Infectious diseases in children

In 2023, through an ongoing respiratory pathogen surveillance system, we observed from mid-September onwards, an increase of respiratory illness among children aged ≤ 15 years presenting at hospital outpatient clinics in Beijing, China. Data indicated that illness was caused by multiple pathogens, predominantly Mycoplasma pneumoniae. Seasonality, periodicity and high prevalence of resistance to macrolide (30 of 30 strains sequenced with the A2063G mutation) were important characteristics of the M. pneumoniae epidemic, which resulted in a rise in consultations at specialised paediatric hospitals.

To advance our understanding of respiratory syncytial virus (RSV) impact through genomic surveillance, we describe two PCR-based sequencing systems, (i) RSVAB-WGS for generic whole-genome sequencing and (ii) RSVAB-GF, which targets major viral antigens, G and F, and is used as a complement for challenging cases with low viral load. These methods monitor RSV genetic diversity to inform molecular epidemiology, vaccine effectiveness and treatment strategies, contributing also to the standardisation of surveillance in a new era of vaccines.

Enteroviruses are a common cause of seasonal childhood infections. The vast majority of enterovirus infections are mild and self-limiting, although neonates can sometimes develop severe disease. Myocarditis is a rare complication of enterovirus infection. Between June 2022 and April 2023, twenty cases of severe neonatal enteroviral myocarditis caused by coxsackie B viruses were reported in the United Kingdom. Sixteen required critical care support and two died. Enterovirus PCR on whole blood was the most sensitive diagnostic test. We describe the initial public health investigation into this cluster and aim to raise awareness among paediatricians, laboratories and public health specialists.

On 5 April 2022, the United Kingdom reported an increase of cases of severe acute hepatitis of unknown aetiology in children, several needing hospitalisation and some required liver transplant or died. Thereafter, 35 countries reported probable cases, almost half of them in Europe. Facing the alert, on 28 April, Portugal created a multidisciplinary Task Force (TF) for rapid detection of probable cases and response. The experts of the TF came from various disciplines: clinicians, laboratory experts, epidemiologists, public health experts and national and international communication. Moreover, Portugal adopted the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) case definition and recommendations. By 31 December 2022, 28 probable cases of severe acute hepatitis of unknown aetiology were reported: 16 male and 17 aged under 2 years. Of these cases, 23 were hospitalised but none required liver transplant or died. Adenovirus was detected from nine of 26 tested cases. No association was observed between adenovirus infection and hospital admission after adjusting for age, sex and region in a binomial regression model. The TF in Portugal may have contributed to increase awareness among clinicians, enabling early detection and prompt management of the outbreak.

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.

To detect potential concern about severe acute hepatitis in children, we conducted a survey among 50 ERN RARE-LIVER centres. By 26 April 2022, 34 centres, including 25 transplant centres, reported an estimated median of 3–5, 0–2 and 3–5 cases in 2021, 2020 and 2019 and a mean of 2 (range: 0–8) cases between January and April 2022 (mean in 10 large liver transplant centres: 3). Twelve centres reported suspicion of an increase, but no rise.