Underdetection of cases of COVID-19 in France threatens epidemic control.

As countries in Europe gradually relaxed lockdown restrictions after the first wave, test-trace-isolate strategies became critical to maintain the incidence of coronavirus disease 2019 (COVID-19) at low levels1,2. Reviewing their shortcomings can provide elements to consider in light of the second wave that is currently underway in Europe. Here we estimate the rate of detection of symptomatic cases of COVID-19 in France after lockdown through the use of virological3 and participatory syndromic4 surveillance data coupled with mathematical transmission models calibrated to regional hospitalizations2. Our findings indicate that around 90,000 symptomatic infections, corresponding to 9 out 10 cases, were not ascertained by the surveillance system in the first 7 weeks after lockdown from 11 May to 28 June 2020, although the test positivity rate did not exceed the 5% recommendation of the World Health Organization (WHO)5. The median detection rate increased from 7% (95% confidence interval, 6-8%) to 38% (35-44%) over time, with large regional variations, owing to a strengthening of the system as well as a decrease in epidemic activity. According to participatory surveillance data, only 31% of individuals with COVID-19-like symptoms consulted a doctor in the study period. This suggests that large numbers of symptomatic cases of COVID-19 did not seek medical advice despite recommendations, as confirmed by serological studies6,7. Encouraging awareness and same-day healthcare-seeking behaviour of suspected cases of COVID-19 is critical to improve detection. However, the capacity of the system remained insufficient even at the low epidemic activity achieved after lockdown, and was predicted to deteriorate rapidly with increasing incidence of COVID-19 cases. Substantially more aggressive, targeted and efficient testing with easier access is required to act as a tool to control the COVID-19 pandemic. The testing strategy will be critical to enable partial lifting of the current restrictive measures in Europe and to avoid a third wave.

Outbreak of Vibrio cholerae, Mayotte, France, April to July 2024.

On 22 April 2024, a locally-acquired case of cholera was confirmed in Mayotte. Subsequently, local transmission resulted in eight outbreak clusters with 221 notified cases in densely populated neighbourhoods with limited or no access to drinking water. The last case was detected on 12 July. A case-area targeted intervention strategy was applied to contain the outbreak. However, improving access to drinking water and basic sanitation is crucial to prevent further exposure.

Spatial and seasonal determinants of Lyme borreliosis incidence in France, 2016 to 2021.

BackgroundLyme borreliosis (LB) is the most widespread hard tick-borne zoonosis in the northern hemisphere. Existing studies in Europe have focused mainly on acarological risk assessment, with few investigations exploring human LB occurrence.AimWe explored the determinants of spatial and seasonal LB variations in France from 2016 to 2021 by integrating environmental, animal, meteorological and anthropogenic factors, and then mapped seasonal LB risk predictions.MethodsWe fitted 2016-19 LB national surveillance data to a two-part spatio-temporal statistical model. Spatial and temporal random effects were specified using a Besag-York-Mollie model and a seasonal model, respectively. Coefficients were estimated in a Bayesian framework using integrated nested Laplace approximation. Data from 2020-21 were used for model validation.ResultsA high vegetation index (≥ 0.6) was positively associated with seasonal LB presence, while the index of deer presence (> 60%), mild soil temperature (15-22 °C), moderate air saturation deficit (1.5-5 mmHg) and higher tick bite frequency were associated with increased incidence. Prediction maps show a higher risk of LB in spring and summer (April-September), with higher incidence in parts of eastern, midwestern and south-western France.ConclusionWe present a national level spatial assessment of seasonal LB occurrence in Europe, disentangling factors associated with the presence and increased incidence of LB. Our findings yield quantitative evidence for national public health agencies to plan targeted prevention campaigns to reduce LB burden, enhance surveillance and identify further data needs. This approach can be tested in other LB endemic areas.

Seroprevalence for Borrelia burgdorferi sensu lato and tick-borne encephalitis virus antibodies and associated risk factors among forestry workers in northern France, 2019 to 2020.

BackgroundLyme borreliosis (LB) is the most common tick-borne disease (TBD) in France. Forestry workers are at high risk of TBD because of frequent exposure to tick bites.AimWe aimed to estimate the seroprevalence of Borrelia burgdorferi sensu lato and tick-borne encephalitis virus (TBEV) antibodies among forestry workers in northern France. We compared seroprevalence by geographical area and assessed factors associated with seropositivity.MethodsBetween 2019 and 2020, we conducted a randomised cross-sectional seroprevalence survey. Borrelia burgdorferi sl seropositivity was defined as positive ELISA and positive or equivocal result in western blot. Seropositivity for TBEV was defined as positive result from two ELISA tests, confirmed by serum neutralisation. We calculated weighted seroprevalence and adjusted prevalence ratios to determine association between potential risk factors and seropositivity.ResultsA total of 1,778 forestry workers participated. Seroprevalence for B. burgdorferi sl was 15.5% (95% confidence interval (CI): 13.9-17.3), 3.5 times higher in the eastern regions than in the western and increased with seniority and with weekly time in a forest environment. Seroprevalence was 2.5 times higher in forestry workers reporting a tick bite during past years and reporting usually not removing ticks rapidly. Seroprevalence for TBEV was 0.14% (95% CI: 0.05-0.42).ConclusionWe assessed for the first time seroprevalence of B. burgdorferi sl and TBEV antibodies among forestry workers in northern France. These results will be used, together with data on LB and tick-borne encephalitis (TBE) incidence and on exposure to tick-bites, to target prevention programmes.

Risk of a blood donation contaminated with hepatitis E virus entering the blood supply before the implementation of universal RNA screening in France.

BACKGROUND AND OBJECTIVES: The risk of a blood donation contaminated with hepatitis E virus (HEV) entering the blood supply before introducing universal HEV-RNA screening in France was estimated to assess the benefit of such a measure. MATERIALS AND METHODS: The results of selective HEV nucleic acid testing (HEV-NAT) performed in mini pool of six plasma donations between 2018 and 2020 were extrapolated to the whole blood donor (BD) population after adjustment on three variables: regional establishment, sex and age group. RESULTS: Among the 246,285 plasma donations collected from 172,635 BDs tested for HEV-RNA, 248 (10.1/10,000) were positive. The extrapolation to all BDs led to an estimated rate of 5.9/10,000 donations (95% confidence interval [CI]: 4.5-7.4) which would be positive to HEV-RNA and a prevalence of 9.9/10,000 BDs (95% CI: 7.5-12.3). This prevalence was 4.4 times higher in males than females (16.8/10,000 vs. 3.8/10,000, p < 10-4 ). The highest prevalence was observed in males in the 30-39 age group (20.5/10,000) and the lowest in females in the 50-70 age group (2.8/10,000). CONCLUSION: The risk of an HEV-RNA-positive donation entering the blood supply was estimated at 1 in 1682 donations. This risk does not translate directly to the risk of HEV transfusion transmission, which mainly depends on the total number of viral particles in the transfused blood component and the sensitivity of NAT.

Impact of the Omicron variant on SARS-CoV-2 reinfections in France, March 2021 to February 2022.

Since the first reports in summer 2020, SARS-CoV-2 reinfections have raised concerns about the immunogenicity of the virus, which will affect SARS-CoV-2 epidemiology and possibly the burden of COVID-19 on our societies in the future. This study provides data on the frequency and characteristics of possible reinfections, using the French national COVID-19 testing database. The Omicron variant had a large impact on the frequency of possible reinfections in France, which represented 3.8% of all confirmed COVID-19 cases since December 2021.

Hepatitis of unknown aetiology in children - epidemiological overview of cases reported in Europe, 1 January to 16 June 2022.

Following the report of an excess in paediatric cases of severe acute hepatitis of unknown aetiology by the United Kingdom (UK) on 5 April 2022, 427 cases were reported from 20 countries in the World Health Organization European Region to the European Surveillance System TESSy from 1 January 2022 to 16 June 2022. Here, we analysed demographic, epidemiological, clinical and microbiological data available in TESSy. Of the reported cases, 77.3% were 5 years or younger and 53.5% had a positive test for adenovirus, 10.4% had a positive RT-PCR for SARS-CoV-2 and 10.3% were coinfected with both pathogens. Cases with adenovirus infections were significantly more likely to be admitted to intensive care or high-dependency units (OR = 2.11; 95% CI: 1.18-3.74) and transplanted (OR = 3.36; 95% CI: 1.19-9.55) than cases with a negative test result for adenovirus, but this was no longer observed when looking at this association separately between the UK and other countries. Aetiological studies are needed to ascertain if adenovirus plays a role in this possible emergence of hepatitis cases in children and, if confirmed, the mechanisms that could be involved.

Evidence of early circulation of SARS-CoV-2 in France: findings from the population-based "CONSTANCES" cohort.

Using serum samples routinely collected in 9144 adults from a French general population-based cohort, we identified 353 participants with a positive anti-SARS-CoV-2 IgG test, among whom 13 were sampled between November 2019 and January 2020 and were confirmed by neutralizing antibodies testing. Investigations in 11 of these participants revealed experience of symptoms possibly related to a SARS-CoV-2 infection or situations at risk of potential SARS-CoV-2 exposure. This suggests early circulation of SARS-CoV-2 in Europe.

Increased awareness and knowledge of Lyme Borreliosis and tick bite prevention among the general population in France: 2016 and 2019 health barometer survey.

BACKGROUND: Lyme borreliosis (LB) is the most frequent tick-borne disease in France. In the absence of a vaccine, LB prevention mainly relies on reducing tick bites. In 2016, the French Ministry of Health launched a national plan against tick-borne infections, including a prevention component. To evaluate the impact of this prevention strategy, we assessed knowledge and practices of tick bite prevention using the 2016 and 2019 national surveys on health attitudes and beliefs known as the French Health Barometer. METHODS: The Health Barometer is a repeated nationwide phone survey conducted annually on a random sample aged 18 to 75 years living in mainland France. In 2016 and 2019, participants were asked, among others, about their exposure to ticks, their behavior and practices regarding tick bites, and their knowledge about LB and its prevention. RESULTS: In 2019, 30% of the population reported a lifetime tick bite and 6% in the last year, an increase from 25% and 4%, respectively, in 2016 (p < 0.001). In 2019, 25% of the population felt exposed to tick bites compared to 23% in 2016 (p < 0.001). The proportion of participants who had heard about LB and who considered themselves well informed respectively increased from 66% and 29% in 2016 to 79% and 41% in 2019, (p < 0.001). In 2019 compared to 2016, a greater part of the French population applied protective measures against tick bites, particularly wearing protective clothing (74% vs 66%, p < 0.001) and regular tick checks and prompt tick removal after exposure (54% vs 47%, p < 0.001). CONCLUSIONS: A substantial proportion of French residents are exposed to tick bites and apply protective measures. Our findings indicate a trend toward an increased knowledge and awareness of tick bites and LB between 2016 and 2019 in France. Our results can be used to target future information campaigns to specific age groups or at-risk areas in addition to the general population. However, we need to further study the barriers to the use of preventive measures.

Two concurrent outbreaks of hepatitis A highlight the risk of infection for non-immune travellers to Morocco, January to June 2018.

From January to June 2018, two ongoing hepatitis A outbreaks affected travellers returning from Morocco and cases in Europe without travel history, resulting in 163 patients in eight European countries. Most interviewed travel-related cases were unaware of the hepatitis A risk in Morocco. Molecular analysis revealed two distinct hepatitis A virus (HAV) strains (subgenotype IA DK2018_231; subgenotype IB V18-16428). Vaccination recommendations should be emphasised to increase awareness among non-immune travellers to Morocco and HAV-endemic countries.

Keeping schools open during the emergence of the COVID-19 alpha variant: Impact on the circulation of SARS-CoV-2 among children during the 2020-2021 school year: Epidemiology of COVID-19 in children and adolescents during the 2020-2021 school year in France.

BACKGROUND: During 2020-2021, in the context of increasing SARS-CoV-2 transmission in the general population, French authorities made the decision to keep schools open and set up massive screening campaigns for students. Here, we describe the impact of this strategy on the circulation of SARS-COV-2 among children and adolescents during this period. METHODS: We analyzed SARS-COV-2 surveillance data provided by the French National Public Health Agency for the 2020-2021 school year along with the results of school-based screening campaigns implemented by the Ministry of National Education. RESULTS: The proportion of 0-17-year-olds among confirmed cases and tested individuals increased throughout the school year, with children and adolescents reaching a maximum of 24 % of confirmed cases in 2021 week (W) 22. During the first semester of 2021 (W3-W22), >2.6 million tests were performed in schools, with a positivity rate of 0.32 % among students. Considering only symptomatic cases, higher incidence rates occurred among children and adolescents during the 2021 wave from W9 to W17 compared with that in 2020 from W40 to W48. The incidence rate did not significantly change following the school closure periods. CONCLUSION: The higher contribution of children and adolescents to viral circulation during the 2020-2021 school year seems more related to the emergence of the alpha variant than to France's decision to keep schools open. Considering the negative impact of school closures on children's mental health, these results support the decision to keep schools open when accompanied by appropriate control measures.

Prevalence and factors associated with a prescription of a Lyme borreliosis serology for erythema migrans diagnosis in general practice: a study from the French sentinel network, 2009-2020.

BACKGROUND: Serological testing of patients consulting for typical erythema migrans (EM) is not recommended in European recommendations for diagnosis of Lyme borreliosis (LB). Little is known on the level of adherence of French general practitioners to these recommendations. The objectives were to estimate the proportion of Lyme borreliosis serological test prescription in patients with erythema migrans seen in general practice consultations in France, and to study the factors associated with this prescription. METHODS: LB cases with an EM reported by the French general practitioners (GPs) of the Sentinelles network between January 2009 and December 2020 were included. To assess the associations with a prescription of a serological test, multilevel logistic regression models were used. RESULTS: Among the 1,831 EM cases included, a prescription for a LB serological test was requested in 24.0% of cases. This proportion decreased significantly over the study period, from 46.8% in 2009 to 15.8% in 2020. A LB serological prescription was associated with patients with no reported tick bite (Odds Ratio (OR): 1.95; 95% confidence interval [1.23-3.09]), multiple EM (OR: 3.82 [1.63-8.92]), EM of five centimeters or more (OR: 4.34 [2.33-8.08]), and GPs having diagnosed less than one EM case per year during the study period (OR: 5.28 [1.73-16.11]). CONCLUSIONS: Serological testing of patients consulting for EM is not recommended in European recommendations for diagnosis of Lyme borreliosis. Therefore, the significant decrease in the rate of LB serological test for EM over the study period is encouraging. The factors identified in this study can be used to improve messaging to GPs and patients. Further efforts are needed to continue to disseminate diagnostic recommendations for LB to GPs, especially those who rarely see patients with EM.

An Update of Evidence for Pathogen Transmission by Ticks of the Genus Hyalomma.

Current and likely future changes in the geographic distribution of ticks belonging to the genus Hyalomma are of concern, as these ticks are believed to be vectors of many pathogens responsible for human and animal diseases. However, we have observed that for many pathogens there are no vector competence experiments, and that the level of evidence provided by the scientific literature is often not sufficient to validate the transmission of a specific pathogen by a specific Hyalomma species. We therefore carried out a bibliographical study to collate the validation evidence for the transmission of parasitic, viral, or bacterial pathogens by Hyalomma spp. ticks. Our results show that there are very few validated cases of pathogen transmission by Hyalomma tick species.

Clustered Cases of Waterborne Hepatitis E Virus Infection, France.

The identification of seven cases of hepatitis E virus infection in a French rural hamlet in April 2015 led to investigations confirming the clustering and identifying the source of the infection. Laboratories and general practitioners in the area actively searched for other cases based on RT-PCR and serological tests. The environment, including water sources, was also checked for HEV RNA. Phylogenetic analyses were performed to compare HEV sequences. No other cases were found. Six of the seven patients lived in the same hamlet, and the seventh used to visit his family who lived there. All HEV strains were very similar and belonged to the HEV3f subgenotype, confirming the clustering of these cases. All the patients drank water from the public network. A break in the water supply to the hamlet was identified at the time the infection probably occurred; HEV RNA was also detected in a private water source that was connected to the public water network. The water flowing from the taps was quite turbid during the break. The private water supply containing HEV RNA was the likely source of the contamination. Private water supplies not disconnected from the public network are still frequent in rural areas, where they may contribute to public water pollution.

Annual change in Friedreich's ataxia evaluated by the Scale for the Assessment and Rating of Ataxia (SARA) is independent of disease severity.

BACKGROUND: The objective of the study was to evaluate the sensitivity to change of the Scale for the Assessment and Rating of Ataxia (score, 0-40) in Friedreich's ataxia. METHODS: This was a follow-up study in adult patients with genetically confirmed Friedreich's ataxia evaluated at least twice (minimum interval, 6 months). Participants were outpatients at the Center for Neurogenetics of the Pitie-Salpêtrière Hospital in Paris. RESULTS: We included 84 patients; 60% had 3 or more evaluations. The mean score on first assessment was 22.7 ± 9, and the mean follow-up was 1.84 ± 1.10 years. The mean increase was 1.36 ± 2.3 points/year; this variation was not significantly linked to factors known to influence disease severity such as age at onset, disease duration, GAA expansion length, and wheelchair use. CONCLUSIONS: In adult Friedreich's ataxia patients the Scale for the Assessment and Rating of Ataxia can detect annual changes independently of disease severity. In future therapeutic trials no patient stratification is globally required.

The control of Hyalomma ticks, vectors of the Crimean-Congo hemorrhagic fever virus: Where are we now and where are we going?

At a time of major global, societal, and environmental changes, the shifting distribution of pathogen vectors represents a real danger in certain regions of the world as generating opportunities for emergency. For example, the recent arrival of the Hyalomma marginatum ticks in southern France and the concurrent appearance of cases of Crimean-Congo hemorrhagic fever (CCHF)-a disease vectored by this tick species-in neighboring Spain raises many concerns about the associated risks for the European continent. This context has created an urgent need for effective methods for control, surveillance, and risk assessment for ticks and tick-borne diseases with a particular concern regarding Hyalomma sp. Here, we then review the current body of knowledge on different methods of tick control-including chemical, biological, genetical, immunological, and ecological methods-and the latest developments in the field, with a focus on those that have been tested against ticks from the genus Hyalomma. In the absence of a fully and unique efficient approach, we demonstrated that integrated pest management combining several approaches adapted to the local context and species is currently the best strategy for tick control together with a rational use of acaricide. Continued efforts are needed to develop and implement new and innovative methods of tick control.

Exploratory Space-Time Analyses of Reported Lyme Borreliosis Cases in France, 2016-2019.

In recent decades, the incidence of Lyme borreliosis (LB) in Europe seems to have increased, underpinning a growing public health concern. LB surveillance systems across the continent are heterogeneous, and the spatial and temporal patterns of LB reports have been little documented. In this study, we explored the spatio-temporal patterns of LB cases reported in France from 2016 to 2019, to describe high-risk clusters and generate hypotheses on their occurrence. The space-time K-function and the Kulldorf's scan statistic were implemented separately for each year to evaluate space-time interaction between reported cases and searching clusters. The results show that the main spatial clusters, of radius size up to 97 km, were reported in central and northeastern France each year. In 2017-2019, spatial clusters were also identified in more southern areas (near the Alps and the Mediterranean coast). Spatio-temporal clustering occurred between May and August, over one-month to three-month windows in 2016-2017 and in 2018-2019. A strong spatio-temporal interaction was identified in 2018 within 16 km and seven days, suggesting a potential local and intense pathogen transmission process. Ongoing improved surveillance and accounting for animal hosts, vectors, meteorological factors and human behaviors are keys to further elucidate LB spatio-temporal patterns.

Standardising surveillance of hepatitis E virus infection in the EU/EEA: A review of national practices and suggestions for the way forward.

BACKGROUND: Hepatitis E virus (HEV) infection is not notifiable at EU/EEA level, therefore surveillance relies on national policies only. Between 2005 and 2015, more than 20,000 cases were reported in EU/EEA countries. HEV testing is established in 26 countries and 19 countries sequence HEV viruses. OBJECTIVE AND STUDY DESIGN: WHO's European Action plan for viral hepatitis recommends harmonised surveillance objectives and case definitions. ECDC's HEV expert group developed minimal and optimal criteria for national hepatitis E surveillance to support EU/EEA countries in enhancing their capacity and to harmonise methods. RESULTS: The experts agreed that the primary objectives of national surveillance for HEV infections should focus on the basic epidemiology of the disease: to monitor the incidence of acute cases and chronic infections. The secondary objectives should be to describe viral phylotypes or subtypes and to identify potential clusters/outbreaks and possible routes of transmission. Seventeen of 20 countries with existing surveillance systems collect the minimal data set required to describe the epidemiology of acute cases. Eleven countries test for chronic infections. Twelve countries collect data to identify potential clusters/outbreaks and information on possible routes of transmission. DISCUSSION: Overall, the majority of EU/EEA countries collect the suggested data and meet the outlined requirements to confirm an acute case.

Incidence of Tuberculosis and Associated Mortality in a Cohort of Human Immunodeficiency Virus-Infected Children Initiating Antiretroviral Therapy.

BACKGROUND.: We assessed the incidence of tuberculosis, risk factors for tuberculosis, and the contribution of tuberculosis on mortality in a large cohort of human immunodeficiency virus (HIV)-infected children <15 years of age initiating first-line antiretroviral therapy (ART) between 1999 and 2012 in Thailand, one of the 22 high tuberculosis burden countries. METHODS.: A physician reviewed and classified tuberculosis cases. Incidence was the number of children with incident tuberculosis, defined as a first or recurrent tuberculosis diagnosis >30 days after ART initiation, divided by the total person-years of follow-up (PYFU). Risk factors for incident tuberculosis were identified using Fine and Gray's competing risks models, with death from other causes treated as a competing event, and risk factors for death were identified using Cox models. RESULTS.: At ART initiation, 670 children (55% female) had a median age of 6.4 years (interquartile range, 2.0-9.6), body mass index-for-age z-score -0.8 (-1.9 to 0.0), HIV ribonucleic acid viral load 5.1 log10 copies/mL (4.6-5.6), and CD4 9% (3-17). Median duration of follow-up was 7.7 years. Tuberculosis incidence was 7 per 1000 PYFU (95% confidence interval [CI], 5-11) and decreased with ART duration. Lower age-adjusted hemoglobin, hematocrit, and CD4 at ART initiation were associated with a higher risk of incident tuberculosis. Of the 30 incident tuberculosis cases, 9 died. Diagnosis of incident tuberculosis was associated with mortality (unadjusted hazard ratio = 10.2, 95% CI = 4.8-21.5, P < .001 and adjusted hazard ratio = 5.4, 95% CI = 2.5-11.7, P < .001). CONCLUSIONS.: Incident tuberculosis was strongly associated with mortality. CD4 counts or hemoglobin or hematocrit levels may prompt clinicians to consider a possible tuberculosis infection.