and characterizing mixed infections with genetic variants of Anaplasma phagocytophilum in roe deer (Capreolus capreolus) by developing an ankA cluster-specific nested PCR

Background

Anaplasma phagocytophilum is a tick-transmitted Gram-negative obligate intracellular bacterium able to infect a wide variety of wild and domestic animals worldwide. Based on the genetic diversity observed with different molecular markers, several host-specific lineages have been identified. Roe deer is one of the most important reservoirs of this bacterium and hosts different genetic groups sometimes found on domestic animals. We therefore developed an ankA cluster-specific nested PCR (nPCR) to evaluate the prevalence of the three different ankA genetic groups described in roe deer (clusters II, III and IV) at three locations in France and the level of co-infections.

Results

The specificity of the three nPCRs was assessed by partially sequencing 35 amplicons of ankA genes obtained from the different nested PCRs. All three genetic lineages were detected in roe deer from all three geographical locations. Of the infected deer population, 60.7% were co-infected by two or three different genetic variants. Co-infections varied from 42.9 to 70.6% of the infected population depending on the local infection prevalences (from 33.3 to 73.9%). All types of mixed infections occurred, suggesting the absence of a strict variant exclusion by another variant.

Conclusions

Mixed infections by two or three genetic variants of A. phagocytopilum are a common feature in roe deer. Genetic variants (cluster IV) also found in domestic ruminants (cattle and sheep) were present in all the roe deer populations analyzed, suggesting a shared epidemiological cycle.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2316-0) contains supplementary material, which is available to authorized users.

Genetic diversity and molecular epidemiology of Anaplasma

Anaplasma are obligate intracellular bacteria of cells of haematopoietic origin and are aetiological agents of tick-borne diseases of both veterinary and medical interest common in both tropical and temperate regions. The recent disclosure of their zoonotic potential has greatly increased interest in the study of these bacteria, leading to the recent reorganisation of Rickettsia taxonomy and to the possible discovery of new species belonging to the genus Anaplasma. This review is particularly focused on the common and unique characteristics of Anaplasma marginale and Anaplasma phagocytophilum, with an emphasis on genetic diversity and evolution, and the main distinguishing features of the diseases caused by the different Anaplasma spp. are described as well.

Ridge preservation of extraction sockets with chronic pathology using Bio-Oss® Collagen with or without collagen membrane: an experimental study in dogs

OBJECTIVES

This study aimed to evaluate the dynamics of newly bone formation and dimensional change in diseased extraction sockets using Bio-Oss^® Collagen with or without a collagen membrane.

MATERIAL AND METHODS

In six beagle dogs, right and left 3rd and 4th mandibular premolars were hemisected and the distal roots were removed. Combined endodontic-periodontic lesions were induced in all sites using black silk, collagen sponge, endodontic files, and application of Porphyromonas gingivalis. After 4 months, among 4 premolars, three teeth were randomly selected per dog and allocated to the following experimental groups: Control group (no treatment but debridement), Test 1 group (only Bio-Oss^® Collagen graft), and Test 2 group (Bio-Oss^® Collagen graft with a collagen membrane). After 7 months from the baseline, the beagle dogs were sacrificed for histomorphometric and Micro-CT analysis.

RESULTS

The vertical distance between buccal and lingual crests in the Control group (2.22 ± 0.26 mm) and Test 2 group (1.80 ± 0.16 mm) was significantly different. The socket of the Test 2 group (27.04 ± 5.25%) was occupied by a greater quantity of bone graft compared to the Test 1 group (18.49 ± 2.11%).

CONCLUSION

Ridge preservation in diseased extraction sockets could compensate for buccal bone resorption by contact osteogenesis surrounding the bone graft particles at the bucco-coronal area during socket healing, and the application of a collagen membrane at the entrance of the socket is useful for preserving graft material at the coronal part of the socket.

Anaplasma marginale and Anaplasma phagocytophilum: Rickettsiales pathogens of veterinary and public health significance

Anaplasma marginale and Anaplasma phagocytophilum are the most important tick-borne bacteria of veterinary and public health significance in the family Anaplasmataceae. The objective of current review is to provide knowledge on ecology and epidemiology of A. phagocytophilum and compare major similarities and differences of A. marginale and A. phagocytophilum. Bovine anaplasmosis is globally distributed tick-borne disease of livestock with great economic importance in cattle industry. A. phagocytophilum, a cosmopolitan zoonotic tick transmitted pathogen of wide mammalian hosts. The infection in domestic animals is generally referred as tick-borne fever. Concurrent infections exist in ticks, domestic and wild animals in same geographic area. All age groups are susceptible, but the prevalence increases with age. Movement of susceptible domestic animals from tick free non-endemic regions to disease endemic regions is the major risk factor of bovine anaplasmosis and tick-borne fever. Recreational activities or any other high-risk tick exposure habits as well as blood transfusion are important risk factors of human granulocytic anaplasmosis. After infection, individuals remain life-long carriers. Clinical anaplasmosis is usually diagnosed upon examination of stained blood smears. Generally, detection of serum antibodies followed by molecular diagnosis is usually recommended. There are problems of sensitivity and cross-reactivity with both the Anaplasma species during serological tests. Tetracyclines are the drugs of choice for treatment and elimination of anaplasmosis in animals and humans. Universal vaccine is not available for either A. marginale or A. phagocytophilum, effective against geographically diverse strains. Major control measures for bovine anaplasmosis and tick-borne fever include rearing of tick-resistant breeds, endemic stability, breeding Anaplasma-free herds, identification of regional vectors, domestic/wild reservoirs and control, habitat modification, biological control, chemotherapy, and vaccinations (anaplasmosis and/or tick vaccination). Minimizing the tick exposure activities, identification and control of reservoirs are important control measures for human granulocytic anaplasmosis.

Candidatus Neoehrlichia mikurensis and Anaplasma phagocytophilum: prevalences and investigations on a new transmission path in small mammals and ixodid ticks

Background

Small mammals are crucial for the life history of ixodid ticks, but their role and importance in the transmission cycle of tick-borne pathogens is mostly unknown. Candidatus Neoehrlichia mikurensis (CNM) and Anaplasma phagocytophilum are both tick-borne pathogens, and rodents are discussed to serve as main reservoir hosts for CNM but not for the latter especially in Germany. Analysing the prevalence of both pathogens in small mammals and their ticks in endemic regions may help to elucidate possible transmission paths in small mammal populations and between small mammals and ticks.

Methods

In 2012 and 2013, small mammals were trapped at three different sites in Germany. DNA was extracted from different small mammal tissues, from rodent neonates, foetuses and from questing and attached ticks. DNA samples were tested for CNM and A. phagocytophilum by real-time PCR. Samples positive for A. phagocytophilum were further characterized at the 16S rRNA gene locus.

Results

CNM was detected in 28.6% of small mammals and in 2.2% of questing and 3.8% of attached ticks. Altogether 33 positive ticks were attached to 17 different hosts, while positive ticks per host ranged between one and seven. The prevalences for this pathogen differed significantly within small mammal populations comparing sites (χ²: 13.3987; p: 0.0004) and between sexes. Male rodents had an approximately two times higher chance of infection than females (OR: 1.9652; 95% CI: 1.32-2.92). The prevalence for CNM was 31.8% (95% CI: 22-44) in rodent foetuses and neonates (23 of 67) from positive dams, and 60% (95% CI: 35.7-80.25) of positive gravid or recently parturient rodents (9 out of 15) had at least one positive foetus or neonate. Anaplasma phagocytophilum was detected at a low percentage in rodents (0-5.6%) and host-attached ticks (0.5-2.9%) with no significant differences between rodent species. However, attached nymphs were significantly more often infected than attached larvae (χ²: 25.091; p: <0.0001).

Conclusion

This study suggests that CNM is mainly a rodent-associated pathogen and provides evidence for a potential transplacental transmission in rodents. In contrast, most of the rodent species captured likely represent only accidental hosts for A. phagocytophilum at the investigated sites.

Ixodes ricinus and Its Transmitted Pathogens in Urban and Peri-Urban Areas in Europe: New Hazards and Relevance for Public Health

Tick-borne diseases represent major public and animal health issues worldwide. Ixodes ricinus, primarily associated with deciduous and mixed forests, is the principal vector of causative agents of viral, bacterial, and protozoan zoonotic diseases in Europe. Recently, abundant tick populations have been observed in European urban green areas, which are of public health relevance due to the exposure of humans and domesticated animals to potentially infected ticks. In urban habitats, small and medium-sized mammals, birds, companion animals (dogs and cats), and larger mammals (roe deer and wild boar) play a role in maintenance of tick populations and as reservoirs of tick-borne pathogens. Presence of ticks infected with tick-borne encephalitis virus and high prevalence of ticks infected with Borrelia burgdorferi s.l., causing Lyme borreliosis, have been reported from urbanized areas in Europe. Emerging pathogens, including bacteria of the order Rickettsiales (Anaplasma phagocytophilum, "Candidatus Neoehrlichia mikurensis," Rickettsia helvetica, and R. monacensis), Borrelia miyamotoi, and protozoans (Babesia divergens, B. venatorum, and B. microti) have also been detected in urban tick populations. Understanding the ecology of ticks and their associations with hosts in a European urbanized environment is crucial to quantify parameters necessary for risk pre-assessment and identification of public health strategies for control and prevention of tick-borne diseases.

Prevalence and Diversity among Anaplasma phagocytophilum Strains Originating from Ixodes ricinus Ticks from Northwest Norway

The tick-borne pathogen Anaplasma phagocytophilum causes great concern for livestock farmers. Tick-borne fever is a widespread disease in Norway, and antibodies have been produced amongst sheep, roe deer, red deer, and moose. The main vector Ixodes ricinus is found along the Norwegian coastline as far north as the Arctic Circle. A total number of 1804 I. ricinus ticks were collected and the prevalence of the pathogen was determined by species-specific qPCR. The overall infection rate varied from 2.83% to 3.32%, but there were no significant differences (p = 0.01) in the overall infection rate in 2010, 2011, or 2012. A multilocus sequencing analysis was performed to further characterise the isolates. The genotyping of 27 strains resulted in classification into 19 different sequences types (ST), none of which was found in the MLST database. The nucleotide diversity was for every locus <0.01, and the number of SNPs was between 1 and 2.8 per 100 bp. The majority of SNPs were synonymous. A goeBURST analysis demonstrated that the strains from northwest Norway cluster together with other Norwegian strains in the MLST database and the strains that are included in this study constitute clonal complexes (CC) 9, 10, and 11 in addition to the singleton.

Distinct Anaplasma phagocytophilum genotypes associated with Ixodes trianguliceps ticks and rodents in Central Europe

Rodents are important reservoir hosts of tick-borne pathogens. Anaplasma phagocytophilum is the causative agent of granulocytic anaplasmosis of both medical and veterinary importance. In Europe, this pathogen is primarily transmitted by the Ixodes ricinus tick among a wide range of vertebrate hosts. However, to what degree A. phagocytophilum exhibits host specificity and vector association is poorly understood. To assess the extent of vector association of this pathogen and to clarify its ecology in Central Europe we have analyzed and compared the genetic variability of A. phagocytophilum strains from questing and feeding I. ricinus and Ixodes trianguliceps ticks, as well as from rodent' tissue samples. Tick collection and rodent trapping were performed during a 2-year study (2011-2012) in ecologically contrasting setting at four sites in Eastern Slovakia. Genetic variability of this pathogen was studied from the collected samples by DNA amplification and sequencing of four loci followed by Bayesian phylogenetic analyses. A. phagocytophilum was detected in questing I. ricinus ticks (0.7%) from all studied sites and in host feeding I. trianguliceps ticks (15.2%), as well as in rodent biopsies (ear - 1.6%, spleen - 2.2%), whereas A. phagocytophilum was not detected in rodents from those sites where I. trianguliceps ticks were absent. Moreover, Bayesian phylogenetic analyses have shown the presence of two distinct clades, and tree topologies were concordant for all four investigated loci. Importantly, the first clade contained A. phagocytophilum genotypes from questing I. ricinus and feeding I. ricinus from a broad array of hosts (i.e.,: humans, ungulates, birds and dogs). The second clade comprised solely genotypes found in rodents and feeding I. trianguliceps. In this study we have confirmed that A. phagocytophilum strains display specific host and vector associations also in Central Europe similarly to A. phagocytophilum' molecular ecology in United Kingdom. This study suggests that A. phagocytophilum genotypes associated with rodents are probably transmitted solely by I. trianguliceps ticks, thus implying that rodent-associated A. phagocytophilum strains may not pose a risk for humans.

Analysis of the population structure of Anaplasma phagocytophilum using multilocus sequence typing

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophils. It is transmitted via tick-bite and causes febrile disease in humans and animals. Human granulocytic anaplasmosis is regarded as an emerging infectious disease in North America, Europe and Asia. However, although increasingly detected, it is still rare in Europe. Clinically apparent A. phagocytophilum infections in animals are mainly found in horses, dogs, cats, sheep and cattle. Evidence from cross-infection experiments that A. phagocytophilum isolates of distinct host origin are not uniformly infectious for heterologous hosts has led to several approaches of molecular strain characterization. Unfortunately, the results of these studies are not always easily comparable, because different gene regions and fragment lengths were investigated. Multilocus sequence typing is a widely accepted method for molecular characterization of bacteria. We here provide for the first time a universal typing method that is easily transferable between different laboratories. We validated our approach on an unprecedented large data set of almost 400 A. phagocytophilum strains from humans and animals mostly from Europe. The typability was 74% (284/383). One major clonal complex containing 177 strains was detected. However, 54% (49/90) of the sequence types were not part of a clonal complex indicating that the population structure of A. phagocytophilum is probably semiclonal. All strains from humans, dogs and horses from Europe belonged to the same clonal complex. As canine and equine granulocytic anaplasmosis occurs frequently in Europe, human granulocytic anaplasmosis is likely to be underdiagnosed in Europe. Further, wild boars and hedgehogs may serve as reservoir hosts of the disease in humans and domestic animals in Europe, because their strains belonged to the same clonal complex. In contrast, as they were only distantly related, roe deer, voles and shrews are unlikely to harbor A. phagocytophilum strains infectious for humans, domestic or farm animals.

Rickettsiaceae and Anaplasmataceae infections in Ixodes ricinus ticks from urban and natural forested areas of Poland

Background

Ixodes ricinus is a major vector for a range of microbial pathogens and the most prevalent and widely distributed tick species on the European continent, occurring in both natural and urban habitats. Nevertheless, little is known about the relative density of ticks in these two ecologically distinct habitats and the diversity of tick-borne pathogens that they carry.

Methods

We compared densities of questing I. ricinus nymphs and adults in urban and natural habitats in Central and Northeastern Poland, assessed the prevalence and rate of co-infection with A. phagocytophilum, Rickettsia, Ehrlichia and ‘Ca. Neoehrlichia spp.’ in ticks, and compared the diversity of tick-borne pathogens using molecular assays (PCR).

Results

Of the 1325 adults and nymphs, 6.2% were infected with at least one pathogen, with 4.4%, 1.7% and less than 0.5% being positive for the DNA of Rickettsia spp., A. phagocytophilum, Ehrlichia spp. and Ca. N. mikurensis, respectively. Although tick abundance was higher in natural habitats, the prevalence of the majority of pathogens was higher in urban forested areas.

Conclusion

We conclude that: (i) zoonotic genetic variants of A. phagocytophilum are widely distributed in the Polish tick population, (ii) although the diversity of tick borne pathogens was higher in natural habitats, zoonotic species/strains were detected only in urban forests, (iii) and we provide the first description of Ca. N. mikurensis infections in ticks in Poland.

Detection of Anaplasma phagocytophilum in red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) from Brandenburg, Germany

Anaplasma phagocytophilum is an obligate intracellular and tick-transmitted bacterium, which causes granulocytic anaplasmosis in animals and humans. Although infection with A. phagocytophilum in domestic animals and vector ticks is documented, there is sparse information on the occurrence of A. phagocytophilum in wild animals. Red foxes (Vulpes vulpes) as well as raccoon dogs (Nyctereutes procyonoides) are wildlife species highly abundant in certain areas of Germany and represent a potential wildlife reservoir for zoonotic diseases. To obtain data about the occurrence of A. phagocytophilum in these animals, red fox and raccoon dog carcasses (hunted or found dead) were collected from January to September 2009 in the Federal State of Brandenburg, Germany. Lung tissue samples were subjected to DNA extraction and were examined for the presence of A. phagocytophilum DNA by means of real-time PCR. Anaplasma phagocytophilum was detected in 10 out of 122 (8.2%) lungs of red foxes and in 3 out of 13 (23%) lungs of raccoon dogs. To the best of our knowledge, A. phagocytophilum was detected for the first time in red foxes and raccoon dogs in Germany.

Ixodes ricinus and Its Transmitted Pathogens in Urban and Peri-Urban Areas in Europe: New Hazards and Relevance for Public Health

Tick-borne diseases represent major public and animal health issues worldwide. Ixodes ricinus, primarily associated with deciduous and mixed forests, is the principal vector of causative agents of viral, bacterial, and protozoan zoonotic diseases in Europe. Recently, abundant tick populations have been observed in European urban green areas, which are of public health relevance due to the exposure of humans and domesticated animals to potentially infected ticks. In urban habitats, small and medium-sized mammals, birds, companion animals (dogs and cats), and larger mammals (roe deer and wild boar) play a role in maintenance of tick populations and as reservoirs of tick-borne pathogens. Presence of ticks infected with tick-borne encephalitis virus and high prevalence of ticks infected with Borrelia burgdorferi s.l., causing Lyme borreliosis, have been reported from urbanized areas in Europe. Emerging pathogens, including bacteria of the order Rickettsiales (Anaplasma phagocytophilum, "Candidatus Neoehrlichia mikurensis," Rickettsia helvetica, and R. monacensis), Borrelia miyamotoi, and protozoans (Babesia divergens, B. venatorum, and B. microti) have also been detected in urban tick populations. Understanding the ecology of ticks and their associations with hosts in a European urbanized environment is crucial to quantify parameters necessary for risk pre-assessment and identification of public health strategies for control and prevention of tick-borne diseases.

Anaplasma phagocytophilum strains from voles and shrews exhibit specific ankA gene sequences

Background

Anaplasma phagocytophilum is a Gram-negative bacterium that replicates obligate intracellularly in neutrophils. It is transmitted by Ixodes spp. ticks and causes acute febrile disease in humans, dogs, horses, cats, and livestock. Because A. phagocytophilum is not transmitted transovarially in Ixodes spp., it is thought to depend on reservoir hosts to complete its life cycle. In Europe, A. phagocytophilum was detected in roe deer, red deer, wild boars, and small mammals. In contrast to roe deer, red deer and wild boars have been considered as reservoir hosts for granulocytic anaplasmosis in humans, dogs, and horses according to groESL- and ankA-based genotyping. A. phagocytophilum variants infecting small mammals in Europe have not been characterized extensively to date.

Results

We amplified the total ankA open reading frames of 27 strains from voles and shrews. The analysis revealed that they harboured A. phagocytophilum strains that belonged to a distinct newly described ankA gene cluster. Further, we provide evidence that the heterogeneity of ankA gene sequences might have arisen via recombination.

Conclusions

Based on ankA-based genotyping voles and shrews are unlikely reservoir hosts for granulocytic anaplasmosis in humans, dogs, horses, and livestock in Europe.

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.

Congenital infection with Anaplasma phagocytophilum in a calf in northern Germany

Anaplasma phagocytophilum is a Gram-negative, obligate intracellular tick-transmitted bacterium that replicates in neutrophils. It causes tick-borne fever (TBF) in sheep and cattle, but also elicits febrile disease in humans as well as in other domestic animals such as dogs, horses, and cats. Although increasingly recognized in Europe, the first laboratory-confirmed case of TBF in cattle from Germany has been published only recently. We here present the unusual case of an intrauterine transmission of A. phagocytophilum in a calf from northern Germany. To our knowledge, this is the first report of such an event occurring under field conditions in cattle.

Co-infection and genetic diversity of tick-borne pathogens in roe deer from Poland

Wild species are essential hosts for maintaining Ixodes ticks and the tick-borne diseases. The aim of our study was to estimate the prevalence, the rate of co-infection with Babesia, Bartonella, and Anaplasma phagocytophilum, and the molecular diversity of tick-borne pathogens in roe deer in Poland. Almost half of the tested samples provided evidence of infection with at least 1 species. A. phagocytophilum (37.3%) was the most common and Bartonella (13.4%) the rarest infection. A total of 18.3% of all positive samples from roe deer were infected with at least 2 pathogens, and one-third of those were co-infected with A. phagocytophilum, Bartonella, and Babesia species. On the basis of multilocus molecular studies we conclude that: (1) Two different genetic variants of A. phagocytophilum, zoonotic and nonzoonotic, are widely distributed in Polish roe deer population; (2) the roe deer is the host for zoonotic Babesia (Bab. venatorum, Bab. divergens), closely related or identical with strains/species found in humans; (3) our Bab. capreoli and Bab. divergens isolates differed from reported genotypes at 2 conserved base positions, i.e., positions 631 and 663; and (4) this is the first description of Bart. schoenbuchensis infections in roe deer in Poland. We present 1 of the first complex epidemiological studies on the prevalence of Babesia, Bartonella, and A. phagocytophilum in naturally infected populations of roe deer. These game animals clearly have an important role as reservoir hosts of tick-borne pathogens, but the pathogenicity and zoonotic potential of the parasite genotypes hosted by roe deer requires further detailed investigation.

Anaplasma phagocytophilum variants in sympatric red deer (Cervus elaphus) and sheep in southern Norway

Infections by the ixodid tick-transmitted bacterial pathogen Anaplasma phagocytophilum are common in domestic ruminants and cervids in the coastal areas of southern Norway. Previous experimental work has shown that A. phagocytophilum strains recovered from red deer (Cervus elaphus) are infective in lambs, but epidemiological links between infections in red deer and sheep have yet to be established. To address this shortfall, the present study explores the genotypic relatedness between A. phagocytophilum strains infecting sympatric red deer and sheep. Blood from 32 lambs grazing on tick-infested pasture, and blood and tissues from 8 red deer shot in proximity to these pastures were collected during the summer and autumn of 2007. The presence of A. phagocytophilum in these samples was determined by PCR-based methods, and genotyping of detected strains was performed using comparative sequence analysis of 16S rDNA and msp4 fragments. A. phagocytophilum DNA was detected in 12 lambs and 7 red deer, 11 and 4 individuals of which 16S rDNA and msp4 sequence data were obtained from, respectively. A total of 9 genotypes were delineated, and only different individuals of the same host species were infected with indistinguishable A. phagocytophilum genotypes. Although 3 of the red deer-infecting genotypes belonged to a cluster of exclusively deer-associated strains phylogenetically remote from those commonly encountered in sheep, one red deer-infecting genotype, although unique, clustered tightly with genotypes associated with a wide range of hosts including sheep.

Candidatus Neoehrlichia mikurensis in rodents in an area with sympatric existence of the hard ticks Ixodes ricinus and Dermacentor reticulatus, Germany

Background

Candidatus Neoehrlichia mikurensis (CNM) has been described in the hard tick Ixodes ricinus and rodents as well as in some severe cases of human disease. The aims of this study were to identify DNA of CNM in small mammals, the ticks parasitizing them and questing ticks in areas with sympatric existence of Ixodes ricinus and Dermacentor reticulatus in Germany.

Methods

Blood, transudate and organ samples (spleen, kidney, liver, skin) of 91 small mammals and host-attached ticks from altogether 50 small mammals as well as questing I. ricinus ticks (n=782) were screened with a real-time PCR for DNA of CNM.

Results

52.7% of the small mammals were positive for CNM-DNA. The majority of the infected animals were yellow-necked mice (Apodemus flavicollis) and bank voles (Myodes glareolus). Small mammals with tick infestation were more often infected with CNM than small mammals without ticks. Compared with the prevalence of ~25% in the questing I. ricinus ticks, twice the prevalence in the rodents provides evidence for their role as reservoir hosts for CNM.

Conclusion

The high prevalence of this pathogen in the investigated areas in both rodents and ticks points towards the need for more specific investigation on its role as a human pathogen.

Babesia spp. and Anaplasma phagocytophilum in questing ticks, ticks parasitizing rodents and the parasitized rodents--analyzing the host-pathogen-vector interface in a metropolitan area

Background

The aims of this study were to evaluate the host-tick-pathogen interface of Babesia spp. and Anaplasma phagocytophilum in restored areas in both questing and host-attached Ixodes ricinus and Dermacentor reticulatus and their small mammalian hosts.

Methods

Questing ticks were collected from 5 sites within the city of Leipzig, Germany, in 2009. Small mammals were trapped at 3 of the 5 sites during 2010 and 2011. DNA extracts of questing and host-attached I. ricinus and D. reticulatus and of several tissue types of small mammals (the majority bank voles and yellow-necked mice), were investigated by PCR followed by sequencing for the occurrence of DNA of Babesia spp. and by real-time PCR for A. phagocytophilum. A selected number of samples positive for A. phagocytophilum were further investigated for variants of the partial 16S rRNA gene. Co-infection with Rickettsia spp. in the questing ticks was additionally investigated.

Results

4.1% of questing I. ricinus ticks, but no D. reticulatus, were positive for Babesia sp. and 8.7% of I. ricinus for A. phagocytophilum. Sequencing revealed B. microti, B. capreoli and Babesia spp. EU1 in Leipzig and sequence analysis of the partial 16S RNA gene of A. phagocytophilum revealed variants either rarely reported in human cases or associated with cervid hosts. The statistical analysis revealed significantly less ticks infected with A. phagocytophilum in a city park in Leipzig as compared to the other sampling sites. A. phagocytophilum-DNA was detected in 2 bank voles, DNA of B. microti in 1 striped field-mouse and of Babesia sp. EU1 in the skin tissue of a mole. Co-infections were detected.

Conclusion

Our results show the involvement of small mammals in the natural endemic cycles of tick-borne pathogens. A more thorough understanding of the interactions of ticks, pathogens and hosts is the essential basis for effective preventive control measures.

Infections and coinfections of questing Ixodes ricinus ticks by emerging zoonotic pathogens in Western Switzerland

In Europe, Ixodes ricinus is the vector of many pathogens of medical and veterinary relevance, among them Borrelia burgdorferi sensu lato and tick-borne encephalitis virus, which have been the subject of numerous investigations. Less is known about the occurrence of emerging tick-borne pathogens like Rickettsia spp., Babesia spp., "Candidatus Neoehrlichia mikurensis," and Anaplasma phagocytophilum in questing ticks. In this study, questing nymph and adult I. ricinus ticks were collected at 11 sites located in Western Switzerland. A total of 1,476 ticks were analyzed individually for the simultaneous presence of B. burgdorferi sensu lato, Rickettsia spp., Babesia spp., "Candidatus Neoehrlichia mikurensis," and A. phagocytophilum. B. burgdorferi sensu lato, Rickettsia spp., and "Candidatus Neoehrlichia mikurensis" were detected in ticks at all sites with global prevalences of 22.5%, 10.2%, and 6.4%, respectively. Babesia- and A. phagocytophilum-infected ticks showed a more restricted geographic distribution, and their prevalences were lower (1.9% and 1.5%, respectively). Species rarely reported in Switzerland, like Borrelia spielmanii, Borrelia lusitaniae, and Rickettsia monacensis, were identified. Infections with more than one pathogenic species, involving mostly Borrelia spp. and Rickettsia helvetica, were detected in 19.6% of infected ticks. Globally, 34.2% of ticks were infected with at least one pathogen. The diversity of tick-borne pathogens detected in I. ricinus in this study and the frequency of coinfections underline the need to take them seriously into consideration when evaluating the risks of infection following a tick bite.

Prevalence of Neoehrlichia mikurensis in ticks and rodents from North-west Europe

BACKGROUND

Neoehrlichia mikurensis s an emerging and vector-borne zoonosis: The first human disease cases were reported in 2010. Limited information is available about the prevalence and distribution of Neoehrlichia mikurensis in Europe, its natural life cycle and reservoir hosts. An Ehrlichia-like schotti variant has been described in questing Ixodes ricinus ticks, which could be identical to Neoehrlichia mikurensis.

METHODS

Three genetic markers, 16S rDNA, gltA and GroEL, of Ehrlichia schotti-positive tick lysates were amplified, sequenced and compared to sequences from Neoehrlichia mikurensis. Based on these DNA sequences, a multiplex real-time PCR was developed to specifically detect Neoehrlichia mikurensis in combination with Anaplasma phagocytophilum in tick lysates. Various tick species from different life-stages, particularly Ixodes ricinus nymphs, were collected from the vegetation or wildlife. Tick lysates and DNA derived from organs of wild rodents were tested by PCR-based methods for the presence of Neoehrlichia mikurensis. Prevalence of Neoehrlichia mikurensis was calculated together with confidence intervals using Fisher's exact test.

RESULTS

The three genetic markers of Ehrlichia schotti-positive field isolates were similar or identical to Neoehrlichia mikurensis. Neoehrlichia mikurensis was found to be ubiquitously spread in the Netherlands and Belgium, but was not detected in the 401 tick samples from the UK. Neoehrlichia mikurensis was found in nymphs and adult Ixodes ricinus ticks, but neither in their larvae, nor in any other tick species tested. Neoehrlichia mikurensis was detected in diverse organs of some rodent species. Engorging ticks from red deer, European mouflon, wild boar and sheep were found positive for Neoehrlichia mikurensis.

CONCLUSIONS

Ehrlichia schotti is similar, if not identical, to Neoehrlichia mikurensis. Neoehrlichia mikurensis is present in questing Ixodes ricinus ticks throughout the Netherlands and Belgium. We propose that Ixodes ricinus can transstadially, but not transovarially, transmit this microorganism, and that different rodent species may act as reservoir hosts. These data further imply that wildlife and humans are frequently exposed to Neoehrlichia mikurensis-infected ticks through tick bites. Future studies should aim to investigate to what extent Neoehrlichia mikurensis poses a risk to public health.

"Candidatus Neoehrlichia mikurensis," Anaplasma phagocytophilum, and lyme disease spirochetes in questing european vector ticks and in feeding ticks removed from people

To estimate the likelihood of people coming into contact with the recently described tick-borne agent "Candidatus Neoehrlichia mikurensis," we compared its prevalence to those of Lyme disease spirochetes and Anaplasma phagocytophilum in questing adult Ixodes ricinus ticks collected in various Central European sites and examined ticks, which had been removed from people, for the presence of these pathogens. Whereas spirochetes infected questing adult ticks most frequently (22.3%), fewer than a third as many ticks were infected by "Ca. Neoehrlichia mikurensis" (6.2%), and about a sixth harbored A. phagocytophilum (3.9%). On average, every twelfth encounter of a person with an I. ricinus tick (8.1%) may bear the risk of acquiring "Ca. Neoehrlichia mikurensis." Although a fifth of the people (20%) had removed at least one tick infected by "Ca. Neoehrlichia mikurensis," none displayed symptoms described for this pathogen, suggesting that its transmission may not be immediate and/or that immunocompetent individuals may not be affected. Because immunosuppressed patients may be at a particular risk of developing symptoms, it should be considered that "Ca. Neoehrlichia mikurensis" appears to be the second most common pathogen in I. ricinus ticks. In our survey, only Borrelia afzelii appears to infect Central European vector ticks more frequently.

The European hedgehog (Erinaceus europaeus)--a suitable reservoir for variants of Anaplasma phagocytophilum?

The European hedgehog (Erinaceus europaeus) is a common insectivore in most parts of Europe and is frequently infested by the ticks Ixodes ricinus and I. hexagonus. I. ricinus ticks have been found infected with Anaplasma phagocytophilum, an obligate intracellular bacterium, but little is known about the potential of the hedgehog as a reservoir host. In this study, the infection with A. phagocytophilum and the genetic variants involved were investigated in a captive hedgehog population which was kept in a fenced, natural grass and bush garden habitat, and also in its ticks. Additionally hedgehogs from hedgehog caretaking stations were investigated. EDTA blood and ticks were collected from the captive hedgehog population once a month from March to October 2007 and in March and April 2008. All 3 developmental stages of I. ricinus and I. hexagonus occurred on the hedgehogs. After DNA extraction, the samples were screened for A. phagocytophilum with a real-time PCR, and selected samples were further investigated with a nested PCR targeting the partial 16S rRNA gene, followed by sequencing. One hundred thirty-six out of 220 hedgehog blood samples (61.8%) from altogether 48 individuals, 413 out of 563 I. ricinus samples and 90 out of 338 I. hexagonus samples were PCR-positive. Thirty-two hedgehogs were positive more than once, most frequently twice or 3 times, but also up to 9 times. Sequencing of the partial 16S rRNA gene resulted in 6 variants, but one variant ('A') was the most frequent which appeared in 93.8% of the positive hedgehogs. This variant (equaling Frankonia II, GenBank AF136712) has recently been reported from human, equine, and canine granulocytic anaplasmosis cases and thus, its specific association with hedgehogs is an important finding in the epidemiology of A. phagocytophilum in Europe. The high infection rate of both hedgehogs and ticks with A. phagocytophilum and the simultaneous infestation with 2 tick species of all developmental stages suggest that the hedgehog may be a suitable reservoir for at least some variants of A. phagocytophilum.

Prevalence of Anaplasma phagocytophilum in Ixodes ricinus in Bavarian public parks, Germany

Previous studies have shown that public parks provide extraordinary habitats for ticks and tick-borne pathogens. Therefore, the aim of this study was to investigate the tick abundance (ticks/100 m(2)) in urban areas and the prevalence of Anaplasma phagocytophilum. Collection of ticks was performed by the flagging method in selected Bavarian public parks in a 2-year survey. DNA from 30 ticks of each developmental stage, sampling site and month was extracted and screened by specific real-time PCR for A. phagocytophilum. Selected positive samples were further genetically differentiated by nested PCR, targeting the 16S rRNA gene. A total of 13,403 Ixodes ricinus were collected with an average tick abundance of 15-53 ticks/100 m(2) in 2009 and 15-35 ticks/100 m(2) in 2010, depending on the sampling site. DNA of A. phagocytophilum was detected in 11.6% (n=146) and 8.5% (n=50) of adult females, 13.3% (n=164) and 9.2% (n=51) of adult males as well as 5% (n=60) and 3.9% (n=29) of nymphs for 2009 (n=3685) and 2010 (n=1884), respectively. 16S rRNA gene analysis revealed 6 different genetic variants, 2 of which were 100% identical to known sequences in humans. The results give strong evidence that the occurrence of A. phagocytophilum in I. ricinus is highly variable in different habitat types due to geographical, climatic, and biological factors as well as different genetic variants of A. phagocytophilum circulated in ticks with a noticeable habitat and host tropism.

Identification of Anaplasma phagocytophilum in tick populations in Estonia, the European part of Russia and Belarus

Anaplasma phagocytophilum is associated with diseases of goats, sheep, cattle, dogs and horses. In the beginning of the 1990s it was identified as a human pathogen, causing human granulocytic anaplasmosis (HGA) in the USA, Europe and the far east of Russia. A. phagocytophilum is maintained in nature in an enzootic cycle including ticks as the main vector and a wide range of mammalian species as reservoirs. Ixodes ricinus and I. persulcatus ticks were collected in Estonia, Belarus and the European part of Russia and screened for the presence of A. phagocytophilum by real-time PCR. Positive samples were found only among I. ricinus, in 13.4% in the European part of Russia, 4.2% in Belarus, 1.7% in mainland Estonia and 2.6% on Saaremaa Island. Positive samples were sequenced for partial 16S rRNA, groESL and ankA genes and phylogenetic analyses were performed. The results showed that A. phagocytophilum circulating in Eastern Europe belongs to different groESL lineages and 16S rRNA gene variants and also consists of variable numbers of repetitive elements within the ankA gene.

Genetic variants of Anaplasma phagocytophilum from 14 equine granulocytic anaplasmosis cases

Background

Equine Granulocytic Anaplasmosis (EGA) is caused by Anaplasma phagocytophilum, a tick-transmitted, obligate intracellular bacterium. In Europe, it is transmitted by Ixodes ricinus. A large number of genetic variants of A. phagocytophilum circulate in nature and have been found in ticks and different animals. Attempts have been made to assign certain genetic variants to certain host species or pathologies, but have not been successful so far. The purpose of this study was to investigate the causing agent A. phagocytophilum of 14 cases of EGA in naturally infected horses with molecular methods on the basis of 4 partial genes (16S rRNA, groEL, msp2, and msp4).

Results

All DNA extracts of EDTA-blood samples of the horses gave bands of the correct nucleotide size in all four genotyping PCRs. Sequence analysis revealed 4 different variants in the partial 16S rRNA, groEL gene and msp2 genes, and 3 in the msp4 gene. One 16S rRNA gene variant involved in 11 of the 14 cases was identical to the "prototype" variant causing disease in humans in the amplified part [GenBank: U02521]. Phylogenetic analysis revealed as expected for the groEL gene that sequences from horses clustered separately from roe deer. Sequences of the partial msp2 gene from this study formed a separate cluster from ruminant variants in Europe and from all US variants.

Conclusions

The results show that more than one variant of A. phagocytophilum seems to be involved in EGA in Germany. The comparative genetic analysis of the variants involved points towards different natural cycles in the epidemiology of A. phagocytophilum, possibly involving different reservoir hosts or host adaptation, rather than a strict species separation.

Mechanisms of obligatory intracellular infection with Anaplasma phagocytophilum

Anaplasma phagocytophilum persists in nature by cycling between mammals and ticks. Human infection by the bite of an infected tick leads to a potentially fatal emerging disease called human granulocytic anaplasmosis. A. phagocytophilum is an obligatory intracellular bacterium that replicates inside mammalian granulocytes and the salivary gland and midgut cells of ticks. A. phagocytophilum evolved the remarkable ability to hijack the regulatory system of host cells. A. phagocytophilum alters vesicular traffic to create an intracellular membrane-bound compartment that allows replication in seclusion from lysosomes. The bacterium downregulates or actively inhibits a number of innate immune responses of mammalian host cells, and it upregulates cellular cholesterol uptake to acquire cholesterol for survival. It also upregulates several genes critical for the infection of ticks, and it prolongs tick survival at freezing temperatures. Several host factors that exacerbate infection have been identified, including interleukin-8 (IL-8) and cholesterol. Host factors that overcome infection include IL-12 and gamma interferon (IFN-γ). Two bacterial type IV secretion effectors and several bacterial proteins that associate with inclusion membranes have been identified. An understanding of the molecular mechanisms underlying A. phagocytophilum infection will foster the development of creative ideas to prevent or treat this emerging tick-borne disease.