Solving the kidney shortage via the creation of kidney donation co-operatives.

Many people object to the creation of a market for kidneys on the grounds that such reform would hurt those patients unable to afford the market price of a kidney and that donors do not understand the risks they are taking when donating. In this paper, we propose a mechanism, the kidney co-operative, designed to provide sufficient incentives to alleviate the kidney shortage while at the same time addressing the concerns regarding the potential losers from reform. We show that it is reasonable to expect that the number of transplants will be larger under the kidney co-operative mechanism than under either the status quo or a conventional market mechanism.

Seven challenges in modeling vaccine preventable diseases.

Vaccination has been one of the most successful public health measures since the introduction of basic sanitation. Substantial mortality and morbidity reductions have been achieved via vaccination against many infections, and the list of diseases that are potentially controllable by vaccines is growing steadily. We introduce key challenges for modeling in shaping our understanding and guiding policy decisions related to vaccine preventable diseases.

Six challenges in measuring contact networks for use in modelling.

Contact networks are playing an increasingly important role in epidemiology. A contact network represents individuals in a host population as nodes and the interactions among them that may lead to the transmission of infection as edges. New avenues for data collection in recent years have afforded us the opportunity to collect individual- and population-scale information to empirically describe the patterns of contact within host populations. Here, we present some of the current challenges in measuring empirical contact networks. We address fundamental questions such as defining contact; measurement of non-trivial contact properties; practical issues of bounding measurement of contact networks in space, time and scope; exploiting proxy information about contacts; dealing with missing data. Finally, we consider the privacy and ethical issues surrounding the collection of contact network data.

Web-based participatory surveillance of infectious diseases: the Influenzanet participatory surveillance experience.

To overcome the limitations of the state-of-the-art influenza surveillance systems in Europe, we established in 2008 a European-wide consortium aimed at introducing an innovative information and communication technology approach for a web-based surveillance system across different European countries, called Influenzanet. The system, based on earlier efforts in The Netherlands and Portugal, works with the participation of the population in each country to collect real-time information on the distribution of influenza-like illness cases through web surveys administered to volunteers reporting their symptoms (or lack of symptoms) every week during the influenza season. Such a large European-wide web-based monitoring infrastructure is intended to rapidly identify public health emergencies, contribute to understanding global trends, inform data-driven forecast models to assess the impact on the population, optimize the allocation of resources, and help in devising mitigation and containment measures. In this article, we describe the scientific and technological issues faced during the development and deployment of a flexible and readily deployable web tool capable of coping with the requirements of different countries for data collection, during either a public health emergency or an ordinary influenza season. Even though the system is based on previous successful experience, the implementation in each new country represented a separate scientific challenge. Only after more than 5 years of development are the existing platforms based on a plug-and-play tool that can be promptly deployed in any country wishing to be part of the Influenzanet network, now composed of The Netherlands, Belgium, Portugal, Italy, the UK, France, Sweden, Spain, Ireland, and Denmark.

The influence of school holiday timing on epidemic impact.

The impact of reactive school closure on an epidemic is uncertain, since it is not clear how an unplanned closure will affect social mixing patterns. The effect of school holidays on social mixing patterns is better understood. Here, we use mathematical models to explore the influence of the timing of school holidays on the final size and peak incidence of an influenza-like epidemic. A well-timed holiday can reduce the impact of an epidemic, in particular substantially reducing an epidemic's peak. Final size and peak incidence cannot both be minimized: a later holiday is optimal for minimizing the final size, while an earlier holiday minimizes peak incidence. Using social mixing data from the UK, we estimated that, had the 2009 influenza epidemic not been interrupted by the school summer holidays, the final size would have been about 20% larger and the peak about 170% higher.

Rapid assessment of influenza vaccine effectiveness: analysis of an internet-based cohort.

The effectiveness of influenza vaccination programmes is seldom known during an epidemic. We developed an internet-based system to record influenza-like symptoms and response to infection in a participating cohort. Using self-reports of influenza-like symptoms and of influenza vaccine history and uptake, we estimated vaccine effectiveness (VE) without the need for individuals to seek healthcare. We found that vaccination with the 2010 seasonal influenza vaccine was significantly protective against influenza-like illness (ILI) during the 2010-2011 influenza season (VE 52%, 95% CI 27-68). VE for individuals who received both the 2010 seasonal and 2009 pandemic influenza vaccines was 59% (95% CI 27-77), slightly higher than VE for those vaccinated in 2010 alone (VE 46%, 95% CI 9-68). Vaccinated individuals with ILI reported taking less time off work than unvaccinated individuals with ILI (3.4 days vs. 5.3 days, P<0.001).

Measuring social networks in British primary schools through scientific engagement.

Primary schools constitute a key risk group for the transmission of infectious diseases, concentrating great numbers of immunologically naive individuals at high densities. Despite this, very little is known about the social patterns of mixing within a school, which are likely to contribute to disease transmission. In this study, we present a novel approach where scientific engagement was used as a tool to access school populations and measure social networks between young (4-11 years) children. By embedding our research project within enrichment activities to older secondary school (13-15) children, we could exploit the existing links between schools to achieve a high response rate for our study population (around 90% in most schools). Social contacts of primary school children were measured through self-reporting based on a questionnaire design, and analysed using the techniques of social network analysis. We find evidence of marked social structure and gender assortativity within and between classrooms in the same school. These patterns have been previously reported in smaller studies, but to our knowledge no study has attempted to exhaustively sample entire school populations. Our innovative approach facilitates access to a vitally important (but difficult to sample) epidemiological sub-group. It provides a model whereby scientific communication can be used to enhance, rather than merely complement, the outcomes of research.

The impact of illness and the impact of school closure on social contact patterns.

BACKGROUND: Mathematical models, based on data describing normal patterns of social mixing, are used to understand epidemics in order to predict patterns of disease spread and plan interventions and responses. However, individuals who are ill show behavioural changes that affect their social mixing patterns and predictive models should take into account these changes if they are to be effective. OBJECTIVES: To describe and quantify the changes in (1) social contact behaviour experienced by individuals when they are ill with pandemic H1N1 influenza (swine flu) and (2) mixing patterns of school children that take place as a result of swine flu-related school closures. METHODS: For the first part of the study, a self-completed questionnaire-based study was carried out in the autumn/winter of 2009-10. The study population was individuals who had been diagnosed with swine flu and who received a swine flu antiviral prescription from an antiviral distribution centre (ADC). It consisted of an initial survey to be filled in when participants were symptomatic with swine flu and a follow-up survey to be filled in when they had recovered. Each part of the questionnaire had two sections: patient details and a contact diary. The second part of the study was adapted to quantify the difference in mixing patterns of pupils between the school term and the half-term holiday as school closures did not occur during the study period. Eight schools participated and questionnaire packs were distributed to them, containing two surveys: one to be filled in during the school term and one during the spring half-term holiday. RESULTS: For the patient study, approximately 3800 surveys were distributed by 31 ADCs. Overall, 317 responses to the initial survey were received and 179 participants returned the follow-up survey. For all types of a contact, except contacts made at home, there were highly significant differences in contact behaviour (Wilcoxon signed-rank test, p < 0.001). Individuals made substantially fewer contacts when they were ill than when they were well. Analysis showed that returning to work was the most significant predictor of increased numbers of contacts. Also, the greater the change in the number of symptoms reported, the greater the change in the number of contacts. For the school study, approximately 1100 questionnaire packs were distributed and 134 responses were received, with 119 paired contact diaries. Pupils reported on average 18.51 contacts each day during term time and 9.24 during the half-term holiday - a reduction of over 50% and a highly significant change (Wilcoxon signed-rank test, p < 0.0001). CONCLUSIONS: The evidence from this study suggests that ill individuals make substantial changes to their social contact patterns. These changes are strongly linked to absence from work and the severity of the reported illness. Epidemiological modellers should therefore consider the implications of illness-related behavioural changes on model predictions. Future studies to measure the extent of behavioural change in a broader cross-section of infected cases could be valuable, along with more detailed studies of the social contact patterns of school children, focusing on differences between school terms and school holidays.

Modelling disease spread through random and regular contacts in clustered populations.

An epidemic spreading through a network of regular, repeated, contacts behaves differently from one that is spread by random interactions: regular contacts serve to reduce the speed and eventual size of an epidemic. This paper uses a mathematical model to explore the difference between regular and random contacts, considering particularly the effect of clustering within the contact network. In a clustered population random contacts have a much greater impact, allowing infection to reach parts of the network that would otherwise be inaccessible. When all contacts are regular, clustering greatly reduces the spread of infection; this effect is negated by a small number of random contacts.

Contact tracing strategies in heterogeneous populations.

Contact tracing is a well-established disease control measure that seeks to uncover cases by following chains of infection. This paper examines mathematical models of both single-step and iterative contact tracing schemes and analyses the ability of these procedures to trace core groups and the sensitivity of the intervention to the timescale of tracing. An iterative tracing process is shown to be particularly effective at uncovering high-risk individuals, and thus it provides a powerful public health tool. Further targeting of tracing effort is considered. When the population exhibits like-with-like (assortative) mixing the required effort for eradication can be significantly reduced by preferentially tracing the contacts of high-risk individuals; in populations where individuals have reliable information about their contacts, further gains in efficiency can be realized. Contact tracing is, therefore, potentially an even more potent tool than its present usage suggests.

Flow cytometric study of nodular fasciitis, proliferative fasciitis, and proliferative myositis.

DNA ploidy was assessed retrospectively, using flow cytometry, in 13 nodular fasciitis (NF) lesions, three proliferative myositis (PM) lesions, one proliferative fasciitis lesion, and 12 other benign fibrous lesions (BFLs). All were diploid. In view of the large amounts of cellular debris, cell cycle analysis was possible in only seven NF lesions, three PM lesions, and six BFLs. The mean percentage of S phase did not differ markedly between the combination of NF and PM lesions (6.6%) and BFLs (7.1%); the mean percentage of G2 + M phase (5.4%) of the NF/PM lesion combination was twice as large as that of the BFLs (2.5%). No correlation was detected between the cell cycle analysis and the mitotic count, the predominant histologic type in NF lesions, or the predominant stroma in PM lesions.

Alcohol consumption, problem drinking and anti-social behaviour in a sample of college students.

A total of 125 male and 145 female students completed a written questionnaire (response rate 68%) on their consumption levels and patterns, problem drinking and vandalism and assaults associated with drinking, Prevalence of heavy drinking was broadly similar to that found in other college student samples in the UK with 25.6% of male students and 14.5% of female students drinking more than their safe limits of 35 and 21 units per week respectively. Six percent of male and one percent of female students exceeded the problem drinking threshold on the MAST. Twenty percent of the male students and 6% of the females admitted having caused at least some damage to property after having been drinking in the past 12 months. Four percent of males and 5% of females admitted 'minor' assaults. Fifty percent of males and 36% of females had witnessed damage to property and 19% of males and 10% of females had experienced some kind of assault. Vandalism and assaults were positively and independently associated with higher levels of consumption, reasons for drinking and patterns of drinking; in particular morning drinking appeared to play a role. Taking amount of drinking into account, males were more likely to commit acts of vandalism but females were more likely to commit assaults. The results reveal that alcohol-related, anti-social behaviour among students is a significant problem and that, while heavy drinking per se plays a role, other factors are also important.

A combined stain for elastin and acid mucopolysaccharides in large blood vessels.

A reliable, reproducible combined stain for elastin and acid mucopolysaccharides has been developed and is particularly suitable for the study of large blood vessels as muscle and collagen are also stained. The technique is described.