Survival of influenza A(H1N1) on materials found in households: implications for infection control.

BACKGROUND: The majority of influenza transmission occurs in homes, schools and workplaces, where many frequently touched communal items are situated. However the importance of transmission via fomites is unclear since few data exist on the survival of virus on commonly touched surfaces. We therefore measured the viability over time of two H1N1 influenza strains applied to a variety of materials commonly found in households and workplaces. METHODOLOGY AND PRINCIPAL FINDINGS: Influenza A/PuertoRico/8/34 (PR8) or A/Cambridge/AHO4/2009 (pandemic H1N1) viruses were inoculated onto a wide range of surfaces used in home and work environments, then sampled at set times following incubation at stabilised temperature and humidity. Virus genome was measured by RT-PCR; plaque assay (for PR8) or fluorescent focus formation (for pandemic H1N1) was used to assess the survival of viable virus. CONCLUSIONS/SIGNIFICANCE: The genome of either virus could be detected on most surfaces 24 h after application with relatively little drop in copy number, with the exception of unsealed wood surfaces. In contrast, virus viability dropped much more rapidly. Live virus was recovered from most surfaces tested four hours after application and from some non-porous materials after nine hours, but had fallen below the level of detection from all surfaces at 24 h. We conclude that influenza A transmission via fomites is possible but unlikely to occur for long periods after surface contamination (unless re-inoculation occurs). In situations involving a high probability of influenza transmission, our data suggest a hierarchy of priorities for surface decontamination in the multi-surface environments of home and hospitals.

Use of antiviral drugs to reduce household transmission of pandemic (H1N1) 2009, United Kingdom.

The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.

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

BACKGROUND: Surveillance indicators of influenza activity have generally provided robust comparative trend data for England. These indicators became less reliable, however, for monitoring trends in activity, or comparisons with previous years, during the influenza pandemic in 2009 because of changes in the perception of risk and changes in the systems of healthcare delivery. An approach was developed to estimate the number of cases of influenza-like illness (ILI) occurring because of infection with pandemic influenza virus. METHODS AND FINDINGS: The number of cases was estimated each week in England on the basis of total number of patients consulting healthcare services with ILI; estimates of the proportion of individuals in the community experiencing an ILI-seeking health care; and the proportion of these positive on laboratory testing. Almost 800,000 cases (range 375,000-1·6 million) of symptomatic ILI cases were estimated to have occurred over the course of the two waves of pandemic activity in England. More cases were estimated to have occurred in the second wave than in the first. CONCLUSIONS: These results underestimate the total number of infections as they do not include asymptomatic infections nor those with mild illness not meeting the definition of a case of ILI. Nevertheless, the case number estimates provide a useful indicator of the trend in influenza activity and weekly data were extensively used in media reports. Although surveillance methods differ between countries, the approach of synthesising available data sources to produce an overall estimate of case numbers could be applied more widely to provide comparative data.

Effectiveness of common household cleaning agents in reducing the viability of human influenza A/H1N1.

BACKGROUND: In the event of an influenza pandemic, the majority of people infected will be nursed at home. It is therefore important to determine simple methods for limiting the spread of the virus within the home. The purpose of this work was to test a representative range of common household cleaning agents for their effectiveness at killing or reducing the viability of influenza A virus. METHODOLOGY/PRINCIPAL FINDINGS: Plaque assays provided a robust and reproducible method for determining virus viability after disinfection, while a National Standard influenza virus RT-PCR assay (VSOP 25, www.hpa-standardmethods.org.uk) was adapted to detect viral genome, and a British Standard (BS:EN 14476:2005) was modified to determine virus killing. CONCLUSIONS/SIGNIFICANCE: Active ingredients in a number of the cleaning agents, wipes, and tissues tested were able to rapidly render influenza virus nonviable, as determined by plaque assay. Commercially available wipes with a claimed antiviral or antibacterial effect killed or reduced virus infectivity, while nonmicrobiocidal wipes and those containing only low concentrations (<5%) of surfactants showed lower anti-influenza activity. Importantly, however, our findings indicate that it is possible to use common, low-technology agents such as 1% bleach, 10% malt vinegar, or 0.01% washing-up liquid to rapidly and completely inactivate influenza virus. Thus, in the context of the ongoing pandemic, and especially in low-resource settings, the public does not need to source specialized cleaning products, but can rapidly disinfect potentially contaminated surfaces with agents readily available in most homes.

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.

A real-time Taqman method for hepatitis C virus genotyping and methods for further subtyping of isolates.

The HCV genome is highly heterogeneous; more and more genotypes, each with several distinct subtypes, are being identified around the world. Knowledge of genotype is important for planning of treatment regimes, whereas subtype identification is useful in epidemiological studies and outbreak investigation. We describe HCV genotyping and subtyping assays, based on real-time PCR, that are sensitive, specific, and reliable. These assays provide fast, accurate, and convenient methods for HCV genotyping/subtyping to support clinical practice.

Establishment of a UK National Influenza H5 Laboratory Network.

Avian (H5N1) influenza continues to pose a significant threat to human health, although it remains a zoonotic infection. Sensitive and robust surveillance measures are required to detect any evidence that the virus has acquired the ability to transmit between humans and emerge as the next pandemic strain. An integral part of the pandemic planning response in the UK was the creation in 2005 of the UK National H5 Laboratory Network, capable of rapidly and accurately identifying potential human H5N1 infections in all regions of the UK, and the Republic of Ireland. This review details the challenges that designing molecular detection methods for a rapidly evolving virus present, and the strategic decisions and choices required to ensure successful establishment of a functional national laboratory network, providing round the clock testing for H5N1. Laboratory partnerships have delivered improved real-time one-step multiplex PCR methodologies to ensure streamlined testing capable of not only detecting H5 but also a differential diagnosis of seasonal influenza A/B. A range of fully validated real-time PCR H5 confirmatory assays have been developed to run in parallel with a universal first-screening assay. Regular proficiency panels together with weekly surveillance runs, intermittent on-call testing for suspect cases of avian flu in returning travellers, and several outbreaks of avian influenza outbreaks in poultry that have occurred since 2005 in the UK have fully tested the network and the current diagnostic strategies for avian influenza. The network has clearly demonstrated its capability of delivering a confirmed H5N1 diagnosis within 3-4 h of receipt of a sample, an essential prerequisite for administration of the appropriate antiviral therapy, effective clinical management, disease containment and implementation of infection control measures. A functional network is an important means of enhancing laboratory capability and building diagnostic capacity for a newly emerging pandemic of influenza, and is an essential part of pandemic preparedness.

A real-time Taqman method for hepatitis C virus genotyping.

BACKGROUND: There is the need for a rapid, inexpensive method for genotyping hepatitis C virus (HCV) to support clinical practice. OBJECTIVES: To develop a real-time (Rotor-Gene 3000) Taqman assay for HCV genotyping in a single tube. STUDY DESIGN: Seven type-specific probes, two for genotypes 1-3 and one for genotype 4 were designed around genotype-specific motifs in the 5' non-coding (NC) region to create two panels of probes. The first panel included two probes for genotype 1 detection and a single probe each for genotypes 2 and 3. The second panel had two probes for confirmation of genotypes 2 and 3 and a first line probe for genotype 4 detection. A comparative analysis of the Taqman assay against our in-house sequence-based method using 154 consecutive clinical samples, from HCV carriers in Cambridge, and four samples from the Quality Control for Molecular Diagnostics (QCMD) System was undertaken. RESULTS: 158 samples were analysed by conventional sequencing: 49% (n=78) were genotype 1, 11% (n=18) genotype 2, 30% (n=47) genotype 3 and 6% (n=10) genotype 4. For two samples, the sequence data was heterogeneous and difficult to analyse, suggesting mixed infection and for three samples, the viral load was insufficient for sequencing. Concordant results were obtained with the novel Taqman assay for 77/78 (99%) of genotype 1 isolates (positive with both genotype 1 probes), 17/18 (94%) of genotype 2 isolates, 43/47 (91%) of genotype 3 isolates and 10/10 (100%) genotype 4 isolates. One isolate, untypeable with sequencing was genotyped with the Taqman assay. CONCLUSIONS: The Taqman assay was sensitive, specific and reliable over a wide range of viral loads and could identify mixed infections. These results highlight the potential of the Taqman assay as a fast, accurate and convenient method for routine HCV genotyping.

Does cytomegalovirus status influence acute and chronic rejection in heart transplantation during the ganciclovir prophylaxis era?

BACKGROUND: The effect of cytomegalovirus (CMV) status on acute rejection in heart transplantation is not well understood. Furthermore, there is some evidence to suggest that CMV antibody positivity is associated with cardiac allograft vasculopathy (CAV). METHODS: This study compared the effect of CMV antibody status in heart transplant donors (D) and recipients (R) on acute and chronic rejection episodes during the ganciclovir prophylaxis era. RESULTS: All heart transplant recipients at Papworth Hospital during the ganciclovir prophylaxis era were included (n = 374). They were grouped according to recipients and their respective donor CMV serology: R(-)/D(-) (n = 82); R(+)/D(-) (n = 114); R(-)/D(+) (n = 73); and R(+)/D(+) (n = 105). Ganciclovir prophylaxis was administered to the R(-)/D(+) group. The mean (SD) recipient and donor ages were 46 (11), 51 (9), 47 (11) and 52 (8) years (p < 0.001), and 32 (11), 33 (14), 36 (12) and 38 (14) years (p = 0.01), respectively, for the CMV groups. The mean number of acute rejection episodes (as confirmed by cardiac biopsy) per 100 patient-days was 0.13 (0.36), 0.11 (0.34), 0.12 (0.34) and 0.12 (0.34), respectively (p > 0.05) There was no statistical difference in the development of CAV as assessed by angiography (p = 0.92). At 2 years, the "freedom from CAV" rates were 96%, 97%, 97% and 98%, respectively. The 5-year post-operative survival rates were 83%, 79%, 67% and 73% (p = 0.08 overall). CONCLUSIONS: CMV status of heart transplant recipients and their respective donors does not influence acute or chronic rejection in terms of cardiac allograft vasculopathy.

Cytomegalovirus antibody status of donor/recipient does not influence the incidence of bronchiolitis obliterans syndrome in lung transplantation.

BACKGROUND: We have previously reported that prophylaxis for cytomegalovirus (CMV) infection does not influence the incidence of bronchiolitis obliterans syndrome (BOS) at 2 years. The effect of CMV infection (without evidence of disease) on BOS is still not well understood. Moreover, the incidence and risk factors for development of BOS in CMV-antibody-negative donor/recipient matches in lung transplantation have not been described. The aim of this study is to determine the incidence of BOS in lung transplant patients with CMV-antibody-negative (-) donors (D) and recipients (R), and to evaluate the risk factors that predispose to BOS in this sub-group. METHOD: A retrospective study of data from the transplant database of our center was performed. All single-lung (SL), double-lung (DL) and heart-lung block (HL) transplant patients who survived >2 years post-transplant were included in the study group. They were grouped as follows: D(-)/R(-), n = 102; D(-)/R(+), n = 70; D(+)/R(-), n = 33, and D(+)/R(+), n = 92. RESULTS: The 3-year BOS-free survival rates were 65%, 56%, 58% and 67%, respectively, and the incidence rates of BOS at 5 years post-transplant in the different groups were 57%, 62%, 78% and 55% (p > 0.05). In the D(-)/R(-) group, the significant risk factor for developing BOS was three or more episodes of acute rejection (p = 0.02). The mean numbers of acute rejection episodes per 100 patients-days within the first 6 months were 1.28, 1.06, 0.50 and 1.11 (p < 0.001 overall) for the four groups, respectively. CONCLUSION: Although CMV is believed to be a risk factor for BOS, its absence did not affect the occurrence or incidence of BOS in lung transplant patients. The main risk factor for BOS in the CMV-antibody-negative population remains the number of acute rejection episodes within the first 6 months after transplantation.