Timing of monoclonal antibody for seasonal RSV prophylaxis in the United Kingdom.

Respiratory syncytial virus (RSV) infection produces more severe disease and increased hospitalization rates in high-risk babies. The monoclonal antibody palivizumab offers protection against complications, and the first of five monthly doses should be administered before the onset of community RSV activity. However, the required real-time prediction of this onset is problematic. We attempted to identify seasonal RSV patterns by retrospectively examining 10 years of laboratory reports for RSV and clinical episode reports for certain respiratory presentations in both primary and secondary care. Analysis of hospital laboratory reports, incidence of acute bronchitis in primary care, and hospital admissions for acute bronchitis and bronchiolitis in young children revealed a consistent increase in RSV activity during week 43 each year. Promptly commencing prophylaxis during the second week of each October (week 42) would precede the onset of the RSV season in the United Kingdom, and provide coverage until its decline in mid-March.

Lessons learned from SARS: the experience of the Health Protection Agency, England.

The United Kingdom was assessed as a low risk country throughout the 2003 global SARS outbreaks. Despite this, 368 reports of potential SARS cases were made to the Health Protection Agency (HPA) between March and July 2003. The public health actions undertaken in response to these reports, the establishment of reporting mechanisms and the development of guidance documents were substantial. Lessons learned from mounting a UK response to SARS included: the importance of international collaboration; formation of a UK-wide, multidisciplinary Task Force; flexible case reporting mechanisms; integration of surveillance and laboratory data; generation of prompt and web-accessible guidance and advice; availability of surge capacity; and contingency planning. Lessons learned are being incorporated into the HPA's preparedness to prevent and control future newly emerging infectious disease threats.

A study of excess mortality during influenza epidemics in the Czech Republic, 1982-2000.

Influenza related mortality rates have been established in many countries; nevertheless, studies focusing on the Central European population have been rare to date. We assess mortality attributable to influenza by comparing all cause mortality and mortality due to diseases of the circulatory system during influenza epidemic and non-epidemic periods, as defined by acute respiratory infection surveillance data. Data on total mortality, mortality due to diseases of the circulatory system and surveillance data for influenza and other respiratory infections were used in a general linear model with a logarithmic link for dependence of left censored mortality data over time, and week as a categorical factor. Results of the analysis show statistically significant (p <0.001) differences in excess mortality rates between influenza epidemic and non-epidemic periods in the Czech Republic between 1982 and 2000. We estimate that 2.17% of all cause mortality, and 2.57% of mortality due to diseases of the circulatory system throughout the study period was attributable to influenza, with an estimated annual average of 2661 and 1752 deaths respectively. The highest numbers of deaths were reported during seasons when influenza A/H3N2 was the predominant circulating strain. Improving vaccination coverage against influenza is considered to be the primary strategy for prevention of influenza associated mortality.

Epidemiological features of a new strain of the influenza A virus--influenza A (H1N2) circulating in England and its public health implications.

The UK influenza season of 2001/2002 was characterized by widespread geographic circulation of a new subtype of influenza A (H1N2) virus throughout the duration of the season. Younger children were predominantly infected, suggesting primary infection. Despite this, the public health impact of this new virus was minimal. It remains to be seen whether influenza A (H1N2) virus will persist and co-circulate with the previously circulating subtypes of influenza A (H1N1 and H3N2), or whether it was a sporadic recombination event that will disappear. Ultimately, the emergence of a new strain highlights the importance of continual surveillance of circulating viruses.

Outbreak of influenza A (H3N2) in a highly-vaccinated religious community: a retrospective cohort study.

An outbreak of influenza occurred at the end of the 2001-2 winter season in a highly-vaccinated, semi-enclosed, religious community. On the basis of retrospective self reporting, 43% met the case definition (151/350) and 81% (25/31) of throat swabs from cases were polymerase chain reaction (PCR) -positive for influenza A (H3N2). The risk of developing influenza in people aged 65 or more was lower than that of children aged 2 years and under (odds ratio 0.1, 95% confidence interval 0.02 to 0.38). The risk of developing symptoms of influenza was not significantly different between people who had been vaccinated in the United Kingdom and those who had not been vaccinated (OR 1.14, CI 0.41 to 3.14). Chronic disease was an independent risk factor for developing symptoms of influenza (OR 1.9, CI 1 to 3.63). Timing of the outbreak, the age structure and mode of communal living may have influenced the efficacy of the influenza vaccine, which was well matched to circulating strains at the time of the outbreak. It is important to consider the diagnosis of influenza even in a highly-vaccinated community.

Three years of low influenza activity--no reason for complacency.

Influenza activity in England and Wales has been unusually low over the last three years. Despite this, substantial morbidity and mortality has occurred in subgroups of the population. Furthermore, the influenza season 2001/02 was characterised by the emergence of a new subtype of the influenza A virus (H1N2), a timely reminder that it is not possible to assess the impact of a change in the virus strains circulating without having a comprehensive surveillance infrastructure in place.

Appropriateness of thresholds currently used to describe influenza activity in England.

The timing and magnitude of influenza virus activity in England each winter remain unpredictable. Nevertheless, it is important to describe levels of activity in a timely manner, using defined 'threshold values'. This informs public health practitioners and the general public of the level of influenza virus circulation, and provides an indication of when sufficient activity is occurring in the community to warrant the use of antiviral drugs. Data presented here suggest that the current numerical thresholds, and their corresponding descriptions, are no longer appropriate for the levels of activity recently observed in England. Based on integrated clinical and virological data, we suggest alternative threshold values of 'baseline' activity (0-30/100,000 population), 'normal seasonal' activity (30-200/100,000) and 'epidemic' activity (> 200/100,000).

Mild to moderate influenza activity in Europe and the detection of novel A(H1N2) and B viruses during the winter of 2001-02.

Influenza activity in Europe during the 2001-02 influenza season was mild to moderate. Compared to historical data, the intensity was low in six countries, medium in eleven and high in one country (Spain). The dominant virus circulating in Europe was influenza A(H3N2). Two novel influenza virus strains were isolated during the 2001-02 season: influenza A(H1N2) viruses (mainly isolated in the United Kingdom and Ireland, but also in Belgium, France, Germany, the Netherlands, Portugal, Sweden, Switzerland and Romania), and influenza B viruses belonging to the B/Victoria/2/87 lineage (mainly isolated in Germany, but also sporadically in France, Italy, the Netherlands and Norway). With the exception of H1N2 virus detections in England, and Ireland and the influenza B viruses belonging to the B/Victoria/2/87 lineage in Germany, these two viruses did not circulate widely in Europe and did not play an important role in influenza activity during the 2001-02 season. An influenza B virus belonging to the B/Victoria/2/87 lineage will be included in the 2002-03 influenza vaccine. The new subtype influenza A(H1N2) is covered by the 2002-03 vaccine, as the haemagglutinin and neuraminidase components of the H1N2 viruses are antigenically similar to the vaccine components (H1N1 and H3N2).

Sequence dependent rigidity of single stranded DNA.

Single stranded DNA (ssDNA) equilibrium dynamics are investigated using a fluorophore/quencher-labeled hairpin structure which thermally fluctuates between open and closed states. Temporal correlations of the fluorescence fluctuations are used to determine the energy barrier to conformational change. We find that ssDNA distortion is purely entropic for poly(T) but requires an additional enthalpy of +0.5 kcal x mol(-1) x base(-1) for poly(A), consistent with the disruption of base stacking. Such sequence dependent dynamics challenge the classical model of ssDNA as a completely flexible coil.

Influenza surveillance in England and Wales: October 1999 to May 2000.

The period of increased influenza activity in England and Wales in the winter of 1999/2000 was associated with considerable morbidity and mortality and well-publicized pressure on hospital services. The influenza activity coincided with the regular annual increase in respiratory syncytial virus infections and the Christmas and New Year holiday period. Consultation rates with general practitioners for influenza-like illness did not reach 'epidemic' levels but were higher than seen in many winters and comparable with those seen in two out of the previous three winters. In common with those winters, attack rates for influenza-like illness and acute bronchitis were especially high in elderly people among whom complications of acute infection and hospital admissions increased. Excess mortality due to influenza during this period appeared to be substantial but was not as high as seen in the last epidemic (1989/90).

Cavity-mode selection in spontaneous emission from oriented molecules in a microparticle.

We observe preferential cavity-mode selection in spontaneous emission by oriented molecules at the surface of a microparticle. Polarization-analyzed images of a levitated microdroplet containing surface active molecules reveal a well-defined system in terms of molecular position and orientation. The measured fluorescence spectrum is compared with that of a semiclassical emission-rate-enhancement model that treats the coupling between an excited state and Mie resonances as an oscillating dipole interacting with its self-scattered field. By comparing results obtained with this theory with the relative strengths of TE to TM modes measured in the emission spectrum, we show that one can elucidate the heterogeneity of a particle from this resonant structure and determine the orientation of the emission moments relative to the phase boundary.