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For the first 3 months of COVID-19 pandemic, COVID-19 was expected to be an immunizing non-relapsing disease. We report a national case series of 11 virologically-confirmed COVID-19 patients having experienced a second clinically- and virologically-confirmed acute COVID-19 episode. According to the clinical history, we discuss either re-infection or reactivation hypothesis. Larger studies including further virological, immunological and epidemiologic data are needed to understand the mechanisms of these recurrences.

Item does not contain fulltext To rapidly assess possible community transmission in Noord-Brabant, the Netherlands, healthcare workers (HCW) with mild respiratory complaints and without epidemiological link (contact with confirmed case or visited areas with active circulation) were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Within 2 days, 1,097 HCW in nine hospitals were tested; 45 (4.1%) were positive. Of six hospitals with positive HCW, two accounted for 38 positive HCW. The results informed local and national risk management.

Background In 2012, cryptosporidiosis cases increased in the Netherlands, but no single source was identified. In April 2013, we began a 3-year population-based case-control study coupled with genotyping to identify risk factors for sporadic cryptosporidiosis. Methods Cryptosporidium cases were laboratory confirmed (by microscopy or polymerase chain reaction), and the species (ie, C. hominis or C. parvum) was determined. We analyzed data by study year, combined and by species. We performed single-variable analysis, and variables with a P value of ≤ .10 were included in a multivariable logistic regression model adjusting for age, sex, and season. Results The study included 609 cases and 1548 frequency-matched controls. C. parvum was the predominant species in the first 2 study years, shifting to C. hominis in the third year. Household person-to-person transmission and eating barbequed food were strongly associated with being a case. Eating tomatoes was negatively associated. When the analysis was stratified by study year, person-to-person transmission was an independent risk factor. Analysis by species identified different risk factors for cases infected with C. parvum and C. hominis. Conclusion This was the first case-control study examining risk factors for sporadic cryptosporidiosis in the Netherlands. Providing information about Cryptosporidium exposure during outdoor activities and improvements in hygiene within households could prevent future sporadic infections., During a 3-year case-control study coupled with genotyping, a Cryptosporidium species shift and different risk factors for sporadic cryptosporidiosis, by species, were identified. Improved hygiene to limit person-to-person transmission is required, and asymptomatic carriers could account for many secondary cases.

Giardia lamblia is a major cause of diarrhoea in children, especially those attending day-care centres (DCCs). Only Giardia assemblages A and B infect humans. Given the lack of assemblage-specific epidemiological data, we aimed to identify risk factors for infection by assemblages A and B in DCC attendees. During 2010-2013, 5,015 faecal samples from ≤4-year-old children attending 40 DCCs participating in laboratory surveillance in the Netherlands were tested for Giardia using RT-PCR. Giardia-positive samples were typed for identification of assemblages A and B. We compared child- and DCC-level characteristics of Giardia-positive children with those of Giardia-negative children using mixed-effects logistic regression. Overall, 226 samples (4.5 %) tested positive for Giardia, and assemblages were determined for 138 of them: 62 (45 %) were assemblage A and 76 (55 %) were B. The only risk factor for assemblage A infection was attending DCCs with indoor sandpits and cats during spring/summer (odds ratio [OR] 13.5; 95% CI 1.8-101.3). For assemblage B, risk factors were attending DCCs with dedicated diaper-changing (OR 3.6; 95% CI 1.7-7.6) and laundry (OR 2.3; 95% CI 1.1-4.9) areas. Preventing sick children from attending day-care and having cloth-towels at the DCC decreased the risk of assemblage B infection (OR 0.0; 95% CI 0.0-0.5 and OR 0.3; 95% CI 0.1-0.6 respectively). Risk factors for assemblages A and B infection in DCC-attending children were different, with assemblage B being mainly related to anthroponotic transmission, and assemblage A being related to zoonotic transmission. Given these differences, interventions to reduce the burden of childhood giardiasis cannot ignore those assemblage-specific preferred reservoirs and transmission routes.

Acute gastroenteritis (AGE) morbidity remains high amongst preschool children, posing a significant societal burden. Empirical data on AGE-causing agents is needed to gauge their clinical relevance and identify agent-specific targets for control. We assessed the prevalence, risk factors and association with symptoms for enteropathogens in households with preschool children. A monthly-repeated cross-sectional survey of enteropathogens in households with preschool children was performed. A parent-child pair per household (n = 907 households) provided faecal samples and reported their symptoms and potential risk exposures. Samples were tested by multiplex reverse transcription polymerase chain reaction (RT-PCR) for 19 enteropathogens. Associations were assessed using logistic regression. 28.3 % of children (n = 981) and 15.6 % of parents (n = 971) carried pathogenic bacteria and/or Escherichia coli-associated pathogenicity genes, and 6.5 % and 3.3 % carried viruses, respectively. Giardia lamblia (4.6 % of children, 2.5 % of parents) and Dientamoeba fragilis (36 %, 39 %, respectively) were the main parasites, and were associated with pet exposure. Living in rural areas was associated with carriage of pathogenic E. coli, norovirus I and D. fragilis. Pathogenic E. coli was associated with summertime and livestock exposure. Attending day-care centres increased the risk of carrying norovirus, sapovirus and G. lamblia. Viruses occurred mainly in winter and were associated with AGE symptoms. Childparent associations were found for bacterial pathogenicity genes, viruses, G. lamblia and D. fragilis. Enteropathogens spread widely in households with preschool children, particularly viruses, which more often cause symptoms. While bacteria predominate during summer and in those exposed to livestock, viruses predominate in wintertime and, like G. lamblia, are widespread amongst day-care centre attendees.

Toxocara canis, Toxocara cati and Ascaris suum are worldwide-distributed zoonotic roundworms of dogs, cats and pigs, respectively. The epidemiology of these parasites in developed countries is largely unclear. Two countrywide cross-sectional serosurveys were therefore conducted in the Netherlands in 1995/1996 and 2006/2007 to investigate the prevalence, trends and risk factors for human Toxocara and Ascaris infections in the general population. The Netherlands is characterized by high pig production, freedom from stray dogs and virtual absence of autochthonous infections with the human-adapted roundworm Ascaris lumbricoides. Over the 10 years between the two serosurveys, Toxocara seroprevalence decreased significantly from 10.7 % (n = 1159) to 8.0 % (n = 3683), whereas Ascaris seroprevalence increased significantly from 30.4 % (n = 1159) to 41.6 % (n = 3675), possibly reflecting concomitant improvements in pet hygiene management and increased exposure to pig manure-contaminated soil. Increased anti-Toxocara IgGs were associated with increasing age, male gender, contact with soil, ownership of cats, cattle or pigs, hay fever, low education, high income and non-Western ethnic origin. Increased anti-Ascaris IgGs were associated with increasing age, owning pigs, low education, childhood geophagia and non-Dutch ethnic origin. Besides identifying specific groups at highest risk of Toxocara and Ascaris infections, our results suggest that these infections mainly occur through environmental, rather than foodborne, routes, with direct contact with soil or cat and pig ownership being potentially modifiable exposures.

Background: Real-time PCR methods are increasingly used in routine patient care settings not only to determine the presence or absence of pathogens in patient materials, but also to obtain semiquantitative results to estimate the pathogen load. However, it is so far unknown how well these methods are harmonized among different laboratories. Methods: Sets of stool samples were distributed three to four times per year to ca. 25–40 participating laboratories within the European Union as part of an external quality assessment scheme (EQAS) for the detection of gastrointestinal protozoa. This paper presents the results obtained over a 3-year period for Entamoeba histolytica, Entamoeba dispar, Giardia lamblia, Cryptosporidium species and Dientamoeba fragilis. Results: Although both false-positive and false-negative results were reported, the overall sensitivity and specificity were high. The substantial differences in the quantitative output of the real-time PCR assays could be traced back to differences in DNA isolation procedures between different laboratories. Conclusions: Participation in an EQAS proved to be important as it provides information on how the real-time PCR methods used by the participant compares to the generally reported results and indicates how procedures could be improved. Semiquantitative results of real-time PCR methods are not exchangeable between laboratories as long as the diagnostic procedures are not harmonized. Intralaboratory comparison of semiquantitative real-time PCR results seems only possible by the use of calibration curves derived from well-validated standards in clinical material and not by spiking solutions with purified DNA.

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.

SUMMARYInsights into transmission dynamics of enteropathogens in children attending daycare are limited. Here we aimed at identifying daycare centre (DCC) characteristics associated with time-clustered occurrence of enteropathogens in DCC-attending children. For this purpose, we used the KIzSS network, which comprises 43 DCCs that participated in infectious disease surveillance in The Netherlands during February 2010–February 2013. Space–time scan statistics were used to identify clusters of rotavirus, norovirus, astrovirus, Giardia lamblia and Cryptosporidium spp. in a two-dimensional DCC characteristic space constructed using canonical correlation analysis. Logistic regression models were then used to further identify DCC characteristics associated with increased or decreased odds for clustering of enteropathogens. Factors associated with increased odds for enteropathogen clustering in DCCs were having indoor/outdoor paddling pools or sandpits, owning animals, high numbers of attending children, and reporting outbreaks to local health authorities. Factors associated with decreased odds for enteropathogen clustering in DCCs were cleaning child potties in designated waste disposal stations, cleaning vomit with chlorine-based products, daily cleaning of toys, extra cleaning of toys during a suspected outbreak, and excluding children with gastroenteritis. These factors provide targets for reducing the burden of gastrointestinal morbidity associated with time-clustered occurrence of major enteropathogens in DCC attendees.

Gastrointestinal infection morbidity remains high amongst preschool children in developed countries. We investigated the societal burden (incidence, healthcare utilization, and productivity loss) and correlates of acute gastroenteritis (AGE) in families with preschoolers. Monthly for 25 months, 2000 families reported AGE symptoms and related care, productivity loss, and risk exposures for one preschooler and one parent. Amongst 8768 child-parent pairs enrolled, 7.3% parents and 17.4% children experienced AGE (0.95 episodes/parent-year and 2.25 episodes/child-year). Healthcare utilization was 18.3% (children) and 8.6% (parents), with 1.6% children hospitalized. Work absenteeism was 55.6% (median 1.5 days) and day-care absenteeism was 26.2% (median 1 day). Besides chronic enteropathies, antacid use, non-breastfeeding, and toddling age, risk factors for childhood AGE were having developmental disabilities, parental occupation in healthcare, multiple siblings, single-parent families, and ≤12-month day-care attendance. Risk factors for parental AGE were female gender, having multiple or developmentally-disabled day-care-attending children, antimicrobial use, and poor food-handling practices. Parents of AGE-affected children had a concurrent 4-fold increased AGE risk. We concluded that AGE-causing agents spread widely in families with preschool children, causing high healthcare-seeking behaviours and productivity losses. Modifiable risk factors provide targets for AGE-reducing initiatives. Children may acquire some immunity to AGE after one year of day-care attendance.

SUMMARYThe child day-care centre (DCC) is often considered as one risk factor for gastroenteritis (GE) rather than a complex setting in which the interplay of many factors may influence the epidemiology of GE. This study aimed to identify DCC-level risk factors for GE and major enteropathogen occurrence. A dynamic network of 100 and 43 DCCs participated in a syndromic and microbiological surveillance during 2010–2013. The weekly incidence of GE events and weekly prevalence of five major enteropathogens (rotavirus, norovirus, astrovirus,Giardia lamblia, Cryptosporidium hominis/parvum) were modelled per DCC using mixed-effects negative binomial/Poisson regression models. Sixteen hundred children were surveyed up to 3 years, during which 1829 GE episodes were reported and 5197 faecal samples were analysed. Identified risk factors were: large DCC capacity, crowding, having animals, nappy changing areas, sandpits, paddling pools, cleaning potties in normal sinks, cleaning vomit with paper towels (but without cleaner), mixing of staff between child groups, and staff members with multiple daily duties. Protective factors were: disinfecting fomites with chlorine, cleaning vomit with paper towels (and cleaner), daily cleaning of bed linen/toys, cohorting and exclusion policies for ill children and staff. Targeting these factors may reduce the burden of DCC-related GE.

Background: Children attending day care experience substantial gastrointestinal morbidity due to circulating seasonal enteropathogens in the day-care environment. The lack of a distinct clinical presentation of gastroenteritis (GE) in these children, in combination with the high diversity of enteropathogenic agents, complicates the assessment of the individual contributions of enteropathogens that may cause GE. We aimed to estimate the proportion of day-care attendees experiencing GE that could be attributed to a range of enteropathogens circulating in day care in the Netherlands in 2010-2013.Methods: Using time-series data from a national laboratory-based and syndrome-based surveillance system in Dutch day-care centers and generalized estimating equation analysis, we modelled the variation in prevalence of 16 enteropathogens of bacterial (8), viral (5) and parasitic origin (3) circulating in day care to the variation of GE incidence among children attending day care.Results: Rotavirus, norovirus, astrovirus, Giardia and Cryptosporidium were significantly associated with GE morbidity among day-care attendees in our time-series analysis. Together, these enteropathogens accounted for 39% of the GE morbidity: 11% by rotavirus, 10% by norovirus, 8% by Giardia, 7% by astrovirus and 3% by Cryptosporidium.Conclusions: We demonstrate that circulating viruses and parasites, rather than bacteria, contribute to seasonal GE experienced by children in day care.

The occurrence of trichinellosis in a resident of the Netherlands prompted us to examine the likelihood of this originating from infected rats in spite of prevailing biosecurity and testing procedures. In so doing, we sought to calculate the possible risks for trichinellosis in countries deemed non-endemic. The infection risk was determined by simulating a scenario from a reservoir of minimally contaminated wildlife to pigs to humans. Results indicate that humans might become infected even in the event that artificial digestion had been performed on individually tested pig carcasses. Our conclusions justify reconsidering Trichinella control strategies based on the current testing protocol, and emphasize the importance of proper cooking as further insurance against human infection.

Background: Gastroenteritis morbidity is high among children under the age of four, especially amongst those who attend day care.Objective: To determine the prevalence of a range of enteropathogens in the intestinal flora of children attending day care and to relate their occurrence with characteristics of the sampled child and the sampling season.Methods: We performed three years of enteropathogen surveillance in a network of 29 child day care centers in the Netherlands. The centers were instructed to take one fecal sample from ten randomly chosen children each month, regardless of gastrointestinal symptoms at time of sampling. All samples were analyzed for the molecular detection of 16 enteropathogenic bacteria, parasites and viruses by real-time multiplex PCR.Results: Enteropathogens were detected in 78.0% of the 5197 fecal samples. Of the total, 95.4% of samples were obtained from children who had no gastroenteritis symptoms at time of sampling. Bacterial enteropathogens were detected most often (most prevalent EPEC, 19.9%), followed by parasitic enteropathogens (most prevalent: D. fragilis, 22.1%) and viral enteropathogens (most prevalent: norovirus, 9.5%). 4.6% of samples related to children that experienced symptoms of gastroenteritis at time of sampling. Only rotavirus and norovirus were significantly associated with gastroenteritis among day care attendees.Conclusions: Our study indicates that asymptomatic infections with enteropathogens in day care attendees are not a rare event and that gastroenteritis caused by infections with these enteropathogens is only one expression of their presence.

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.

Diagnostic methods for parasite infections still highly depend on the identification of the parasites by direct methods such as microscopic examination of blood, stool and tissue biopsies. Serodiagnosis is often carried out to complement the direct methods; however, few synthetic antigens with sufficient sensitivity and specificity are available. Here we evaluated a glycan microarray approach to select for synthetic glycan antigens that could be used for serodiagnosis of parasitic infections. Using a glycan array containing over 250 different glycan antigens, we identified GalNAcβ1–4(Fucα1–3)GlcNAc-R (LDNF) as a glycan antigen that is recognized by antibodies from Trichinella-infected individuals. We synthesized a neoglycoconjugate, consisting of five LDNF molecules covalently coupled to bovine serum albumin (BSA), and used this neoglycoconjugate as an antigen to develop a highly sensitive total-Ig ELISA for serological screening of trichinellosis. The results indicate that glycan microarrays constitute a promising technology for fast and specific identification of parasite glycan antigens to improve serodiagnosis of different parasitic infections, either using an ELISA format, or parasite-specific glycan arrays.

To establish the prevalence of human echinococcosis in the Netherlands by using data from laboratories carrying out diagnostic procedures and data from pathology registries from 1997-2008.Descriptive.Data on serological diagnostic tests for Echinococcus granulosus carried out from 1997 to 2008 were gathered from the National Institute for Public Health and the Environment (RIVM) in Bilthoven and Leiden University Medical Center (LUMC). Additionally, all echinococcosis patients registered on the pathology database of the Dutch pathological anatomy national automated archive (PALGA) were analysed.A total of 7314 serum samples from 5125 patients were examined for antibodies. Cyst material from 39 patients was examined using molecular methods. The number of serum samples sent in annually was stable at 550 to 600. Over the period investigated, 1997-2008, on serological investigation a total of 485 patients were found to have a positive result on IgG-ELISA. Of these, the diagnosis of echinococcosis was confirmed in 445 patients by further serological investigation (on average 37 new patients each year (range: 19-59)) and/or a positive PCR result. Over the duration of the study period the number of new patients decreased from over 40 to fewer than 30 patients per year. Going by the family name, 95.5% of the 445 patients were probably imported cases of disease.In the Netherlands, echinococcosis is primarily seen as an imported disease with the majority of patients originating from areas around the Mediterranean Sea where it is endemic. Each year there are nearly 30 confirmed cases.

Objective In 2009, in a European survey, around a quarter of Europeans reported witnessing discrimination or harassment at their workplace. The parity committee from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) designed a questionnaire survey to investigate forms of discrimination with respect to country, gender and ethnicity among medical professionals in hospitals and universities carrying out activities in the clinical microbiology (CM) and infectious diseases (ID) fields. Design The survey consisted of 61 questions divided into five areas (sociodemographic, professional census and environment, leadership and generic) and ran anonymously for nearly 3 months on the ESCMID website. Subjects European specialists in CM/ID. Results Overall, we included 1274 professionals. The majority of respondents (68%) stated that discrimination is present in medical science. A quarter of them reported personal experience with discrimination, mainly associated with gender and geographic region. Specialists from South-Western Europe experienced events at a much higher rate (37%) than other European regions. The proportion of women among full professor was on average 46% in CM and 26% in ID. Participation in high-level decision-making committees was significantly (>10 percentage points) different by gender and geographic origin. Yearly gross salary among CM/ID professionals was significantly different among European countries and by gender, within the same country. More than one-third of respondents (38%) stated that international societies in CM/ID have an imbalance as for committee member distribution and speakers at international conferences. Conclusions A quarter of CM/ID specialists experienced career and research discrimination in European hospitals and universities, mainly related to gender and geographic origin. Implementing proactive policies to tackle discrimination and improve representativeness and balance in career among CM/ID professionals in Europe is urgently needed.

PURPOSE. Consumption of undercooked pork meat products has been considered a major risk factor for contracting toxoplasmosis in humans. Indoor farming and improved hygiene have drastically reduced Toxoplasma infections in pigs over the past decades. Whether introduction of animal-friendly production systems will lead to a reemergence of Toxoplasma infections in pigs is not yet known. Investigating this possibility was the purpose of this study. METHODS. Blood was obtained from pigs raised for slaughter and tested for Toxoplasma antibodies by using latex agglutination and indirect immunofluorescence testing, with confirmation by immunoblotting. RESULTS. None of the slaughter pigs (n 621) from conventional farms (n 30) were positive, whereas 38 (2.9%) of 1295 animals from animal-friendly systems tested positive (n 33 farms; 13 [39%] farms positive). CONCLUSIONS. The following conclusions may be derived from this study: Conventionally (indoors) raised pigs are free from Toxoplasma infection, and (2) animal-friendly production systems may lead to a reemergence of Toxoplasma infections, although many of these farms remain Toxoplasma free. Slaughterhouse monitoring of pigs from animal-friendly production systems combined with on-farm prevention strategies should be applied to ensure safety for consumers of the meat products obtained from these animals. (Invest Ophthalmol Vis Sci. 2004; 45:3165‐3169) DOI:10.1167/iovs.04-0326