Publications by authors named "Henriette de Valk"

Article Synopsis
  • In European France, malaria cases are primarily travel-related, but locally acquired cases are monitored to assess the risk of re-emergence.
  • A study analyzed malaria cases from 1995 to 2022, identifying transmission modes and species involved, which mostly occurred in the Île-de-France region.
  • The findings revealed 117 local cases, predominantly classified as Odyssean malaria, with a need for increased vigilance due to potential re-emergence linked to climate change and local mosquito populations.
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BackgroundWastewater surveillance is an effective approach to monitor population health, as exemplified by its role throughout the COVID-19 pandemic.AimThis study explores the possibility of extending wastewater surveillance to the Paris 2024 Olympic and Paralympic Games, focusing on identifying priority pathogen targets that are relevant and feasible to monitor in wastewater for these events.MethodsA list of 60 pathogens of interest for general public health surveillance for the Games was compiled.

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Objectives: The aim was to estimate the effect of reported history of smallpox vaccination prior to 1980 on clinical expression of mpox.

Methods: We included all confirmed mpox cases identified by the national mpox surveillance system in France between May and July 2022. Cases tested positive for monkeypox virus or orthopoxviruses by PCR.

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Article Synopsis
  • The mpox epidemic in France, which saw an increase in locally-acquired cases starting in May 2022, was analyzed through data collected until September 2022.
  • A total of 4,856 cases were reported, primarily affecting male individuals aged 15 and older, with specific demographic changes noted over the summer months.
  • The study observed a decline in the number of cases attending men-who-have-sex-with-men (MSM) venues and a reduction in sexual partners, which may reflect shifts in behavior and virus transmission dynamics.
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We developed mathematical models to analyze a large dengue virus (DENV) epidemic in Reunion Island in 2018-2019. Our models captured major drivers of uncertainty including the complex relationship between climate and DENV transmission, temperature trends, and underreporting. Early assessment correctly concluded that persistence of DENV transmission during the austral winter 2018 was likely and that the second epidemic wave would be larger than the first one.

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  • Serological testing for Lyme borreliosis (LB) in patients with erythema migrans (EM) is not advised per European guidelines, prompting a study on French general practitioners' (GPs) adherence to these recommendations.
  • The study included 1,831 EM cases and found that only 24.0% resulted in a serological test prescription, showing a significant decline from 46.8% in 2009 to 15.8% in 2020.
  • Key factors leading to serological test prescriptions included the absence of a reported tick bite, presence of multiple EM lesions, larger EM size, and GPs who diagnosed fewer than one EM case per year, indicating a
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BackgroundLyme borreliosis (LB) is the most common tick-borne disease (TBD) in France. Forestry workers are at high risk of TBD because of frequent exposure to tick bites.AimWe aimed to estimate the seroprevalence of sensu lato and tick-borne encephalitis virus (TBEV) antibodies among forestry workers in northern France.

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Chikungunya is an arboviral disease causing arthralgia which may develop into a debilitating chronic arthritis. In Mayotte, a French overseas department in the Indian Ocean, a chikungunya outbreak was reported in 2006, affecting a third of the population. We aimed at assessing the chikungunya seroprevalence in this population, after over a decade from that epidemic.

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  • A study was conducted to estimate the prevalence of Puumala virus (PUUV) among 1777 forestry workers in northern France, focusing on sociodemographic risk factors.
  • The research found an overall seroprevalence of 5% in northeastern France, with a notable absence of cases in northwestern France, suggesting regional differences in virus circulation.
  • Age, sex, and years of experience in forestry were identified as factors linked to increased seropositivity, indicating that even non-endemic regions may have low levels of PUUV circulation.
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BackgroundTravellers are generally considered good sentinels for infectious disease surveillance.AimTo investigate whether health data from travellers arriving from Africa to Europe could provide evidence to support surveillance systems in Africa.MethodsWe examined disease occurrence and estimated risk of infection among travellers arriving from Africa to Europe from 2015 to 2019 using surveillance data of arthropod-borne disease cases collected through The European Surveillance System (TESSy) and flight passenger volumes from the International Air Transport Association.

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Since the start of the COVID-19 pandemic, French health authorities have encouraged barrier measures and implemented three lockdowns to slow SARS-CoV-2 transmission. We aimed to examine the impact of these measures on the epidemiology of acute gastroenteritis (AGE) in France, from November 2019 to August 2021. We describe trends in AGE indicators from syndromic surveillance and a sentinel surveillance network.

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An extensive multi-country outbreak of multidrug-resistant monophasic Typhimurium infection in 10 countries with 150 reported cases, predominantly affecting young children, has been linked to chocolate products produced by a large multinational company. Extensive withdrawals and recalls of multiple product lines have been undertaken. With Easter approaching, widespread product distribution and the vulnerability of the affected population, early and effective real-time sharing of microbiological and epidemiological information has been of critical importance in effectively managing this serious food-borne incident.

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Article Synopsis
  • Viruses spread by Aedes mosquitoes have recently increased their global range, posing significant public health risks, especially in Europe.
  • A mathematical model was created to analyze chikungunya virus transmission using data from outbreaks in Southern France, allowing predictions about future transmission dynamics based on response times and virus introduction timing.
  • Simulation outcomes highlight the critical role of early detection of cases and efficient vector control strategies to strengthen public health interventions and surveillance systems.
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BackgroundDengue is a disease with major impacts on public health in tropical and subtropical countries. In Europe, in the past decade, few autochthonous outbreaks were described.AimWe aimed to identify factors associated with frequency of dengue virus infection among European travellers and at assessing how surveillance data could support preparedness against autochthonous outbreaks within Europe.

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  • Lyme borreliosis (LB) is the most common tick-borne disease in France, and since there’s no vaccine, the focus is on preventing tick bites, reinforced by a national health plan launched in 2016.
  • A comparison of national surveys from 2016 and 2019 shows an increase in both the reported lifetime tick bites from 25% to 30% and awareness of LB and its preventive measures among the French population.
  • The findings suggest that although tick exposure remains significant, more people are taking protective measures against tick bites and have better knowledge about LB, indicating an overall improvement in public awareness over the three years.
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BackgroundToxoplasmosis during pregnancy can result in congenital anomalies or fetal death. Universal antenatal screening is recommended in France, a strategy in place since the 1970s.AimWe determined the seroprevalence of toxoplasmosis among pregnant women participating in the 2016 national perinatal survey (ENP), compared results with previous ENPs, and investigated factors associated with infection.

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Article Synopsis
  • - The spread of the Aedes albopictus mosquito has increased the risk of dengue and chikungunya virus transmission in Southern Europe, necessitating better understanding of the factors contributing to this emergence for effective public health strategies
  • - Analysis of data from Southern France (2010-2018) revealed that a long reporting delay of over 21 days for imported cases was a key factor in local transmission, along with environmental factors like proximity to wooded areas and seasonal heat accumulation
  • - The findings emphasize the need for timely reporting and surveillance systems and can guide policy-makers in addressing emerging threats from these viruses, as well as others like Zika and yellow fever that share the same mosquito vector
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On 27 December 2019, the French Public Health Agency identified a large increase in the number of acute gastroenteritis and vomiting visits, both in emergency departments and in emergency general practitioners' associations providing house-calls. In parallel, on 26 and 27 December, an unusual number of food-borne events suspected to be linked to the consumption of raw shellfish were reported through the mandatory reporting surveillance system. This paper describes these concomitant outbreaks and the investigations' results.

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On 1 October 2019, a locally-acquired Zika virus disease case was laboratory confirmed in Hyères, Var department. Active case finding identified two additional locally-acquired cases living within 90 m, with symptom onset 8 days before the index case. Extensive patient interviews did not yield information supporting transmission through sexual contact or substances of human origin.

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We report an outbreak of Shiga toxin-producing (STEC) associated paediatric haemolytic uraemic syndrome linked to the consumption of raw cow's milk soft cheeses. From 25 March to 27 May 2019, 16 outbreak cases infected with STEC O26 (median age: 22 months) were identified. Interviews and trace-back investigations using loyalty cards identified the consumption of raw milk cheeses from a single producer.

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We describe a Poona outbreak involving 31 infant cases in France. Following outbreak detection on 18 January 2019, consumption of rice-based infant formula manufactured at a facility in Spain was identified as the probable cause, leading to a recall on 24 January. Whole genome sequencing analysis linked present outbreak isolates to a 2010-11 Poona outbreak in Spain associated with formula manufactured in the same facility, indicating a persistent source of contamination.

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IntroductionHaemolytic uraemic syndrome (HUS) related to Shiga toxin-producing (STEC) is the leading cause of acute renal failure in young children. In France, HUS surveillance in children aged < 15 years was implemented starting from 1996.AimWe present the results of this surveillance between 2007 and 2016.

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To generate hypotheses on possible sources of Shiga toxin-producing Escherichia coli (STEC) serogroup O80 associated hemolytic-uremic syndrome (HUS), we explored differences in factors associated with STEC O80 associated HUS, compared with STEC O157 or STEC of other serogroups, in France during 2013-16. STEC was isolated from 153/521 (30%) reported HUS cases: 45 serogroup O80, 46 O157 and 62 other serogroups. Median ages were 1.

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Objectives: Hepatitis E virus (HEV) is a major cause of acute hepatitis worldwide. However, our understanding of the source of contamination is incomplete and the frequency of neurological manifestations in still unknown.

Methods: 200 eligible cases reported to the French National Reference Center from January 2015 to December 2015 were prospectively included in this case-control study (1 case: 1 control, matched for sex, age and area of living) to investigate the risk of infection.

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