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The leading cause of hemolytic uremic syndrome (HUS) in children is Shiga toxin-producing Escherichia coli (STEC) infection, which has a major outbreak potential. Since the early 2010s, STEC epidemiology is characterized by a decline of the historically predominant O157 serogroup and the emergence of non-O157 STEC, especially O26 and O80 in France. STEC contamination occurs through the ingestion of contaminated food or water, person-to-person transmission, or contact with ruminants or their contaminated environment. The main symptom is diarrhea, which is bloody in about 60% of patients and occurs after a median incubation period of three days. Shiga toxins released by STEC induce a cascade of thrombogenic and inflammatory changes of microvascular endothelial cells. HUS is observed in 5-15% of STEC infection cases, defined by the triad of mechanical hemolytic anemia, thrombocytopenia, and acute renal injury. The diagnosis of STEC infection relies on biological screening for Shiga toxins and STEC in stools and serology. Treatment of STEC-HUS is mainly symptomatic, as no specific drug has proved effective. The effect of antibiotics in STEC infection and STEC-HUS remains debated; however, some bacteriostatic antibiotics might have a beneficial effect. Proofs of evidence of a benefit from complement blockade therapy in STEC-HUS are also lacking. Clinical and bacteriological STEC-HUS surveillance needs to be continued. Ongoing prospective studies will document the role of bacteriostatic antibiotics in STEC infection and STEC-HUS, and of complement blockade therapy in STEC-HUS.

Objective: Aging societies will bring an increase in the number of long-term care residents with mental-physical multimorbidity. To optimize care for these residents, it is important to study their care needs, since unmet needs lower quality of life. To date, knowledge about care needs of residents with mental-physical multimorbidity is limited. The aim of this study was to explore (un)met care needs of residents with mental-physical multimorbidity and determinants of unmet needs.Methods: Cross-sectional cohort study among 141 residents with mental-physical multimorbidity without dementia living in 17 geronto-psychiatric nursing home units across the Netherlands. Data collection consisted of chart review, semi-structured interviews, (brief) neuropsychological testing, and self-report questionnaires. The Camberwell Assessment of Need for the Elderly (CANE) was used to rate (un)met care needs from residents' and nursing staff's perceptions. Descriptive and multivariate regression analyses were conducted.Results: Residents reported a mean number of 11.89 needs (SD 2.88) of which 24.2% (n = 2.88, SD 2.48) were unmet. Nursing staff indicated a mean number of 14.73 needs (SD 2.32) of which 10.8% (n = 1.59, SD 1.61) were unmet. According to the residents, most unmet needs were found in the social domain as opposed to the psychological domain as reported by the nursing staff. Different opinions between resident and nursing staff about unmet needs was most common in the areas accommodation, company, and daytime activities. Further, nearly half of the residents indicated 'no need' regarding behavior while the nursing staff supposed that the resident did require some kind of support. Depression, anxiety and less care dependency were the most important determinants of unmet needs.Conclusions: Systematic assessment of care needs showed differences between the perspectives of resident and nursing staff. These should be the starting point of a dialogue between them about needs, wishes and expectations regarding care. This dialogue can subsequently lead to the most optimal individually tailored care plan. To achieve this, nurses with effective communication and negotiation skills, are indispensable.

Introduction La borreliose de Lyme (BL) est la maladie vectorielle transmise par les tiques la plus frequente en France. En l’absence de vaccin, la prevention individuelle contre les piqures de tiques est le seul moyen pour en reduire la transmission. En 2016, un plan national de lutte contre les maladies transmises par les tiques a ete lance par le Ministere de la Sante, incluant l’amelioration de la prevention contre les piqures de tiques. Materiels et methodes Pour evaluer l’impact des campagnes de prevention, nous avons analyse la connaissance de la population francaise sur la BL et la prevention contre les piqures de tiques a partir des Barometre de Sante publique France 2016 et 2019. Ces deux enquetes realisees par telephone ont respectivement interrogees 14 875 et 9 611 personnes âgees de 18 a 75 ans vivant en France metropolitaine sur leurs expositions aux piqures de tiques, leurs comportements et pratiques de prevention vis-a-vis des piqures de tiques et leurs connaissances sur la BL. Pour les analyses, nous avons defini des regions de haute, moyenne et basse incidence a partir du niveau d’incidence estime par un reseau sentinelle de medecins generalistes (> 100 cas pour 100 000 habitants, entre 50 et 100 et inferieur a 50). Resultats En 2019, 30 % de la population a ete piquee par une tique au cours de la vie et 6 % au cours des 12 derniers mois. Ces proportions etaient respectivement de 25 % et 4 % en 2016 (p Conclusion Une proportion importante de la population se sent exposee aux piqures de tiques et applique les mesures de prevention. Une augmentation des connaissances et de l’application des mesures de prevention a ete observee entre 2016 et 2019. Ces resultats permettront de cibler les futures campagnes de prevention aupres de certaines tranches d’âge ou regions plus a risque. Les barrieres a l’utilisation des moyens de prevention necessiteraient neanmoins d’etre etudiees pour adapter au mieux les messages de prevention.

Objective: Aging societies will bring an increase in the number of long-term care patients with mental-physical multimorbidity (MPM). This paper aimed to describe the natural course of neuropsychiatric symptoms (NPS) in patients with MPM in the first 8 months after admission to a geronto-psychiatric nursing home (GP-NH) unit. Methods: Longitudinal cohort study among 63 patients with MPM no dementia living in 17 GP-NH units across the Netherlands. Data collection consisted of chart review, semi-structured interviews, and brief neuropsychological testing, among which our primary outcome measure the Neuropsychiatric Inventory (NPI). Descriptive and bivariate analyses were conducted. Results: Our study showed a significant increase of the NPI total score (from 25.3 to 29.3, p = 0.045), and the total scores of a NPI hyperactivity cluster (from 9.7 to 11.8, p = 0.039), and a NPI mood/apathy cluster (from 7.7 to 10.1, p = 0.008). Just over 95% had any clinically relevant symptom at baseline and/or six months later, of which irritability was the most prevalent and persistent symptom and the symptom with the highest incidence. Hyperactivity was the most prevalent and persistent symptom cluster. Also, depression had a high persistence. Conclusions: Our results indicate the omnipresence of NPS of which most were found to be persistent. Therefore, we recommend to explore opportunities to reduce NPS in NH patients with MPM, such as creating a therapeutic milieu, educating the staff, and evaluating patient's psychotropic drug use.

Issue/Problem Waterborne disease outbreaks (WBDOs) remain a public health issue in developed countries, but to date the surveillance of WBDOs in France, mainly based on the voluntary reporting of clusters of acute gastrointestinal infections (AGIs) by general practitioners to health authorities, is characterized by low sensitivity. In this context an integrated and automatized approach to detect WBDO relying on the identification of clusters of medicalized AGI cases sharing a same drinking water networks (DWN) was developed, evaluated in a simulation study and tested in a pilot study by the French National Public Health Agency. Description of the problem Two national big databases support the detection process of potential WBDO: health insurance database for AGI, ministry of health database for drinking water system information. Each detected outbreak has to be investigated regarding environmental criteria during the days before the onset of the outbreak: results on bacterial water monitoring, weather (e.g. heavy rain), technical incidents in the drinking water system (e.g. chlorination breakdown, alarm malfunction). To evaluate the strength of association with drinking water, four levels are proposed based on epidemiological and environmental criteria (strong, probable, possible and undetermined). Results The WBDO surveillance system has been implemented in all french departments since start of 2019 and support by the ministry of health. A web-application, named “EpiGEH”, was also developed to support the surveillance system. A retrospective study between 2010 and 2017 has detected almost 300 to 550 potential WBDO per year while voluntary reporting identified 2 to 3 WBDO each year during the same period. Lessons Such a specific surveillance system should help health authorities to formulate recommendations regarding the management of drinking water systems and propose appropriate preventive measures, in accordance with the water safety plans. Key messages The WBDO surveillance system based from health insurance databases constitutes a daily surveillance system of drinking water quality. The WBDO surveillance system should drastically improve the detection sensitivity by a factor 100 to 200 compared to voluntary reporting.

Background: Lyme borreliosis (LB) is the most frequent vector-borne disease in France. Since 2009, surveillance of LB is conducted by a sentinel network of general practitioners (GPs). This system, in conjunction with the national hospitalisation database was used to estimate the incidence and describe the characteristics of LB in France. Aim: To describe the estimated incidence and trends in GP consultations and hospital admissions for LB in France and identify risk groups and high-incidence regions. Results: From 2011 to 2016, the mean yearly incidence rate of LB cases was 53 per 100,000 inhabitants (95% CI: 41–65) ranging from 41 in 2011 to 84 per 100 000 in 2016. A mean of 799 cases per year were hospitalised with LB associated diagnoses 2005–16. The hospitalisation incidence rate (HIR) ranged from 1.1 cases per 100,000 inhabitants in 2005 to 1.5 in 2011 with no statistically significant trend. We observed seasonality with a peak during the summer, important inter-regional variations and a bimodal age distribution in LB incidence and HIR with higher incidence between 5 and 9 year olds and those aged 60 years. Erythema migrans affected 633/667 (95%) of the patients at primary care level. Among hospitalised cases, the most common manifestation was neuroborreliosis 4,906/9,594 (51%). Conclusion: Public health strategies should focus on high-incidence age groups and regions during the months with the highest incidences and should emphasise prevention measures such as regular tick checks after exposure and prompt removal to avoid infection.

Introduction L’implantation de l’Aedes albopictus, vecteur des virus de la dengue, du chikungunya et du zika, a rapidement progresse en France metropolitaine exposant de plus en plus de personnes au risque de transmission autochtone de ces arbovirus. Une surveillance renforcee est active depuis 2006 en France ou le vecteur est implante. La notification de cas entraine des investigations epidemiologiques et des mesures de lutte anti-vectorielle (LAV) visant a prevenir l’apparition de cas autochtones. Materiels et methodes Nous avons decrit les transmissions autochtones de ces arboviroses survenues en France metropolitaine entre 2006 et 2019, a partir des publications et documents d’investigation produits. Resultats Onze episodes de dengue (23 cas), trois de chikungunya (31 cas), et un de zika (3 cas) ont ete recenses, tous dans les territoires et pendant les periodes ou la densite vectorielle etait la plus importante. Les zones de circulation virale etaient limitees (rayon inferieur a 300 metres) et composaient essentiellement d’habitat individuel pavillonnaire. Les serotypes 1 et 2 pour la dengue, le lignage East Central South Africa pour le chikungunya, et un lignage asiatique pour le zika, etaient a l’origine des transmissions autochtones. Les mesures de lutte anti-vectorielle (LAV) ont ete efficaces : un seul des 57 cas autochtones est apparu apres leur mise en place. La survenue de neuf episodes etait due a un defaut d’identification du cas primaire importe, et pour six a une absence, ou a une insuffisance, des actions de LAV autour du cas primaire importe. Conclusion La transmission d’arbovirus en France metropolitaine est frequente et illustre le risque en Europe. Le dispositif de surveillance epidemiologique et les investigations menees autour des cas autochtones ont montre leur efficacite. Neanmoins, l’experience acquise et les causes d’emergences font ressortir des besoins d’evolution de cette surveillance et la sensibilisation des professionnels de sante doit etre renforcee.

Introduction Le virus zika (ZIKV) est un flavivirus. Du fait de l’implantation de l’Aedes albopictus, les infections a ZIKV, comme la dengue et le chikungunya, sont sous surveillance renforcee en France metropolitaine. La notification de cas entraine des investigations epidemiologiques et des mesures de lutte anti-vectorielle (LAV) visant a prevenir l’apparition de cas autochtones. En 2019, le premier episode de transmission vectorielle de ZIKV a ete identifie dans le sud de la France. Il s’agissait de trois cas, malades debut aout, habitant un meme quartier. Une enquete de seroprevalence a ete menee afin de determiner l’etendue de la transmission autochtone, et la part des infections asymptomatiques et paucisymptomatiques. Materiels et methodes En novembre 2019, des echantillons de sang capillaire, des informations sur les antecedents medicaux et les expositions a risque (voyages, piqures de moustiques), ont ete collectes aupres des residents consentants, et des travailleurs exposes au vecteur, dans un rayon de 200 metres autour des cas. Les infections recentes ont ete recherchees par serologie IgM et IgG ELISA flavivirus. Les serums positifs sont testes en seroneutralisation pour le zika, la dengue et le West-Nile. La seroneutralisation permet de caracteriser la reponse anticorps et determiner un antecedent d’infection par le ZIKV. Resultats L’enquete a pu etre menee aupres de 61 % des foyers de la zone etudiee (89/146). Quatre-vingt-six pour cent des personnes eligibles des logements enquetes ont ete preleves (165/192). Ce pourcentage est de 82 % pour les travailleurs (69/84). Huit personnes presentaient une serologie IgG anti-flavivirus positive (trois symptomatiques et cinq asymptomatiques). Toutes avaient des antecedents de voyage en zone intertropicale, cinq avaient eu la dengue et cinq avaient ete vaccinees contre la fievre jaune. Les seroneutralisations sont en cours. Conclusion Les premiers resultats obtenus sont en faveur d’un foyer limite d’infection a ZIKV et d’une faible part d’asymptomatiques. Cette etude doit permettre d’apprehender le potentiel de diffusion du ZIKV sur le continent europeen et de guider les mesures de controle a mettre en place en cas d’emergence.

Background Aedes albopictus, vector of dengue and chikungunya viruses, is implanted in mainland France, exposing to the risk of autochthonous transmission. Since 2006, epidemiological and entomological surveillance activities aim to prevent or limit the occurrence of autochthonous cases. We aimed to describe episodes of transmission and control measures implemented in order to reflect on surveillance activities. Methods We reviewed all publications and documents produced on autochthonous transmission episodes in France and surveillance protocols. We reviewed surveillance activities, investigation methods and control measures implemented. Results Between 2010 and 2018, eight episodes of autochthonous dengue fever transmission and three of chikungunya were recorded in mainland France. All of them occurred in the South east of France, between July and October, when vector density was the highest. Transmission areas were limited to single domestic houses located in discontinuous urban areas. Only two episodes happened in two distinct areas. Chikungunya episodes led to 31 cases and dengue fever episodes to 23 cases. Most cases were identified by door-to-door investigations set-up in transmission areas. We isolated serotypes 1 and 2 for dengue and East Central South Africa lineage for chikungunya in autochthonous cases. Adulticide vector control measures were effective in controlling transmission. Seven episodes of transmission were due to failure in identifying primary imported cases. Four episodes occurred because of the absence or the lack of vector controls measures around primary imported cases. Conclusions Surveillance activities, and autochthonous cases investigations, were effective in limiting the extent of transmission, but were highly demanding for surveillance actors. Identified causes of transmission highlight the need of regular awareness campaigns targeting physicians and biologists. Key messages Effectiveness of the surveillance system of dengue, chikungunya and zika viruses, and autochthonous cases investigations. Needs of awareness and training courses targeting health professionals to the risk represented by these viruses.

SUMMARYA better understanding of physician practices in requesting stool samples for patients with acute gastroenteritis (AG) is needed to more accurately interpret laboratory-based surveillance data. A survey was conducted in General Practitioners (GPs) between August 2013 and July 2014 to estimate the proportion of stool samples requested for patients with AG and to identify factors associated with GP requests for a stool sample. National health insurance (NHI) data together with surveillance data from a French Sentinel GP network were also used to estimate the proportion of stool samples requested. This proportion was estimated at 4·3% in the GP survey and 9·1% (95% confidence interval 8·7–9·6) using NHI data. Multivariate analysis indicated that the ratio of stool samples requested was almost five times higher in patients with bloody diarrhoea and 10–20 times higher in patients with a long duration of illness before consultation. Laboratory-based surveillance data underestimates the actual burden of disease as fewer than one in 10 AG cases consulting their GP will be requested to submit a stool sample for laboratory testing. This underestimation varies by pathogen as stool samples are more frequently requested for severe illness.

In addition to the economic consequences and threats associated with outbreaks, listeriosis remains of great public health concern, as it has one of the highest case fatality rates of all the foodborne infections (20%-30%), and has common source epidemic potential. Changes in the way food is produced, distributed and stored have created the potential for diffuse and widespread outbreaks involving many countries. In 2002, a survey was carried out to assess the need for and the feasibility of a European network on listeria infections in humans. Data on surveillance systems and laboratory methods were collected through two postal surveys sent to the national Centres for communicable disease surveillance and to the listeria reference laboratories. Surveillance systems for listeria infections were in operation in 16 out of the 17 countries surveyed, and 16 countries had a national reference laboratory (NRL). All countries based their case definition of listeriosis on the isolation of Listeria monocytogenes. Fourteen NRLs performed at least one typing method on human strains. At least 13 countries already carried out or expressed willingness to carry out characterisation of isolates by pulsed field gel electrophoresis (PFGE) of L. monocytogenes strains isolated from human cases following a standard protocol. The participants concluded that there was a clear added value to having a European surveillance network for listeria infections, particularly for outbreak detection and investigation, and that a surveillance network based on the existing national surveillance systems was feasible.

Following the events of 11 September 2001, the ensuing spectre of bioterrorism and considerable efforts planning for the unthinkable (1), this Eurosurveillance issue reminds us of the continuing threat to public health from well-recognised pathogens, sometimes mistakenly judged to be controlled. Recently the incidence of salmonellosis has decreased substantially across the European Union, the number of cases reported to Enternet (2) declining from 100 267 in the peak year of 1997 to 73 006 in 2001 (I.S.T. Fisher - personal communication). However, recent events and the following articles illustrate continued challenges in salmonella control.

SUMMARYBrucellosis is usually acquired by humans through contact with infected animals or the consumption of raw milk from infected ruminants.Brucella suisbiovar 2 (BSB2) is mainly encountered in hares and wild boars (Sus scrofa), and is known to have very low pathogenicity to humans with only two case reports published in the literature. Human cases of brucellosis caused by BSB2 were identified through the national mandatory notification of brucellosis. The identification of the bacterium species and biovar were confirmed by the national reference laboratory. Epidemiological data were obtained during medical follow-up visits. Seven human cases were identified between 2004 and 2016, all confirmed by the isolation of BSB2 in clinical specimens. All patients had direct contact with wild boars while hunting or preparing wild boar meat for consumption. Five patients had chronic medical conditions possibly responsible for an increased risk of infection. Our findings suggest that BSB2 might be an emerging pathogen in hunters with massive exposure through the dressing of wild boar carcasses. Hunters, especially those with chronic medical conditions, should be informed about the risk of BSB2 infection and should receive information on protective measures.

Introduction Les vibrions non choleriques (VNC) sont des hotes naturels du milieu marin responsables d’infections intestinales et extra-intestinales graves. Le nombre d’infections a VNC a recemment augmente dans plusieurs pays europeens en lien avec le changement climatique. Cette etude des donnees de surveillance du centre de reference a pour objectifs de faire un etat des lieux des donnees epidemiologiques et microbiologiques des cas d’infections a VNC et des sites favorables a leur transmission en France metropolitaine. Materiels et methodes Les donnees microbiologiques, cliniques et epidemiologiques ont ete collectees pour les souches de VNC adressees de 1995 a 2017 par les laboratoires de biologie medicale metropolitains au centre de reference. A partir des series chronologiques du reseau national de surveillance des parametres marins, les donnees de temperature et de salinite de la surface de la mer ont ete cartographiees en regard du lieu de diagnostic des cas d’infections de VNC acquis en France metropolitaine. Resultats Au total, 236 cas d’infections a VNC ont ete recenses de 1995 a 2017. Les especes les plus frequemment identifiees etaient V. cholerae non-O1/non-O139 (VC) (n = 124, 53 %), V. parahaemolyticus (VP) (n = 47, 20 %), V. alginolyticus (VA) (n = 33, 14 %) et V. vulnificus (VV) (n = 21, 9 %). 46 % des patients presentaient un tableau de gastro-enterite aigue, 19 % une infection des plaies et 16 % un sepsis severe. L’âge moyen etait de 60,5 ans (intervalle interquartile, 38–73). Un total de 69 % des patients ont ete hospitalises (n = 159/231), 41 % presentaient une forme septique (n = 94/232) et la mortalite globale etait de 7 % (n = 16/235). Les infections a VC presentaient la plus grande diversite clinique. VV etait associe aux infections cutanees les plus severes avec un taux de letalite de 25 % (n = 5/20) chez des patients presentant un terrain predisposant (74 %, n = 14/19) (p Conclusion Les infections a VNC–bien que rares–restent probablement sous diagnostiquees. Un renforcement de la surveillance, epidemiologique et environnementale, est necessaire pour mieux comprendre les determinants associes aux infections a VNC et ameliorer leur prevention. Il est crucial de rechercher une infection a VNC en cas d’infections intestinales et de graves infections extra-intestinales dans un contexte d’exposition au milieu marin ou de consommation de produits de la mer.

Background:Long-term care facilities have partly taken over the traditional asylum function of psychiatric hospitals and house an increasing group of patients with mental–physical multimorbidity (MPM). Little is known about the characteristics, behavior, and care dependency of these patients. This paper aims to describe these aspects.Methods:Explorative, descriptive study among patients with MPM without dementia (n = 142), living in 17 geronto-psychiatric nursing home (NH) units across the Netherlands, stratified by those referred from mental healthcare services (MHS) and other healthcare services (OHS). Data collection consisted of chart review, semi-structured interviews, (brief) neuropsychological testing, and self-report questionnaires. Patients referred from MHS (n = 58) and from OHS (n = 84) were compared by descriptive statistics.Results:Despite exclusion of patients with dementia, the majority of participants had cognitive impairment. Prevalence and severity of frontal impairment were high, as well as the number of patients with clinically relevant neuropsychiatric symptoms. MHS patients were younger, had more chronic psychiatric disorders, and more often used antipsychotics. Neuropsychiatric symptoms, domains of care dependency, physical conditions and concomitant medication use differed not significantly between the subgroups.Conclusions:Both groups of patients with MPM showed heterogeneity in various aspects but differed not significantly regarding the consequences of their multimorbidity. In a variety of characteristics, this group seems to be different from other NH patient groups, which requires extra knowledge and skills of the staff. To uncover which knowledge and skills are necessary, the next step should be to investigate the specific care needs of NH patients with MPM without dementia.

Brucellosis is a bacterial zoonotic disease mainly transmitted to humans by ruminants. In France, brucellosis has disappeared from ruminants herds. Human brucellosis surveillance is performed through mandatory notification and the national reference center. Methods We report the results of human brucellosis surveillance from 2004 to 2013 with regards to epidemiological, clinical and microbiological data. Results A total of 250 cases were notified, making an annual incidence of 0.3 cases per million inhabitants. Brucella melitensis biovar 3 was the most frequently identified bacterium (79% of isolated strains). In total, 213 (85%) cases had been contaminated abroad in endemic countries. In 2012, an episode of re-emergence of brucellosis in cattle occurred in Haute-Savoie, in the French Alps, and was responsible for 2 human cases. Conclusion Brucellosis has become a disease of travelers in France. However, maintaining a stringent epidemiological surveillance is necessary to be able to early detect any local re-emergence in humans or animals. The multidisciplinary surveillance was implemented in France years ago and is a successful example of the One Health Concept.

During summer 2016, all the conditions for local mosquito-borne transmission of Zika virus (ZIKV) are met in mainland France: a competent vector, Aedes albopictus, a large number of travellers returning from ZIKV-affected areas, and an immunologically naive population. From 1 January to 15 July 2016, 625 persons with evidence of recent ZIKV infection were reported in mainland France. We describe the surveillance system in place and control measures implemented to reduce the risk of infection.

SUMMARYIn France surveillance underestimates the true burden of acute gastroenteritis (AG). We conducted a population-based, retrospective cross-sectional telephone survey between May 2009 and April 2010 in order to obtain more accurate estimates of the incidence and the burden of AG and to describe healthcare-seeking behaviour for AG. Of the 10 080 persons included in the survey, 260 respondents reported 263 episodes of AG. The incidence rate of AG was estimated at 0·33 cases/person-year (95% CI 0·28–0·37). It was highest in children aged

One of the objectives of the surveillance systems implemented by the French National Institute for Public Health Surveillance is to detect communicable diseases and to reduce their impact. For emerging infections, the detection and risk analysis pose specific challenges due to lack of documented criteria for the event. The surveillance systems detect a variety of events, or "signals" which represent a potential risk, such as a novel germ, a pathogen which may disseminate in a non-endemic area, or an abnormal number of cases for a well-known disease. These signals are first verified and analyzed, then classified as: potential public health threat, event to follow-up, or absence of threat. Through various examples, we illustrate the method and criteria which are used to analyze and classify these events considered to be emerging. The examples highlight the importance of host characteristics and exposure in groups at particular risk, such as professionals in veterinarian services, health care workers, travelers, immunodepressed patients, etc. The described method should allow us to identify future needs in terms of surveillance and to improve timeliness, quality of expertise, and feedback information regarding the public health risk posed by events which are insufficiently documented.

Infant botulism is caused by the ingestion of spores of Clostridium botulinum and affects newborns and infants under 12 months of age. Ingested spores multiply and produce botulinum toxin in the digestive tract, which then induces clinical symptoms. A single French case was described in the literature prior to 1991. We describe the cases of infant botulism identified in France between 1991 and 2009. All clinical suspicions of botulism must be declared in France. Biological confirmation of the disease is provided by the National reference laboratory for anaerobic bacteria and botulism at the Pasteur Institute. During this period, 7 cases of infant botulism were identified, 1 per year from 2004 to 2008 and 2 in 2009. The median age of affected infants was 119 days and all were female. All infants presented with constipation and oculomotor symptoms. All were hospitalized and required mechanical ventilation. The infants recovered from their botulism. The diagnosis of infant botulism was biologically confirmed for all patients. One 4-month-old infant was treated with a single dose of the human-derived botulism antitoxin specific for infant botulism types A and B (BabyBIG®). The infants all had different feeding habits ranging from exclusive breast feeding to a mix of formula feeding and solid food consumption. The consumption of honey, the only documented risk food for this disease, was reported for 3 of the infants. The honey had been placed on the pacifier of 2 infants and directly in the mouth of the 3rd by the mother. Infant botulism, a form of botulism that was previously rarely recognized in France, has been reported more frequently during the last 6 years. This disease remains rare but nonetheless severe. In light of recent epidemiological data, efforts to raise awareness among parents of infants and health professionals on the danger of infant botulism and particularly, its association with honey consumption seems necessary.

An interlaboratory study was performed with the aim of investigating the reproducibility of a multiplex microbial microsatellite-based typing assay for Aspergillus fumigatus in different settings using a variety of experimental and analytical conditions and with teams having variable prior microsatellite typing experience. In order to circumvent problems with exchange of sizing data, allelic ladders are introduced as a straightforward and universally applicable concept for standardization of such typing assays. Allelic ladders consist of mixtures of well-characterized reference fragments to act as reference points for the position in an electrophoretic trace of fragments with established repeat numbers. Five laboratories independently analysed six microsatellite markers in 18 samples that were provided either as DNA or as A. fumigatus conidia. Allelic data were reported as repeat numbers and as sizes in nucleotides. Without the use of allelic ladders, size differences of up to 6.7 nucleotides were observed, resulting in interpretation errors of up to two repeat units. Difficulties in interpretation were related to non-specific amplification products (which were resolved with explanation) and bleed-through of the different fluorescent labels. In contrast, after resolution of technical or interpretive problems, standardization of sizing data by using allelic ladders enabled all participants to produce identical typing data. The use of allelic ladders as a routine part of molecular typing using microsatellite markers provides robust results suitable for interlaboratory comparisons and for deposition in a global typing database.

Aspergillus species are widely distributed fungi that release large amounts of airborne conidia, which are dispersed in the environment. Several Aspergillus species have been described as human pathogens. Molecular techniques have been developed to investigate the epidemiological relation between environmental and clinical isolates. Several typing methods have been described for Aspergillus species, most of them with reference to Aspergillus fumigatus. Here, we summarise all the different available molecular typing techniques for Aspergillus. The performance of these techniques is evaluated with respect to their practical feasibility, and their interpretation and discriminatory power assessed. For A. fumigatus isolates, a large extent of genetic variability is demonstrated and therefore fingerprinting techniques with high discriminatory power and high reproducibility are required for this species. Afut1-restriction fragment length polymorphism and microsatellite typing showed the highest discriminatory power. In addition, the microsatellites show excellent reproducibility. Other typing techniques are still useful for smaller epidemiological problems and for less well-equipped laboratories.

An outbreak (or epidemic) is a higher number of cases of a given disease in a given population and time interval. A timely investigation has for aim to identify the source and vehicle of the outbreak and provides unique opportunities to better understand its occurrence and the role of contributing risk factors to implement the most appropriate measures to control it and prevent further recurrences. The investigation of an outbreak is based on a multidisciplinary approach (clinical, epidemiological, environmental, and microbiological) with a descriptive and analytical (hypothesis testing) phase. In this article, we describe the methodological approach of a field outbreak investigation illustrated by examples taken from our experience. The investigation includes the following steps: establishing the existence of the outbreak; defining the disease; finding cases; describing cases by time, place, and person characteristics; establishing a hypothesis related to the mode of occurrence; testing the hypotheses; conducting an environmental investigation; conducting a microbiological investigation; controlling the outbreak, preventing further occurrences, and writing an investigation report to share experience with the public health and scientific community. The investigation of an outbreak is an evolving process: information gathered or conclusions made at a given stage must be fully used for following steps. The social, institutional, and political background associated with outbreaks usually makes their investigation complex and should be taken into account. The earlier the outbreak is detected and investigated in close relation with public health authorities, the greater will be the potential preventive impact of control measures.

Dans les pays occidentaux, le risque de transmission du virus de l’hepatite C (VHC) par la transfusion est tres faible depuis le milieu des annees 1990. La connaissance des modes de transmission actuels necessite d’etre actualisee. Cependant, l’etude des facteurs de risque a jusqu’a present essentiellement repose sur des cas prevalents d’infection par le VHC. Dns cet article, nous decrivons les principales enquetes cas-temoins en termes de methodes et selon les principaux resultats qui ont contribue aux connaissances sur les modes de transmission. Nous rapportons aussi les resultats d’une enquete cas-temoins incidente realisee recemment en France qui confirme le role majeur de l’usage de drogue intraveineux dans la dynamique actuelle de l’infection par le VHC et montre que la transmission liee aux soins invasifs demeurait entre 1995 et 2001 une source potentielle d’infections a VHC.

To quantify the impact of foodborne diseases on health, and set priorities for data collection, prevention and control of these diseases, we compiled and analyzed information from surveillance systems and other sources on the morbidity and mortality due to foodborne infectious diseases in mainland France in the last decade of the 20th century. Illness due to 13 bacteria, two viruses, and eight parasites were studied. The number of foodborne infections, hospitalizations, and deaths were estimated from multiple data sources. For each agent, several estimates were derived from the different sources. Estimates were ranked according to their plausibility, based on an assessment of the validity of the data source, and are presented as a "plausible interval" consisting of a low and high estimate. We estimate that these pathogens caused 10,200-17,800 hospitalizations per year. Salmonella is the most frequent cause (5,700-10,200 cases), followed by Campylobacter (2,600-3,500 cases) and Listeria (304 cases). Toxoplasmosis accounts for the majority of hospitalizations (426 cases) attributable to the studied parasitic infections. The number of deaths related to foodborne infection was estimated between 228 and 691. Bacterial pathogens account for the majority (191 to 652) of deaths of which 92 to 535 are attributable to salmonellosis, ranking as the first cause of death, and 78 to listeriosis, the second cause. Salmonella, Campylobacter, and Listeria are the main causes of severe foodborne illness in France. For several pathogens, data are insufficient to derive exact estimates of the disease burden. Nevertheless, it has been possible to derive plausible estimates for the majority, and to rank them according to their impact on public health.

At the end of the 70s, it was said that eradicating infectious diseases was possible. With the occurrence of AIDS and the discovery of new pathogens the come-back of infectious diseases was noted, 15 to 20 years later, and the concept of emerging infections was defined. An emerging infection is the appearance of a new infection or the increase of its incidence if not new. It also includes infections for which the incidence could increase because of favorable conditions. Several scenarios can be proposed: 1) the appearance of a new infection (AIDS or SARS); 2) the appearance of a known infection where it did not exist previously (West Nile virus infection in the USA); 3) an infection that existed but that was not diagnosed or could not be linked precisely to a particular infectious agent (hepatitis C before the discovery of the hepatitis C virus; 4) a known infection that increases its usual incidence (outbreaks...); 5) infectious diseases for which current conditions may facilitate transmission (decrease of immunization coverage...). The deliberate release of a biological agent is one of the possible scenarios of emergence. Qualitative changes of infectious agents such as the resistance to anti-infectious agents may also contribute, through a selection mechanism, to the emergence of new infectious threat. Emerging infections result from the interaction between the agent, the host, and environment evolving according to human activity. Surveillance, research, laboratory capacity, and an effective public health system are key factors for their control.

To assess the impact of preventive measures by the food industry, we analyzed food monitoring data as well as trends in the incidence of listeriosis estimated through three independent sources: the National Reference Center of Listeriosis; a laboratory-based active surveillance network; and two consecutive nationwide surveys of public hospital laboratories. From 1987 to 1997, the incidence of listeriosis decreased by an estimated 68%. A substantial reduction in the proportion of Listeria monocytogenes-contaminated products was observed at the retail level. The temporal relationship between prevention measures by the food industry, reduction in L. monocytogenes-contaminated foodstuffs, and reduction in listeriosis incidence suggests a causal relationship and indicates that a substantial part of the reduction in illness is related to prevention efforts.

In 1997, a community-wide outbreak of Salmonella enterica serotype Typhimurium (S. typhimurium) infection occurred in France. The investigation included case searching and a case-control study. A case was defined as a resident of the Jura district with fever or diarrhoea between 12 May and 8 July 1997, from whom S. typhimurium was isolated in stool or blood. One hundred and thirteen cases were identified. Thirty-three (83%) of 40 cases but only 23 (55%) of 42 community controls, matched for age and area of residence, reported eating Morbier cheese (Odds ratio: 6·5; 95% Confidence Interval: 1·4–28·8). Morbier cheese samples taken from the refrigerators of two case-patients and one symptom-free neighbour cultured positive for S. typhimurium of the same phage type as the human isolates. The analysis of distribution channels incriminated one batch from a single processing plant. These findings show that an unpasteurized soft cheese is an effective vehicle of S. typhimurium transmission.

Resume Transmis principalement par le sang, le virus de l'hepatite C (VHC) s'est repandu de maniere relativement silencieuse pendant plusieurs decennies par la transfusion sanguine, dont il a accompagne l'essor, et s'est ensuite introduit dans la population des toxicomanes intraveineux ou il a ≪ explose ≫. Il est aussi devenu, ces dernieres annees, le ≪ prototype du virus ≫ a transmission nosocomiale. En France, la seroprevalence pour le VHC est estimee aux environ de 1,1 %, ce qui correspond a 500 000 a 650 000 personnes touchees, dont 80 % porteuses du virus. En 1994, la proportion de patients connaissant leur statut serologique vis-a-vis du VHC etait de 20 a 25 % environ. Elle a depuis progresse, mais reste mal appreciee. La prevalence varie selon les regions; elle apparait sensiblement plus elevee dans la region Provence-Alpes-Cote d'Azur (1,7 %). La prevalence augmente avec l'âge, surtout chez les femmes apres 50 ans, probablement du fait des transfusions frequentes au decours des accouchements dans les annees 1960–1970. Si le risque de transmission par la transfusion est maitrise (risque residuel estime a 3,6 par million de dons), la transmission chez les toxicomanes demeure frequente malgre la politique de reduction des risques. La transmission nosocomiale a ete documentee ces dernieres annees. Bien que le risque soit faible, la frequence des expositions aux gestes invasifs et la prevalence de l'infection chez les patients hospitalises justifient le renforcement des precautions standards, des procedures d'asepsie et de desinfection. La transmission sexuelle et celle de la mere a l'enfant est tres faible, voire negligeable, de meme que la transmission horizontale non sexuelle. Pour evaluer les mesures de prevention et de prise en charge, la surveillance de l'hepatite C doit reposer sur la collecte d'informations continue sur les hepatites C nouvellement diagnostiquees, les seroconversions, les hepatopathies chroniques et la mortalite imputable a l'hepatite C.

Resume Le depistage de l'hepatite C se justifie par le fait que cette infection est un probleme de sante publique de par sa frequence, sa gravite et le cout de sa prise en charge, que les examens de depistage preclinique sont fiables et acceptables, que l'on dispose d'un traitement de plus en plus efficace et qu'il existe un benefice preventif individuel et collectif. Le depistage de l'hepatite C doit s'inscrire dans une strategie globale de prevention et de prise en charge de l'infection et de ses complications. Malgre l'amelioration de la structuration des soins notamment par la creation de poles de reference et de reseaux de soins, le recours aux soins des patients depistes est encore insuffisant. Ainsi, il apparait necessaire d'affiner les connaissances sur les determinants de la prise en charge, aussi bien du point de vue des malades que des professionnels de sante afin d'identifier les eventuelles barrieres et d'etre en mesure de les lever pour, a terme, augmenter la proportion de recours aux soins et de suivi chez les patients depistes.

International audience; Given the regular occurrence of salmonellosis outbreaks in France, evaluating the timeliness of laboratory reporting is critical for maintaining an effective surveillance system. Laboratory-confirmed human cases of Salmonella infection from whom strains were isolated from 2007 to 2011 in France (n=38,413) were extracted from the surveillance database. Three delay intervals were defined: transport delay (strain isolation, transport from primary laboratory to national reference laboratory), analysis delay (serotyping, reporting) and total reporting delay. We calculated the median delay in days and generated the cumulative delay distribution for each interval. Variables were tested for an association with reporting delay using a multivariable generalised linear model. The median transport and analysis delays were 7 and 6 days respectively (interquartile range (IQR: 6-10 and 4-9 respectively), with a median total reporting delay of 14 days (IQR: 11-19). Timeliness was influenced by various external factors: decreasing serotype frequency, geographical zone of primary laboratory and strain isolation on Sundays were the variables most strongly associated with increased length of delay. The effect of season and day of the week of isolation was highly variable over the study period. Several areas for interventions to shorten delays are identified and discussed for both transport and analysis delays.

SUMMARYToxoplasmosis is a worldwide zoonosis due to Toxoplasma gondii, a ubiquitous protozoan parasite of warm-blooded animals including humans. In pregnant women, primary infection can cause congenital toxoplasmosis resulting in severe malformations in the newborn. Since 1978, public health authorities in France have implemented a congenital toxoplasmosis prevention programme, including monthly serological screening of all seronegative pregnant women, and treatment in case of seroconversion. However, this programme does not produce systematic surveillance data on incidence and prevalence. Our objective was to estimate the incidence and prevalence of T. gondii infection, and the incidence of seroconversion during pregnancy in women in France. We used a catalytic model to estimate incidence and prevalence of Toxoplasma infection between 1980 and 2020 in women of childbearing age. We used age- and time-specific seroprevalence data obtained from the National Perinatal Surveys (NPS) conducted in 1995, 2003 and 2010. We assumed that incidence depends both on age and calendar time, and can be expressed as the product of two unknown functions. We also estimated incidence of seroconversion during pregnancy in 2010 from the NPS and the National Surveillance of Congenital Toxoplasmosis (ToxoSurv). We combined data of 42208 women aged 15–45 years with serology available from the three NPS. For women aged 30 years the modelled incidence decreased from 7·5/1000 susceptible women in 1980 to 3·5/1000 in 2000. In 2010 the incidence was 2·4/1000. The predicted incidence and prevalence for 2020 was 1·6/1000 and 27%, respectively. The incidence of seroconversion during pregnancy in 2010 was estimated at 2·1/1000 susceptible pregnant women (95% CI 1·3–3·1) from the NPS and 1·9 (95% CI 1·8–2·1) from ToxoSurv. Incidence and prevalence of Toxoplasma infection has decreased markedly during the last 30 years. This decrease may be explained by a lower exposure to the parasite by changes in food habits and by improved hygiene practices in meat production. Modelled estimations were consistent with estimates observed in other studies conducted previously in France. The catalytic modelling provides reliable estimates of incidence and prevalence of Toxoplasma infection over time. This approach might be useful for evaluating preventive programme for toxoplasmosis.

International audience; From January to September 2013, a marked increase in notifications of Salmonella Paratyphi A infections among travellers returning from Cambodia occurred in France. An investigation revealed 35 cases without a common source: 21 in France, five in Germany, three in the Netherlands, one in Norway, one in the United Kingdom, four in New-Zealand. Data suggest an ongoing event that should trigger further investigation. Travellers to Cambodia should observe preventive measures including good personal hygiene and food handling practices.

SUMMARYAs a major foodborne pathogen,Campylobacteris frequently isolated from food sources of animal origin. In contrast, humanCampylobacterillness is relatively rare, but has a considerable health burden due to acute enteric illness as well as severe sequelae. To study silent transmission, serum antibodies can be used as biomarkers to estimate seroconversion rates, as a proxy for infection pressure. This novel approach to serology shows that infections are much more common than disease, possibly because most infections remain asymptomatic. This study used antibody titres measured in serum samples collected from healthy subjects selected randomly in the general population from several countries in the European Union (EU). Estimates of seroconversion rates toCampylobacterwere calculated for seven countries: Romania, Poland, Italy, France, Finland, Denmark and The Netherlands. Results indicate high infection pressures in all these countries, slightly increasing in Eastern EU countries. Of these countries, the differences in rates of notified illnesses are much greater, with low numbers in France and Poland, possibly indicating lower probability of detection due to differences in the notification systems, but in the latter case it cannot be excluded that more frequent exposure confers better protection due to acquired immunity.

International audience; To investigate an increased incidence of human cultures growing Salmonella enterica ssp. diarizonae serotype 61:k:1,5,7 in France in 2008, we reviewed medical records of case patients and identified the material used during invasive procedures and for bacterial culture. Trace-back investigations incriminated culture media containing contaminated sheep blood agar.

One of the objectives of the surveillance systems implemented by the French National Institute for Public Health Surveillance is to detect communicable diseases and to reduce their impact. For emerging infections, the detection and risk analysis pose specific challenges due to lack of documented criteria for the event. The surveillance systems detect a variety of events, or "signals" which represent a potential risk, such as a novel germ, a pathogen which may disseminate in a non-endemic area, or an abnormal number of cases for a well-known disease. These signals are first verified and analyzed, then classified as: potential public health threat, event to follow-up, or absence of threat. Through various examples, we illustrate the method and criteria which are used to analyze and classify these events considered to be emerging. The examples highlight the importance of host characteristics and exposure in groups at particular risk, such as professionals in veterinarian services, health care workers, travelers, immunodepressed patients, etc. The described method should allow us to identify future needs in terms of surveillance and to improve timeliness, quality of expertise, and feedback information regarding the public health risk posed by events which are insufficiently documented.

Infant botulism is caused by the ingestion of spores of Clostridium botulinum and affects newborns and infants under 12 months of age. Ingested spores multiply and produce botulinum toxin in the digestive tract, which then induces clinical symptoms. A single French case was described in the literature prior to 1991. We describe the cases of infant botulism identified in France between 1991 and 2009. All clinical suspicions of botulism must be declared in France. Biological confirmation of the disease is provided by the National reference laboratory for anaerobic bacteria and botulism at the Pasteur Institute. During this period, 7 cases of infant botulism were identified, 1 per year from 2004 to 2008 and 2 in 2009. The median age of affected infants was 119 days and all were female. All infants presented with constipation and oculomotor symptoms. All were hospitalized and required mechanical ventilation. The infants recovered from their botulism. The diagnosis of infant botulism was biologically confirmed for all patients. One 4-month-old infant was treated with a single dose of the human-derived botulism antitoxin specific for infant botulism types A and B (BabyBIG®). The infants all had different feeding habits ranging from exclusive breast feeding to a mix of formula feeding and solid food consumption. The consumption of honey, the only documented risk food for this disease, was reported for 3 of the infants. The honey had been placed on the pacifier of 2 infants and directly in the mouth of the 3rd by the mother. Infant botulism, a form of botulism that was previously rarely recognized in France, has been reported more frequently during the last 6 years. This disease remains rare but nonetheless severe. In light of recent epidemiological data, efforts to raise awareness among parents of infants and health professionals on the danger of infant botulism and particularly, its association with honey consumption seems necessary.

A family cluster of three cases of type E botulism were identified in south-east France in September 2009. The suspected food source of infection was a vacuum packed hot-smoked whitefish of Canadian origin purchased by the family during a visit to Finland and consumed several weeks later in France on the day prior to symptom onset. No leftover fish was available to confirm this hypothesis. Vacuum packed hot-smoked whitefish has previously been associated with cases of type E botulism in multiple countries, including Finland, Germany, the United States and Israel.

Salmonella enterica serotype Muenster (hereafter referred to as S. Muenster) is rare in France and in Europe. In France, a nationwide outbreak of gastrointestinal illness due to S. Muenster occurred during March and April 2008. Twenty-five laboratory-confirmed cases of S. Muenster were documented by telephone using a trawling questionnaire. Four patients were admitted to hospital and no death was recorded. Among the 21 interviewed cases, 16 reported consumption of goat's cheese in the days prior to symptoms. The investigation incriminated goat's cheese from producer X as being the most likely source of the outbreak. S. Muenster was isolated from both cases and the incriminated goat's cheese. The pulsed-field gel electrophoresis profiles of the food isolates of producer X and the isolates from cases were indistinguishable. Following the withdrawal of the contaminated batch of cheese, the number of cases decreased to its usual level. To our knowledge, this is the first published outbreak of S. Muenster associated with food consumption in Europe.

Resume L’existence d’un passage sanguin asymptomatique de certains agents infectieux entraine un risque de transmission de ces agents lors d’une transfusion sanguine. Si ce risque est actuellement bien maitrise pour certains agents infectieux (VIH, HTLV, VHC, VHB), il n’est en revanche pas documente et quantifie pour d’autres agents pathogenes, responsables d’infections non depistees ou encore indetectables par serologie au moment du don. Ce risque est generalement faible en situation endemique, mais il augmente dans le temps et l’espace lors de la survenue de cas groupes ou d’epidemies. Des mesures de prevention peuvent alors etre mises en place (suspension de la collecte, mise en quarantaine des dons…). Ces mesures pouvant avoir d’importantes repercussions, notamment en limitant l’approvisionnement des etablissements de soins en produits sanguins labiles, il est important qu’elles soient adaptees au risque de transmission par transfusion. Des estimations quantitatives du risque de contamination d’un don de sang peuvent ainsi permettre de les orienter. C’est dans ce contexte que l’Institut de veille sanitaire (InVS) a initie, debut 2005, un projet visant a disposer a priori d’estimations quantitatives du risque de contamination d’un don de sang par des agents infectieux pour differents scenarii en termes d’incidence et de distribution spatiotemporelle. L’objectif de cet article est d’actualiser les dernieres estimations du risque residuel de contamination d’un don de sang par les virus depistes de facon systematique (VIH, HTLV VHC, VHB) et de presenter le travail realise par le groupe de travail « Estimation quantitative du risque de contamination d’un don de sang par des agents infectieux ».

Since September 2008, 26 cases of hepatitis A with a history of travel to Egypt have been reported in France. Investigations indicate that a common source of contamination linked to Nile river cruises is the most likely explanation of the increase in the number of cases reported in France as well as in several other European Union countries.

Since September 2008, 26 cases of hepatitis A with a history of travel to Egypt have been reported in France. Investigations indicate that a common source of contamination linked to Nile river cruises is the most likely explanation of the increase in the number of cases reported in France as well as in several other European Union countries.

Seven international laboratories tested the recently proposed single-locus typing strategy for Aspergillus fumigatus subtyping for interlaboratory reproducibility. Comparative sequence analyses of portions of the locus AFUA_3G08990, encoding a putative cell surface protein (denoted CSP), was performed with a panel of Aspergillus isolates. Each laboratory followed very different protocols for extraction of DNA, PCR, and sequencing. Results revealed that the CSP typing method was a reproducible and portable strain typing method.

On Thursday 18 September 2008, the hospital of Nantes in west France informed the District Health Office of a case of salmonellosis in an exclusively bottle-fed infant. On Monday morning 22 September, two additional cases of salmonellosis in infants were reported by the hospital of Niort in southwest France. The serotype of the three cases was unknown at that time.

SUMMARYIn France, salmonellosis is the main cause of foodborne bacterial infection with serotypes Enteritis (SE) and Typhimurium (ST) accounting for 70% of all cases. French authorities implemented a national control programme targeting SE and ST in poultry and eggs from October 1998 onwards. A 33% decrease in salmonellosis has been observed since implementation. We designed an evaluation of the impact of this control programme on SE and ST human infections in France. Using monthly Salmonella human isolate reports to the National Reference Centre we defined two intervention series (SE and ST) and one control series comprising serotypes not know to be associated with poultry or eggs. The series, from 1992 to 2003, were analysed using autoregressive moving average models (ARMA). To test the hypothesis of a reduction of SE and ST human cases >0 after the programme started and to estimate its size, we introduced an intervention model to the ARMA modelling. In contrast to the control series, we found an annual reduction of 555 (95% CI 148–964) SE and of 492 (95% CI 0–1092) ST human infections, representing respectively a 21% and 18% decrease. For SE, the decrease occurred sharply after implementation while for ST, it followed a progressive decrease that started early in 1998. Our study, suggests a true relation between the Salmonella control programme and the subsequent decrease observed for the two targeted serotypes. For ST, however, the decrease prior to the intervention may also reflect control measures implemented earlier by the cattle and milk industry.

An outbreak (or epidemic) is a higher number of cases of a given disease in a given population and time interval. A timely investigation has for aim to identify the source and vehicle of the outbreak and provides unique opportunities to better understand its occurrence and the role of contributing risk factors to implement the most appropriate measures to control it and prevent further recurrences. The investigation of an outbreak is based on a multidisciplinary approach (clinical, epidemiological, environmental, and microbiological) with a descriptive and analytical (hypothesis testing) phase. In this article, we describe the methodological approach of a field outbreak investigation illustrated by examples taken from our experience. The investigation includes the following steps: establishing the existence of the outbreak; defining the disease; finding cases; describing cases by time, place, and person characteristics; establishing a hypothesis related to the mode of occurrence; testing the hypotheses; conducting an environmental investigation; conducting a microbiological investigation; controlling the outbreak, preventing further occurrences, and writing an investigation report to share experience with the public health and scientific community. The investigation of an outbreak is an evolving process: information gathered or conclusions made at a given stage must be fully used for following steps. The social, institutional, and political background associated with outbreaks usually makes their investigation complex and should be taken into account. The earlier the outbreak is detected and investigated in close relation with public health authorities, the greater will be the potential preventive impact of control measures.

An outbreak of Shiga toxin-producing Escherichia coli (STEC) O148 infection occurred among wedding attendees in France in June 2002. A retrospective cohort study was performed and ten cases were identified, including two adults with haemolytic uraemic syndrome (HUS). The analytical study revealed that > 80% of affected individuals had eaten lightly roasted mutton and poultry pâte, but only the consumption of pâte tended to be associated with illness (relative risk 3.4; 95% CI 0.8–14.4). Leftovers (cooked mutton and raw offal) and processed foods (pâte) from the same batches as served at the party were sampled. Human, food and environmental samples were examined for the Shiga toxin ( stx ) gene and virulence traits by PCR. Stx -positive samples were cultured for STEC. HUS cases were tested for serum antibodies against 26 major STEC serogroups. An STEC O 2 6 strain ( stx1, eae, ehxA ) was isolated from one case with diarrhoea, and an STEC O148 strain ( stx2c ) from one case of HUS. Serum antibodies against O 2 6 were not detected in either of these patients; antibodies against O148 were not tested. Three STEC strains were isolated from the mutton and the offal ( stx2c , O148), and two from the pâte ( stx2c , O-X and O-Y). The isolates from the mutton were indistinguishable from the human stx2c isolate, whereas the pâte isolates differed. Although four different STEC strains were identified in patients and foods, the results of molecular subtyping, in conjunction with analysis of food consumption patterns, strongly suggested that this outbreak was caused by mutton contaminated with STEC O148.

Mandatory notification of listeriosis began in France in 1999. Enhanced public health surveillance, including routine molecular characterisation of Listeria monocytogenes strains, epidemiologic follow up of cases, and collection of food samples, has improved the sensitivity of outbreak detection and response. The incidence of listeriosis declined from 4.5 cases/million in 1999-2000 to approximately 3.5 cases/million during the period 2001-2003. Clinical, demographic and microbiological characteristics of listeriosis in France remained stable during this time period. Maternal-fetal infections accounted for 24% of all cases. Serovar 4b accounted for 49% of cases and 60% of case clusters. The incidence of listeriosis in France has declined and is now lower than in several other European countries.