Cassandra Powers

Monitoring the emergence of community transmission of influenza A/H1N1 2009 in England: a cross sectional opportunistic survey of self sampled telephone callers to NHS Direct

Objective To evaluate ascertainment of the onset of community transmission of influenza A/H1N1 2009 (swine flu) in England during the earliest phase of the epidemic through comparing data from two surveillance systems. Design Cross sectional opportunistic survey. Study samples Results from self samples by consenting patients who had called the NHS Direct telephone health line with cold or flu symptoms, or both, and results from Health Protection Agency (HPA) regional microbiology laboratories on patients tested according to the clinical algorithm for the management of suspected cases of swine flu. Setting Six regions of England between 24 May and 30 June 2009. Main outcome measure Proportion of specimens with laboratory evidence of influenza A/H1N1 2009. Results Influenza A/H1N1 2009 infections were detected in 91 (7%) of the 1385 self sampled specimens tested. In addition, eight instances of influenza A/H3 infection and two cases of influenza B infection were detected. The weekly rate of change in the proportions of infected individuals according to self obtained samples closely matched the rate of increase in the proportions of infected people reported by HPA regional laboratories. Comparing the data from both systems showed that local community transmission was occurring in London and the West Midlands once HPA regional laboratories began detecting 100 or more influenza A/H1N1 2009 infections, or a proportion positive of over 20% of those tested, each week. Conclusions Trends in the proportion of patients with influenza A/H1N1 2009 across regions detected through clinical management were mirrored by the proportion of NHS Direct callers with laboratory confirmed infection. The initial concern that information from HPA regional laboratory reports would be too limited because it was based on testing patients with either travel associated risk or who were contacts of other influenza cases was unfounded. Reports from HPA regional laboratories could be used to recognise the extent to which local community transmission was occurring.

Lymphogranuloma venereum diagnoses among men who have sex with men in the UK: interpreting a cross-sectional study using an epidemic phase-specific framework

Objectives To investigate the drivers behind the epidemic expansion of lymphogranuloma venereum (LGV) cases in late 2009 to help inform infection control. Methods An epidemic curve of all LGV diagnoses between 2003 and mid-2012 was plotted and divided into the initial detection period, and endemic, growth and hyperendemic phases. Detailed clinical and behavioural data were collected and logistic regression was used to compare the characteristics of diagnoses made during the growth and endemic phases. Results Between April 2003 and June 2012, 2138 cases of LGV were diagnosed. Enhanced surveillance data were available for 1370 of whom 1353 were men who have sex with men (MSM). 98% of MSM presented with proctitis, 82% were HIV positive, 20% were hepatitis C virus (HCV) antibody positive, and 67% lived in London. Growth phase cases (n=488) were more likely to report meeting sexual contacts at sex parties (11% vs 6%, p=0.014), unprotected receptive or insertive oral intercourse (93% vs 86%, p=0.001; 92% vs 85%, p=0.001) and sharing sex toys (8% vs 4%; p=0.011), and to be diagnosed HIV positive (86% vs 80%; p=0.014), than endemic phase cases (n=423). Unprotected receptive anal intercourse was equally likely to be reported in both phases (71% vs 73%). After adjustment, cases in the growth phase were more likely to meet new contacts at sex parties (p=0.031) and be HIV positive (p=0.045). Conclusions Rapid epidemic growth coincided with an intensification of unprotected sexual activity among a core population of HIV-positive MSM. Efforts to develop innovative interventions for this hard-to-reach population are needed.

Has estimation of numbers of cases of pandemic influenza H1N1 in England in 2009 provided a useful measure of the occurrence of disease

Please cite this paper as:  Evans et al. (2011) Has estimation of numbers of cases of pandemic influenza H1N1 in England in 2009 provided a useful measure of the occurrence of disease? Influenza and Other Respiratory Viruses 5(6), e504–e512.

Virological self-sampling to monitor influenza antiviral susceptibility in a community cohort

Abstract Objective To perform antiviral susceptibility monitoring of treated individuals in the community during the 2009 influenza A(H1N1) pandemic in England. Patients and methods Between 200 and 400 patients were enrolled daily through the National Pandemic Flu Service (NPFS) and issued with a self-sampling kit. Initially, only persons aged 16 and over were eligible, but from 12 November (week 45), self-sampling was extended to include school-age children (5 years and older). All samples received were screened for influenza A(H1N1)pdm09 as well as seasonal influenza [A(H1N1), A(H3N2) and influenza B] by a combination of RT–PCR and virus isolation methods. Influenza A(H1N1)pdm09 RT–PCR-positive samples were screened for the oseltamivir resistance-inducing H275Y substitution, and a subset of samples also underwent phenotypic antiviral susceptibility testing by enzyme inhibition assay. Results We were able to detect virus by RT–PCR in self-taken samples and recovered infectious virus enabling further virological characterization. The majority of influenza A(H1N1)pdm09 RT–PCR-positive NPFS samples (n = 1273) were taken after oseltamivir treatment had begun. No reduction in phenotypic susceptibility to neuraminidase inhibitors was detected, but five cases with minority quasi-species of oseltamivir-resistant virus (an H275Y amino acid substitution in neuraminidase) were detected. Conclusions Self-sampling is a useful tool for community surveillance, particularly for the follow-up of drug-treated patients. The virological study of self-taken samples from the NPFS provided a unique opportunity to evaluate the emergence of oseltamivir resistance in treated individuals with mild illness in the community, a target population that may not be captured by traditional sentinel surveillance schemes.

Self-sampling for community respiratory illness: a new tool for national virological surveillance.

This report aims to evaluate the usefulness of self-sampling as an approach for future national surveillance of emerging respiratory infections by comparing virological data from two parallel surveillance schemes in England. Nasal swabs were obtained via self-administered sampling from consenting adults (≥ 16 years-old) with influenza symptoms who had contacted the National Pandemic Flu Service (NPFS) health line during the 2009 influenza pandemic. Equivalent samples submitted by sentinel general practitioners participating in the national influenza surveillance scheme run jointly by the Royal College of General Practitioners (RCGP) and Health Protection Agency were also obtained. When comparable samples were analysed there was no significant difference in results obtained from self-sampling and clinician-led sampling schemes. These results demonstrate that self-sampling can be applied in a responsive and flexible manner, to supplement sentinel clinician-based sampling, to achieve a wide spread and geographically representative way of assessing community transmission of a known organism.

P1-S2.48 Exponential growth of Lymphogranuloma venereum diagnoses in the UK: Investigation of the largest documented outbreak among men who have sex with men

Background With over 1500 cases reported, the UK now has the largest documented outbreak of Lymphogranuloma venereum (LGV) among men who have sex with men (MSM). Of particular concern is the recent exponential rise in cases—a third of all cases have been reported since 2010. We investigated the characteristics of this outbreak and specifically whether any factors were associated with the sharp upsurge in cases in 2010. Methods The UK LGV Incident Group launched a diagnostic reference service and enhanced surveillance of LGV in the UK in October 2004. All symptomatic patients attending UK GUM clinics who were chlamydia-positive or contacts of positive cases were referred to STBRL in London and later also to the Scottish Bacterial Sexually Transmitted Infections Reference Laboratory in Edinburgh for confirmation. Enhanced LGV surveillance forms were completed by clinicians caring for cases and submitted to the HPA for analysis. An epidemic curve was plotted and the point of exponential growth estimated. The characteristics of cases prior to and during the exponential growth phase were compared. Results Since 2003, 1570 LGV cases have been reported in the UK, of which 1268 (81%) had enhanced surveillance forms available. All but 8 (99%) were in MSM and most (77%) were seen in London, Brighton and Manchester. The point of exponential growth was estimated as 1st October 2009. Compared to cases prior to this date, cases in the growth phase were more likely to be older (41% vs 38% aged over 40), to be HIV positive (84% vs 78%), to be HCV antibody positive (27% vs 22%), to report unprotected anal intercourse (UAI) (80% vs 77%) and fisting (19% vs 14%), to present outside London (32% vs 27%), and to have acquired LGV in the UK (91% vs 87%). Overall, median case age was 38, 84% were white and 11% reported they acquired the infection outside the UK, mostly in Western European countries associated with the epidemic. UAI was reported by 78% of cases and at least 50 were identified as re-infections. Conclusions LGV is becoming endemic in the UK and is characterised by HIV positive MSM involved in dense sexual networks. Although cases associated with the recent upsurge are more geographically widespread, there is no evidence of dispersal among lower risk or HIV negative MSM. LGV control will require intensified awareness raising and outreach among at risk populations. Regression modelling of key variables is underway to investigate and validate these findings.