Ingrid H M Friesema

• PhD
• Researcher/Epidemiologist at National Institute for Public Health and the Environment

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen associated with illness ranging from mild diarrhoea to haemolytic uremic syndrome (HUS) or even death. Cross-sectoral data sharing provides an opportunity to gain insight in reservoirs and sources of human infections and starting points for pro-active measures. Nevertheless, phylo...

The COVID-19 pandemic impacted the transmission of many pathogens. The aim was to determine the effect of non-pharmaceutical interventions on the incidence of diseases transmitted via food. Weekly incidence rates for nine foodborne pathogens were collected from national surveillance registries. Weekly pathogen incidence during lockdown weeks of 202...

On 6 April 2022, the Public Health Service of Kennemerland, the Netherlands, was notified about an outbreak of fever and abdominal complaints on a retired river cruise ship, used as shelter for asylum seekers. The diagnosis typhoid fever was confirmed on 7 April. An extensive outbreak investigation was performed. Within 47 days, 72 typhoid fever ca...

Listeria monocytogenes (Lm) is ubiquitous in nature and known for its ability to contaminate foods during production processes. Near real-time monitoring of whole genome sequences from food and human isolates, complemented with epidemiological data, has been used in the Netherlands since 2019 to increase the speed and success rate of source finding...

A third nationally-representative serosurvey was performed to study the changes in Toxoplasma gondii (T. gondii) seroprevalence in the Netherlands over a 20-year timespan, and to identify and confirm risk factors for acquired toxoplasmosis. This cross-sectional study (conducted in 2016/2017) was designed similarly to the previous two studies (1995...

We provide incidences (cases/10 million persons) in the Netherlands during 2009-2019 for pathogens listed as potential bioterrorism agents. We included pathogens from the highest categories of the European Medicines Agency or the US Centers for Disease Control and Prevention. Notifiable diseases and recently published data were used to calculate th...

Toxoplasmosis caused by the protozoan parasite Toxoplasma gondii occurs worldwide. Infections range from asymptomatic to life-threatening. T. gondii infection is acquired either via bradyzoites in meat or via oocysts in the environment, but the relative importance of these path ways and the different sources remains unclear. In this study, possible...

Introduction Listeriosis, caused by infection with Listeria monocytogenes (Lm), is a relatively rare but severe disease with one of the highest mortality rates among bacterial foodborne illnesses. A better understanding on the degree of Lm clustering, the temporal distribution of the clusters, and their association with the various food sources is...

[This corrects the article DOI: 10.1016/j.lanepe.2021.100142.].

In early May 2022, a global outbreak of mpox started among persons without travel history to regions known to be enzootic for monkeypox virus (MPXV). On 8 August 2022, the Netherlands reported its 1,000th mpox case, representing a cumulative incidence of 55 per million population, one of the highest cumulative incidences worldwide. We describe char...

In early May 2022 a global outbreak of monkeypox (MPX) started among persons without a travel history to regions known to be enzootic for monkeypox-virus. On August 8 2022, the Netherlands reported its 1000 th monkeypox case representing a cumulative incidence of 55 per million population, one of the highest cumulative incidences worldwide. Here we...

We describe the recent detection of 3 Shiga toxin-producing enteroaggregative Escherichia coli O104:H4 isolates from patients and 1 from pork in the Netherlands that were genetically highly similar to isolates from the 2011 large-scale outbreak in Europe. Our findings stress the importance of safeguarding food supply production chains to prevent fu...

Background A wide variety of pathogens can cause disease in humans via consumption of contaminated food. Although food-borne outbreaks only account for a small part of the food-borne disease burden, outbreak surveillance can provide insights about the pathogens, food products implied as vehicle, points of contamination, and the settings in which tr...

Consumer purchase data (CPD) can be a powerful tool in the investigation of foodborne outbreaks through analyses of electronic records of food that individuals buy. The objective of this study was to develop a common framework for use of CPD in foodborne outbreak investigations using the expertise of European public health professionals from 11 Eur...

Objectives We aimed to identify populations at a high risk for SARS-CoV-2 infection but who are less likely to present for testing, by determining which sociodemographic and household factors are associated with a lower propensity to be tested and, if tested, with a higher risk of a positive test result. Design and setting Internet-based participa...

Background Voluntary testing for SARS-CoV-2 infection is an integral component of an effective response to the COVID-19 pandemic. It is essential to identify populations at a high risk for infection but who are less likely to present for testing. Here, we use internet-based participatory surveillance data from the Netherlands to identify sociodemog...

During the first wave of the SARS-CoV-2 epidemic in the Netherlands, notifications consisted mostly of patients with relatively severe disease. To enable real-time monitoring of the incidence of mild COVID-19 - for which medical consultation might not be required - the Infectieradar web-based syndromic surveillance system was launched in mid-March...

Background Concerns about long-lasting symptoms attributed to Lyme borreliosis (LB) are widespread in the Western world, while such symptoms are highly prevalent in the general population. Methods In the largest prospective study to date, adults with physician-confirmed LB were included at the start of antibiotic treatment. Primary outcomes, preva...

We describe the consequences of 2 major changes in notification criteria for Shiga toxin–producing Escherichia coli surveillance in the Netherlands. The change to reporting acute, more severe infections appears to be a good compromise between workload, redundancy, and public health relevance, provided isolates remain available for typing and sequen...

Whole genome sequencing (WGS) is increasingly used by food regulatory agencies and public health institutes. It is a powerful tool to identify the source of a foodborne outbreak. Real-time WGS analysis helps to act fast during a foodborne outbreak, and with that the impact of an outbreak can be significantly decreased. In The Netherlands real-time...

Objective: To determine whether children play a role in the transmission of SARS-CoV-2 to other children and adults, and to gain insight into symptomatic and asymptomatic infections in children. Design: Analysis of national COVID-19 notifications and prospective observational study in families with children. Method: Information about COVID-19...

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...

Background: Shigella spp. and entero-invasive E. coli (EIEC) use the same invasive mechanism to cause diarrheal diseases. Public health regulations apply only to Shigella spp. infections, but are hampered by the lack of simple methods to distinguish them from EIEC. In the last decades, molecular methods for detecting Shigella spp. and EIEC were im...

Background: Shigella spp. and entero-invasive E. coli (EIEC) use the same invasive mechanism to cause diarrheal diseases. Public health regulations apply only to Shigella spp. infections, but are hampered by the lack of simple methods to distinguish them from EIEC. In the last decades, molecular methods for detecting Shigella spp. and EIEC were imp...

Background: Shigella spp. and entero-invasive E. coli (EIEC) use the same invasive mechanism to cause diarrheal diseases. Public health regulations apply only to Shigella spp. infections, but are hampered by the lack of simple methods to distinguish them from EIEC. In the last decades, molecular methods for detecting Shigella spp. and EIEC were imp...

Background Shigella spp. and entero-invasive E. coli (EIEC) use the same invasive mechanism to cause diarrheal diseases. Public health regulations apply only to Shigella spp. infections, but are hampered by the lack of simple methods to distinguish them from EIEC. In the last decades, molecular methods for detecting Shigella spp. and EIEC were impl...

Background Shigella spp. and entero-invasive E. coli (EIEC) use the same invasive mechanism to cause diarrheal diseases. Public health regulations apply only to Shigella spp. infections, but are hampered by the lack of simple methods to distinguish them from EIEC. In the last decades, molecular methods for detecting Shigella spp. and EIEC were impl...

Background Salmonella spp are a major cause of food-borne outbreaks in Europe. We investigated a large multi-country outbreak of Salmonella enterica serotype Enteritidis in the EU and European Economic Area (EEA). Methods A confirmed case was defined as a laboratory-confirmed infection with the outbreak strains of S Enteritidis based on whole-geno...

Background Wild birds, in particular pigeons are considered a natural reservoir for stx2f-carrying E. coli. An extensive comparison of isolates from pigeons and humans from the same region is lacking, which hampers justifiable conclusions on the epidemiology of these pathogens. Over two hundred human and pigeon stx2f-carrying E. coli isolates predo...

Background: Shiga toxin-producing Escherchia coli O157:H7 is a zoonotic pathogen which causes numerous food and waterborne disease outbreaks. It is globally distributed but its origin and temporal sequence of geographical spread is unknown. Methods: We analysed Whole Genome Sequencing data of 757 isolates from 4 continents and performed a pan ge...

This study describes an outbreak investigation of 14 hepatitis A cases in the Netherlands. The hepatitis A virus (HAV) genotype IB sequences in cases were highly similar (459/460 nt). The origin of strains could be narrowed to Bulgaria based on information from EPIS-FWD. As an association with consumption of soft fruit was suspected, a case–control...

Union (EU) and European Economic Area countries reported 4,096 cases associated with a multi-country hepatitis A (HA) outbreak. Molecular analysis identified three co-circulating hepatitis A virus (HAV) strains of genotype IA: VRD_521_2016, V16-25801 and RIVM-HAV16-090. We categorised cases as confirmed, probable or possible, according to the EU ou...

Introduction. On 23 October 2015, six related cases with gastroenteritis called the Netherlands Food and Consumer Product Safety Authority. They suspected filet américain, a raw beef spread, to be the source of infection. Leftovers and stool samples tested positive for Salmonella Typhimurium. Multiple locus variable-number of tandem repeat analysis...

From January to June 2018, two ongoing hepatitis A outbreaks affected travellers returning from Morocco and cases in Europe without travel history, resulting in 163 patients in eight European countries. Most interviewed travel-related cases were unaware of the hepatitis A risk in Morocco. Molecular analysis revealed two distinct hepatitis A virus (...

Since 2015, outbreaks of hepatitis A among men who have sex with men (MSM) have been reported worldwide. To examine the impact of these MSM outbreaks in the Netherlands, we combined notification and epidemiological data with sequence analysis. Our results show the hazards of outbreaks within risk-groups spilling over into the largely susceptible ge...

Background Travel to countries with high or intermediate hepatitis A virus (HAV) endemicity is a risk factor for infection in residents of countries with low HAV endemicity. Aim: The objective of this study was to estimate the risk for hepatitis A among European travellers using surveillance and travel denominator data. Methods: We retrieved hepati...

Aims: Seoul orthohantavirus (SEOV) and Leptospira spp. are zoonotic pathogens with rats as main reservoir. Recently, the presence of SEOV in brown rats was reported in one region in the Netherlands. Brown rats are a frequent bycatch in traps placed to catch muskrats (Ondatra zibethicus) and coypus (Myocastor coypus), and thus are a potential health...

Background: We aimed to estimate population-level exposure to Campylobacter and associated risk factors, using three approaches for serological data analysis. Methods: Nationwide, population-based serosurvey in the Netherlands (Feb2006-Jun2007). Anti-Campylobacter IgG, IgM and IgA were measured using ELISA, and analysed via: a) seroincidence est...

Poultry meat is an important source of foodborne infections. Safe food-handling could lower the number of infections. Since 2001, a label containing safe food-handling instructions is required on the retail packages of raw poultry in the Netherlands. The aim was to determine the impact of this label on risk perception and food-handling behavior. A...

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern whose sources and transmission routes are difficult to trace. Using a combined source attribution and case–control analysis, we determined the relative contributions of four putative livestock sources (cattle, small ruminants, pigs, poultry) to human STEC...

The Ministry of VWS has requested RIVM to present an annual update on the number of illnesses, disease burden and cost-of-illness caused by 14 enteric pathogens. These pathogens can be transmitted by food, the environment, animals and humans. The disease burden is expressed in DALYs (Disability Adjusted Life Years), a metric integrating morbidity a...

Trends in reports of shigellosis in the Netherlands, 1988-2015; Increased reports of shigellosis among males having sex with males.

The Netherlands Early Warning Committee (NEWC) aims to identify infectious diseases causing a potential threat to Dutch public health. Threats are assessed and published as (information) alerts for public health experts. To identify threats from abroad, the NEWC screens 10 sources reporting disease outbreaks each week. To identify the sources essen...

A multi-country outbreak of Salmonella Enteritidis phage type (PT) 8 with multiple locus variable-number tandem repeat analysis (MLVA) profiles 2-9-7-3-2 and 2-9-6-3-2, linked to eggs, is ongoing in the EU/EEA. Based on whole genome sequencing (WGS), isolates are part of two distinct but related genetic clusters. ECDC and EFSA are liaising with rel...

Between July 2016 and February 2017, 48 male cases of hepatitis A were notified in the Netherlands. Of these, 17 identified as men who have sex with men (MSM). Ten of the 13 cases for whom sequencing information was available, were infected with a strain linked with the EuroPride that took place in Amsterdam in 2016. This strain is identical to a s...

Between 2014 and 2015, the European Centre for Disease Prevention and Control was informed of an increase in numbers of Salmonellaenterica serotype Chester cases with travel to Morocco occurring in six European countries. Epidemiological and microbiological investigations were conducted. In addition to gathering information on the characteristics o...

Between 2014 and 2015, the European Centre for Disease Prevention and Control was informed of an increase in numbers of Salmonellaenterica serotype Chester cases with travel to Morocco occurring in six European countries. Epidemiological and microbiological investigations were conducted. In addition to gathering information on the characteristics o...

Zoonotic Diseases Report 2015 Zoonoses are infectious diseases that can be transmitted from animals to humans. The zoonoses that play a role in the Netherlands are listed annually in the Zoonotic Diseases Report, in this case for the year 2015. This report also contains a summary of the degree in which notifiable zoonoses occur in animals and in hu...

Background: In 2012, the Netherlands experienced the most extensive food-related outbreak of Salmonella ever recorded. It was caused by smoked salmon contaminated with Salmonella Thompson during processing. In total, 1149 cases of salmonellosis were laboratory confirmed and reported to RIVM. Twenty percent of cases was hospitalised and four cases...

From 1 May 2016 to 12 October 2016, seven EU/EEA countries have reported 112 confirmed cases and 148 probable cases of Salmonella Enteriditis. This document assesses the risk associated with this multi-country outbreak of Salmonella Enteritidis PT 8 associated with two MLVA types, initially confirmed and delineated by whole genome sequencing method...

Voedselgerelateerde ziekten leiden wereldwijd tot aanzienlijke ziektelast. In Nederland wordt het aantal patiënten geschat op ongeveer 700.000 mensen per jaar. Dit aantal is mede gebaseerd op de geregistreerde aantallen zieken binnen onder andere de meldingsplicht en laboratoriumsurveillance. Door surveillance en meldingsplicht van voedselgerelatee...

De surveillance van shigatoxineproducerende Escherichia coli (STEC) in Nederland is in 1999 gestart met de meldingen van STEC O157-infecties. In 2007 zijn STEC non-O157-infecties hieraan toegevoegd, hoewel de surveillance op deze groep niet volledig landelijk dekkend is. Om mogelijke infectiebronnen vast te stellen onderzoekt de Nederlandse Voedsel...

Incidence of food-related outbreaks in the Netherlands, 2015 In 2015 more outbreaks of food-borne infections were registered in the Netherlands than in previous years. This increase is largely caused by the fact that all non-anonymous reports to the Food and Consumer Product Safety Authority (NVWA) of outbreaks (i.e. two or more persons affected) h...

Het bepalen van de ziektelast veroorzaakt door consumptie van met ziekteverwekkers besmette levensmiddelen is lastig. Naast de verscheidenheid aan micro-organismen, kunnen deze micro-organismen via meer transmissieroutes dan alleen voedsel de mens besmetten. Door surveillance van voedselgerelateerde uitbraken en ziekte door specifieke micro-organis...

This report describes an outbreak investigation starting with two closely related suspected food-borne clusters of Dutch hepatitis A cases, nine primary cases in total, with an unknown source in the Netherlands. The hepatitis A virus (HAV) genotype IA sequences of both clusters were highly similar (459/460 nt) and were not reported earlier. Food qu...

Extreme rainfall events may cause pluvial flooding, increasing the transmission of several waterborne pathogens. However, the risk of experiencing clinically overt infections following exposure to pluvial floodwater is poorly estimated. A retrospective cross-sectional survey was performed to quantify the occurrence of self-reported gastrointestinal...

Registry data of food-borne infections and food poisoning in the Netherlands in 2014. In 2014 there were fewer outbreaks of food-borne infections and food poisoning in the Netherlands than in previous years. However, due to a rise in the number of affected individuals per reported outbreak, the total number of sick persons increased by 13 percent c...

Although the disease burden of listeriosis on population level is low, on individual level the impact is high, largely due to severe illness and a high case fatality. Identification of risk factors supports and specifies public health actions needed for prevention. We performed a case–control study to determine host- and food-related risk factors f...

During 2008 to 2013, 215 outbreak alerts, also known as ‘urgent inquiries’ (UI), for food- and waterborne diseases were launched in Europe, the majority of them (135; 63%) being related to salmonellosis. For 110 (51%) UI, a potential food vehicle of infection was identified, with vegetables being the most reported category (34; 31%). A total of 28%...

Zowel de Nederlandse Voedsel en Waren Autoriteit (NVWA) als de GGD’en onderzoeken en registreren uitbraken van voedselinfecties en –vergiftigingen, elk vanuit het eigen werkveld. Dit is het eerste jaar dat de meldingen uit beide registraties zijn samengevoegd en als één besproken worden. Deze nieuwe aanpak zorgt voor een betere integratie van de ge...

Shiga toxin-producing Escherichia coli (STEC) infections have been associated with severe illness. Ruminants are seen as the main reservoir and the major transmission route is considered to be foodborne. In The Netherlands, a case-control study was conducted, using data collected during 2008–2012. Patients were interviewed and controls completed a...

Voedselinfecties zijn een belangrijke oorzaak van ziekte. Door de verschillende ziekteverwekkers met elkaar te vergelijken met betrekking tot ziektelast en ziekte-gerelateerd kosten kunnen beleidsprioriteiten aangemerkt worden en kan onderzoek naar interventiemogelijkheden worden gestart. Sinds 2009 schat het RIVM jaarlijks de ziektelast van 14 voe...

On 15 August 2012, an increase in the number of Salmonella Thompson cases was noticed by the Salmonella surveillance in the Netherlands. A case– control study was performed, followed by a food investigation. In total 1,149 cases were laboratory-confirmed between August and December 2012 of which four elderly (76–91 years) were reported to have died...

On 15 August 2012, an increase in the number of Salmonella Thompson cases was noticed by the Salmonella surveillance in the Netherlands. A case-control study was performed, followed by a food investigation. In total 1,149 cases were laboratory-confirmed between August and December 2012 of which four elderly (76-91 years) were reported to have died...

Shiga toxin-producing Escherichia coli (STEC) infections have been associated with severe illness. Ruminants are seen as the main reservoir and the major transmission route is considered to be foodborne. In The Netherlands, a case-control study was conducted, using data collected during 2008–2012. Patients were interviewed and controls completed a...

Background: Public health surveillance is an important tool for monitoring cases of infectious diseases. Identification of risk factors requires the comparison of exposure between cases and controls. However, standard surveillance systems do not routinely collect information on controls. Methods: Since 2008, we have extended the surveillance of...

Infection rates of Ixodes ricinus ticks with Borrelia miyamotoi and B. burgdorferi

The Shiga toxins of Shiga toxin-producing Escherichia coli (STEC) can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) with several sub-variants. Variant Stx2f is one of the latest described, but has been rarely associated with symptomatic human infections. In the enhanced STEC surveillance in the Netherlands, 198 STEC O157 cases and 3...