Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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First experiences with a novel farmer citizen science approach : crowdsourcing participatory variety selection through on-farm triadic comparisons of technologies (tricot)
Etten, Jacob van; Beza, Eskender ; Calderer, Lluís ; Duijvendijk, Kees van; Fadda, Carlo ; Fantahun, Basazen ; Kidane, Yosef Gebrehawaryat ; Gevel, Jeske van de; Gupta, Arnab ; Mengistu, Dejene Kassahun - \ 2019
Experimental Agriculture 55 (2019)S1. - ISSN 0014-4797 - p. 275 - 296.

Rapid climatic and socio-economic changes challenge current agricultural R&D capacity. The necessary quantum leap in knowledge generation should build on the innovation capacity of farmers themselves. A novel citizen science methodology, triadic comparisons of technologies or tricot, was implemented in pilot studies in India, East Africa, and Central America. The methodology involves distributing a pool of agricultural technologies in different combinations of three to individual farmers who observe these technologies under farm conditions and compare their performance. Since the combinations of three technologies overlap, statistical methods can piece together the overall performance ranking of the complete pool of technologies. The tricot approach affords wide scaling, as the distribution of trial packages and instruction sessions is relatively easy to execute, farmers do not need to be organized in collaborative groups, and feedback is easy to collect, even by phone. The tricot approach provides interpretable, meaningful results and was widely accepted by farmers. The methodology underwent improvement in data input formats. A number of methodological issues remain: integrating environmental analysis, capturing gender-specific differences, stimulating farmers' motivation, and supporting implementation with an integrated digital platform. Future studies should apply the tricot approach to a wider range of technologies, quantify its potential contribution to climate adaptation, and embed the approach in appropriate institutions and business models, empowering participants and democratizing science.

Kwantificering nutriëntensituatie van de bodem in het beheergebied van Waterschap Noorderzijlvest
Ros, G.H. ; Kros, Hans ; Vliet, Petra van; Duijvendijk, K. van - \ 2018
Wageningen : Nutriënten Management Instituut NMI B.V. (Rapport / Nutriënten Management Instituut NMI 1708.N.17) - 22
Het waterschap Noorderzijlvest wil een beter inzicht in de ruimtelijke variatie in bodemkwaliteit en (potentiële) bronnen van stikstof- en fosfaatuitspoeling naar het oppervlaktewater. Via dit inzicht is het mogelijk om het belang van de emissies vanuit de bodem te bepalen ten opzichte vanandere bronnen. Dit kan bijdragen om eenonderbouwd handelingsperspectief te bieden aan de agrarische sector om de nutriëntenbelasting van het watersysteem terug te dringen. Gebaseerd op de meest actuele gegevens uit agrarische meetnetten en beschikbare informatie bij kennisinstellingen geeft de voorliggende rapportage ruimtelijk inzicht in : - de hoeveelheid fosfaat (P), stikstof (N) en organische stof in de bodem; - de aanvoer van stikstofen fosfaat via dierlijke mest en kunstmest; - de N-en P-bodemoverschotten(de niet opgenomen nutriënten); - de P-verzadiging van de bodem; en - de verwachte verliesfracties van N en P.
Kwantificering nutriëntensituatie van de bodem in het beheergebied van Wetterskip Fryslân
Ros, G.H. ; Kros, Hans ; Vliet, Petra van; Duijvendijk, K. van - \ 2018
Wageningen : Nutriënten Management Instituut NMI (Rapport / Nutriënten Management Instituut 1708.N.17) - 24
The genetic diversity of Borrelia afzelii is not maintained by the diversity of the rodent hosts
Coipan, Claudia E. ; Duijvendijk, L.A.G. van; Hofmeester, T.R. ; Takumi, Katsuhisa ; Sprong, H. - \ 2018
Borrelia burgdorferi - Ixodes ricinus larvae - rodents - IGS - ospC - dbpA
Background Small mammals are essential in the enzootic cycle of many tick-borne pathogens (TBP). To understand their contribution to the genetic diversity of Borrelia afzelii, the most prevalent TBP in questing Ixodes ricinus, we compared the genetic variants of B. afzelii at three distinct genetic loci. We chose two plasmid loci, dbpA and ospC, and a chromosomal one, IGS. Results While the larvae that fed on shrews (Sorex sp.) tested negative for B. afzelii, those fed on bank voles (Myodes glareolus) and wood mice (Apodemus sylvaticus) showed high infection prevalences of 0.13 and 0.27, respectively. Despite the high genetic diversity within B. afzelii, there was no difference between wood mice and bank voles in the number and types of B. afzelii haplotypes they transmit. Conclusions The genetic diversity in B. afzelii cannot be explained by separate enzootic cycles in wood mice and bank voles.
Kansen voor het sluiten van de mineralenbalansen in Noord-Nederland : effecten op regionale schaal en bedrijfsschaal
Vries, Wim de; Kros, Hans ; Voogd, Jan-Cees ; Duijvendijk, Kees van; Ros, Gerard - \ 2018
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2925) - 71
The genetic diversity of Borrelia afzelii is not maintained by the diversity of the rodent hosts
Coipan, Claudia E. ; Duijvendijk, Gilian L.A. van; Hofmeester, Tim R. ; Takumi, Katsuhisa ; Sprong, Hein - \ 2018
Parasites & Vectors 11 (2018)1. - ISSN 1756-3305
Borrelia burgdorferi (s.l.) - dbpA - IGS - Ixodes ricinus larvae - ospC - Rodents

Background: Small mammals are essential in the enzootic cycle of many tick-borne pathogens (TBP). To understand their contribution to the genetic diversity of Borrelia afzelii, the most prevalent TBP in questing Ixodes ricinus, we compared the genetic variants of B. afzelii at three distinct genetic loci. We chose two plasmid loci, dbpA and ospC, and a chromosomal one, IGS. Results: While the larvae that fed on shrews (Sorex sp.) tested negative for B. afzelii, those fed on bank voles (Myodes glareolus) and wood mice (Apodemus sylvaticus) showed high infection prevalences of 0.13 and 0.27, respectively. Despite the high genetic diversity within B. afzelii, there was no difference between wood mice and bank voles in the number and types of B. afzelii haplotypes they transmit. Conclusions: The genetic diversity in B. afzelii cannot be explained by separate enzootic cycles in wood mice and bank voles.

Oral Nutrition as a Form of Pre-Operative Enhancement in Patients Undergoing Surgery for Colorectal Cancer : A Systematic Review
Bruns, Emma R.J. ; Argillander, Tanja E. ; Heuvel, Baukje Van Den; Buskens, Christianne J. ; Duijvendijk, Peter Van; Winkels, Renate M. ; Kalf, Annette ; Zaag, Edwin S. Van Der; Wassenaar, Eelco B. ; Bemelman, Willem A. ; Munster, Barbara C. Van - \ 2018
Surgical Infections 19 (2018)1. - ISSN 1096-2964 - p. 1 - 10.
colorectal cancer - nutrition - prehabilitation - surgery
Background: Nutritional status has major impacts on the outcome of surgery, in particular in patients with cancer. The aim of this review was to assess the merit of oral pre-operative nutritional support as a part of prehabilitation in patients undergoing surgery for colorectal cancer. Methods: A systematic literature search and meta-analysis was performed according to the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA) recommendations in order to review all trials investigating the effect of oral pre-operative nutritional support in patients undergoing colorectal surgery. The primary outcome was overall complication rate. Secondary outcomes were incision infection rate, anastomotic leakage rate, and length of hospital stay. Results: Five randomized controlled trials and one controlled trial were included. The studies contained a total of 583 patients with an average age of 63 y (range 23-88 y), of whom 87% had colorectal cancer. Malnourishment rates ranged from 8%-68%. All investigators provided an oral protein supplement. Overall patient compliance rates ranged from 72%-100%. There was no significant reduction in the overall complication rate in the interventional groups (odds ratio 0.82; 95% confidence interval 0.52 - 1.25). Conclusion: Current studies are too heterogeneous to conclude that pre-operative oral nutritional support could enhance the condition of patients undergoing colorectal surgery. Patients at risk have a relatively lean body mass deficit (sarcopenia) rather than an absolute malnourished status. Compliance is an important element of prehabilitation. Targeting patients at risk, combining protein supplements with strength training, and defining standardized patient-related outcomes will be essential to obtain satisfactory results.
Global-Detector; GIS- and Knowledge-based tool for a global detection of the potential for production, supply and demand
Hennen, W.H.G.J. ; Daane, P.A.J. ; Duijvendijk, Kees van - \ 2017
In: Proceedings of the 3rd International Conference on Geographical Information Systems Theory, Applications and Management; Porto, Portugal, 27-28 April 2017. - SciTePress - ISBN 9789897582523 - p. 161 - 168.
Wageningen Economic Research has developed Global-Detector, a knowledge-based Geographic Information System that aims to detect the worldwide potential for production, demand and market strategies. At any spot in the world Global-Detector can show the values from a large amount of indicators, such as climate, infrastructure, and land characteristics. A large set of indicators is readily available for use without any GIS-processing, and the model builder together with the expert can instantly start building the knowledge base for the concerning research aim. Knowledge from experts is applied to combine relevant indicators to create new indicators. The concept of Global-Detector and 10 applications developed by this tool are described. As a generic tool with increased flexibility, Global-Detector has many application possibilities in a wide variety of fields.
Estimating costs of nature management in the European Union : Exploration modelling for PBL’s Nature Outlook
Verburg, R.W. ; Hennen, W.H.G.J. ; Puister, L.F. ; Michels, R. ; Duijvendijk, Kees van - \ 2017
Wageningen : Wageningen University & Research, Statutory Research Tasks Unit for Nature & the Environment (WOt-technical report 97) - 109
A cost model was developed for the Nature Outlook of PBL Netherlands Environmental Assessment Agency.This cost model estimates one-off and recurrent costs of natural vegetation based on Corine land cover typesthroughout Europe. Cost estimates were made for the base year 2000 and future scenarios, including aTrend scenario based on current EU policies and normative perspectives, including Strengthening CulturalIdentity (SCI), Allowing Nature to Find its Way (NFW), Going with the Economic Flow (GEF) and Workingwith Nature (WWN). These scenarios all have a time horizon of 2050. To estimate various costs acomprehensive data analysis was carried out and a cost model was developed based on the IKN model forDutch Nature Policy. The model estimates costs of recurrent management in the base year on € 5.6 billionper year in the EU-28. Costs of recurrent management within the Natura 2000 network is estimated on € 3.5billion per year. Recurrent management costs in 2050 in the Trend scenario were estimated on € 5.2 billionper year. One-off costs of land purchase are estimated at € 450 per hectare per year and construction costs€ 1028 per hectare per year. One-off costs of the perspectives are 5.09 (SCI), 6.56 (NFW), 6.20 (GEF) and9.79 billion euro per year (WWN)
A Borrelia afzelii Infection Increases Larval Tick Burden on Myodes glareolus (Rodentia : Cricetidae) and Nymphal Body Weight of Ixodes ricinus (Acari: Ixodidae)
Duijvendijk, Gilian van; Andel, Wouter van; Fonville, Manoj ; Gort, Gerrit ; Hovius, Joppe W. ; Sprong, Hein ; Takken, Willem - \ 2017
Journal of Medical Entomology 54 (2017)2. - ISSN 0022-2585 - p. 422 - 428.
behavior - Borrelia burgdorferi - Ixodes ricinus - manipulation - rodent
Several microorganisms have been shown to manipulate their host or vector to enhance their own transmission. Here we examined whether an infection with Borrelia afzelii affects its transmission between its bank vole (Myodes glareolus, Schreber, 1780) host and tick vector. Captive-bred bank voles were inoculated with B. afzelii or control medium, after which host preference of Ixodes ricinus L. nymphs was determined in a Y-tube olfactometer. Thereafter, infected and uninfected bank voles were placed in a semifield arena containing questing larvae to measure larval tick attachment. Engorged larvae were collected from these bank voles, molted into nymphs, weighed, and analyzed for infection by PCR.Nymphs were attracted to the odors of a bank vole compared to ambient air and preferred the odors of an infected bank vole over that of an uninfected bank vole. In the semifield arena, infected male bank voles had greater larval tick burdens then uninfected males, while similar larval tick burdens were observed on females regardless of infection status. Nymphal ticks that acquired a B. afzelii infection had higher body weight than nymphs that did not acquire an infection regardless of the infection status of the vole. These results show that a B. afzelii infection in bank voles increases larval tick burden and that a B. afzelii infection in larvae increases nymphal body weight. This finding provides novel ecological insights into the enzootic cycle of B. afzelii.
An increase in physical activity after colorectal cancer surgery is associated with improved recovery of physical functioning : A prospective cohort study
Zutphen, Moniek van; Winkels, Renate M. ; Duijnhoven, Fränzel J.B. van; Harten-Gerritsen, Suzanne A. van; Gils-Kok, Dieuwertje van; Duijvendijk, Peter van; Halteren, Henk K. van; Hansson, Bibi M.E. ; Kruyt, Flip M. ; Spillenaar Bilgen, Ernst J. ; Wilt, Johannes H.W. de; Dronkers, Jaap J. ; Kampman, Ellen - \ 2017
BMC Cancer 17 (2017)1. - ISSN 1471-2407
Colorectal cancer - Colorectal surgery - Epidemiology - Physical activity - Recovery of function - Rehabilitation
Background: The influence of physical activity on patient-reported recovery of physical functioning after colorectal cancer (CRC) surgery is unknown. Therefore, we studied recovery of physical functioning after hospital discharge by (a) a relative increase in physical activity level and (b) absolute activity levels before and after surgery. Methods: We included 327 incident CRC patients (stages I-III) from a prospective observational study. Patients completed questionnaires that assessed physical functioning and moderate-to-vigorous physical activity shortly after diagnosis and 6 months later. Cox regression models were used to calculate prevalence ratios (PRs) of no recovery of physical functioning. All PRs were adjusted for age, sex, physical functioning before surgery, stage of disease, ostomy and body mass index. Results: At 6 months post-diagnosis 54% of CRC patients had not recovered to pre-operative physical functioning. Patients who increased their activity by at least 60 min/week were 43% more likely to recover physical function (adjusted PR 0.57 95%CI 0.39-0.82), compared with those with stable activity levels. Higher post-surgery levels of physical activity were also positively associated with recovery (P for trend = 0.01). In contrast, activity level before surgery was not associated with recovery (P for trend = 0.24). Conclusions: At 6 month post-diagnosis, about half of CRC patients had not recovered to preoperative functioning. An increase in moderate-to-vigorous physical activity after CRC surgery was associated with enhanced recovery of physical functioning. This benefit was seen regardless of physical activity level before surgery. These associations provide evidence to further explore connections between physical activity and recovery from CRC surgery after discharge from the hospital.
Veilig stijgen en landen op Schiphol : actualisatie vergoedingsregeling graanteelt om ganzen te weren
Rijk, Piet ; Jager, Jakob ; Duijvendijk, Kees van - \ 2017
Wageningen : Wageningen Economic Research (Wageningen Economic Research rapport 2017-006) - ISBN 9789463430883 - 49
In het Convenant reduceren risico vogelaanvaringen Schiphol 2016-2018 van maart 2016 is door een groot aantal partijen afspraken gemaakt om het aantal vogelaanvaringen met vliegtuigen rond Schiphol te verminderen. Het convenant is getekend door de Vereniging van Nederlandse Verkeersvliegers (VNV), Schiphol, Vereniging Natuurmonumenten, Staatsbosbeheer, Landschap Noord-Holland, Land- en Tuinbouworganisatie (LTO) Nederland, B&W Gemeente Haarlemmermeer, Gedeputeerde Staten van Noord-Holland, Zuid-Holland en Utrecht, en de Nederlandse Staat (vertegenwoordigd door de staatssecretaris van Infrastructuur en Milieu). In het convenant staan een aantal voornemens en maatregelen. Eén van de maatregelen is het zo veel mogelijk beperken van het foerageren van ganzen en andere vogels in de zomerperiode in de buurt van start- en landingsbanen. Het versneld onderwerken van graanresten kan hieraan een bijdrage leveren. Ganzen en andere vogels komen in de zomer na de graanoogst graankorrels zoeken en opeten. De afgelopen jaren is er een (vrijwillige) vergoedingsregeling geweest; hierbij zijn voor ruim 2.000 ha contracten afgesloten. De contracten lopen tot en met 2017. Voor de jaren na 2018 hebben de convenantpartijen gevraagd om opnieuw te kijken naar de opbouw van de verschillende posten voor het voorstel voor de basisvergoeding. Het ministerie van Infrastructuur en Milieu (I&M), afdeling Luchtvaartveiligheid, heeft deze adviesaanvraag bij het Wageningen Economic Research (voorheen LEI Wageningen UR) ingediend. Ook is gevraagd naar de ontwikkeling van het areaal granen in de afgelopen jaren in het gebied in vergelijking met het hele land en de ons omringende landen.
Behavioural responses of Ixodes ricinus nymphs to carbon dioxide and rodent odour
Duijvendijk, G. van; Gort, G. ; Sprong, H. ; Takken, W. - \ 2017
Medical and Veterinary Entomology 31 (2017)2. - ISSN 0269-283X - p. 220 - 223.
CO - Ectoparasites - Host - Odour - Olfaction - Questing - Tick
Many haematophagous ectoparasites use carbon dioxide (CO2) and host odour to detect and locate their hosts. The tick Ixodes ricinus (Linnaeus) (Ixodida: Ixodidae) walks only small distances and quests in vegetation until it encounters a host. The differential effects of CO2 and host odour on the host-finding behaviour of I. ricinus have, however, never been clarified and hence represent the subject of this study. The effects of CO2 and odour from bank voles on the activation and attraction of I. ricinus nymphs were analysed in a Y-tube olfactometer. Carbon dioxide evoked a response in the absence and presence of host odour, but did not attract nymphs. Host odour, however, did not evoke a response but did attract nymphs in the absence and presence of CO2. The current results show that CO2 is an activator, but not an attractant, and that host odour is an attractant, but not an activator, of I. ricinus nymphs, and provide ecological insights into the host-finding behaviour of I. ricinus.
IKN status A+ : Tussenrapportage WOT-04-011-036.72
Verburg, R.W. ; Duijvendijk, Kees van; Puister-Jansen, L.F. ; Michels, R. - \ 2016
Wageningen : WOT Natuur en Milieu (WOt-interne notitie 164) - 98 p.
NVK Modellering : Tussenrapportage WOT-04-011-034
Verburg, R.W. ; Hennen, W.H.G.J. ; Puister-Jansen, L.F. ; Michels, R. ; Duijvendijk, Kees van - \ 2016
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-interne notitie 145) - 115 p.
The ecology of Lyme borreliosis risk : interactions between lxodes ricinus, rodents and Borrelia burgdorferi sensu lato
Duijvendijk, Gilian van - \ 2016
Wageningen University. Promotor(en): Willem Takken, co-promotor(en): H. Sprong. - Wageningen : Wageningen University - ISBN 9789462579408 - 186
rodents - ixodes ricinus - disease vectors - tickborne diseases - borrelia burgdorferi - borrelia miyamotoi - hosts - ecological risk assessment - risk analysis - knaagdieren - ixodes ricinus - vectoren, ziekten - ziekten overgebracht door teken - borrelia burgdorferi - borrelia miyamotoi - gastheren (dieren, mensen, planten) - ecologische risicoschatting - risicoanalyse

The sheep tick (Ixodes ricinus) is widespread throughout Europe and can transmit Borrelia burgdorferi sensu lato (s.l.), which can cause Lyme borreliosis and B. miyamotoi, the agent of Borrelia miyamotoi disease in humans. Borrelia afzelii is the most common genospecies of Borrelia burgdorferi s.l. in western Europe and it circulates between I. ricinus and rodents. The density of infected nymphs determines disease risk and is affected by complex multi-trophic interactions between factors that are not well understood. The aim of this thesis was, therefore, to gain insight into the multi-trophic interactions that affect the density of B. afzelii-infected and B. miyamotoi-infected I. ricinus nymphs.

Interactions between I. ricinus, rodents (wood mice and bank voles) and B. afzelii were reviewed to elucidate knowledge gaps concerning these interactions. The effect of rodent density on the density of infected nymphs and the factors that affect the contribution of a rodent to the density of infected nymphs were investigated in field experiments. The effects of a B. afzelii infection on larval tick burden of bank voles and nymphal body weight were investigated in the laboratory. The effects of CO2 and host odour on the host-seeking behaviour of I. ricinus were investigated in a Y-tube olfactometer. Finally, the ability of field-collected I. ricinus larvae to transmit B. afzelii and B. miyamotoi was analysed.

The review showed that rodent density, rodent infection rate, and larval tick burden are the major factors affecting the density of B. afzelii-infected nymphs one year later. The field experiments showed that rodent density can positively affect the density of B. burgdorferi s.l.- infected nymphs one year later. However, the effect of rodent density was small when the density of infected nymphs was limited by the density of questing larvae in the previous year. Rodent density had, however, no effect on the density of B. miyamotoi-infected nymphs. The field studies also showed that tick burdens are 2.4 times higher on wood mice than on bank voles and that body weight of emerged nymphs was 36% higher for ticks that fed on wood mice compared to ticks that fed on bank voles. Bank voles infected with B. afzelii acquired a larger larval tick burden, resulting in a 27% increase in nymphal infection prevalence. Furthermore, infected nymphs had a 10% greater the body weight. Ixodes ricinus nymphs are activated by but not attracted to CO2, whereas they are attracted to and not activated by host odour. Ixodes ricinus larvae transmitted both B. afzelii and B. miyamotoi to rodents and it was calculated that rodents have a chance of about 25-75% of acquiring B. afzelii from larvae relative to the chance of acquiring B. afzelii from nymphs. The main conclusions of this thesis are discussed and suggestions are made for future research.

Larvae of Ixodes ricinus transmit Borrelia afzelii and B. miyamotoi to vertebrate hosts
Duijvendijk, Gilian van; Coipan, Claudia ; Wagemakers, Alex ; Fonville, Manoj ; Ersöz, Jasmin ; Oei, Anneke ; Földvári, Gábor ; Hovius, Joppe ; Takken, Willem ; Sprong, Hein - \ 2016
Parasites & Vectors 9 (2016). - ISSN 1756-3305
Borrelia burgdorferi - Borrelia miyamotoi - Infection - Ixodes ricinus - Larva - Rodent - Tick - Transmission - Vector - 016-3918

Background: Lyme borreliosis is the most common tick-borne human disease and is caused by Borrelia burgdorferi sensu lato (s.l.). Borrelia miyamotoi, a relapsing fever spirochaete, is transmitted transovarially, whereas this has not been shown for B. burgdorferi (s.l). Therefore, B. burgdorferi (s.l) is considered to cycle from nymphs to larvae through vertebrates. Larvae of Ixodes ricinus are occasionally B. burgdorferi (s.l) infected, but their vector competence has never been studied. Methods: We challenged 20 laboratory mice with field-collected larvae of I. ricinus. A subset of these larvae was analysed for infections with B. burgdorferi (s.l) and B. miyamotoi. After three to four challenges, mice were sacrificed and skin and spleen samples were analysed for infection by PCR and culture. Results: Field-collected larvae were naturally infected with B. burgdorferi (s.l) (0.62 %) and B. miyamotoi (2.0 %). Two mice acquired a B. afzelii infection and four mice acquired a B. miyamotoi infection during the larval challenges. Conclusion: We showed that larvae of I. ricinus transmit B. afzelii and B. miyamotoi to rodents and calculated that rodents have a considerable chance of acquiring infections from larvae compared to nymphs. As a result, B. afzelii can cycle between larvae through rodents. Our findings further imply that larval bites on humans, which easily go unnoticed, can cause Lyme borreliosis and Borrelia miyamotoi disease.

Multi-trophic interactions driving the transmission cycle of Borrelia afzelii between Ixodes ricinus and rodents : A review
Duijvendijk, Gilian Van; Sprong, Hein ; Takken, Willem - \ 2015
Parasites & Vectors 8 (2015)1. - ISSN 1756-3305
Apodemus - Borrelia burgdorferi - Ecology - Ixodes ricinus - Lifecycle - Myodes - Pathogen transmission - Trophic interactions

The tick Ixodes ricinus is the main vector of the spirochaete Borrelia burgdorferi sensu lato, the causal agent of Lyme borreliosis, in the western Palearctic. Rodents are the reservoir host of B. afzelii, which can be transmitted to I. ricinus larvae during a blood meal. The infected engorged larvae moult into infected nymphs, which can transmit the spirochaetes to rodents and humans. Interestingly, even though only about 1 % of the larvae develop into a borreliae-infected nymph, the enzootic borreliae lifecycle can persist. The development from larva to infected nymph is a key aspect in this lifecycle, influencing the density of infected nymphs and thereby Lyme borreliosis risk. The density of infected nymphs varies temporally and geographically and is influenced by multi-trophic (tick-host-borreliae) interactions. For example, blood feeding success of ticks and spirochaete transmission success differ between rodent species and host-finding success appears to be affected by a B. afzelii infection in both the rodent and the tick. In this paper, we review the major interactions between I. ricinus, rodents and B. afzelii that influence this development, with the aim to elucidate the critical factors that determine the epidemiological risk of Lyme borreliosis. The effects of the tick, rodent and B. afzelii on larval host finding, larval blood feeding, spirochaete transmission from rodent to larva and development from larva to nymph are discussed. Nymphal host finding, nymphal blood feeding and spirochaete transmission from nymph to rodent are the final steps to complete the enzootic B. afzelii lifecycle and are included in the review. It is concluded that rodent density, rodent infection prevalence, and tick burden are the major factors affecting the development from larva to infected nymph and that these interact with each other. We suggest that the B. afzelii lifecycle is dependent on the aggregation of ticks among rodents, which is manipulated by the pathogen itself. Better understanding of the processes involved in the development and aggregation of ticks results in more precise estimates of the density of infected nymphs, and hence predictions of Lyme borreliosis risk.

Circulation of four Anaplasma phagocytophilum ecotypes in Europe
Jahfari, S. ; Coipan, E.C. ; Fonville, M. ; Leeuwen, A.D. van; Hengeveld, P. ; Heylen, D. ; Heyman, P. ; Maanen, C. van; Butler, C.M. ; Foldvari, G. ; Szekeres, S. ; Duijvendijk, L.A.G. van; Tack, W. ; Rijks, J.M. ; Giessen, J. van der; Takken, W. ; Wieren, S.E. van; Takumi, K. ; Sprong, H. - \ 2014
Parasites & Vectors 7 (2014)1. - ISSN 1756-3305
candidatus neoehrlichia mikurensis - human granulocytic anaplasmosis - ixodes-ricinus ticks - borrelia-burgdorferi - borne diseases - phylogenetic analyses - sequence-analysis - ehrlichiosis - strains - gene
Background: Anaplasma phagocytophilum is the etiological agent of granulocytic anaplasmosis in humans and animals. Wild animals and ticks play key roles in the enzootic cycles of the pathogen. Potential ecotypes of A. phagocytophilum have been characterized genetically, but their host range, zoonotic potential and transmission dynamics has only incompletely been resolved. Methods. The presence of A. phagocytophilum DNA was determined in more than 6000 ixodid ticks collected from the vegetation and wildlife, in 289 tissue samples from wild and domestic animals, and 69 keds collected from deer, originating from various geographic locations in The Netherlands and Belgium. From the qPCR-positive lysates, a fragment of the groEL-gene was amplified and sequenced. Additional groEL sequences from ticks and animals from Europe were obtained from GenBank, and sequences from human cases were obtained through literature searches. Statistical analyses were performed to identify A. phagocytophilum ecotypes, to assess their host range and their zoonotic potential. The population dynamics of A. phagocytophilum ecotypes was investigated using population genetic analyses. Results: DNA of A. phagocytophilum was present in all stages of questing and feeding Ixodes ricinus, feeding I. hexagonus, I. frontalis, I. trianguliceps, and deer keds, but was absent in questing I. arboricola and Dermacentor reticulatus. DNA of A. phagocytophilum was present in feeding ticks and tissues from many vertebrates, including roe deer, mouflon, red foxes, wild boar, sheep and hedgehogs but was rarely found in rodents and birds and was absent in badgers and lizards. Four geographically dispersed A. phagocytophilum ecotypes were identified, that had significantly different host ranges. All sequences from human cases belonged to only one of these ecotypes. Based on population genetic parameters, the potentially zoonotic ecotype showed significant expansion. Conclusion: Four ecotypes of A. phagocytophilum with differential enzootic cycles were identified. So far, all human cases clustered in only one of these ecotypes. The zoonotic ecotype has the broadest range of wildlife hosts. The expansion of the zoonotic A. phagocytophilum ecotype indicates a recent increase of the acarological risk of exposure of humans and animals.
Influence of air composition during egg storage on egg characteristics, embryonic development, hatchability, and chick quality
Reijrink, I.A.M. ; Duijvendijk, L.A.G. van; Meijerhof, R. ; Kemp, B. ; Brand, H. van den - \ 2010
Poultry Science 89 (2010)9. - ISSN 0032-5791 - p. 1992 - 2000.
stored hatching eggs - plastic bags - carbon-dioxide - albumin characteristics - prestorage incubation - broiler breeders - weight-loss - age - temperature - growth
Egg storage beyond 7 d is associated with an increase in incubation duration and a decrease in hatchability and chick quality. Negative effects of prolonged egg storage may be caused by changes in the embryo, by changes in egg characteristics, or by both. An adjustment in storage air composition may reduce negative effects of prolonged egg storage because it may prevent changes in the embryo and in egg characteristics. An experiment was conducted to investigate the effects of high CO(2) concentrations or a low O(2) concentration in the storage air on egg characteristics, embryonic development, hatchability, and chick quality. Eggs were stored for 14 d in 4 different storage air compositions: normal air (control; 20.9% O(2), 0.05% CO(2), 78.1% N(2)), 0.74% CO(2) treatment (20.8% O(2), 0.74% CO(2), 77.5% N(2)), 1.5% CO(2) treatment (20.6% O(2), 1.5% CO(2), 77.0% N(2))(,) or 3.0% O(2) treatment (3.0% O(2), 0.04% CO(2), 96.0% N(2)). The storage temperature was 16 degrees C and the RH was 75%. Results showed that the change in albumen pH and albumen height between oviposition and the end of storage was less in the 0.74 and 1.5% CO(2) treatments than in the control and 3.0% O(2) treatments (P <0.001 and P <0.001, respectively). None of the treatments affected the stage of embryonic development on d 4 of incubation, hatchability, or chick quality on the day of hatch in terms of BW, chick length, and yolk-free body mass. Although high CO(2) concentrations in the storage air had a positive effect on albumen height and albumen pH, it is concluded that the storage air compositions, studied in the current study, do not affect embryonic development, hatchability, or chick quality when eggs are stored for 14 d at a storage temperature of 16 degrees C
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