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Background Toxoplasma gondii is a ubiquitous protozoan parasite that can infect virtually all warm-blooded animals. It is the causative agent of toxoplasmosis, a significant public health issue worldwide. Mathematical models are useful to study the transmission dynamics of T. gondii infection in different settings, and may be used to compare the effectiveness of prevention measures. Methods To obtain an overview of existing mathematical models for transmission of T. gondii, a systematic review was undertaken. The review was conducted according to an a priori protocol and the results were reported according to the PRISMA guidelines. Specific search terms were developed and used in the search of three databases (Scopus, PubMed, and Embase). Results In total, 484 unique records were retrieved from the systematic search. Among them, 15 studies that used mathematical models to study the transmission of T. gondii. These studies were categorized into four groups based on the primary aims: dynamics of transmission (n = 8), intervention (n = 5), spatial distribution (n = 1), and outbreak investigation (n = 1). Conclusions Considering the high disease burden caused by T. gondii, the number of studies using mathematical models to understand the transmission dynamics of this parasite and to evaluate the effectiveness of intervention measures was only 15. This systematic review provides an overview of existing mathematical models and identifies the data gaps for model building. The results from this study can be helpful for further development of mathematical models and improved understanding of the transmission dynamics of T. gondii infection., Highlights • We identified 15 mathematical models studying the transmission of T. gondii. • An overview of existing mathematical models on transmission of T. gondii is presented. • Modelling approaches and control strategies investigated by the models are compared.

Soil has been identified as an important source of exposure to a variety of chemical and biological contaminants. Toxoplasma gondii is one of those potential biological contaminants associated with serious health effects in pregnant women and immunocompromised patients. Gardening or consumption of homegrown vegetables may present an important route of T. gondii infection via accidental ingestion of soil. In the Netherlands, there is quantitative information on the risk of T. gondii infection via meat products, but not on the risk of infection through soil. The objective of this study was to develop a quantitative microbial risk assessment (QMRA) model for estimating the risk associated with T. gondii exposure via accidental soil ingestion in the Netherlands. In order to obtain the needed information, a magnetic capture method for detection of T. gondii oocysts in soil samples was developed, and T. gondii DNA was detected using qPCR targeting the 529 bp repeat element. The method was shown to provide 95% probability of detection (95% CI: 88–100%) when at least 34 oocysts are present in 25 g of soil. T. gondii DNA was detected in 5 of 148 soil samples with interpretable results (3%, 95% CI: 1.5–7.7%). Results for 18 samples were not interpretable due to PCR inhibition. The estimated amount of oocysts presented in qPCR positive samples was quantified by a linear model, and the amount varied from 8 to 478 in 25 g of soil. The estimated incidence rate of T. gondii infection from the QMRA model via soil varied from 0.3 to 1.8 per 1000 individuals per day. Several data gaps (e.g., soil contamination/ingestion and oocysts viability) have been identified in this study, the structure of the model can be applied to obtain more accurate estimates of the risk of T. gondii infection via soil when data become available.

Toxoplasmosis is a zoonosis of public health concern worldwide. Toxoplasma gondii can be transmitted to humans through the consumption of raw or undercooked meat, but little is known about...

Toxoplasma gondii infections cause a large disease burden in the Netherlands, with an estimated health loss of 1,900 Disability Adjusted Life Years and a cost-of-illness estimated at Euro44 million annually. Infections in humans occur via exposure to oocysts in the environment and after eating undercooked meat containing tissue cysts, leading to asymptomatic or mild symptoms, but potentially leading to the development of ocular toxoplasmosis. Infection in pregnant women can lead to stillbirth and disorders in newborns. At present, prevention is only targeted at pregnant women. Cat vaccination, freezing of meat destined for undercooked consumption and enhancing biosecurity in pig husbandries are possible interventions to prevent toxoplasmosis. As these interventions bear costs for sectors in society that differ from those profiting from the benefits, we perform a social cost-benefit analysis (SCBA). In an SCBA, costs and benefits of societal domains affected by the interventions are identified, making explicit which stakeholder pays and who benefits. Using an epidemiological model, we consider transmission of T.gondii after vaccination of all owned cats or cats at livestock farms. To identify relevant high-risk meat products that will be eaten undercooked, a quantitative microbial risk assessment model developed to attribute predicted T.gondii infections to specific meat products will be used. In addition, we evaluate serological monitoring of pigs at slaughter followed by an audit and tailor made advice for farmers in case positive results were found. The benefits will be modelled stochastically as reduction in DALYs and monetized in Euro's following reference prices for DALYs. If the balance of total costs and benefits is positive, this will lend support to implementation of these preventive interventions at the societal level. Ultimately, the SCBA will provide guidance to policy makers on the most optimal intervention measures to reduce the disease burden of T.gondii in the Netherlands.

Background In the Netherlands, toxoplasmosis ranks third in disease burden among foodborne pathogens, with an estimated health loss of 1,900 Disability Adjusted Life Years and a cost-of-illness estimated at €44 million annually. We performed a Social Cost-Benefit Analysis (SCBA) to evaluate the net value of two potential interventions, freezing meat and improving biosecurity in pig farms, for the Dutch society. Methods We assessed the costs and benefits of the two interventions and compared them with the current practice of education, especially during pregnancy. A ‘minimum scenario’ and a ‘maximum scenario’ was assumed, using input parameters with least benefits to society and input parameters with most benefits to society, respectively. Results The freezing meat intervention was far more effective than the biosecurity intervention. Despite high freezing costs, freezing two meat products: steak tartare and mutton leg yielded net social benefits in both the minimum and maximum scenario, ranging from €10.6 million to €31 million for steak tartare and €0.6 million to €1.5 million for mutton leg. The biosecurity intervention would result in net costs in all scenarios ranging from €1 million to €2.5 millions. Conclusions From a public health perspective (i.e. reducing the burden of toxoplasmosis) freezing steak tartare and leg of mutton is to be considered.

The protozoan parasite Toxoplasma gondii can infect all warm-blooded animals and it causes the disease toxoplasmosis. Meat containing viable T. gondii tissue cysts is considered one of the main sources of human infection. The relative importance of the different types of meat depends, not only on the prevalence of T. gondii infection in the different livestock species, but also on consumed volumes and preparation habits. To take these factors into account and to estimate the relative contribution of different meat products to human infection, a quantitative risk assessment model for meat-borne T. gondii infection was previously developed. However, at the time, the effect of salting on parasite viability was estimated based on a single experiment. In recent years, data using salting methods that are more in line with processing of meat products have come available. Literature data on the effect of salting on T. gondii viability were collected and used to fit a predictive model. In addition to the new salting model, a lower concentration of bradyzoites in cattle, more specific heating profiles, and more recent consumption data were implemented in the QMRA model for meat-borne T. gondii infection in the Netherlands. Results show that beef remains the most important source, as it contributed 84% of the total number of predicted infections in the Dutch population, followed by pork (12%), mutton (3.7%), lamb (0.2%) pork/beef mixed products (0.1%), and veal (0.01%). The predicted number of T. gondii infections is reasonably in line with epidemiological data. At the product level, filet americain (a raw beef spread) alone contributed 80% of the total predicted infections in the base model, but scenario analyses demonstrate that its contribution is highly dependent on the salting parameters. A clear identification of the most risky meat products is important, as interventions focussing on these products could have a great impact on reducing T. gondii disease burden in the Netherlands. For that reason, it is important that the effects of salting and other processing methods are evaluated in line with industrial processing and incorporated in quantitative risk assessment models for meat-borne toxoplasmosis.

Intro: Toxoplasmosis has high disease burden in the Netherlands and in the rest of Europe. It can be acquired directly by ingestion of Toxoplasma gondii (T. gondii) oocysts shed by infected cats, or indirectly via consumption of undercooked meat from infected livestock. Cat vaccination has been proposed for reducing oocyst-acquired human infections but it remains unclear whether such an intervention can be effective. In this study we quantified the effects of using cat vaccination on reducing oocyst-originated T. gondii human infections. Method: By using a disease dynamics compartmental model for T. gondii infections in cats and mice we studied the effects of a hypothetical cat vaccine on the presence of T. gondii oocysts in the environment. A fitted dose response model was used to assess the effect of oocyst reduction on the expected human infections. Results: For rats, mice and pigs, and possibly intermediate hosts in general, ingestion of one oocyst provides 30%–60% probability of T. gondii infection. Assuming a favourable ideal scenario where vaccination completely prevents oocyst shedding and predation rate is of one mouse per week per cat, eight cats can be left susceptible in order to achieve elimination and stop oocyst-originated transmission, independent of the total cat population. Considering populations of 1000, 100, 50 and 20 cats, cat vaccination coverage of 94%, 68%, 54% and 35%, respectively, would reduce expected oocyst-originated human cases by 50%. Conclusion: For attaining elimination of oocyst-originated human infections, only few cats may remain unvaccinated, regardless of the cat-population size, and only a few more cats may remain unvaccinated for reducing infections substantially. Such vaccination coverages can in practice be achieved only when small cat-populations are considered, but in larger cat-populations the large efficacy and vaccination coverage needed are unfeasible. Keywords: Toxoplasmosis, Cat vaccination, Control, Compartmental model, Dose response

Consumption of raw or undercooked meat increases the risk of infection with Toxoplasma gondii. Freezing meat products can eliminate this risk. Freezing of meat may affect consumers' valuation of meat products in two different ways: it may be valued positively because of increased food safety or valued negatively because of (perceived) loss of quality. In a Discrete Choice Experiment on four different meat products we studied the difference in willingness to pay for frozen and non-frozen meat products in the Netherlands. Analyses revealed that most Dutch consumer groups prefer non frozen meat. Price was important in consumer decisions, whereas the meat being frozen appeared to play a minor role in the decision to purchase meat products. Even though it may seem obvious that people would prefer safe food to unsafe food, in a context where consumers presume food being safe, many consumers appear unwilling to pay for freezing of meat as additional measure to reduce the risk of food borne infections such as toxoplasmosis.

Puumala hantavirus (PUUV) is the most common and widespread hantavirus in Europe and is associated with a mild form of haemorrhagic fever with renal syndrome in humans, called nephropathia epidemica. This study presents the molecular characterization of PUUV circulating in bank voles in two regions of the Netherlands. Most human cases of hantavirus infection are from these two regions. Phylogenetic analysis of the (partial) S, M and L-segments indicated that the Dutch strains belong to the CE lineage, which includes PUUV strains from France, Germany and Belgium. We have identified two distinct groups of PUUV, corresponding with their geographic origin and with adjoining regions in neighbouring countries.

Toxoplasma gondii, a protozoan zoonotic parasite, has a worldwide distribution. It can cause severe pathological damage to the fetus in primary infected pregnant women and life-threatening encephalitis in immunocompromised patients. One of the main transmission routes to humans is consumption of raw or undercooked meat containing viable T. gondii tissue cysts. In China, the lack of quantitative information on the risk and incidence of infection due to consumption of meat hampers the development of prevention strategies to reduce the burden of toxoplasmosis. The aim of this study was to set up a quantitative microbial risk assessment (QMRA) model to estimate the relative attribution of different types of meat (i.e., pork, beef, lamb and mutton, chicken and duck) to human T. gondii infections in China. The model was built based on the structure of the first meat-borne T. gondii infection QMRA model developed in the Netherlands and applied for seven regions of mainland China. Data on the prevalence of T. gondii in livestock and consumption were obtained from China, however information on preparation habits was lacking. Consumption data were available as average consumption amounts per day collected over three days. The results calculated from the QMRA model were at least thousand-fold higher compared to the incidence rate obtained from an epidemiological susceptible-infected (SI) type model. In general, pork and chicken meat contributed more to the estimated number of infections than beef, small ruminant and duck meat. Cooking temperature was identified as one of the parameters that most strongly affected the estimated incidence rate in the QMRA model. Sensitivity analysis showed that the estimated incidence rate from the QMRA model would be comparable to the results obtained from the SI model if final cooking temperatures are around 1.7 times higher than the temperatures based on a dataset for American consumers. Scenario analysis demonstrated that it is important to know portion size and frequency of consumption in addition to total consumed amounts to calculate incidence of infection. Due to uncertainties present in the input data and the at least thousand-fold overestimated incidence rates, the results merely give an indication of the relative importance of different types of meat. However, the QMRA model clearly identified the key knowledge gaps for future research and can subsequently support cost-effective decisions to reduce the disease burden of human toxoplasmosis.

Toxoplasma gondii is a globally prevalent, zoonotic parasite of major importance to public health. Various indirect and direct methods can be used for the diagnosis of toxoplasmosis. Whereas serological tests are useful to prove contact with the parasite has occurred, the actual presence of the parasite in the tissues of a seropositive animal is not demonstrated. For this, a bioassay is still the reference method. As an alternative, various PCR methods have been developed, but due to the limited amount of sample that can be tested, combined with a low tissue cyst density, those have proved to be insufficiently sensitive. A major improvement of the sensitivity was achieved with magnetic capture-based DNA extraction. By combining the hybridization of specific, biotinylated probes with the capture of those probes with streptavidin-coated paramagnetic beads, T. gondii DNA can selectively be "fished out" from a large volume of meat lysate. Still, several studies showed an insufficient sensitivity compared with the mouse bioassay. Here we present a method that is more sensitive (99% limit of detection: 65.4 tachyzoites per 100g of meat), economical and reliable (ISO 17025 validated) by adding a non-competitive PCR inhibition control (co-capture of cellular r18S) and making the release of the target DNA from the streptavidin-coated paramagnetic beads UV-dependent. The presented results demonstrate the potential of the modified Magnetic Capture real time PCR as a full alternative to the mouse bioassay for the screening of various types of tissues and meat, with the additional advantage of being quantitative.

Background Consumption of undercooked or insufficiently cured meat is a major risk factor for human infection with Toxoplasma gondii. Although horsemeat is typically consumed rare or undercooked, information on the risk of T. gondii from infected horse meat to humans is scarce. Here, we present the results of a study to determine the presence of T. gondii infection in slaughter horses in Serbia, and to attempt to isolate viable parasites. Methods The study included horses from all regions of Serbia slaughtered at two abattoirs between June 2013 and June 2015. Blood sera were tested for the presence of specific IgG T. gondii antibodies by the modified agglutination test (MAT), and samples of trypsin-digested heart tissue were bioassayed in mice. Cyst-positive mouse brain homogenates were subjected to DNA extraction and T. gondii strains were genotyped using 15 microsatellite markers (MS). Results A total of 105 slaughter horses were sampled. At the 1:6 cut-off 48.6% of the examined horses were seropositive, with the highest titre being 1:400. Viable parasites were isolated from two grade type mares; both parasite isolates (RS-Eq39 and RS-Eq40) were T. gondii type III, and both displayed an increased lethality for mice with successive passages. These are the first cases of isolation of T. gondii from horses in Serbia. When compared with a worldwide collection of 61 type III and type III-like strains, isolate RS-Eq39 showed a combination of MS lengths similar to a strain isolated from a duck in Iran, and isolate RS-Eq40 was identical in all markers to three strains isolated from a goat from Gabon, a sheep from France and a pig from Portugal. Interestingly, the source horses were one seronegative and one weakly seropositive. Conclusions The isolation of viable T. gondii parasites from slaughter horses points to horsemeat as a potential source of human infection, but the fact that viable parasites were isolated from horses with only a serological trace of T. gondii infection presents further evidence that serology may not be adequate to assess the risk of toxoplasmosis from horsemeat consumption. Presence of T. gondii type III in Serbia sheds more light into the potential origin of this archetypal lineage in Europe. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2104-x) contains supplementary material, which is available to authorized users.

Infection with Toxoplasma gondii is acquired through consumption of undercooked infected meat, or by uptake of cat-shed oocysts. Although congenital toxoplasmosis is generally considered to contribute most to the disease burden of T. gondii, ocular disease from acquired infection was recently shown to add substantially to the burden. In addition, toxoplasmosis in immune-compromised individuals usually results from reactivation of an infection acquired earlier in life. Nevertheless, prevention of toxoplasmosis commonly targets mainly pregnant women. We summarize current prevention strategies of congenital toxoplasmosis and evaluate options to improve protection of the general population (including pregnant women). To protect the general population, freezing of meat destined for raw or undercooked consumption is the most readily applicable option, especially when limited to meat from animals originating from nonbiosecure husbandry systems. In the long term, more health benefits are expected from cat vaccination; therefore, development of a cat vaccine and evaluation of its implementation is a research priority.

Beginning in 2007, the largest human Q fever outbreak ever described occurred in the Netherlands. Dairy goats from intensive farms were identified as the source, amplifying Coxiella burnetii during gestation and shedding large quantities during abortions. It has been postulated that wild rodents are reservoir hosts from which C. burnetii can be transmitted to domestic animals and humans. However, little is known about the infection dynamics of C. burnetii in wild rodents. The aim of this study was to investigate whether brown rats ( Rattus norvegicus ) can be experimentally infected with C. burnetii and whether transmission to a cage mates occurs. Fourteen male brown rats (wild type) were intratracheally or intranasally inoculated with a Dutch C. burnetii isolate obtained from a goat. At 3 days postinoculation, a contact rat was placed with each inoculated rat. The pairs were monitored using blood samples and rectal and throat swabs for 8 weeks, and after euthanasia the spleens were collected. Rats became infected by both inoculation routes, and detection of C. burnetii DNA in swabs suggests that excretion occurred. However, based on the negative spleens in PCR and the lack of seroconversion, none of the contact animals was considered infected; thus, no transmission was observed. The reproduction ratio R 0 was estimated to be 0 (95% confidence interval = 0 to 0.6), indicating that it is unlikely that rats act as reservoir host of C. burnetii through sustained transmission between male rats. Future research should focus on other transmission routes, such as vertical transmission or bacterial shedding during parturition.

To allow processing of serum samples from animals experimentally infected with Coxiella burnetii outside the BSL-3 facility, an inactivation or clearance protocol that does not hamper serological testing may be required. The effects of filtration (0.1 µm pore size), heating at 56 °C for 30 min, addition of NaN3 (0.09% w/v), and combinations thereof on the presence of viable C. burnetii as well as OD-values in ELISA were tested. Only filtration was shown to effectively clear all culturable C. burnetii.

This chapter discusses Toxoplasma gondii natural history, survival in the environment, clinical features, treatment, methods of detection, genetic variation, epidemiology, risk assessment and risk management. Toxoplasma gondii is arguably one of the most successful parasites, being able to infect all warm blooded animals including humans leading to lifelong infections. Transmission to humans can occur by eating undercooked meat, containing the parasite, or by ingestion of oocysts, which are the environmentally stable form of the parasite. Oocysts are produced by cats and are excreted in their faeces. The infective dose is very low, with less than 10 oocysts being required to establish an infection. Contact with oocysts can occurs while cleaning cat litter trays, gardening, eating contaminated fruit or vegetables and by drinking oocysts in water. Toxoplasma gondii oocysts can survive drinking water treatment but infection with the parasite is rarely noticed, and therefore very few outbreaks have been reported. Recent research from the USA suggests that human infection with oocysts is far more common than previously thought; however, the role of waterborne transmission still needs to be investigated further.

To the Editor: Toxoplasma gondii, a zoonotic protozoan parasite for which felids are the only definitive hosts, can infect humans and other warm-blooded animals. Transmission usually occurs orally from oocysts shed by felids in water and on food, through tissue cysts in undercooked meat, or transplacentally. In particular, young cats shed oocysts that can sporulate and become infectious within a day, depending on temperature and humidity. Sporulated oocysts can survive in moist soil for months to years (1). In September 2014, the number of dead squirrels reported to the Dutch Wildlife Health Centre and the Dutch Mammal Society increased suddenly. The red squirrel (Sciurus vulgaris) is the only species of squirrel endemic to the Netherlands. Members of the public claimed that squirrels were “dropping dead from trees.” Subsequently, the public was encouraged to report and submit dead squirrels. A total of 187 animals were reported through October 2014, of which 37 were submitted for necropsy. Necropsy included macroscopic examination; cytologic analysis of liver, spleen, lungs, and intestinal contents stained with hemacolor (Merck, Darmstadt, Germany); and histologic examination of samples of various organs fixed in formalin, embedded in paraffin, cut into 4-μm sections, and stained with hematoxylin and eosin. For 8 adult animals, body condition (based on degree of fat storage and muscle development) was good; 12 juveniles were in poor condition. Typically, the trachea contained foam, and lungs were hyperemic and edematous. The liver was enlarged and pale, and the spleen was enlarged. In 13 animals, numerous small crescent-shaped organisms, with eccentrically placed nuclei consistent with tachyzoites of T. gondii, were identified by cytology in lung, liver, and spleen (2). Main histopathologic findings were pulmonary interstitial lymphoplasmocytic and neutrophilic infiltrates with edema and numerous intra-alveolar macrophages (17/20) and multifocal lymphoplasmocytic infiltrates with necrosis in the liver (13/20). Extensive splenic necrosis was occasionally observed (4/20). Intestines contained mild plasmacytic infiltrates. Numerous tachyzoites consistent with T. gondii were present in alveolar macrophages and epithelial cells, splenic macrophages, and hepatocytes. Duplicate slides were stained immunohistochemically by using polyclonal antibodies against T. gondii following a standard ABC protocol (3). Organisms stained for T. gondii in liver, spleen, lungs, and intestine. Toxoplasma was not detected in any brain. DNA was isolated (DNeasy Blood and Tissue Kit; QIAGEN, Hilden, Germany) from tissues of 14 squirrels and tested by quantitative PCR (1); T. gondii DNA was detected in 13. We successfully sequenced the T. gondii GRA6 gene for 11 squirrels and identified sequences to clonal type II T. gondii previously identified in sheep from the Netherlands (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"GU325790","term_id":"283580620","term_text":"GU325790"}}GU325790) (4). Incidental findings in the animals tested were encephalitis (2/20), coccidiosis (5/20), trauma (6/20), myocarditis (4/20), nephritis (1/20), lymphadenitis (1/20), and intestinal (3/20) and external (5/20) parasites. The remaining 17 animals showed >1 of the following pathologic conditions: hemorrhages consistent with trauma (12/17), mild to severe intestinal coccidiosis (12/17), pneumonia (3/17), splenitis (1/17), Taenia martis cysticerci (1/17), and external parasites (8/17). Immunohistochemistry results for all 17 were negative for T. gondii. On the basis of necropsy and molecular findings, we conclude that 20 of 37 examined squirrels died of disseminated T. gondii type II infection. These animals included adults and juveniles and were not restricted to specific geographic areas (Figure). The remaining animals died of trauma (12/17) or other causes (5/17). Figure Spatial distribution of wild red squirrels (Sciurus vulgaris) investigated for Toxoplasma gondii and classified by cause of death, the Netherlands, 2014. Red squirrels are susceptible to T. gondii, and infection can lead to death. However, in our sample, the proportion of squirrels that died of toxoplasmosis (>50%) was higher than in other studies (≈16%) (5–7). The apparent increase in squirrel deaths and unexpectedly high proportion of fatal T. gondii infections suggests a toxoplasmosis outbreak among red squirrels. Possible explanations for this surge in cases include increased exposure to the parasite, increased susceptibility to infection, or increased virulence of the pathogen. Clonal T. gondii type II, the strain most frequently involved in human cases and endemic to Europe and North America, was identified. An increased virulence of the pathogen could not be proven (8). On the basis of lymphoid hyperplasia in the spleen and lymph nodes, affected squirrels had no signs of immunosuppression. Thus, the most likely explanation is increased exposure to the parasite. Sources of infection for red squirrels are not known; however, oocysts shed in cat feces may contaminate the nuts, fungi, shoots, and berries that constitute the diet of the squirrel. Stray, unspayed cats are common in the Dutch countryside. More than 3 million domestic cats (Felis domesticus) exist in the Netherlands, including several tens of thousands of free-roaming cats that reproduce (9). Determining the exact source of infection is important because humans also harvest wild fruits, nuts, and fungi from these areas. This outbreak highlights that contamination of the environment with T. gondii oocysts is of concern not only from a public health viewpoint but from a biodiversity perspective as well (1,10).

Toxoplasma gondii is an important zoonotic parasite with a worldwide distribution. Felids are the definitive hosts and, upon primary infection, they shed millions of oocysts into the environment. These oocysts are infectious to a wide range of warm-blooded animals, and these intermediate hosts develop tissue cysts. Humans can be infected through oocysts, or by consumption of raw or undercooked meat containing tissue cysts. If a woman is infected for the first time during pregnancy, the parasite can be transmitted transplacentally, which may result in death of the fetus, or a baby born with nervous system abnormalities or chorioretinitis. Moreover, all people infected with T. gondii are at risk of developing ocular toxoplasmosis, and immunocompromised individuals are at risk for disseminated toxoplasmosis. Prevention strategies are usually aimed at pregnant women and are based on health education or early detection and treatment. Insight into the relative attribution of the different sources of infection and the possible intervention measures associated with these sources will aid the development of more effective prevention strategies that also will protect the general population.

Undercooked meat containing tissue cysts is one of the most common sources of Toxoplasma gondii infection in humans. Goats are very susceptible to clinical toxoplasmosis, and especially kids are common food animals, thereby representing a risk for human infection. A sequence-specific magnetic capture method was used for isolation of T. gondii DNA from tissue samples from experimentally infected goat-kids and real-time PCR for the 529 bp repeat element allowed quantification of T. gondii DNA. The contamination level in different types of tissue and in two groups of goats euthanized 30 and 90 dpi was compared. The highest concentration of T. gondii DNA in both groups of goats was found in lung tissue, but only the higher parasite count in lung tissue compared to other organs in group A (euthanized 30 dpi) was statistically significant. T. gondii concentrations were higher in liver and dorsal muscle samples from goats euthanized 90 dpi than in goats euthanized at 30 dpi, while the T. gondii concentration in hearts decreased. This study describes for the first time distribution of T. gondii parasites in post-weaned goat kids. New information about T. gondii predilection sites in goats and about the progression of infection between 30 and 90 dpi was achieved.

Toxoplasma gondii is an important zoonotic pathogen that is best known as a cause of abortion or abnormalities in the newborn after primary infection during pregnancy. Our aim was to determine the prevalence of T. gondii in wild boar to investigate the possible role of their meat in human infection and to get an indication of the environmental contamination with T. gondii. The presence of anti-T. gondii antibodies was determined by in-house ELISA in 509 wild boar shot in 2002/2003 and 464 wild boar shot in 2007. Most of the boar originated from the "Roerstreek" (n = 673) or the "Veluwe" (n = 241). A binormal mixture model was fitted to the log-transformed optical density values for wild boar up to 20 months old to estimate the optimal cut-off value (-0.685) and accompanying sensitivity (90.6%) and specificity (93.6%). The overall seroprevalence was estimated at 24.4% (95% CI: 21.1-27.7%). The prevalence did not show variation between sampling years or regions, indicating a stable and homogeneous infection pressure from the environment. The relation between age and seroprevalence was studied in two stages. Firstly, seroprevalence by age group was determined by fitting the binary mixture model to 200 animals per age category. The prevalence showed a steep increase until approximately 10 months of age but stabilized at approximately 35% thereafter. Secondly, we fitted the age-dependent seroprevalence data to several SIR-type models, with seropositives as infected (I) and seronegatives as either susceptible (S) or resistant (R). A model with a recovery rate (SIS) was superior to a model without a recovery rate (SI). This finding is not consistent with the traditional view of lifelong persistence of T. gondii infections. The high seroprevalence suggests that eating undercooked wild boar meat may pose a risk of infection with T. gondii.

The Q fever outbreak in the Netherlands in 2007-2010 prompted government interventions to reduce the human incidence by reduction of Q fever shedding at dairy goat farms. Mandatory hygiene measures were taken, including the control of animal reservoirs. It has been postulated that brown rats, through their commensal nature, form an important factor in the persistent dissemination of endemic circulating Coxiella burnetii in nature to domestic animals, livestock and humans. Here, the occurrence of C. burnetii in rats captured at different types of location during the Q fever outbreak in the Netherlands, viz. urban areas, nature areas and various types of farm has been determined. This is a first step towards the elucidation of the reservoir status of rats in veterinary and human Q fever epidemiology. C. burnetii DNA was detected in the spleen of 4.9% of the brown rats (Rattus norvegicus) and 3.0% of the black rats (Rattus rattus). Evidence for C. burnetii infection was also found in liver, kidney, lung and intestinal tissue but not in heart, brain and pancreas. C. burnetii IgGs were detected in 15.8% of the brown rats. Positive rats were collected at goat, pig, cattle and poultry farms, and urban locations; including locations outside the designated 5km "increased-risk" zones around bulk milk positive goat farms. The percentage of rat-positive locations was the highest for goat farms (50%) and cattle farms (14.3%). The presence of actively infected rats outside the lambing season and at multiple environmental settings including urban locations might suggest that rats are not merely a spill-over host due to infection by a contaminated environment but might represent true reservoirs, capable of independent maintenance of C. burnetii infection cycles and thereby contributing to spread and transmission of the pathogen. If frequent (re)introduction of C. burnetii to small ruminant farms can be caused by rats as maintenance reservoirs, mandatory wildlife control and lifelong vaccination of herds will be necessary.