Dataset Information

Rickettsia helvetica in Human-Parasitizing and Free-Living Ixodes ricinus from Urban and Wild Green Areas in the Metropolitan City of Rome, Italy.

ABSTRACT: Rickettsia helvetica is an emerging human pathogen, belonging to the spotted fever group (SFG) rickettsiae, associated with generally aneruptive fever, meningitis, and sudden death in chronic perimyocarditis. In this study, we describe the detection of R. helvetica in human-parasitizing and free-living Ixodes ricinus from the Metropolitan City of Rome. The pathogen was found in a tick acquired by a woman in an urban park. The circulation of R. helvetica was further confirmed by its detection in free-living ticks from a wild green area. These findings demonstrate that urban as well as wild green areas can represent a risk of infection to humans by R. helvetica, with potentially severe sequelae. To the best of our knowledge, this is the first report of R. helvetica in the Lazio region. Large-scale studies are needed to evaluate and quantify the presence of R. helvetica and other SFG rickettsiae in the urban and periurban context and to assess the risk to humans and animals related to their frequentation.

SUBMITTER: Scarpulla M

PROVIDER: S-EPMC6067101 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Rickettsia helvetica in Human-Parasitizing and Free-Living Ixodes ricinus from Urban and Wild Green Areas in the Metropolitan City of Rome, Italy.

Scarpulla Manuela M Barlozzari Giulia G Salvato Laura L De Liberato Claudio C Lorenzetti Raniero R Macrì Gladia G

Vector borne and zoonotic diseases (Larchmont, N.Y.) 20180417 8

Rickettsia helvetica is an emerging human pathogen, belonging to the spotted fever group (SFG) rickettsiae, associated with generally aneruptive fever, meningitis, and sudden death in chronic perimyocarditis. In this study, we describe the detection of R. helvetica in human-parasitizing and free-living Ixodes ricinus from the Metropolitan City of Rome. The pathogen was found in a tick acquired by a woman in an urban park. The circulation of R. helvetica was further confirmed by its detection in ...[more]

PMID: 29664700

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Project description:Rickettsia helvetica is an emerging pathogen of the Spotted Fever Group Rickettsia (SFGR) causing spotted fever diseases in various European countries. This tick-borne pathogen replicates in tick tissues such as the midgut and salivary gland, but its potential interactions with the vector microbiota is poorly characterized. The vector microbiome plays a pivotal role in tick-pathogen interactions, and some microbiota members facilitate or impede tick-borne pathogen infection. Manipulations of the tick microbiome have led to reduction in pathogen colonization in the tick vector. However, translating these findings into disease control applications requires a thorough characterization of vector microbiota response to different pathogens. In this study, we analyzed and compared the microbiota of Ixodes ricinus ticks attached on humans and collected in Serbia. Ticks were either infected with R. helvetica, or uninfected with major tick-borne pathogens (referred hereafter as 'pathogen-free'). We used microbial co-occurrence network analysis to determine keystone taxa of each set of samples, and to study the interaction patterns of the microbial communities in response to pathogen infection. The inferred functional profiles of the tick microbiome in R. helvetica-positive and pathogen-free samples were also compared. Our results show that R. helvetica infection reduces significantly the diversity of the microbiota and the connectivity of the co-occurrence network. In addition, using co-occurrence network we identified bacterial taxa (i.e., Enterobacteriaceae, Comamonadaceae, and Bacillus) that were negatively associated with 'Rickettsia' in R. helvetica-infected ticks, suggesting competition between R. helvetica and some members of the tick microbiota. The reconstruction of microbial metabolic pathways shows that the presence of R. helvetica might have a major impact on the metabolic functions of the tick microbiome. These results can inform novel interventions for the prevention of R. helvetica, or other SFGR infections in humans.

Project description:BACKGROUND: Ixodes ricinus, a competent vector of several pathogens, is the tick species most frequently reported to bite humans in Europe. The majority of human cases of Lyme borreliosis (LB) and tick-borne encephalitis (TBE) occur in the north-eastern region of Italy. The aims of this study were to detect the occurrence of endemic and emergent pathogens in north-eastern Italy using adult tick screening, and to identify areas at risk of pathogen transmission. Based on our results, different strategies for tick collection and pathogen screening and their relative costs were evaluated and discussed. METHODS: From 2006 to 2008 adult ticks were collected in 31 sites and molecularly screened for the detection of pathogens previously reported in the same area (i.e., LB agents, TBE virus, Anaplasma phagocytophilum, Rickettsia spp., Babesia spp., "Candidatus Neoehrlichia mikurensis"). Based on the results of this survey, three sampling strategies were evaluated a-posteriori, and the impact of each strategy on the final results and the overall cost reductions were analyzed. The strategies were as follows: tick collection throughout the year and testing of female ticks only (strategy A); collection from April to June and testing of all adult ticks (strategy B); collection from April to June and testing of female ticks only (strategy C). RESULTS: Eleven pathogens were detected in 77 out of 193 ticks collected in 14 sites. The most common microorganisms detected were Borrelia burgdorferi sensu lato (17.6%), Rickettsia helvetica (13.1%), and "Ca. N. mikurensis" (10.5%). Within the B. burgdorferi complex, four genotypes (i.e., B. valaisiana, B. garinii, B. afzelii, and B. burgdorferi sensu stricto) were found. Less prevalent pathogens included R. monacensis (3.7%), TBE virus (2.1%), A. phagocytophilum (1.5%), Bartonella spp. (1%), and Babesia EU1 (0.5%). Co-infections by more than one pathogen were diagnosed in 22% of infected ticks. The prevalences of infection assessed using the three alternative strategies were in accordance with the initial results, with 13, 11, and 10 out of 14 sites showing occurrence of at least one pathogen, respectively. The strategies A, B, and C proposed herein would allow to reduce the original costs of sampling and laboratory analyses by one third, half, and two thirds, respectively. Strategy B was demonstrated to represent the most cost-effective choice, offering a substantial reduction of costs, as well as reliable results. CONCLUSIONS: Monitoring of tick-borne diseases is expensive, particularly in areas where several zoonotic pathogens co-occur. Cost-effectiveness studies can support the choice of the best monitoring strategy, which should take into account the ecology of the area under investigation, as well as the available budget.

Dataset Information

Rickettsia helvetica in Human-Parasitizing and Free-Living Ixodes ricinus from Urban and Wild Green Areas in the Metropolitan City of Rome, Italy.

Publications

Rickettsia helvetica in Human-Parasitizing and Free-Living Ixodes ricinus from Urban and Wild Green Areas in the Metropolitan City of Rome, Italy.

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