Investigation of a COVID-19 outbreak on the Charles de Gaulle aircraft carrier, March to April 2020: a retrospective cohort study.

BackgroundSARS-CoV-2 emergence was a threat for armed forces. A COVID-19 outbreak occurred on the French aircraft carrier Charles de Gaulle from mid-March to mid-April 2020.AimTo understand how the virus was introduced, circulated then stopped circulation, risk factors for infection and severity, and effectiveness of preventive measures.MethodsWe considered the entire crew as a cohort and collected personal, clinical, biological, and epidemiological data. We performed viral genome sequencing and searched for SARS-CoV-2 in the environment.ResultsThe attack rate was 65% (1,148/1,767); 1,568 (89%) were included. The male:female ratio was 6.9, and median age was 29 years (IQR: 24-36). We examined four clinical profiles: asymptomatic (13.0%), non-specific symptomatic (8.1%), specific symptomatic (76.3%), and severe (i.e. requiring oxygen therapy, 2.6%). Active smoking was not associated with severe COVID-19; age and obesity were risk factors. The instantaneous reproduction rate (Rt) and viral sequencing suggested several introductions of the virus with 4 of 5 introduced strains from within France, with an acceleration of Rt when lifting preventive measures. Physical distancing prevented infection (adjusted OR: 0.55; 95% CI: 0.40-0.76). Transmission may have stopped when the proportion of infected personnel was large enough to prevent circulation (65%; 95% CI: 62-68).ConclusionNon-specific clinical pictures of COVID-19 delayed detection of the outbreak. The lack of an isolation ward made it difficult to manage transmission; the outbreak spread until a protective threshold was reached. Physical distancing was effective when applied. Early surveillance with adapted prevention measures should prevent such an outbreak.

Mental health consequences of military sexual trauma: results from a national survey in the French military.

BACKGROUND: Military sexual trauma (MST) is a major public health concern, given its prevalence and mental health sequelae. This phenomenon is particularly prevalent among women in the US military, although more cases involve men given their overrepresentation. Little is known about MST and its consequences in other military settings, including in Europe. METHODS: This study draws from a national survey in the French military, including 1268 servicemen and 232 servicewomen. We conducted bivariate and multivariate analysis, using simple and multinomial logistic regressions to evaluate the associations between different forms of MST (repeated sexual comments alone/one form of sexual oppression (coercion, repeated verbal unwanted attention or assault)/ several sexual stressors) and symptoms of depression and of positive post-traumatic stress disorder (PTSD) screening scores. RESULTS: Women were both more likely to experience MST and to experience more severe forms of MST than men. Women were also more likely than men to report mental health symptoms (31% versus 18% for symptoms of depression and 4.0% versus 1.8% for positive PTSD screening scores). Different forms of MST were associated with different levels of psychological distress. Women reporting repeated sexual comments alone had higher odds of depressive symptoms (OR=3.1 [1.7, 5.5]) relative to women with no MST. Likewise, the odds of depressive symptoms were 6.5 times higher among women and 8.0 times higher among men who experienced several sexual stressors relative to those who reported no MST. We also found higher relative risk of subthreshold PTSD screening scores among women reporting any form of sexual stressor, including sexual comments alone (RRR = 4.5 [2.8, 7.4]) and an elevenfold increase in the relative risk of positive PTSD screen scores (RRR = 11.3 [2.3, 55.6]) among women who experienced several sexual stressors relative to women with no MST. CONCLUSION: MST is associated with mental health distress among service members in the French military, especially for women. The heightened risk of MST coupled with psychological sequelae call for preventive programs to reduce MST and for screening programs to provide adequate psychological support.

From sexual harassment to sexual assault: Prevalence and correlates of sexual trauma in the French military.

BACKGROUND: Sexual harassment (SH) is prevalent in military settings and dependent on the workplace environment. Few studies have investigated this issue in non-US military settings nor have examined how contextual and individual factors related to Military Sexual Trauma (MST) vary by gender. METHODS: This study draws on a national sexual survey in the French military including 1268 servicemen and 232 servicewomen. We examined four sexual stressors (repeated sexual comments, sexual coercion, repeated unwanted verbal sexual attention and sexual assault (SA)) and two combined measures of verbal SH (comments, unwanted attention) and MST (all forms). We conducted multivariate logistic regressions to identify contextual and individual factors related to these outcomes. RESULTS: 36.7% of women and 17.5% of men experienced MST in the last year and 12.6% and 3.5% reported SA. Factors associated with verbal SH differed from those related to SA. The odds of verbal SH were elevated among men who had sex with men (OR = 3.5) and among women officers (OR = 4.6) while the odds of SA were elevated among men less than 25 years (OR = 3.5) and women with less than a high school diploma (OR = 10.9). The odds of SH increased by 20% to 80% when men worked in units with higher female representation, higher prevalence of MST (sexual comments, or sexual assault, coercion, repeated unwanted attention) and lower acceptance of women in the miliatry. The odds of SA also increased by 70% among men working in units with higher female representation and higher prevalence of sexual oppression. The odds of SA against women were particular high (OR = 5.7) in units with a high prevalence of sexual assault, coercion, or repeated unwanted attention. CONCLUSION: MST is common in the French military, with women experiencing more severe forms than men. Our resuls call for programmatic action to reduce workplace factors related to verbal SH and SA in the French military.

COVID-19 outbreak among French firefighters, Marseille, France, 2020.

We investigated a COVID-19 outbreak at a fire station in Marseille, France. Confirmed cases were defined as individuals with positive SARS-CoV-2 reverse transcription (RT)-PCR and/or neutralising antibodies. All 85 firefighters at work during the outbreak period were included after questioning and sampled for RT-PCR and viral neutralisation assay. Twenty-three firefighters were confirmed positive, 19 of them were symptomatic, and four asymptomatic cases were confirmed by virus neutralisation. A total of 22 firefighters had specific neutralising antibodies against SARS-CoV-2. Neutralising antibodies were found in four asymptomatic and 18 symptomatic cases. Eleven symptomatic cases had high titres (≥ 1:80). The earliest detection of neutralising antibodies was 7 days after symptom onset, and 80% had neutralising antibodies 15 days after onset. One viral culture was positive 13 days after onset. The attack rate was 27%. We identified two introductions of the virus in this outbreak, through a presymptomatic and a paucisymptomatic case. Asymptomatic cases were not the source of a third generation of cases, although they worked without wearing a mask, indicating that asymptomatic cases did not play a significant role in this outbreak. Management and strategy based on early research of clinical signs associated with self-quarantine was effective.

Histamine food poisoning: a sudden, large outbreak linked to fresh yellowfin tuna from Reunion Island, France, April 2017.

On 20 April 2017, an outbreak of histamine food poisoning occurred in a French military unit located near Paris. A total of 40 cases were identified (attack rate: 16.6%). We conducted a case-control study on 31 cases and 63 controls. Multivariate analysis pointed to cooked yellowfin tuna fillet as the very likely source of food poisoning (odds ratio = 156.8; 95% confidence interval: 18.4-1,338.4). The fresh yellowfin tuna was from Reunion Island and was supplied vacuum-sealed and packed with ice at the principal food market of Paris. No cold chain issues could be established in the upstream and downstream supply chains. Histamine concentration was found to be 1,720 mg/kg in leftover raw tuna, and 3,720 mg/kg in control cooked tuna, well above the threshold limit values defined by European regulations (200 mg/kg). The presence of Klebsiella variicola and Pantoea agglomerans, microorganisms of the Enterobacterales order that have been reported to produce histamine, was confirmed in the leftover raw tuna. This type of food poisoning is rarely recognised and confirmed. We describe the outbreak to highlight the specific key points of this type of investigation.

Correction to: Using decision fusion methods to improve outbreak detection in disease surveillance.

Following publication of the original article [1], the authors reported that one of the authors' names is spelled incorrectly.

Using decision fusion methods to improve outbreak detection in disease surveillance.

BACKGROUND: When outbreak detection algorithms (ODAs) are considered individually, the task of outbreak detection can be seen as a classification problem and the ODA as a sensor providing a binary decision (outbreak yes or no) for each day of surveillance. When they are considered jointly (in cases where several ODAs analyze the same surveillance signal), the outbreak detection problem should be treated as a decision fusion (DF) problem of multiple sensors. METHODS: This study evaluated the benefit for a decisions support system of using DF methods (fusing multiple ODA decisions) compared to using a single method of outbreak detection. For each day, we merged the decisions of six ODAs using 5 DF methods (two voting methods, logistic regression, CART and Bayesian network - BN). Classical metrics of accuracy, prediction and timelines were used during the evaluation steps. RESULTS: In our results, we observed the greatest gain (77%) in positive predictive value compared to the best ODA if we used DF methods with a learning step (BN, logistic regression, and CART). CONCLUSIONS: To identify disease outbreaks in systems using several ODAs to analyze surveillance data, we recommend using a DF method based on a Bayesian network. This method is at least equivalent to the best of the algorithms considered, regardless of the situation faced by the system. For those less familiar with this kind of technique, we propose that logistic regression be used when a training dataset is available.

Tracking Rift Valley fever: From Mali to Europe and other countries, 2016.

On 16 September 2016, the World Health Organization confirmed a Rift Valley fever (RVF) outbreak in Niger. Epidemiological surveillance was reinforced among the French Armed Forces deployed in Niger and bordering countries: Chad, Mali and Burkina Faso. On 26 October, a probable case of RVF was reported in a service member sampled in Mali 3 weeks earlier. At the time the result was reported, the patient was on vacation on Martinique. An epidemiological investigation was conducted to confirm this case and identify other cases. Finally, the case was not confirmed, but three suspected cases of RVF were confirmed using serological and molecular testing. RVF viral RNA was detectable in whole blood for 57 and 67 days after onset of symptoms for two cases, although it was absent from plasma and serum. At the time of diagnosis, these cases had already returned from Mali to Europe. The infectivity of other arboviruses in whole blood has already been highlighted. That RVF virus has been detected in whole blood that long after the onset of symptoms (67 days) raises the question of its potential prolonged infectivity. Because of exposure to tropical infectious diseases during deployment, military populations could import emerging pathogens to Europe.

Sexual health in the French military: a multidimensional and gendered perspective.

BACKGROUND: Sexual health in the military comprises a range of concerns including sexually transmitted infections (STI), unintended pregnancy, sexual violence and sexual dysfunction. This study aims to estimate the prevalence of sexual health concerns by gender in the French military and compare these prevalences to estimates in the general population. METHODS: COSEMIL, the first sexual health survey in the French military comprises a probability sample of 1500 military personnel. Chi-square tests were used to compare lifetime abortion, STIs and sexual assault, and recent sexual dysfunction and sexual satisfaction by gender and explore the association between these indicators and current sexual risk (condom use at last intercourse). RESULTS: Women were more likely than men to declare negative sexual health outcomes, with the greatest difference related to sexual assault (24.3% versus 5.1% of males, p < 0.001) and sexual dysfunction hindering sexuality (15.2% of females versus 5.3% of males, p < 0.001). Women were also twice as likely to report ever having an STI (6.7% versus 3.4%, p = 0.03). Comparison with the French general population indicates lower percentages of STIs among military men (2.9% versus 4.9%) and higher percentages of abortion (17.6% versus 14.3%) forced sex (10.6% versus 7.4%) and sexual dysfunction (14.2% versus 9.3%) among military women. CONCLUSION: These results highlight gendered pattern of sexual health in the French military with women suffering greater sexual risks than men. Military health services should include women's health services to address the sexual and reproductive health gender gap.

Prevalence and risk factors of sexually transmitted infections among French service members.

INTRODUCTION: Sexually Transmitted Infections (STIs) have always represented a public health concern in the military, yet most studies rely on self-reports among non-random samples of military populations. In addition, most of the studies exploring STI rates among the military focus on US service members. This paper assesses the prevalence and correlates of STIs in the French military using biomarkers and compares self-reported versus diagnosed STIs. METHODS: Data are drawn from the COSEMIL study, a national sexual health survey conducted in the French military in 2014 and 2015. A random sample of 784 men and 141 women aged 18-57 years completed a self-administered questionnaire and provided biological samples for STI testing. We used logistic regression modeling to identify the correlates of STI diagnosis and self-reports. RESULTS: The prevalence of diagnosed STIs was 4.7% [3.8-5.9], mostly due to Chlamydia trachomatis. This rate was four times higher than the 12 months self-reported rate of 1.1% [0.6-2.3]. Reported STI rates were similar among men and women (1.1% versus 1.8%), but diagnosed STI rates were twice as high among females versus males (10.4% versus 4.1%, p = 0.007). There were significant differences in the determinants of reported versus diagnosed STIs. In particular, age and sexual orientation were associated with reported STIs, but not with diagnosed STIs. Conversely, STI counseling and depression were associated with STI diagnosis but not with STI reports. CONCLUSION: This study underlines the need to use biomarkers in population-based surveys, given the differential and substantial underreporting of STIs. Results also highlight the need for programmatic adaptation to address gender inequalities in STI rates, by developing women's health services in the French military. Addressing such needs not only benefits women but could also serve as a strategy to reduce overall STI rates as most military women have military partners, increasing the risk of internal transmission.

[The study of social representations of alcohol within French Navy]. / Représentations sociales de l'alcool au sein de la Marine nationale.

INTRODUCTION: The misuse of alcohol has harmful social and health impacts within a population. The French military must be particularly vigilant with alcohol, due to specificities linked with weaponry. This study was designed to explore social representations of alcohol based on a sample of the French Navy in order to prioritize prevention focuses on alcohol misuses in a military environment. METHODS: A semi-directed interview-based exploratory study was conducted in the south of France at the end of 2015. Data was submitted to manual categorical analysis and textual analysis (Iramuteq software). RESULTS: Sixty-two marines from the French Navy were interviewed including 30 Navy and 32 Marine Firefighters. Data analysis indicated that the motivation to consume alcohol comes more from a social influence (extrinsic motivations) than for pleasure induced by alcohol effects (intrinsic motivations). For Navy personnel, the sense of belonging to the Navy is strengthened by drinking habits with a strong social cohesion. In contrast, the Marine Firefighters had a negative perception of alcohol because of a possible degradation of their professional image for the civilian population. CONCLUSION: The identification of social representations of alcohol allows for a better apprehension of drinking behavior within a French military population, particularly by focusing on content and organization of discourses about alcohol. Following this survey, a quantitative study is currently being drawn up among military personnel from the French Navy in order to clarify some of the elements identified and presented within this article.

Monitoring of returnees from Ebola-affected areas: lessons learned based on the experience of French armed forces deployed in Guinea, 2015.

Introduction: During the 2014-15 Ebola virus disease (EVD) outbreak in West Africa, French armed forces were involved in the treatment and management of Ebola patients in Guinea. The constant flow of military personnel returning from their deployment posed a risk of secondary dissemination of the Ebola virus. Our objective was to describe the follow-up of returning service members that was implemented to prevent this risk of dissemination in France. Method: For the French military, a specific complementary follow-up was added to the national monitoring to take into account the need for a detailed record for follow-up of returning military personnel and to keep the military chain of command informed. Results: All the 410 service members deployed in Guinea underwent monitoring among whom 22 were suspected of EVD. Three of them were considered as possible EVD cases but none of them was tested positive for EVD. Conclusion: The monitoring organized for French service members deployed in Guinea made it possible to follow all exposed military personnel after their return, know their health status on a near real-time basis and be aware of all alerts. To reach this goal the collaboration with French national health agencies was necessary and should be improved in the future.

Building test data from real outbreaks for evaluating detection algorithms.

Benchmarking surveillance systems requires realistic simulations of disease outbreaks. However, obtaining these data in sufficient quantity, with a realistic shape and covering a sufficient range of agents, size and duration, is known to be very difficult. The dataset of outbreak signals generated should reflect the likely distribution of authentic situations faced by the surveillance system, including very unlikely outbreak signals. We propose and evaluate a new approach based on the use of historical outbreak data to simulate tailored outbreak signals. The method relies on a homothetic transformation of the historical distribution followed by resampling processes (Binomial, Inverse Transform Sampling Method-ITSM, Metropolis-Hasting Random Walk, Metropolis-Hasting Independent, Gibbs Sampler, Hybrid Gibbs Sampler). We carried out an analysis to identify the most important input parameters for simulation quality and to evaluate performance for each of the resampling algorithms. Our analysis confirms the influence of the type of algorithm used and simulation parameters (i.e. days, number of cases, outbreak shape, overall scale factor) on the results. We show that, regardless of the outbreaks, algorithms and metrics chosen for the evaluation, simulation quality decreased with the increase in the number of days simulated and increased with the number of cases simulated. Simulating outbreaks with fewer cases than days of duration (i.e. overall scale factor less than 1) resulted in an important loss of information during the simulation. We found that Gibbs sampling with a shrinkage procedure provides a good balance between accuracy and data dependency. If dependency is of little importance, binomial and ITSM methods are accurate. Given the constraint of keeping the simulation within a range of plausible epidemiological curves faced by the surveillance system, our study confirms that our approach can be used to generate a large spectrum of outbreak signals.

Dealing with uncertainty when using a surveillance system.

INTRODUCTION: Epidemiologists manage outbreak identification and confirmation by means of a "situation diagnosis", which involves validating (or invalidating) an alarm (signal identified as abnormal) as an alert (a real, characterized outbreak) and proposing the first countermeasures. This work investigates how uncertainty is materialized during this stage, and how experts develop strategies to address this uncertainty with the help of an early warning system. METHODS: We built an experiment using a simulation platform with a scenario involving both a natural and an intentional outbreak. Observations of expert activities were recorded and formalised using a specific task analysis method. These formatted data were then categorized by applying RAWFS (Reduction- Assumption - Weighing - Forestalling- Suppression) heuristics. RESULTS: We quantified uncertainty and the mechanisms involved. During the situation diagnosis, two sorts of uncertainty were characterized: practice-imposed uncertainty and situation-imposed uncertainty. We did not find either weighing pros and cons or suppression strategies in this area of expertise, but highlight the predominance of coping strategies that relied on reduction (66,4%) and assumption-based reasoning. We observed a predominance of the phone (89%) to cope with uncertainty and among electronic tools, the surveillance system plays a major role (69% of cases) and is mainly used in reduction strategies. We detail tools and systems used to support experts in their coping strategy. CONCLUSION: We confirmed that a surveillance system must include different features that provide relevant information to help users reduce uncertainty and thus support their decision making. In that perspective, the flow diagram and proposal presented in this study can help prioritize the necessary changes to surveillance system design.

Factor associated with risky sexual behaviors among the French general population.

Background: Despite prevention programs, a rising incidence of sexually transmitted infections is currently reported in France. Aims: Research factors associated with risky sexual behaviors (RSBs) among the French population. Methods: Subjects aged 15-54 years from the French national survey 'Baromètre santé 2010' were included (n = 16 598). RSB was defined as having multiple partners or failure to use condom at first intercourse with a new partner over past 12 months. Factors associated were identified using one logistic regression by gender. Results: The overall RSB prevalence was 9.5%, being higher among men (P < 0.001). Factors associated with RSB for both genders were young age (OR = 1.5), single status (men: OR = 7.1; women: OR = 6.4), homosexual relations (men: OR = 2.0; women: OR = 3.2), low incomes (men: OR = 1.5; women: OR = 1.4), use of cannabis (men: OR = 1.4; women: OR = 3.0). Men-specific factors were history of STI (OR = 2.5) and alcohol drunkenness (OR = 2.2), and women-specific factors history of suicide attempt (OR = 1.6) and history of sexual assault (OR = 1.6). Conclusions: Confirming most of known determinants of RSB, this study also identified some specific risky patterns for whom preventive actions can be developed: multiusers of psychoactive substances, people living with low incomes, women having sex with women or presenting history of psychological vulnerability (suicide attempts, sexually harassed).

Outbreak definition by change point analysis: a tool for public health decision?

BACKGROUND: Most studies of epidemic detection focus on their start and rarely on the whole signal or the end of the epidemic. In some cases, it may be necessary to retrospectively identify outbreak signals from surveillance data. Our study aims at evaluating the ability of change point analysis (CPA) methods to locate the whole disease outbreak signal. We will compare our approach with the results coming from experts' signal inspections, considered as the gold standard method. METHODS: We simulated 840 time series, each of which includes an epidemic-free baseline (7 options) and a type of epidemic (4 options). We tested the ability of 4 CPA methods (Max-likelihood, Kruskall-Wallis, Kernel, Bayesian) methods and expert inspection to identify the simulated outbreaks. We evaluated the performances using metrics including delay, accuracy, bias, sensitivity, specificity and Bayesian probability of correct classification (PCC). RESULTS: A minimum of 15 h was required for experts for analyzing the 840 curves and a maximum of 25 min for a CPA algorithm. The Kernel algorithm was the most effective overall in terms of accuracy, bias and global decision (PCC = 0.904), compared to PCC of 0.848 for human expert review. CONCLUSIONS: For the aim of retrospectively identifying the start and end of a disease outbreak, in the absence of human resources available to do this work, we recommend using the Kernel change point model. And in case of experts' availability, we also suggest to supplement the Human expertise with a CPA, especially when the signal noise difference is below 0.

Factors associated with malaria chemoprophylaxis compliance among French service members deployed in Central African Republic.

BACKGROUND: Malaria is a public health concern in the French armed forces, with 400-800 cases reported every year and three deaths in the past 2 years. However, lack of chemoprophylaxis (CP) compliance is often reported among service members. The aim of this study was to explore factors associated with CP compliance. METHODS: A retrospective study (1296 service members) was carried out among troops deployed in Central African Republic. Determinants of CP were collected by self-questionnaire. Socio-demographic variables, behavioural characteristics, belief variables, operational determinants such as troops in contact (TIC) and number of nights worked per week and peer-to-peer reinforcement were studied. Relationships between covariates and compliance were explored using logistic regressions (outcome: compliance as a dummy variable). RESULTS: Chemoprophylaxis compliance was associated with other individual preventive measures against mosquito bites (bed net use, OR (odds ratio) = 1.41 (95% CI [1.08-1.84]), and insecticide on clothing, OR = 1.90 ([1.43-2.51]) and malaria-related behaviours (taking chemoprophylaxis at the same time every day, OR = 2.37 ([1.17-4.78]) and taking chemoprophylaxis with food, OR = 1.45 ([1.11-1.89])). High perceived risk of contracting malaria, OR = 1.59 ([1.02-2.50]), positive perception of CP effectiveness, OR = 1.62 ([1.09-2.40]) and the practice of peer-to-peer reinforcement, OR = 1.38 ([1.05-1.82]) were also associated with better compliance. No association was found with TIC and number of nights worked. CONCLUSIONS: This study, which shows a positive relationship between peer-to-peer reinforcement and CP compliance, also suggests the existence of two main personality profiles among service members: those who seek risks and those who are health-conscious. Health education should be expanded beyond knowledge, know-how and motivational factors by using a comprehensive approach based on identification of health determinants, development of psychosocial skills and peer-to-peer reinforcement.

Electronic cigarette: use and perceptions among French military nurses in 2013.

AIMS: Paramedical personnel are exposed to tobacco smoking. Electronic cigarettes (e-cigarettes) may be considered as a lower-risk substitute for cigarettes. The aim of the study was to estimate the prevalence of e-cigarette use, the motives for use and the perceptions among French military nurses. METHODS: A cross-sectional survey, using self-administered questionnaires, was conducted in 2013 among 300 students and instructors of the French school of military paramedical personnel. Prevalences of e-cigarette use among smokers and nonsmokers were compared using logistic regressions adjusted on age and gender. RESULTS: The prevalence of smoking was 40% among the 200 responders. E-cigarette current use prevalence was 25% (6% daily users), without significant difference according to gender and age. Tobacco smokers reported significantly more e-cigarette current use (51% vs7%). Motives for e-cigarette use reported by smokers were curiosity (48%), intention to reduce tobacco consumption (43%) or to quit smoking (8%). Among users of both tobacco and e-cigarettes, 48% reported a significant decrease in tobacco consumption following e-cigarette initiation (average decrease of 5-10 cigarettes smoked per day; p <0.001). Both tobacco smokers and nonsmokers (88%) estimated that e-cigarette use was potentially harmful for health, but it was perceived as less harmful than tobacco by 46%. CONCLUSIONS: E-cigarette use among military nurses follows the trends observed in the general population in terms of prevalence and motives. E-cigarettes, which are seen as an attractive alternative to cigarettes, may contribute to a reduction in tobacco use among healthcare workers.