Nienke Hartemink

Wageningen University & Research | WUR · Biometris (Mathematics and Statistics group)

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 temp...

Biological control of ticks using entomopathogenic fungi (EPF) is a highly desired alternative to chemical acaricides for the control of tick-borne pathogens. For Metarhizium anisopliae isolate ICIPE 7, one of these EPFs, efficacy against multiple tick species has been demonstrated in laboratory and field settings. However, we currently have little...

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is one of the most challenging and persistent health issues in many countries worldwide. In several countries, bTB control is complicated due to the presence of wildlife reservoirs of infection, i.e. European badger (Meles meles) in Ireland and the UK, which can transmit infection to cattle....

From 08-12 August, 2022, 32 individuals participated in a workshop, Stability and Fluctuations in Complex Ecological Systems, at the Lorentz Center, located in Leiden, The Netherlands. An interdisciplinary dialogue between ecologists, mathematicians, and physicists provided a foundation of important problems to consider over the next 5-10 years. Th...

The risk of spillover of zoonotic diseases to humans is changing in response to multiple environmental and societal drivers, particularly in tropical regions where the burden of neglected zoonotic diseases is highest and land use change and forest conversion is occurring most rapidly. Neglected zoonotic diseases can have significant impacts on poor...

The risk of spillover of zoonotic diseases to humans is changing in response to multiple environmental and societal drivers, particularly in tropical regions where the burden of neglected zoonotic diseases is highest and land use change and forest conversion is occurring most rapidly. In these regions, neglected zoonotic diseases can have significa...

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 te...

For wildlife diseases, one often relies on host density to predict host infection prevalence and the subsequent force of infection to humans in the case of zoonoses. Indeed, if transmission is mainly indirect, i.e., by way of the environment, the force of infection is expected to increase with host density, yet the laborious field data supporting t...

Longitudinal studies are fundamental in the assessment of the effect of environmental factors on tick population dynamics. In this study, we use data from a 10-year study in 11 different locations in the Netherlands to gauge the effects of climatic and habitat factors on the temporal and spatial variation in questing tick activity. Marked differenc...

Variance in longevity among individuals may arise as an effect of heterogeneity (differences in mortality rates experienced at the same age or stage) or as an effect of individual stochasticity (the outcome of random demographic events during the life cycle). Decomposing the variance into components due to heterogeneity and stochasticity is crucial...

This paper presents a comprehensive theory for the demographic analysis of populations in which individuals are classified by both age and stage. The earliest demographic models were age‐classified. Ecologists adopted methods developed by human demographers and used life tables to quantify survivorship and fertility of cohorts and the growth rates...

West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can form hybrids. Differences between biotypes, such as...

MATLAB scripts to calculate and decompose the variance in longevity for the matrix formulation of the gamma-Gompertz?Makeham model.

Inter-individual variance in longevity (or any other demographic outcome) may arise from heterogeneity or from individual stochasticity. Heterogeneity refers to differences among individuals in the demographic rates experienced at a given age or stage. Stochasticity refers to variation due to the random outcome of demographic rates applied to indiv...

p>West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can form hybrids. Differences between biotypes, such a...

Because tick and tick-borne disease distributions are so tightly linked to the environment, a robust conceptual background is necessary to build useful empirical and process-based models and to interpret results coherently with pathogen, vector and host ecology. This is especially pressing when considering that tick-borne pathogen circulation is a...

A longitudinal investigation on tick populations and their Borrelia infections in the Netherlands was undertaken between 2006 and 2011 with the aim to assess spatial and temporal patterns of the acarological risk in forested sites across the country and to assess variations in Borrelia genospecies diversity. Ticks were collected monthly in 11 sites...

In Europe, tick-borne diseases are the most important group of vector-borne diseases (Heyman et al. 2011; Randolph 2001; Randolph and Šumilo 2007). Research focus has long been on Lyme borreliosis and tick-borne encephalitis (TBE), because of their prevalence and public health impact. However, recently, new pathogens have emerged or re-emerged and...

Over the past decades, the Asian tiger mosquito (Aedes albopictus (Skuse, 1895)) has emerged in many countries, and it has colonized new environments, including urban areas. The species is a nuisance and a potential vector of several human pathogens, and a better understanding of the habitat preferences of the species is needed for help in successf...

Mathematical modeling and notably the basic reproduction number R0 have become popular tools for the description of vector-borne disease dynamics. We compare two widely used methods to calculate the probability of a vector to survive the extrinsic incubation period. The two methods are based on different assumptions for the duration of the extrinsi...

Background Models for the spatial distribution of vector species are important tools in the assessment of the risk of establishment and subsequent spread of vector-borne diseases. The aims of this study are to define the environmental conditions suitable for several mosquito species through species distribution modelling techniques, and to compare...

Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the path...

Accurate estimation of population size is key to understanding the ecology of disease vectors, as well as the epidemiology of the pathogens they carry and to plan effective control activities. Population size can be estimated through mark-Release-Recapture (MRR) experiments that are based on the assumption that the ratio of recaptured individuals t...

A key factor in the success of parasites is the ability to move between hosts. Some parasites make use of an intermediate arthropod host to move between their primary hosts. Several examples exist where such parasites manipulate their intermediate host to enhance their transmission, but examples for ticks are scarce. In this chapter, we describe ho...

The abundance of infected Ixodid ticks is an important component of human risk of Lyme disease, and various empirical studies have shown that this is associated, at least in part, to landscape fragmentation. In this study, we aimed at exploring how varying woodland fragmentation patterns affect the risk of Lyme disease, through infected tick abunda...

Bluetongue (BT) is an economically important disease of ruminants caused by bluetongue virus (BTV) and transmitted by Culicoides biting midges. The most practical and effective way to protect susceptible animals against BTV is by vaccination. Data from challenge studies in calves and sheep conducted by Intervet International b.v., in particular, pr...

H5N1, highly pathogenic avian influenza, continues to pose a public health risk in the countries of southeast Asia where it has become endemic. However, in Thailand, which experienced two of the largest recorded epidemics in 2004-2005, the disease has been successfully reduced to very low levels. We fitted a spatio-temporal model of the spread of i...

Zoonotic visceral leishmaniasis is endemic in the Mediterranean Basin, where the dog is the main reservoir host. The disease's causative agent, Leishmania infantum, is transmitted by blood-feeding female sandflies. This paper reports an integrative study of canine leishmaniasis in a region of France spanning the southwest Massif Central and the nor...

Capturing mosquitoes in models; the use of mathematical models for studying and controlling vector-borne diseases Vector-borne diseases are transmitted from an infected individual to another individual by vectors, usually arthropods, such as mosquitoes, midges and ticks. There is an increasing interest in this type of diseases, due to some recent,...

Ecology Letters (2009) 12: 1298–1305 The application of projection matrices in population biology to plant and animal populations has a parallel in infectious disease ecology when next-generation matrices (NGMs) are used to characterize growth in numbers of infected hosts (R0). The NGM is appropriate for multi-host pathogens, where each matrix elem...

Geographical maps indicating the value of the basic reproduction number, R₀, can be used to identify areas of higher risk for an outbreak after an introduction. We develop a methodology to create R₀ maps for vector-borne diseases, using bluetongue virus as a case study. This method provides a tool for gauging the extent of environmental effects on...

This thesis deals with the derivation of the basic reproduction number (R0) for vector-borne diseases, in the context of studying the effect of climate change on the risk of emergence diseases. Vector-borne diseases are transmitted from an infected individual to another individual by vectors, usually arthropods. Striking examples of emergence of ve...

Characterizing the basic reproduction number, R(0), for many wildlife disease systems can seem a complex problem because several species are involved, because there are different epidemiological reactions to the infectious agent at different life-history stages, or because there are multiple transmission routes. Tick-borne diseases are an important...

West Nile virus (WNV) is principally considered to be maintained in a mosquito-bird transmission cycle. Under experimental conditions, several other transmission routes have been observed, but the significance of these additional routes in nature is unknown. Here, we derive an expression for the basic reproduction number (R0) for WNV including all...

One of the most important aspects of vector-borne infections is the strong influence of weather and climate on the transmission. In response to the major epidemic of bluetongue in north western Europe between summer and autumn 2006, an interest in BTV control issues developed. In this context, a map indicating the spatial variation in BTV risk in t...

Studies on a dose-response relation often report separate relative risks for several risk classes compared with a referent class. When performing a meta-analysis of such studies, one has to convert these relative risks into an overall relative risk for a continuous effect. Apart from taking the dependence between separate relative risks into accoun...

Flexible life history responses to flower and rosette bud removal in three perennial herbs Nienke Hartemink, Eelke Jongejans and Hans de Kroon, In a garden experiment we investigated the response to continuous removal of either flower buds or rosette buds in three perennial grassland species (Hypochaeris radicata, Succisa pratensis and Centaurea ja...