Outbreak of Corynebacterium diphtheriae among asylum seekers in Belgium in 2022: operational challenges and lessons learnt.

Since 2022, European countries have been facing an outbreak of mainly cutaneous diphtheria caused by toxigenic Corynebacterium diphtheriae among asylum seekers. In Belgium, between 1 March and 31 December 2022, 25 cases of toxigenic C. diphtheriae infection were confirmed among asylum seekers, mostly among young males from Afghanistan. Multi-locus sequence typing showed that most isolates belonged to sequence types 574 or 377, similar to the majority of cases in other European countries. The investigation and management of the outbreak, with many asylum seekers without shelter, required adjustments to case finding, contact tracing and treatment procedures. A test-and-treat centre was organised by non-governmental organisations, the duration of the antimicrobial treatment was shortened to increase compliance, and isolation and contact tracing of cases was not possible. A vaccination centre was opened, and mobile vaccination campaigns were organised to vaccinate a maximum of asylum seekers. No more cases were detected between end December 2022 and May 2023. Unfortunately, though, three cases of respiratory diphtheria, including one death, were reported at the end of June 2023. To prevent future outbreaks, specific attention and sufficient resources should be allocated to this vulnerable population, in Belgium and at international level.

Outbreak of invasive meningococcal disease caused by a meningococcus serogroup B in a nursery school, Wallonia, Belgium, 2018.

Although most invasive meningococcal disease (IMD) cases are sporadic without identified transmission links, outbreaks can occur. We report three cases caused by meningococcus B (MenB) at a Belgian nursery school over 9 months. The first two cases of IMD occurred in spring and summer 2018 in healthy children (aged 3-5 years) attending the same classroom. Chemoprophylaxis was given to close contacts of both cases following regional guidelines. The third case, a healthy child of similar age in the same class as a sibling of one case, developed disease in late 2018. Microbiological analyses revealed MenB with identical finetype clonal complex 269 for Case 1 and 3 (unavailable for Case 2). Antimicrobial susceptibility testing revealed no antibiotic resistance. Following Case 3, after multidisciplinary discussion, chemoprophylaxis and 4CMenB (Bexsero) vaccination were offered to close contacts. In the 12-month follow-up of Case 3, no additional cases were reported by the school. IMD outbreaks are difficult to manage and generate public anxiety, particularly in the case of an ongoing cluster, despite contact tracing and management. This outbreak resulted in the addition of MenB vaccination to close contacts in Wallonian regional guidelines, highlighting the potential need and added value of vaccination in outbreak management.

The health and economic impact of acute gastroenteritis in Belgium, 2010-2014.

Acute gastroenteritis (AGE) remains a common condition in both low- and high-income countries. In Belgium, however, there is currently a lack of information on the societal health and economic impact of AGE. We conducted a retrospective study using mortality and cause-of-death data, hospital data, primary care data, health interview survey data and other published data. We estimated the burden of illness during a 5-year period (2010-2014) in Belgium in terms of deaths, patients admitted to hospitals, patients consulting their general practitioner (GP) and cases occurring in the community. We further quantified the health impact in terms of disability-adjusted life years (DALYs) and the economic impact in terms of cost-of-illness estimates. We estimated 343 deaths, 27 707 hospitalised patients, 464 222 GP consultations and 10 058 741 episodes occurring in the community (0.91 cases/person) on average per year. AGE was associated with 11 855 DALYs per year (107 DALY per 100 000 persons). The economic burden was estimated to represent direct costs of €112 million, indirect costs of €927 million (90% of the total costs) and an average total cost of €103 per case and €94 per person. AGE results in a substantial health and economic impact in Belgium, justifying continued mitigation efforts.

The burden of legionnaires' disease in Belgium, 2013 to 2017.

BACKGROUND: Legionnaires' disease (LD) is a severe bacterial infection causing pneumonia. Surveillance commonly underestimates the true incidence as not all cases are laboratory confirmed and reported to public health authorities. The aim of this study was to present indicators for the impact of LD in Belgium between 2013 and 2017 and to estimate its true burden in the Belgian population in 2017, the most recent year for which the necessary data were available. METHODS: Belgian hospital discharge data, data from three infectious disease surveillance systems (mandatory notification, sentinel laboratories and the national reference center), information on reimbursed diagnostic tests from the Belgian National Institute for Health and Disability Insurance and mortality data from the Belgian statistical office were used. To arrive at an estimate of the total number of symptomatic cases in Belgium, we defined a surveillance pyramid and estimated a multiplication factor to account for LD cases not captured by surveillance. The multiplication factor was then applied to the pooled number of LD cases reported by the three surveillance systems. This estimate was the basis for our hazard- and incidence-based Disability-Adjusted Life Years (DALYs) calculation. To account for uncertainty in the estimations of the DALYs and the true incidence, we used Monte Carlo simulations with 10,000 iterations. RESULTS: We found an average of 184 LD cases reported by Belgian hospitals annually (2013-2017), the majority of which were male (72%). The surveillance databases reported 215 LD cases per year on average, 11% of which were fatal within 90 days after diagnosis. The estimation of the true incidence in the community yielded 2674 (95% Uncertainty Interval [UI]: 2425-2965) cases in 2017. LD caused 3.05 DALYs per case (95%UI: 1.67-4.65) and 8147 (95%UI: 4453-12,426) total DALYs in Belgium in 2017, which corresponds to 71.96 (95%UI: 39.33-109.75) DALYs per 100,000 persons. CONCLUSIONS: This analysis revealed a considerable burden of LD in Belgium that is vastly underestimated by surveillance data. Comparison with other European DALY estimates underlines the impact of the used data sources and methodological approaches on burden estimates, illustrating that national burden of disease studies remain essential.

Legionnaires' disease: overview of the situation concerning notification in Wallonia (Belgium) in 2012, a retrospective descriptive study based on a capture-recapture method.

BACKGROUND: Legionnaires' disease is a severe form of pneumonia, and although public health medical inspectors must be notified, it is often under-reported. The objectives of this study were to determine the completeness rate of notification of Legionnaires' disease and to estimate the incidence of this disease in Wallonia, the southern part of Belgium, in 2012. METHOD: This retrospective, transversal descriptive study was based on a capture-recapture method using two sources. An estimation of the total number of Legionnaires' disease cases was calculated using Chapman and Seber's estimators for small numbers, thereby allowing us to estimate the real incidence of this disease in Wallonia as well as the completeness rate of notification. RESULTS: The total number of estimated Legionella cases for 2012 was 45 (IC 95%:41-48) and the completeness rate was 65% (IC 95%:61-70%). The estimated incidence of Legionnaires' disease in Wallonia was 1.27/100,000 inhabitants. CONCLUSIONS: The notification rate of Legionella must be improved in Wallonia. Doctors should be made aware of the importance of diagnosing and reporting Legionnaires' disease.

INTRODUCTION: Malgré une mortalité et morbidité non négligeables, la maladie du légionnaire est une maladie à déclaration obligatoire auprès des médecins inspecteurs qui est fréquemment sous rapportée. Les objectifs de cette étude furent le calcul de l'exhaustivité de la déclaration obligatoire de la maladie du légionnaire et l'estimation de son incidence en Wallonie, la partie sud de la Belgique, pour l'année 2012. MÉTHODOLOGIE: Cette étude descriptive transversale rétrospective s'est basée sur une méthode capture-recapture à 2 sources. Une estimation du nombre total de cas de maladie du légionnaire a été réalisée en utilisant les estimateurs de Chapman et Seber pour effectifs faibles. Ensuite, l'incidence réelle de la maladie du légionnaire en Wallonie ainsi que l'exhaustivité de la déclaration ont pu être calculées. RÉSULTATS: Le nombre total de cas estimés de maladie du légionnaire pour l'année 2012 est de 45 (IC 95% : 41­48) et le taux d'exhaustivité de la déclaration obligatoire est de 65% (IC 95% : 61-70%). L'incidence estimée de maladie du légionnaire en région wallonne est de 1,27/100.000 habitants. CONCLUSION: Le taux de notification de la maladie du légionnaire doit être amélioré en Wallonie. Les médecins devraient être mieux sensibilisés à la déclaration et au diagnostic de la maladie du légionnaire.