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.

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    Efficacy of management and monitoring methods to prevent post‐harvest losses caused by rodents
    Krijger, Inge M. ; Gort, Gerrit ; Belmain, Steven R. ; Groot Koerkamp, Peter ; Shafali, Rokeya B. ; Meerburg, Bastiaan G. - \ 2020
    Animals 10 (2020)9. - ISSN 2076-2615 - p. 1 - 19.
    Bandicota bengalensis - Grain store - Post‐harvest losses - Rattus rattus - Rice - Rodent management

    The presence of pest rodents around food production and storage sites is one of many underlying problems contributing to food contamination and loss, particularly influencing food and nutrition security in low‐income countries. By reducing both pre‐ and post‐harvest losses by rodents, millions of food‐insecure people would benefit. As there are limited quantitative data on post‐harvest rice losses due to rodents, our objectives were to assess stored rice losses in local households from eight rural communities and two rice milling factories in Bangladesh and to monitor the effect of different rodent control strategies to limit potential losses. Four treatments were applied in 2016 and 2017, (i) untreated control, (ii) use of domestic cats, (iii) use of rodenticides, (iv) use of snap‐traps. In total, over a two‐year period, 210 rodents were captured from inside people’s homes, with Rattus rattus trapped most often (n = 91), followed by Mus musculus (n = 75) and Bandicota bengalensis (n = 26). In the milling stations, 68 rodents were trapped, of which 21 were M. musculus, 19 R. rattus, 17 B. bengalensis, 8 Rattus exulans, and 3 Mus terricolor. In 2016, losses from standardised baskets of rice within households were between 13.6% and 16.7%. In 2017, the losses were lower, ranging from 0.6% to 2.2%. Daily rodent removal by trapping proved to be most effective to diminish stored produce loss. The effectiveness of domestic cats was limited.

    Wild rodents and insectivores as carriers of pathogenic Leptospira and Toxoplasma gondii in The Netherlands
    Krijger, Inge M. ; Ahmed, Ahmed A.A. ; Goris, Maria G.A. ; Cornelissen, Jan B.W.J. ; Groot Koerkamp, Peter W.G. ; Meerburg, Bastiaan G. - \ 2020
    Veterinary Medicine and Science 6 (2020)3. - ISSN 2053-1095 - p. 623 - 630.
    leptospirosis - mice - pathogen–host relationship - rats - reservoir - zoonoses

    Small mammals such as rodents can to carry zoonotic pathogens. Currently, there is impaired knowledge on zoonotic pathogens in rodents and insectivores in the Netherlands. This limits opportunities for preventive measures and complicates risk-assessments for zoonotic transmission to humans. Leptospira spp. and Toxoplasma gondii are present on a list of prioritized emerging pathogens in the Netherlands and were therefore the focus of this study. Both pathogens have the ability to survive under moist environmental conditions. In total, a group of 379 small mammals (rodents & insectivores) were tested on pathogenic Leptospira spp., and 312 on T. gondii. Rodents and insectivores were trapped at various sites, but mostly on pig and dairy farms throughout the country. Over five percent of the animals (5.3%, n = 379) tested positive for Leptospira DNA, and five of the animals (1.6%, n = 312) tested were positive for T. gondii DNA. The animals positive for T.gondii were all brown rats and the ones for Leptospira spp. were various species. Our results show that insectivores and rodents might be used as an indicator for the environmental contamination and/or the contamination in wildlife for Leptospira spp.

    Farm rodents source of diseases
    Krijger, Inge - \ 2020
    Rodent-borne health risks in farming systems
    Krijger, Inge Milou - \ 2020
    Wageningen University. Promotor(en): P.W.G. Groot Koerkamp, co-promotor(en): B.G. Meerburg; S.R. Belmain. - Wageningen : Wageningen University - ISBN 9789463951890 - 197

    Rodents represent the largest order of mammals (>40%) and consist of over 2000 species. However, only a small portion (<10%) of all rodent species can be referred to as pest species. There is a knowledge gap on the biology and habitat specialisations and distribution of many rodent species in Asia and in Europe, which is essential for the species-specific management of pest rodents. The main aim of this thesis was to obtain more knowledge about rodent-borne health risks in farming systems in both Europe and Asia. The chapters of this thesis describe several studies into rodents from the Netherlands and Bangladesh in order to find an answer to the main research question of this thesis.

    In this thesis, for both countries rodent presence is demonstrated, as well of the presence of zoonotic pathogens in these animals. It can be concluded that there are serious rodent-borne health risks in farming systems in both in the Netherlands and in Bangladesh. The results of this thesis may help to improve the preparedness for potential disease outbreaks. It is essential to gain a more thorough understanding of the ecology of rodent-borne pathogens in rodents and humans in order to determine the public health risks associated with commensal rodents.

    A risk based surveillance programme for Toxoplasma gondii in pigs using a combination of farm auditing and serological screening
    Wisselink, H.J. ; Swanenburg, M. ; Gonzales Rojas, Jose ; Asseldonk, M.A.P.M. van; Wagenberg, Coen van; Giessen, J. van der; Meerburg, B.G. ; Krijger, Inge ; Eppink, D.M. ; Bouwknegt, M. ; Oorburg, D. - \ 2019
    Toxoplasma gondii is recognized as one of the major foodborne pathogens with a high human disease burden. In the Netherlands, pork contributes to about 11 % of the meatborne T. gondii infections. To control T. gondii infections in pigs, EFSA has advised to perform serological testing of pigs and audits of pig farms on risk factors for T. gondii infection. In the Netherlands, a program was started to translate the EFSA advice into a practical risk based surveillance system. In first instance, a large scale serological monitoring of fattening pigs was started and seroprevalence over time was determined. Next, the association between within-herd seroprevalence and risk factors for T. gondii on fattening pig farms in the Netherlands was determined. For this, a questionnaire for auditing farms for the presence of risk factors of T. gondii was developed and used on 25 case and 50 control farms. Results show that there is a significant association between seroprevalence and risk factors as cats present on farms, use of unheated feed products and feeding wet feed. Moreover, on-farm presence of rats and mice also increases Toxoplasma transmission risks. Subsequently, a study was started on farms to quantify the effectiveness of interventions on farms. A cross-over clinical trial was set up in which case farms were their own control and the cross-over moment is the implementation of interventions on risk factors to change farm management. Farms with a high within-herd seroprevalence were followed for at least during a year and monitored periodically for seroprevalence and implementation of interventions to eventually reduce the disease burden. The break-even point was calculated for which the intervention cost at fattening pig farms equal averted human disease burden and averted cost-of-illness minus cost of the surveillance program. The results shows favourable economic perspectives for interventions to control pig meat-born transmission of T. gondii.
    Evidence of Toxoplasma gondii in rodents from Bangladesh
    Krijger, I.M. ; Cornelissen, J.B.W.J. ; Belmain, Steven R. ; Begum Shafali, R. ; Meerburg, B.G. - \ 2019
    Vector-Borne and Zoonotic Diseases 19 (2019)12. - ISSN 1530-3667
    Rodents contribute to the life cycle of the protozoan parasite Toxoplasma gondii as an intermediate host and key prey animal of cats, the definitive host. As there is limited scientific knowledge available about the incidence and prevalence of T. gondii in commensal rodents in many Asian countries, we tested rodents from a commercial rice mill and eight local villages in Bangladesh for the presence of T. gondii DNA using rodent brain material preserved in ethanol. Overall, 10 of 296 (3.4%) rodent samples tested positive for Toxoplasma DNA. Our results indicate that rodents present in food production and food storage facilities may carry T. gondii.
    Identification of potential risk factors for Toxoplasma gondii in fattening pigs in the Netherlands using a Bayesian approach
    Eppink, D.M. ; Bouwknegt, M. ; Oorburg, D. ; Urlings, H.A.P. ; Asseldonk, Marcel van; Wagenberg, Coen van; Krijger, Inge ; Giessen, J.W.P. van der; Swanenburg, M. ; Wisselink, H.J. - \ 2019
    Introduction
    Toxoplasma gondii is a relevant foodborne pathogen,it is estimated that up to one third of the worldpopulation has been exposed to the parasite (Tenteret al. 2000). In the Netherlands toxoplasmosis rankssecond on a list of prioritized emerging zoonosis(Havelaar et al. 2010) and also second in disease burden among 14 foodborne diseases (Mangen et al.2017). Data suggest that ingesting improperly cooked meat containing T. gondii is one of the major sources of infection in Europe and North America (Crotta et al. 2017; Guo et al. 2015). The contribution of pork to meatborne T. gondii infections is estimated to be11 % in the Netherlands (Opsteegh 2011) and is seen as an important possible source of human T. gondii infections (Foroutan et al. 2019). The European Food Safety Authority (EFSA) advised to perform serological testing of pigs and on farm audits on risk factors (EFSA 2011). To that end, a serological monitoring program was developed in a slaughterhouse in the Netherlands. In this study, the objective is to determine the association between within herd seroprevalence, corrected for misclassification of samples through Bayesian analyses, and risk factors for T. gondii on fattening pig farms in TheNetherlands.
    Materials and MethodsFrom 2015 to 2018, HACCP based audits were performedon 75 fattening pig farms in The Netherlands to identify the presence of potential T. gondii risk factors. All farms were conventional pig farms, with 15 farms being farrow to finish. As overall seroprevalence of T. gondii in pigs in the Netherlands is low, estimated at 5 % (1-12 % 95 % CI) by Foroutanet al. 2019, approached farms were chosen with the knowledge of previous serology data. In this way there would be farms with positive serum samples and farms without them included in the study. The audits were based on an updated version of the questionnaire from Mul et al. (2015) and covered the following topics: outdoor access, farm biosecurity, rodent control, presence of cats, feed and watersupply. In addition, serum samples (n=6272) from fattening pigs were obtained at slaughter throughout the year before the audit on the farm was performed. These samples were used for antibody testing bya PrioCHECK™ Toxoplasma Antibody ELISA. Data were analysed using Bayesian statistics, with the within farm T. gondii prevalence as dependent variable and potential risk factors as independent variables. As always with serology, misclassification due to false-positive or false-negative results can occur. Statistical methods have been developed to account for such misclassification, based on frequentistic as well as Bayesian approaches (Hui & Walter 1980; Josephet al. 1995). First, all independent variables wereanalysed in a univariate logistic model, and variables with a probability ≤0.25 that zero is included in the 95 % interval were analysed in a multivariable model. The multivariate logistic model was fitted using backward elimination until all remaining variables showed a probability ≤0.05 that zero is included in the 95 % interval. Two-way interaction terms were evaluated similarly to the main variables regarding statistical significance.
    ResultsDescriptive results showed that 50 out of the 75 farms had 1 or more positive serum samplein the year before the audit was performed. In total 438 samples were positive out of the 6272 samples. Final Bayesian analyses are currently being conducted. However, preliminary results from data analysis using frequentistic logistic multivariate regression identified two significant risk factors: the accessibility of pig feed for cats and theprovision of well water as drinking water for the pigs (Table 1).
    Discussion and ConclusionsThe use of serological testing seems to be a valuable guide and monitoring tool for the control of T.gondii in pork production. In a preliminary analysis, a higher within-herd T. gondii seroprevalence on fattening pig farms in the Netherlands was associated with the accessibility of pig feed for cats and the provision of well water as drinking water for the pigs. Improvements in farm management on fattening pig farms will likely contribute to reduction of the human disease burden and is presently studied.
    Prevalence of leptospira infection in rodents from Bangladesh
    Krijger, Inge M. ; Ahmed, Ahmed A.A. ; Goris, Marga G.A. ; Groot Koerkamp, Peter W.G. ; Meerburg, Bastiaan G. - \ 2019
    International Journal of Environmental Research and Public Health 16 (2019)12. - ISSN 1661-7827
    Food safety - Leptospirosis - Reservoir - Rodents - Zoonosis

    Worldwide, Leptospira infection poses an increasing public health problem. In 2008, leptospirosis was recognised as a re-emerging zoonosis of global importance with South-East Asia being one of the most significant centres of the disease. Rodents are thought to be the most important host for a variety of Leptospira serovars. Because Bangladesh offers a suitable humid climate for the survival of these pathogenic bacteria, the presence of rodents could be a serious risk for human infection, especially in peri-urban areas or locations where food is stored. In order to gain more understanding of the multi-host epidemiology, a prevalence study was conducted in Comilla, Bangladesh to determine the presence of pathogenic Leptospira species in rodents. Real-time Polymerase Chain Reaction (qPCR) and sequencing showed that 13.1% (61/465) of the trapped rodents were infected with pathogenic Leptospira. Sequencing of the qPCR products identified the presence of three species: Leptospira interrogans, Leptospira borgpetersenii, and Leptospira kirschneri. Rodents of the genus, Bandicota, were significantly more likely to be positive than those of the genus, Rattus and Mus. Our results confirm the importance of rodents as hosts of pathogenic Leptospira and indicate that human exposure to pathogenic Leptospira may be considerable, also in places where food (rice) is stored for longer times. This study emphasizes the need to improve rodent management at such locations and to further quantify the public health impacts of this neglected emerging zoonosis in Bangladesh.

    Clostridium difficile in wild rodents and insectivores in the Netherlands
    Krijger, I.M. ; Meerburg, B.G. ; Harmanus, C. ; Burt, S.A. - \ 2019
    Letters in Applied Microbiology (2019). - ISSN 0266-8254
    animal to human - Clostridioides difficile - farms - house mouse - Mus musculus - Rattus rattus - transmission - zoonotic pathogen

    With wild rodents and insectivores being present around humans and their living, working and food production environments, it is important to gain knowledge of the zoonotic pathogens present in these animals. The enteropathogen Clostridium difficile, an opportunistic anaerobic bacteria, can be carried by both animals and humans, and is distributed globally. It is known that there is genetic overlap between human and animal sources of C. difficile. In this study, the aim was to assess the presence of C. difficile in rodents and insectivores trapped on and around pig and cattle farms in the Netherlands. In total 347 rodents and insectivores (10 different species) were trapped and 39·2% tested positive for presence of C. difficile. For all positive samples the ribotype (RT) was determined, and in total there were 13 different RTs found (in descending order of frequency: 057, 010, 029, 005, 073, 078, 015, 035, 454, 014, 058, 062, 087). Six of the RTs isolated from rodents and insectivores are known to be associated with human C. difficile infection; RT005, RT010, RT014, RT015, RT078 and RT087. The presence of rodents and insectivores in and around food production buildings (e.g. farms) could contribute to the spread of C. difficile in the human environment. In order to enable on-farm management for pathogen control, it is essential to comprehend the role of wild rodents and insectivores that could potentially affect the ecology of disease agents on farms. Significance and Impact of the Study: This study shows that rodents and insectivores in and around food production buildings (e.g. farms) can carry Clostridium difficile ribotypes associated with human C. difficile infection (CDI). C. difficile spores in rodent and insectivore droppings are able to survive in the environment for prolonged periods, leading to host-to-host exposure and transmission. Therefore we can state that rodent and insectivore presence on farms is a risk for zoonotic pathogen transmission of C. difficile.

    Association between within-herd seroprevalence and risk factors for Toxoplasma gondii in fattening pigs in the Netherlands
    Eppink, D.M. ; Bouwknegt, M. ; Oorburg, D. ; Urlings, H.A.P. ; Asseldonk, Marcel van; Wagenberg, Coen van; Krijger, I.M. ; Giessen, J.W.P. Van der; Swanenburg, M. ; Wisselink, H.J. - \ 2018
    In: Annual General Meeting of the European College of Veterinary Public Health, "Fading of the HACCP after four decades: new trends in VPH for food safety ", Perugia, 17th-19th October 2018. - European College of Veterinary Public Health (ECVPH) - p. 40 - 40.
    Rodents from a rice milling station in Bangladesh infected with Toxoplasma gondii
    Krijger, I.M. ; Cornelissen, J.B.W.J. ; Belmain, Steven R. ; Groot Koerkamp, P.W.G. ; Meerburg, B.G. - \ 2018
    - 1 p.
    Using serological monitoring, internet-based feedback and on-farm auditing to improve Toxoplasma gondii control at Dutch pig farms
    Oorburg, D. ; Eppink, Dorien ; Heijltjes, Janneke ; Bouwknegt, Martijn ; Urlings, Bert ; Giessen, Joke van der; Krijger, Inge ; Mul, Monique ; Swanenburg, M. ; Wisselink, H.J. - \ 2017
    In: 12th International Symposium on the Epidemiology and Control of Biological,Chemical and Physical Hazards in Pigs and Pork - Proceedings Book, Foz doIguaçu, august 21-24, 2017. - Embrapa - p. 201 - 201.
    Toxoplasma gondii is a relevant foodborne pathogen due to its human disease burden. In the Netherlands, pork is estimated to contribute to 11% of the meatborne T. gondii infections. The European Food Safety Authority advised to perform serological testing of pigs and on farm audits on risk factors for T. gondii infection.
    The need to implement the landscape of fear within rodent pest management strategies
    Krijger, Inge M. ; Belmain, Steven R. ; Singleton, Grant R. ; Groot Koerkamp, Peter W.G. ; Meerburg, Bastiaan G. - \ 2017
    Pest Management Science 73 (2017)12. - ISSN 1526-498X - p. 2397 - 2402.
    ecologically based rodent management - GUD - IPM - landscape of fear - predation risk - rodent control - rodent ecology
    Current reactive pest management methods have serious drawbacks such as the heavy reliance on chemicals, emerging genetic rodenticide resistance and high secondary exposure risks. Rodent control needs to be based on pest species ecology and ethology to facilitate the development of ecologically based rodent management (EBRM). An important aspect of EBRM is a strong understanding of rodent pest species ecology, behaviour and spatiotemporal factors. Gaining insight into the behaviour of pest species is a key aspect of EBRM. The landscape of fear (LOF) is a mapping of the spatial variation in the foraging cost arising from the risk of predation, and reflects the levels of fear a prey species perceives at different locations within its home range. In practice, the LOF maps habitat use as a result of perceived fear, which shows where bait or traps are most likely to be encountered and used by rodents. Several studies have linked perceived predation risk of foraging animals with quitting-harvest rates or giving-up densities (GUDs). GUDs have been used to reflect foraging behaviour strategies of predator avoidance, but to our knowledge very few papers have directly used GUDs in relation to pest management strategies. An opportunity for rodent control strategies lies in the integration of the LOF of rodents in EBRM methodologies. Rodent management could be more efficient and effective by concentrating on those areas where rodents perceive the least levels of predation risk.
    Prevalence of Toxoplasma gondii in common moles (Talpa europaea)
    Krijger, I.M. ; Cornelissen, J.B.W.J. ; Wisselink, H.J. ; Meerburg, B.G. - \ 2014
    Acta Veterinaria Scandinavica 56 (2014). - ISSN 0044-605X
    brain-tissue - costa-rica - oocysts - cysts - farms - hosts - pcr
    Background: The prevalence of Toxoplasma gondii in common moles, Talpa europaea, was investigated in order to determine whether moles can serve as an indicator species for T. gondii infections in livestock. Findings: In total, 86 moles were caught from 25 different sites in the Netherlands. Five different trapping habitats were distinguished: pasture, garden, forest, roadside, and recreation area. No positive samples (brain cysts) were found during microscopic detection (n¿=¿70). Using the Latex Agglutination Test (LAT), sera of 70 moles were examined, whereby no sample reacted with T. gondii antigen. Real Time-PCR tests on brain tissue showed 2 positive samples (2.3%). Conclusions: Because of the low number of positives in our study, the use of the common mole as an indicator species for livestock infections is currently not recommended.
    Mollen als indicatorsoort voor Toxoplasma?
    Krijger, I.M. ; Meerburg, B.G. - \ 2013
    Dierplagen informatie 3 (2013). - ISSN 1388-137X - p. 26 - 27.
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