13 research outputs found

    Human to human transmission of arthropod-borne pathogens

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    Human-to-human (H2H) transmitted arthropod-borne pathogens are a growing burden worldwide, with malaria and dengue being the most common mosquito-borne H2H transmitted diseases. The ability of vectors to get infected by humans during a blood meal to further propel an epidemic depends on complex interactions between pathogens, vectors and humans, in which human interventions and demographic and environmental conditions play a significant role. Herein, we discuss the distal and proximal drivers affecting H2H vector-borne pathogen transmission and identify knowledge gaps and future perspectives.This work was supported by the EU project ANTIGONE (Grant agreement number 278976).Peer Reviewe

    Emerging rodent-borne viral zoonoses in Trento, Italy

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    Rodent-borne hanta- and arenaviruses are an emerging public health threat in Europe; however, their circulation in human populations is usually underestimated since most infections are asymptomatic. Compared to other European countries, Italy is considered ‘low risk’ for these viruses, yet in the Province of Trento, two pathogenic hantaviruses (Puumala and Dobrava-Belgrade virus) and one arenavirus (Lymphocytic Choriomeningitis Virus) are known to circulate in rodent reservoirs. In this paper, we performed a follow up serological screening in humans to detect variation in the prevalence of these three viruses compared to previous analyses carried out in 2002. We also used a statistical model to link seropositivity to risk factors such as occupational exposure, cutting firewood, hunting, collecting mushrooms, having a garden, and owning a woodshed, a dog or a companion rodent. We demonstrate a significant increase in the seroprevalence of all three target viruses between 2002 and 2015, but no risk factors that we considered were significantly correlated with this increase. We conclude that the general exposure of residents in the Alps to these viruses has probably increased during the last decade. These results provide an early warning to public health authorities, and we suggest more detailed diagnostic and clinical investigations on suspected cases

    Interdisciplinarity and infectious diseases: an Ebola case study

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    High-profile epidemics such as Ebola, avian influenza, and severe acute respiratory syndrome (SARS) repeatedly thrust infectious diseases into the limelight. Because the emergence of diseases involves so many factors, the need for interdisciplinary approaches to studying emerging infections, particularly those originating from animals (i.e., zoonoses), is frequently discussed . However, effective integration across disciplines is challenging in practice. Ecological ideas, for example, are rarely considered in biomedical research, while insights from biomedicine are often neglected in ecological studies of infectious diseases. One practical reason for this is that researchers in these fields focus on vastly different scales of biological organization , which are difficult to bridge both intellectually and methodologically. Nevertheless, integration across biological scales is increasingly needed for solving the complex problems zoonotic diseases pose to human and animal well-being. Motivated by current events, we use Ebola virus as a case study to highlight fundamental questions about zoonoses that can be addressed by integrating insights and approaches across scales

    Pattern of tick aggregation on rodents: larger than expected tail distribution enhances the spread of tick-borne pathogens

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    The spread of tick-borne encephalitis (TBE) represents an important threat to human and animal health in many places of Eurasia. TBE enzootic cycles are strongly influenced by the non-systemic transmission of the infection between ticks co-feeding on the same rodent host. In this context, the frequency distribution of ticks on rodents plays a crucial role in amplifying TBE virus (TBEv) transmission. Here we analysed a 9-year time series (from 2000 to 2008) of Ixodes ricinus ticks (main TBE vector in Europe) feeding on Apodemus flavicollis mice (main TBE reservoir-competent host) sampled in a TBE focus in Trentino (Northern Italy). The tail of the distribution of the number of ticks per host was fitted by two theoretical distributions: the widely used Negative Binomial (NB) and the power-law (PL). In order to investigate the effect of different tail of tick distribution on the persistence and spread of a non-systemically transmitted pathogen, we simulated, through a stochastic network model, the transmission of TBEv between susceptible and infective ticks considering only co-feeding transmission. The dynamics of tick-host interaction is included in model simulations by distributing ticks on mice, independently from their epidemic state, accordingly to both fitted distributions. Empirical distribution of feeding ticks on mice was skewed and heavy-tailed. The fit with theoretical distributions indicated that the tail of tick infestation pattern on rodents is better described by PL distribution rather than by NB distribution. Model simulations indicated different outcomes of disease spreading when considering different distribution laws of ticks among hosts. Specifically, we found that the probability of pathogen persistence and spread was higher when the tail of the distribution is described by a PL distribution. In conclusion, our results suggest that the heterogeneity of the number of ticks feeding on rodents strongly influences the spreading of non-systematically transmitted tick-borne pathogen

    Metagenomic Profile of the Bacterial Communities Associated with Ixodes ricinus Ticks

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    Assessment of the microbial diversity residing in arthropod vectors of medical importance is crucial for monitoring endemic infections, for surveillance of newly emerging zoonotic pathogens, and for unraveling the associated bacteria within its host. The tick Ixodes ricinus is recognized as the primary European vector of disease-causing bacteria in humans. Despite I. ricinus being of great public health relevance, its microbial communities remain largely unexplored to date. Here we evaluate the pathogen-load and the microbiome in single adult I. ricinus by using 454- and Illumina-based metagenomic approaches. Genomic DNA-derived sequences were taxonomically profiled using a computational approach based on the BWA algorithm, allowing for the identification of known tick-borne pathogens at the strain level and the putative tick core microbiome. Additionally, we assessed and compared the bacterial taxonomic profile in nymphal and adult I. ricinus pools collected from two distinct geographic regions in Northern Italy by means of V6-16S rRNA amplicon pyrosequencing and community based ecological analysis. A total of 108 genera belonging to representatives of all bacterial phyla were detected and a rapid qualitative assessment for pathogenic bacteria, such as Borrelia, Rickettsia and Candidatus Neoehrlichia, and for other bacteria with mutualistic relationship or undetermined function, such as Wolbachia and Rickettsiella, was possible. Interestingly, the ecological analysis revealed that the bacterial community structure differed between the examined geographic regions and tick life stages. This finding suggests that the environmental context (abiotic and biotic factors) and host-selection behaviors affect their microbiome
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