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Hartemink N, Gort G, Krawczyk AI, Fonville M, van Vliet AJ, Takken W, Sprong H. Spatial and temporal variation of five different pathogens and symbionts in Ixodes ricinus nymphs in the Netherlands. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2024; 6:100209. [PMID: 39309546 PMCID: PMC11414485 DOI: 10.1016/j.crpvbd.2024.100209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 07/25/2024] [Accepted: 08/16/2024] [Indexed: 09/25/2024]
Abstract
The incidence of diseases caused by pathogens transmitted by the tick Ixodes ricinus vary over time and space through incompletely understood mechanisms. An important determinant of the disease risk is the density of infected ticks, which is the infection prevalence times the density of questing ticks. We therefore investigated the spatial and temporal variation of four pathogens and one of the most abundant symbionts in Ixodes ricinus in questing nymphs over four years of monthly collections in 12 locations in the Netherlands. The infection prevalence of all microbes showed markedly different patterns with significant spatial variation for Borrelia burgdorferi (s.l.), Neoehrlichia mikurensis, Rickettsia helvetica, and Midichloria mitochondrii, significant seasonal variation of B. burgdorferi (s.l.), N. mikurensis, and M. mitochondrii and a significant interannual variation of R. helvetica. Despite its ubiquitous presence, no spatio-temporal variation was observed for the infection prevalence of B. miyamotoi. The variation in infection prevalence was generally smaller than the variation in the density of nymphs, which fluctuated substantially both seasonally and between locations. This means that the variation in the densities of infected nymphs for all pathogens was mostly the result of the variation in densities of nymphs. We also investigated whether there were positive or negative associations between the symbionts, and more specifically whether ticks infected with vertically transmitted symbionts like M. mitochondrii and R. helvetica, have a higher prevalence of horizontally transmitted symbionts, such as B. burgdorferi (s.l.) and N. mikurensis. We indeed found a clear positive association between M. mitochondrii and B. burgdorferi (s.l.). The positive association between R. helvetica and B. burgdorferi (s.l.) was less clear and was only shown in two locations. Additionally, we found a clear positive association between B. burgdorferi (s.l.) and N. mikurensis, which are both transmitted by rodents. Our longitudinal study indicated strong between-location variation, some seasonal patterns and hardly any differences between years for most symbionts. Positive associations between symbionts were observed, suggesting that infection with a (vertically transmitted) symbiont may influence the probability of infection with other symbionts, or that there is a common underlying mechanism (e.g. feeding on rodents).
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Affiliation(s)
- Nienke Hartemink
- Biometris, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Gerrit Gort
- Biometris, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Aleksandra I. Krawczyk
- Jacob Blaustein Center for Scientific Cooperation, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Manoj Fonville
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3720 BA, Bilthoven, Bilthoven, the Netherlands
| | - Arnold J.H. van Vliet
- Earth Systems and Global Change Group, Wageningen University & Research, Droevendaalsesteeg 3a, 6708 PB, Wageningen, the Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Hein Sprong
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3720 BA, Bilthoven, Bilthoven, the Netherlands
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
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D'Ambrosio M, Locke T, Hendricks-Sturrup R. Addressing Climate Change-Induced Tick-borne Lyme Disease Patterns Through Data-Driven 'One Health' Policy. JOURNAL OF PUBLIC HEALTH MANAGEMENT AND PRACTICE 2024; 30:E157-E160. [PMID: 38870383 DOI: 10.1097/phh.0000000000001975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Affiliation(s)
- Matt D'Ambrosio
- Duke-Margolis Institute for Health Policy in Washington, Washington, District of Columbia
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Gomes IRC, Gurgel-Gonçalves R, Gazeta GS, Borsoi ABP, Bitencourth K, Leite LF, Coelho NGSS, Dislich R, Wiederhecker HC, Santos EG, Guimarães M. Effect of environmental variables on the abundance of Amblyomma ticks, potential vectors of Rickettsia parkeri in central Brazil. PLoS One 2024; 19:e0301685. [PMID: 38748697 PMCID: PMC11095677 DOI: 10.1371/journal.pone.0301685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/20/2024] [Indexed: 05/19/2024] Open
Abstract
Amblyomma ticks are vectors of both Rickettsia rickettsii and R. parkeri in the Americas, where capybaras (Hydrochoerus hydrochaeris) are the main hosts in urban areas, thus contributing to the transmission of spotted fever. Herein, we studied: (i) the seasonal dynamics and abundance of ticks in areas where capybaras live, (ii) the effect of environmental variables on tick abundance, and (iii) the presence of Rickettsia-infected ticks. Between September 2021 and September 2022, we sampled ticks using cloth-dragging at 194 sites on the shore of Lake Paranoá in Brasília, Brazil. We measured environmental data (season, vegetation type, canopy density, temperature, humidity, and presence or vestige of capybara) at each site. Nymphs and adults were morphologically identified to the species level, and a selected tick sample including larvae was subjected to genotypic identification. We investigated Rickettsia-infected ticks by PCR (gltA, htrA, ompB, and ompA genes) and associations between tick abundance and environmental variables using Generalized Linear Models. A total of 30,334 ticks (96% larvae) were captured. Ticks were identified as Amblyomma, with A. sculptum comprising 97% of the adult/nymphs. Genotype identification of a larval sample confirmed that 95% belonged to A. dubitatum. Seasonal variables showed significant effects on tick abundance. Most larvae and nymphs were captured during the early dry season, while the adults were more abundant during the wet season. Vegetation variables and the presence of capybaras showed no association with tick abundance. Rickettsia parkeri group and R. bellii were identified in A. dubitatum, while A. sculptum presented R. bellii. We conclude that: (i) Amblyomma ticks are widely distributed in Lake Paranoá throughout the year, especially larvae at the dry season, (ii) the abundance of Amblyomma ticks is explained more by climatic factors than by vegetation or presence of capybaras, and (iii) A. dubitatum ticks are potential vectors of R. parkeri in Brasília.
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Affiliation(s)
- Isadora R. C. Gomes
- Biological Sciences Course, Catholic University of Brasília, Federal District, Brasília, Brazil
- Faculty of Medicine, Laboratory of Medical Parasitology and Vector Biology, University of Brasília, Federal District, Brasília, Brazil
| | - Rodrigo Gurgel-Gonçalves
- Faculty of Medicine, Laboratory of Medical Parasitology and Vector Biology, University of Brasília, Federal District, Brasília, Brazil
| | - Gilberto S. Gazeta
- National Reference Laboratory for Rikettsiosis Vectors, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Ana B. P. Borsoi
- National Reference Laboratory for Rikettsiosis Vectors, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Karla Bitencourth
- National Reference Laboratory for Rikettsiosis Vectors, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Letícia F. Leite
- Biological Sciences Course, Catholic University of Brasília, Federal District, Brasília, Brazil
| | | | - Ricardo Dislich
- Ministry of Planning and Budget, Esplanade of Ministries, Federal District, Brasília, Brazil
| | | | - Eduardo G. Santos
- Post Graduation Program in Ecology, Institute of Biological Sciences, University of Brasília, Federal District, Brasília, Brazil
| | - Melina Guimarães
- Biological Sciences Course, Catholic University of Brasília, Federal District, Brasília, Brazil
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Comparing Vector-Borne Disease Surveillance and Response in Beijing and the Netherlands. Ann Glob Health 2022; 88:59. [PMID: 35974985 PMCID: PMC9336689 DOI: 10.5334/aogh.3672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 06/29/2022] [Indexed: 11/20/2022] Open
Abstract
Background: Objective(s): Methods: Findings: Conclusions:
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Bregnard C, Rais O, Herrmann C, Kahl O, Brugger K, Voordouw MJ. Beech tree masting explains the inter-annual variation in the fall and spring peaks of Ixodes ricinus ticks with different time lags. Parasit Vectors 2021; 14:570. [PMID: 34749794 PMCID: PMC8577035 DOI: 10.1186/s13071-021-05076-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 10/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The tick Ixodes ricinus is an important vector of tick-borne diseases including Lyme borreliosis. In continental Europe, the nymphal stage of I. ricinus often has a bimodal phenology with a large spring peak and a smaller fall peak. There is consensus about the origin of the spring nymphal peak, but there are two alternative hypotheses for the fall nymphal peak. In the direct development hypothesis, larvae quest as nymphs in the fall of the same year that they obtained their larval blood meal. In the developmental diapause hypothesis, larvae overwinter in the engorged state and quest as nymphs one year after they obtained their larval blood meal. These two hypotheses make different predictions about the time lags that separate the larval blood meal and the density of questing nymphs (DON) in the spring and fall. METHODS Inter-annual variation in seed production (masting) by deciduous trees is a time-lagged index for the density of vertebrate hosts (e.g., rodents) which provide blood meals for larval ticks. We used a long-term data set on the masting of the European beech tree and a 15-year study on the DON at 4 different elevation sites in western Switzerland to differentiate between the two alternative hypotheses for the origin of the fall nymphal peak. RESULTS Questing I. ricinus nymphs had a bimodal phenology at the three lower elevation sites, but a unimodal phenology at the top elevation site. At the lower elevation sites, the DON in the fall was strongly correlated with the DON in the spring of the following year. The inter-annual variation in the densities of I. ricinus nymphs in the fall and spring was best explained by a 1-year versus a 2-year time lag with the beech tree masting index. Fall nymphs had higher fat content than spring nymphs indicating that they were younger. All these observations are consistent with the direct development hypothesis for the fall peak of I. ricinus nymphs at our study site. Our study provides new insight into the complex bimodal phenology of this important disease vector. CONCLUSIONS Public health officials in Europe should be aware that following a strong mast year, the DON will increase 1 year later in the fall and 2 years later in the spring. Studies of I. ricinus populations with a bimodal phenology should consider that the spring and fall peak in the same calendar year represent different generations of ticks.
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Affiliation(s)
- Cindy Bregnard
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Olivier Rais
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Laboratory of Eco-Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Coralie Herrmann
- Laboratory of Eco-Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Olaf Kahl
- tick-radar GmbH, 10555 Berlin, Germany
| | - Katharina Brugger
- Unit for Veterinary Public Health and Epidemiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Maarten J. Voordouw
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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Seasonal patterns and spatial variation of Borrelia burgdorferi (sensu lato) infections in Ixodes ricinus in the Netherlands. Parasit Vectors 2021; 14:121. [PMID: 33627166 PMCID: PMC7905678 DOI: 10.1186/s13071-021-04607-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/23/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The incidence of Lyme borreliosis varies over time and space through as yet incompletely understood mechanisms. In Europe, Lyme borreliosis is caused by infection with a Borrelia burgdorferi (s.l.) genospecies, which is primarily transmitted by a bite of Ixodes ricinus nymphs. The aim of this study was to investigate the spatial and temporal variation in nymphal infection prevalence of B. burgdorferi (s.l.) (NIP), density of questing nymphs (DON) and the resulting density of infected nymphs (DIN). METHODS We investigated the infection rates in I. ricinus nymphs that were collected monthly between 2009 and 2016 in 12 locations in the Netherlands. Using generalized linear mixed models, we explored how the NIP, DON and DIN varied during the seasons, between years and between locations. We also determined the genospecies of the Borrelia infections and investigated whether the genospecies composition differed between locations. RESULTS The overall NIP was 14.7%. A seasonal pattern in infection prevalence was observed, with higher estimated prevalences in the summer than in the spring and autumn. This, combined with higher nymphal densities in summer, resulted in a pronounced summer peak in the estimated DIN. Over the 7.5-year study period, a significant decrease in infection prevalence was found, as well as a significant increase in nymphal density. These two effects appear to cancel each other out; the density of infected nymphs, which is the product of NIP × DON, showed no significant trend over years. Mean infection prevalence (NIP, averaged over all years and all months) varied considerably between locations, ranging from 5 to 26%. Borrelia genospecies composition differed between locations: in some locations almost all infections consisted of B. afzelii, whereas other locations had more diverse genospecies compositions. CONCLUSION In the Netherlands, the summer peak in DIN is a result of peaks in both NIP and DON. No significant trend in DIN was observed over the years of the study, and variations in DIN between locations were mostly a result of the variation in DON. There were considerable differences in acarological risk between areas in terms of infection prevalence and densities of ticks as well as in Borrelia genospecies composition.
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Borşan SD, Toma-Naic A, Péter Á, Sándor AD, Peștean C, Mihalca AD. Impact of abiotic factors, habitat type and urban wildlife on the ecology of hard ticks (Acari: Ixodidae) in urban and peri-urban habitats. Parasit Vectors 2020; 13:476. [PMID: 32948235 PMCID: PMC7501622 DOI: 10.1186/s13071-020-04352-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/11/2020] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Ticks are increasingly acknowledged as significant vectors for a wide array of pathogens in urban environments with reports of abundant tick populations in recreational areas. The study aims to contribute to a better knowledge of the abiotic and biotic factors which impact the ecology of hard ticks in urban and peri-urban habitats in Romania. METHODS Questing ticks were collected by flagging in seven recreational locations, from four types of habitats in Cluj-Napoca, Romania: parks; gardens; a cemetery; and peri-urban forests. Hedgehogs, birds and micromammals were also sampled and searched for ticks, using standard methods (i.e. torch-based searches, ornithological mist nets, snap-traps, etc.), while vegetation was evaluated on surveyed areas. Data on questing ticks were converted to abundance indices. Mood's median tests were used to assess the relationship between the abiotic and biotic factors and the abundance of questing ticks. RESULTS Two species of questing ticks were found: Ixodes ricinus (96.8%) and Haemaphysalis punctata (3.2%). Ixodes ricinus was also the predominant engorged tick collected from urban wildlife. For I. ricinus the highest mean total abundance index/location (total no. of ticks/100 m2) was recorded in the urban gardens (3.79, 95% CI: ± 1.59) and parks (2.68, 95% CI: ± 0.75), whereas the lowest mean total abundance index was noted in the peri-urban forests (0.06, 95% CI: ± 0.03) and the urban cemetery (0.04, 95% CI: ± 0.02). The adults and nymphs of I. ricinus displayed a bimodal activity pattern, while the larvae showed a unimodal questing behaviour with an autumnal peak. Positive correlations were found between the mean total abundance index and the rise in the daily mean temperature and relative humidity, and between the global abundance of questing ticks and the presence of hedgehogs in the respective locations (P < 0.01). CONCLUSIONS Ticks were collected in all the recreational sites surveyed in Cluj-Napoca. Ixodes ricinus was the dominant questing and engorged tick species. Several abiotic and biotic factors shape the ecology of ticks in Cluj-Napoca city, with climate and the local presence of suitable hosts being the most important.
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Affiliation(s)
- Silvia-Diana Borşan
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
| | - Andra Toma-Naic
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
| | - Áron Péter
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
| | - Attila D. Sándor
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
- Department of Parasitology and Zoology, University of Veterinary Medicine, Budapest, Hungary
| | - Cosmin Peștean
- Department of Surgery, Anesthesiology and Intensive Therapy, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
| | - Andrei-Daniel Mihalca
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
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Bregnard C, Rais O, Voordouw MJ. Climate and tree seed production predict the abundance of the European Lyme disease vector over a 15-year period. Parasit Vectors 2020; 13:408. [PMID: 32778177 PMCID: PMC7418309 DOI: 10.1186/s13071-020-04291-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 08/05/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND To predict the risk of tick-borne disease, it is critical to understand the ecological factors that determine the abundance of ticks. In Europe, the sheep tick (Ixodes ricinus) transmits a number of important diseases including Lyme borreliosis. The aim of this long-term study was to determine the abiotic and biotic factors driving the annual abundance of I. ricinus at a location in Switzerland where Lyme borreliosis is endemic. METHODS Over a 15-year period (2004 to 2018), we monitored the abundance of I. ricinus ticks on a monthly basis at three different elevations on Chaumont Mountain in Neuchâtel, Switzerland. We collected climate variables in the field and from nearby weather stations. We obtained data on beech tree seed production from the literature, as the abundance of Ixodes nymphs can increase dramatically two years after a masting event. We used AIC-based model selection to determine which ecological variables drive annual variation in tick density. RESULTS We found that elevation site, year, seed production by beech trees two years prior, and mean annual relative humidity together explained 73.2% of the variation in our annual estimates of nymph density. According to the parameter estimates of our models, (i) the annual density of nymphs almost doubled over the 15-year study period, (ii) changing the beech tree seed production index from very poor mast (1) to full mast (5) increased the abundance of nymphs by 86.2% two years later, and (iii) increasing the field-collected mean annual relative humidity from 50.0 to 75.0% decreased the abundance of nymphs by 46.4% in the same year. Climate variables collected in the field were better predictors of tick abundance than those from nearby weather stations indicating the importance of the microhabitat. CONCLUSIONS From a public health perspective, the increase in nymph abundance is likely to have increased the risk of tick-borne disease in this region of Switzerland. Public health officials in Europe should be aware that seed production by deciduous trees is a critical driver of the abundance of I. ricinus, and hence the risk of tick-borne disease.
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Affiliation(s)
- Cindy Bregnard
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Olivier Rais
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Maarten Jeroen Voordouw
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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Norte AC, Lopes de Carvalho I, Núncio MS, Araújo PM, Matthysen E, Albino Ramos J, Sprong H, Heylen D. Getting under the birds' skin: tissue tropism of Borrelia burgdorferi s.l. in naturally and experimentally infected avian hosts. MICROBIAL ECOLOGY 2020; 79:756-769. [PMID: 31612324 DOI: 10.1007/s00248-019-01442-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/11/2019] [Indexed: 06/10/2023]
Abstract
Wild birds are frequently exposed to the zoonotic tick-borne bacteria Borrelia burgdorferi sensu lato (s.l.), and some bird species act as reservoirs for some Borrelia genospecies. Studying the tropism of Borrelia in the host, how it is sequestered in different organs, and whether it is maintained in circulation and/or in the host's skin is important to understand pathogenicity, infectivity to vector ticks and reservoir competency.We evaluated tissue dissemination of Borrelia in blackbirds (Turdus merula) and great tits (Parus major), naturally and experimentally infected with Borrelia genospecies from enzootic foci. We collected both minimally invasive biological samples (feathers, skin biopsies and blood) and skin, joint, brain and visceral tissues from necropsied birds. Infectiousness of the host was evaluated through xenodiagnoses and infection rates in fed and moulted ticks. Skin biopsies were the most reliable method for assessing avian hosts' Borrelia infectiousness, which was supported by the agreement of infection status results obtained from the analysis of chin and lore skin samples from necropsied birds and of their xenodiagnostic ticks, including a significant correlation between the estimated concentration of Borrelia genome copies in the skin and the Borrelia infection rate in the xenodiagnostic ticks. This confirms a dermatropism of Borrelia garinii, B. valaisiana and B. turdi in its avian hosts. However, time elapsed from exposure to Borrelia and interaction between host species and Borrelia genospecies may affect the reliability of skin biopsies. The blood was not useful to assess infectiousness of birds, even during the period of expected maximum spirochetaemia. From the tissues sampled (foot joint, liver, spleen, heart, kidney, gut and brain), Borrelia was detected only in the gut, which could be related with infection mode, genospecies competition, genospecies-specific seasonality and/or excretion processes.
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Affiliation(s)
- Ana Cláudia Norte
- Marine and Environmental Sciences Centre, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Largo Marquês de Pombal, 3004-517, Coimbra, Portugal.
- Centre for Vectors and Infectious Diseases Dr. Francisco Cambournac, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal.
| | - Isabel Lopes de Carvalho
- Centre for Vectors and Infectious Diseases Dr. Francisco Cambournac, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Maria Sofia Núncio
- Centre for Vectors and Infectious Diseases Dr. Francisco Cambournac, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Pedro Miguel Araújo
- Marine and Environmental Sciences Centre, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Largo Marquês de Pombal, 3004-517, Coimbra, Portugal
| | - Erik Matthysen
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Jaime Albino Ramos
- Marine and Environmental Sciences Centre, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Largo Marquês de Pombal, 3004-517, Coimbra, Portugal
| | - Hein Sprong
- Centre for Infectious Disease Control (CIb), vhNational Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Dieter Heylen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium
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Krawczyk AI, van Duijvendijk GLA, Swart A, Heylen D, Jaarsma RI, Jacobs FHH, Fonville M, Sprong H, Takken W. Effect of rodent density on tick and tick-borne pathogen populations: consequences for infectious disease risk. Parasit Vectors 2020; 13:34. [PMID: 31959217 PMCID: PMC6971888 DOI: 10.1186/s13071-020-3902-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/08/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Rodents are considered to contribute strongly to the risk of tick-borne diseases by feeding Ixodes ricinus larvae and by acting as amplifying hosts for pathogens. Here, we tested to what extent these two processes depend on rodent density, and for which pathogen species rodents synergistically contribute to the local disease risk, i.e. the density of infected nymphs (DIN). METHODS In a natural woodland, we manipulated rodent densities in plots of 2500 m2 by either supplementing a critical food source (acorns) or by removing rodents during two years. Untreated plots were used as controls. Collected nymphs and rodent ear biopsies were tested for the presence of seven tick-borne microorganisms. Linear models were used to capture associations between rodents, nymphs, and pathogens. RESULTS Investigation of data from all plots, irrespective of the treatment, revealed a strong positive association between rodent density and nymphal density, nymphal infection prevalence (NIP) with Borrelia afzelii and Neoehrlichia mikurensis, and hence DIN's of these pathogens in the following year. The NIP, but not the DIN, of the bird-associated Borrelia garinii, decreased with increasing rodent density. The NIPs of Borrelia miyamotoi and Rickettsia helvetica were independent of rodent density, and increasing rodent density moderately increased the DINs. In addition, NIPs of Babesia microti and Spiroplasma ixodetis decreased with increasing rodent density, which had a non-linear association with DINs of these microorganisms. CONCLUSIONS A positive density dependence for all rodent- and tick-associated tick-borne pathogens was found, despite the observation that some of them decreased in prevalence. The effects on the DINs were variable among microorganisms, more than likely due to contrasts in their biology (including transmission modes, host specificity and transmission efficiency). The strongest associations were found in rodent-associated pathogens that most heavily rely on horizontal transmission. Our results draw attention to the importance of considering transmission mode of a pathogen while developing preventative measures to successfully reduce the burden of disease.
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Affiliation(s)
- Aleksandra I Krawczyk
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands. .,Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands.
| | | | - Arno Swart
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands
| | - Dieter Heylen
- Interuniversity Institute for Biostatistics and statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.,Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Ln, Princeton, NJ, 08544, USA
| | - Ryanne I Jaarsma
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands
| | - Frans H H Jacobs
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Manoj Fonville
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands
| | - Hein Sprong
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands.
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands
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