Characteristics of women presenting with hepatitis B at antenatal care services in London, 2008-2018.

BACKGROUND: To support interventions to prevent mother-to-child transmission of hepatitis B and fill gaps in surveillance, the Enhanced Surveillance of Antenatal Hepatitis B (ESAHB) programme was implemented in London from 2008 to 2018 to collect demographic information on women who tested positive for hepatitis B during antenatal screening. We describe the epidemiology of hepatitis B in pregnancy, as reported to ESAHB. METHODS: The characteristics of pregnant women living with hepatitis B were described and rates were calculated by year, local authority and residence deprivation decile (1 being most deprived). Poisson regression tested the association between pregnant women living with hepatitis B and deprivation decile. RESULTS: Between 2008 and 2018, 8879 women living with hepatitis B in London (0.35 per 1000 women) reported 11 193 pregnancies. Annual hepatitis B rates remained stable, but there was strong evidence for an inverse association between rate and deprivation decile (P < 0.001). The majority of women in the cohort presented late to antenatal care, were born outside the UK in a hepatitis B endemic area or required an interpreter for consultations. CONCLUSIONS: ESAHB provided important data to inform service quality improvements for women living with hepatitis B. This analysis highlights the link between deprivation and hepatitis B.

Lessons learned from the investigation and management of an outbreak of Shigella flexneri associated with a restaurant in London, 2019-2020.

BACKGROUND: Foodborne outbreaks of Shigella flexneri infection are uncommon in the UK. In November 2019, the United Kingdom Health Security Agency investigated an outbreak of S. flexneri associated with a fast-food restaurant in London. METHODS: Epidemiological investigations included case ascertainment and interviewing suspected cases using enhanced surveillance questionnaires. Whole-genome sequencing (WGS) was used for characterisation of human isolates. Environmental investigations included a review of food safety processes at the implicated restaurant, administration of exposure questionnaires and stool sampling of staff. RESULTS: Between November 2019 and February 2020, 17 cases were confirmed as part of the outbreak by WGS in London. Among these, 15 were linked to the implicated restaurant. A review of the food safety processes at the restaurant was satisfactory. Despite initial suboptimal coverage of stool screening of staff, all staff members working at the restaurant during the sampling period were screened and an asymptomatic food handler tested positive for S.flexneri with the outbreak WGS profile. The individual underwent microbiological clearance, and no further cases were reported. It was not possible to confirm the direction of transmission for the community cases or the staff member. CONCLUSION: We report an outbreak of S. flexneri in a fast-food restaurant in London with previous inspection ratings indicating good compliance with food safety and hygiene standards. WGS was crucial in identifying cases linked to the outbreak. This outbreak highlights the importance of prompt testing of food handlers in outbreaks suspected to be associated with food businesses.

Whole-Genome Sequencing Reveals the Contribution of Long-Term Carriers in Staphylococcus aureus Outbreak Investigation.

Whole-genome sequencing (WGS) makes it possible to determine the relatedness of bacterial isolates at a high resolution, thereby helping to characterize outbreaks. However, for Staphylococcus aureus, the accumulation of within-host diversity during carriage might limit the interpretation of sequencing data. In this study, we hypothesized the converse, namely, that within-host diversity can in fact be exploited to reveal the involvement of long-term carriers (LTCs) in outbreaks. We analyzed WGS data from 20 historical outbreaks and applied phylogenetic methods to assess genetic relatedness and to estimate the time to most recent common ancestor (TMRCA). The findings were compared with the routine investigation results and epidemiological evidence. Outbreaks with epidemiological evidence for an LTC source had a mean estimated TMRCA (adjusted for outbreak duration) of 243 days (95% highest posterior density interval [HPD], 143 to 343 days) compared with 55 days (95% HPD, 28 to 81 days) for outbreaks lacking epidemiological evidence for an LTC (P = 0.004). A threshold of 156 days predicted LTC involvement with a sensitivity of 0.875 and a specificity of 1. We also found 6/20 outbreaks included isolates with differing antimicrobial susceptibility profiles; however, these had only modestly increased pairwise diversity (mean 17.5 single nucleotide variants [SNVs] [95% confidence interval {CI}, 17.3 to 17.8]) compared with isolates with identical antibiograms (12.7 SNVs [95% CI, 12.5 to 12.8]) (P < 0.0001). Additionally, for 2 outbreaks, WGS identified 1 or more isolates that were genetically distinct despite having the outbreak pulsed-field gel electrophoresis (PFGE) pulsotype. The duration-adjusted TMRCA allowed the involvement of LTCs in outbreaks to be identified and could be used to decide whether screening for long-term carriage (e.g., in health care workers) is warranted. Requiring identical antibiograms to trigger investigation could miss important contributors to outbreaks.

Nosocomial outbreak of staphyloccocal scalded skin syndrome in neonates in England, December 2012 to March 2013.

Staphylococcal scalded skin syndrome (SSSS) is a blistering skin condition caused by exfoliative toxin-producing strains of Staphylococcus aureus. Outbreaks of SSSS in maternity settings are rarely reported. We describe an outbreak of SSSS that occurred among neonates born at a maternity unit in England during December 2012 to March 2013. Detailed epidemiological and microbiological investigations were undertaken. Eight neonates were found to be infected with the outbreak strain of S. aureus, of spa type t346, representing a single pulsotype. All eight isolates contained genes encoding exfoliative toxin A (eta) and six of them contained genes encoding toxin B (etb). Nasal swabs taken during targeted staff screening yielded a staphylococcal carriage rate of 21% (17/80), but none contained the outbreak strain. Mass screening involving multi-site swabbing and pooled, enrichment culture identified a healthcare worker (HCW) with the outbreak strain. This HCW was known to have a chronic skin condition and their initial nasal screen was negative. The outbreak ended when they were excluded from work. This outbreak highlights the need for implementing robust swabbing and culture methodswhen conventional techniques are unsuccessful in identifying staff carrier(s). This study adds to the growing body of evidence on the role of HCWs in nosocomial transmission of S. aureus.

Opportunistic MMR vaccination for unimmunized children at the time of routine teenage booster vaccination in secondary schools: implications for policy.

With the aim of minimizing adverse health outcomes and reducing the risk of outbreaks, we offered one dose of MMR vaccine to children known to be incompletely immunized at the time of teenage booster vaccination in secondary schools in Swindon in 2011. The Child Health Department database was queried to identify Year 10 children who had had zero or one dose of MMR vaccine previously. Of the 316 children offered vaccination, 60 received a first dose and 87 received a second dose of MMR vaccine. Fourteen children had two documented doses in the past and two had contraindications to the vaccine. Overall uptake of two doses of MMR vaccine increased from 86·3% to 90·6%. The valuable uptake achieved demonstrates that an opportunistic offer of MMR vaccine for unimmunized children at schools is feasible and beneficial. MMR vaccine should be offered routinely to unimmunized children at the time of school vaccination programmes, especially in areas with sub-optimal coverage.

Challenges in investigating transient rash illness in nursery children.

INTRODUCTION: In October 2007, the Thames Valley Health Protection Unit (TVHPU) was notified by a parent that her child developed a transient rash after eating lunch at a nursery in Oxfordshire. An initial investigation undertaken by TVHPU was escalated when similar incidents were reported in nurseries in other parts of England. METHODS: A detailed epidemiological and food tracing investigation was conducted to ascertain the aetiology. RESULTS: Investigations revealed 11 incidents affecting 164 children between July and November 2007 in six nurseries operated by two companies. The symptoms included a transient rash around the mouth and hands of children who ate meals prepared on site by the nurseries. Consumption of the lunch main course appeared to be a strong aetiological factor. Expert opinion pointed to biogenic amines (e.g. histamine) as a possible cause for the symptoms displayed, but there was insufficient evidence to support testing of food samples. CONCLUSION: The incident highlighted significant gaps in reporting of unexplained symptoms among children in nurseries, indicating that such incidents do not always come to the attention of public health authorities. Timely notification to HPUs will enable prompt investigation, increase the likelihood of identifying the cause and inform appropriate responses to prevent future incidents.

Invasive meningococcal disease: completeness and timeliness of reporting of confirmed cases in Thames Valley, 2006-2007.

OBJECTIVES: Regular evaluation of disease surveillance systems is essential. This study assessed the completeness and timeliness of reporting of invasive meningococcal disease (IMD) in Thames Valley in 2006-2007. STUDY DESIGN: Retrospective review of two data sources used in disease surveillance: the list of notified cases to the Thames Valley Health Protection Unit (TVHPU) and the list of confirmed cases at the reference laboratory during 2006-2007. METHODS: The datasets were compared by checking patient name, date of birth, sample date and date of onset of illness. Completeness was estimated using Tilling's capture-recapture method. Timeliness was assessed by calculating the difference between the date of admission and the date of notification to the TVHPU. RESULTS: The estimated completeness of reporting of IMD cases was calculated as 90.5% (95% confidence interval 88.6-92.4). Thirty-six percent of cases were notified on the day of admission, 63% were notified within 1 day and 72% were notified within 2 days (range 0-36 days). CONCLUSIONS: Timeliness and completeness of reporting of IMD was clearly suboptimal. It is critical to educate clinicians on the need to notify all suspected cases of IMD to public health authorities in a timely manner.