High impact of COVID-19 outbreak in a nursing home in the Nouvelle-Aquitaine region, France, March to April 2020.

BACKGROUND: Elderly people in nursing homes are particularly vulnerable to COVID-19 due to their age, the presence of comorbidities, and community living. On March 14, 2020, at the beginning of the first epidemic wave of COVID-19 in France, a cluster was reported in a nursing home in the Nouvelle-Aquitaine region. We monitored the outbreak as well as the infection prevention and control (IPC) measures implemented. METHODS: A confirmed case was defined as laboratory-confirmed COVID-19 in a resident or staff member present in the nursing home between March 7 and May 1, 2020; and a probable case as a person presenting an acute respiratory illness after contact with a confirmed case. Symptomatic inpatient residents and symptomatic staff members were systematically tested for SARS-CoV-2. In addition, two screening sessions were held on site. RESULTS: We identified 109 cases (98 confirmed, 11 probable). The attack rate was 66% among residents and 45% among staff. Half of all cases were identified during the screening sessions. One-quarter of cases had minor symptoms or were asymptomatic. The case fatality rate among residents was 29%. IPC measures were rapidly implemented such as the quarantine of residents, the reinforcement of staff personal protective equipment, and home quarantine of staff testing positive, which were supplemented in April by systematic controls at the entrance of the nursing home and the creation of additional staff break rooms. CONCLUSIONS: This outbreak confirmed the considerable health impact of SARS-CoV-2 transmission in a nursing home. In addition to the implementation of IPC measures, the early detection of cases through the screening of residents and staff is essential to identify asymptomatic and pre-symptomatic cases and limit the spread of the virus.

A cross sectional survey to estimate prevalence and associated factors of asthma on Reunion Island, Indian Ocean.

BACKGROUND: Previous studies on asthma mortality and hospitalizations in Reunion Island indicate that this French territory is particularly affected by this pathology. Epidemiological studies conducted in schools also show higher prevalence rates in Reunion than in Mainland France. However, no estimates are provided on the prevalence of asthma among adults. In 2016, a cross-sectional survey was conducted to estimate the prevalence of asthma and to identify its associated factors in the adult population of Reunion Island. METHODS: A random sample of 2419 individuals, aged 18-44 years, was interviewed by telephone using a standardized, nationally validated questionnaire. Information was collected on the respiratory symptoms, description of asthma attacks and triggering factors for declared asthmatics, as well as data on the indoor and outdoor home environment. "Current asthma" was defined as an individual declaring, at the time of the survey, having already suffered from asthma at some point during his/her life, whose asthma was confirmed by a doctor, and who had experienced an asthma attack in the last 12 months or had been treated for asthma in the last 12 months. "Current suspected asthma" was defined as an individual presenting, in the 12 months preceding the study, groups of symptoms suggestive of asthma consistent with the literature. RESULTS: The estimated prevalence of asthma was 5.4% [4.3-6.5]. After adjustment, women, obesity, a family member with asthma, tenure in current residence and presence of indoor home heating were associated with asthma. The prevalence of symptoms suggestive of asthma was 12.0% [10.2-13.8]. After adjustment, marital status, passive smoking, use of insecticide sprays, presence of mold in the home and external sources of atmospheric nuisance were associated with the prevalence of suspected asthma. CONCLUSION: Preventive actions including asthma diagnosis, promotion of individual measures to reduce risk exposure as well as the development of study to improve knowledge on indoor air allergens are recommended.

Investigation of a leptospirosis outbreak in triathlon participants, Réunion Island, 2013.

We report herein the investigation of a leptospirosis outbreak occurring in triathlon competitors on Réunion Island, Indian Ocean. All participants were contacted by phone or email and answered a questionnaire. Detection and molecular characterization of pathogenic Leptospira was conducted in inpatients and in rodents trapped at the vicinity of the event. Of the 160 athletes competing, 101 (63·1%) agreed to participate in the study. Leptospirosis was biologically confirmed for 9/10 suspected cases either by real-time PCR or serological tests (MAT or ELISA). The total attack rate, children's attack rate, swimmers' attack rate, and the attack rate in adult swimmers were respectively estimated at 8·1% [95% confidence interval (CI) 4·3-14·7], 0%, 12·7% (95% CI 6·8-22·4) and 23·1% (95% CI 12·6-33·8). Leptospirosis cases reported significantly more wounds [risk ratio (RR) 4·5, 95% CI 1·6-13], wore complete neoprene suits less often (RR 4·3, 95% CI 1·3-14·5) and were most frequently unlicensed (RR 6·6, 95% CI 2·9-14·8). The epidemiological investigation supported that some measures such as the use of neoprene suits proved efficient in protecting swimmers against infection. PCR detection in rats revealed high Leptospira infection rates. Partial sequencing of the 16S gene and serology on both human and animal samples strongly suggests that rats were the main contaminators and were likely at the origin of the infection in humans.

Sentinel physician's network in Reunion Island: a tool for infectious diseases surveillance.

UNLABELLED: The surveillance of infectious diseases in Reunion Island is based on a sentinel network of family physicians (FPs) coordinated by the Indian Ocean regional institute for public health surveillance (French acronym OI Cire). The objectives are to identify and monitor outbreaks of influenza, gastroenteritis, and chicken pox, and to characterize circulating influenza viruses. The network can monitor other potentially epidemic diseases. METHOD: The Réunion sentinel network ensures a continuous and permanent surveillance. Physicians send their weekly activity data to the Cire that collects, processes, and interprets it; they also collect samples for biological surveillance of influenza. Statistical thresholds, based on historical data and the estimated numbers of incident cases, are calculated to follow the trend, detect outbreaks, and quantify their impact. RESULTS: The network currently includes 56 FPs and pediatricians, accounting for 6.5% of FPs on the island. The network has clarified the seasonality of influenza during the austral winter and identified the seasonality of acute diarrhea with an epidemic peak when school starts in August. The sentinel FPs's reports allowed monitoring the epidemic trend and estimating the number of cases during the 2005 and 2006 chikungunya outbreaks and 2009 influenza A (H1N1) outbreaks. CONCLUSION: The network has proven its contribution, responsiveness, and reliability for epidemiological surveillance during outbreak. It is an essential tool for infectious diseases surveillance in Reunion Island.

Influenza season in Réunion dominated by influenza B virus circulation associated with numerous cases of severe disease, France, 2014.

The 2014 seasonal influenza in Réunion, a French overseas territory in the southern hemisphere, was dominated by influenza B. Resulting morbidity impacted public health. Relative to the total number of all-cause consultations over the whole season, the rate of acute respiratory infection (ARI) consultations was 6.5%. Severe disease occurred in 32 laboratory-confirmed influenza cases (31.7 per 100,000 ARI consultations), 16 with influenza B. The observed disease dynamics could present a potential scenario for the next European influenza season.

[Discovery and follow-up of a lead-poisoning outbreak in a shantytown of Le Port, Reunion Island]. / Investigation et gestion d'un foyer de saturnisme infantile dans un quartier de la commune du Port, Île de la Réunion.

BACKGROUND: A national survey conducted in 2008-2009 by the French Institute for Public Health Surveillance for detection of lead impact in childhood identified a high blood lead level in a young boy living in the town of "Le Port", Reunion Island. Previously, cases of lead-poisoning on the island had been exceptional; only a dozen cases were reported in the 1980s in adults, related to the use of lead-containing instruments for food preparations. METHODS: The family of the index case was invited to participate in screening tests and an environmental investigation was conducted using a standardized questionnaire. Screening was then broadened to the neighborhood of the index case and samples of soil outside the home and in the immediate vicinity were taken. The environmental survey was then extended with soil samples taken from the entire geographical area. Information was then provided to local inhabitants (87 families and 287 people) in order to encourage lead blood testing for all children under six years and all pregnant women living in the area. RESULTS: The index case lived in the neighborhood of "The Oasis", a shantytown of Le Port. The results of soil analysis revealed heterogeneous pollution of superficial soils by lead throughout the area of the shantytown, the highest level recorded (5200mg/kg) reached more than 300 times the background level of the natural soils of the island. The screening identified 76 cases of childhood lead-poisoning (blood lead level greater or equal to 100µg/L) among 148 samples (51%). All cases of blood poisoning involved children under the age of 15 years. The median age of children with a positive test was 5.6 years; the median blood lead level was 196µg/L [102-392µg/L]. CONCLUSION: The main hypothesis to explain the contamination of the soil in the area of the shantytown is the presence of waste deposits (car batteries) and diffuse activities of metal recovery. The authorities managed to remove all the families from the environmental exposure to lead by rapidly ensuring rehousing outside the contaminated area.

A major outbreak of gastroenteritis in Réunion Island in 2012: first identification of G12 rotavirus on the Island.

Between August and November 2012 a severe outbreak of gastroenteritis occurred on Réunion Island, affecting more than 50,000 cases, particularly young children. Virological analyses showed that the virus responsible for this epidemic was rotavirus. Genotyping of stool samples indicated circulation of rotavirus type G3P[8] but also G12P[8], highlighting the risk of global emergence of this genotype in the coming years.

[The concept of emerging viral diseases: what risk for Reunion Island?]. / Le concept de maladies virales émergentes : quel risque de zoonose pour La Réunion ?

In Reunion Island, the risk of emerging infectious diseases lies mainly in several viral zoonoses: West Nile fever, Sindbis virus, Nipah virus, Wesselsbron virus, Rift Valley fever and Japanese encephalitis. There morbidity and consequences are more or less important but they all have a non-negligible epidemic potential, so they have to be monitored. Indeed, the struggle against these emerging infectious diseases requires an early detection of the cases, thus a surveillance system capable of detecting them as early as possible, thanks to a real international network of information, warning and prevention.

Reunion, a sentinel territory for influenza surveillance in Europe.

In Réunion, a French overseas territory located in the southern hemisphere, increase in influenza activity is generally observed several months earlier than in Europe. Influenza activity is monitored in Réunion through a multi-source surveillance system including sentinel practitioners network, hospital emergency department, laboratory and mortality. Since 2009, three successive influenza epidemics occurred on the island. The largest was observed in 2009 while epidemics in 2010 and 2011 were much weaker. In terms of circulating strains, B viruses were predominant at the beginning of the 2009 epidemic but they were completely evicted once A(H1N1)pdm09 circulation started. In 2010, A(H1N1)pdm09 virus was predominant again, but a constant co-circulation of B viruses was observed. In 2011, A(H3N2) virus circulated. The same viruses were identified a few months later in mainland France in the respective seasons. Since 2009, virus circulation, epidemiological trends and health impact of influenza have been similar to those observed in Europe. Influenza surveillance in Réunion may therefore give reliable early information which should be considered apart from the surveillance in mainland France. Then, it might be even a more suitable predictor for Europe than other temperate southern hemisphere countries.

[Epidemiological surveillance du chikungunya on Reunion Island from 2005 to 2011]. / La surveillance epidémiologique du chikungunya a la Réunion entre 2005 et 2011.

INTRODUCTION: The largest chikungunya epidemic in history hit Reunion Island in 2005/6. At that time, a specific monitoring system was set up. Since the end of the epidemic, this monitoring system has continued to operate and has been enhanced. The main objectives of the system are early detection of any case of chikungunya virus infection and epidemiological monitoring. METHODS: During nonepidemic periods, surveillance is focused on active detection of all cases. During epidemic periods, weekly incidence is estimated using data collected via a sentinel physician network. Occurrence of severe and fatal forms is tracked during all epidemiologic situations. RESULTS: In 2005-2006, the estimated number of symptomatic chikungunya-virus infections diagnosed on Reunion Island was 266 000, i.e., an attack rate of 34%. A total of 222 severe cases and 44 mother-to-child transmissions were recorded. Since the end of the outbreak, two clusters have been detected in the western region of the island in 2010 and 2011. The second cluster was non-negligible since it involved 164 cases including 112 that were biologically confirmed. CONCLUSION: Based on results recorded from 2005 to 2006, the chikungunya monitoring system appears to have good sensitivity and reactivity. Recent detection of two disease clusters confirms the system's efficacy.

[New vector control measures implemented between 2005 and 2011 on Reunion Island: lessons learned from chikungunya epidemic]. / L'evolution de la lutte anti-vectorielle entre 2005 et 2011 a la Réunion: les enseignements de l'epidémie de chikungunya.

A major chikungunya outbreak concerned 38% of people living in Reunion Island in 2005-2006. Chikungunya is an arthropod-born-virus disease conveyed by mosquitoes called Aedes albopictus. The health agency in Indian Ocean is responsible for vector control. Previously, in the early 40s, vector control concerned only malaria prophylaxis in La Réunion. Then, during the chikungunya outbreak, a new vector control team was installed and learned from this epidemic. The lessons drawn from chikungunya outbreak in La Réunion are about global executive management and organization linked the local partners and population. The lessons also concern technical topics such as the need of scientific research about vectors and vector-control methods. Finally, the regional cooperation in Indian Ocean (Réunion, Maurice, Seychelles, Comoros, Madagascar) has to be developed to share epidemiologic and entomologic data in order to prevent new chikungunya or dengue outbreak.

Re-emergence of dengue in Reunion, France, January to April 2012.

Since January 2012, 20 autochthonous cases of dengue virus (DENV) infection have been identified in Réunion. The first cases were detected on the western coast, but the two co-circulating viruses (DENV-1 and DENV-3) seemed to have spread later to different cities of the island. There is a non-negligible risk of increase in viral transmission over the following weeks, so health professionals and public health authorities in Réunion are preparing to face a potential epidemic.

How to explain the re-emergence of chikungunya infection in Reunion Island in 2010?

In March 2010, a new outbreak of chikungunya infection was detected in the west of Reunion Island. An investigation was launched to describe the incident cases occurrence and to raise hypotheses on factors that could explain the occurrence of this outbreak. All probable or confirmed cases detected by the surveillance system in the western area between March 1st and July 2nd, 2010 were included in the investigation. A standardized questionnaire was performed by phone, including sociodemographic, environmental and behaviour data. A total of 74 cases were described (i.e. response rate of 72%). They were mainly women (sex ratio M/F=0.7), all ages were represented. Most of them (76%) resided in a house; 31% had recently moved, including 22% from metropolitan France. They reported to have been more exposed to mosquitoes and to infected patients than during the major epidemic of 2005-2006. In addition, 41% reported to have reduced their protection against mosquitoes. The results suggest that several concomitant factors contributed to this outbreak: the reintroduction of the chikungunya virus in the island, the population characteristics and environmental factors.

Epidemiology of Chikungunya infection on Reunion Island, Mayotte, and neighboring countries.

Since 2004, the frequency of chikungunya virus infections has been increasing in Africa, Indian Ocean islands, and Asia. The epidemic began on the Kenyan coast, and reached the Comoros at the end of 2004 before spreading to the South-western Indian Ocean islands (SWIOI) in 2005 and especially in 2006. The epidemic then spread to Asia where epidemic foci are still active today. This increase also affected temperate zone countries where imported cases were reported, and indigenous transmission was reported in Italy in 2007, and in France (Var) in 2010. This review provides an update on the knowledge gained from monitoring chikungunya infections in SWIOI. Despite significant differences in design and performance, the implementation of surveillance systems has allowed describing the evolution of epidemic waves in the affected areas. Synchronous epidemic waves were observed in SWIOI, despite the differences between the preventive measures locally implemented. Between 2005 and 2007, all SWIOI were in inter-epidemic situation, except for Madagascar where a persistent virus circulation in an endemic-epidemic pattern was observed. In 2009, and in 2010, two moderate indigenous outbreaks were identified on the Reunion Island by the inter-epidemic surveillance system. Strains analyses demonstrated a reintroduction of the virus from Madagascar. These limited outbreaks should be a reminder of the vulnerability of SWIOI to arbovirosis, since the entomological indexes for competent vectors are high and the virus keeps on circulating more or less actively in the area.

Emergence of dengue virus serotype 3 on Mayotte Island, Indian Ocean.

A serosurvey carried out in 2006 in Mayotte, a French overseas collectivity in the Indian Ocean, confirmed previous circulation of dengue virus (DENV) on the island, but since the set up of a laboratory-based surveillance of dengue-like illness in 2007, no case of DENV has been confirmed. In response to an outbreak of DENV-3 on Comoros Islands in March 2010 surveillance of dengue-like illness in Mayotte was enhanced. By September 15, 76 confirmed and 31 probable cases of DENV have been identified in Mayotte. In urban and periurban settings on the island, Aedes albopictus is the predominant Aedes species, but Ae. aegyptii remains the most common species in rural areas. Given the epidemic potential of dengue virus in Mayotte, adequate monitoring including early detection of cases, timely investigation and sustained mosquito control actions remain essential.

[Using French national health insurance data for non-specific monitoring on Reunion Island]. / Utilisation des données de la Caisse générale de Sécurité sociale de la Réunion dans le cadre de la surveillance non spécifique.

BACKGROUND: In Reunion Island, non-specific surveillance developed mainly in 2009 and was based on the activity of hospital emergency department, emergency calls and mortality. From March 2010, a new surveillance was implemented in collaboration between the Indian Ocean regional epidemiology unit and the regional office of the National Health Insurance. The system is based on the weekly number of general practitioner consultations and home visits by municipality. This article presents methods of using these data for non-specific monitoring in Reunion Island. MATERIALS AND METHODS: Data analyzed cover consultations and visits to general practitioners and pediatricians for each of the 24 municipalities. Data were received in week S+1 and were updated week by week following the flow of repayments. To perform weekly monitoring, determine monitoring impact and detect any unusual health event, a correction factor was thus calculated and applied for the overall data set and for each municipality. Received data covered 72% of the population of the island. RESULTS: Over the study period from 2005 to 2009, the monthly average of consultations was 80,000 (min: 58,000 - max 12,0000). Two main peaks of activity were noticed throughout the island during the study period, the first one from weeks 4 to 9 of 2006 with a peak of 105,000 consultations in week 8 and the second one from weeks 34 to 41 of 2009 with a peak of 120,000 consultations in week 35. CONCLUSION: The two peaks described in 2006 and 2009 respectively correspond to outbreaks of chikungunya and influenza A(H1N1) 2009. This monitoring study has two main advantages: an almost exhaustive data set corresponding to three-quarters of the Reunion Island population and the geographic analysis by municipality. Positioned alongside other monitoring networks, this system expands the indicators monitored reflecting varying uses of care.

[Malaria in France: Mainland and territories]. / Le paludisme en France : métropole et outre-mer.

Malaria, which was eliminated first from Metropolitan France (mainland and Corsica), then in the French West Indies and the Reunion Island during the 20(th) century, remains endemic in two French territories: French Guiana and the Indian Ocean Mayotte island. Despite differences in the dominating plasmodial species and epidemiological patterns, these two territories have achieved marked quantitative improvements (in the reported number of cases and severe cases) thanks to efforts undertaken over the past decade. The situation, however, remains a concern from a qualitative standpoint with the emergence of resistance to antimalarial drugs and logistical and administrative issues which hinder access to treatment. Although malaria was eradicated in Metropolitan France half a century ago, competent vectors remain present in part or all of these territories and can give rise to limited outbreaks.

[Dengue fever in the Reunion Island and in South Western islands of the Indian Ocean]. / Dengue à la Réunion et dans les îles du sud-ouest de l'océan Indien.

South Western islands of the Indian Ocean are permanently threatened by dengue fever outbreaks. On the Reunion Island, two dengue outbreaks were biologically documented (1977-1978 and 2004). And since July 2004 there has been an inter-epidemic period for the island with sporadic cases and clusters. Between January 1, 2007 and October 5, 2009, the epidemiologic surveillance system detected five confirmed autochthonous cases, five confirmed imported cases (South-East Asia), and 71 probable cases. All the five autochthonous confirmed cases occurred in Saint-Louis during two consecutive clusters. In other South Western islands of the Indian Ocean, several dengue fever outbreaks have been reported. Importation of dengue virus from South-East Asia is a major risk for a new outbreak on the island. The introduction of a new serotype could lead to the emergence of new and severe clinical forms, including dengue hemorrhagic fever.