The global transmission and control of influenza

New strains of influenza spread around the globe via the movement of infected individuals. The global dynamics of influenza are complicated by different patterns of influenza seasonality in different regions of the world. We have released an open-source stochastic mathematical model of the spread of influenza across 321 major, strategically located cities of the world. Influenza is transmitted between cities via infected airline passengers. Seasonality is simulated by increasing the transmissibility in each city at the times of the year when influenza has been observed to be most prevalent. The spatiotemporal spread of pandemic influenza can be understood through clusters of global transmission and links between them, which we identify using the epidemic percolation network (EPN) of the model. We use the model to explain the observed global pattern of spread for pandemic influenza A(H1N1) 2009-2010 (pandemic H1N1 2009) and to examine possible global patterns of spread for future pandemics depending on the origin of pandemic spread, time of year of emergence, and basic reproductive number (). We also use the model to investigate the effectiveness of a plausible global distribution of vaccine for various pandemic scenarios. For pandemic H1N1 2009, we show that the biggest impact of vaccination was in the temperate northern hemisphere. For pandemics starting in the temperate northern hemisphere in May or April, vaccination would have little effect in the temperate southern hemisphere and a small effect in the tropics. With the increasing interconnectedness of the world's population, we must take a global view of infectious disease transmission. Our open-source, computationally simple model can help public health officials plan for the next pandemic as well as deal with interpandemic influenza.     

Prevalence and control of hypertension in an Ontario county

A survey of a representative population sample was carried out to evaluate the prevalence and control of hypertension in Middlesex County, Ontario. Of the 3067 subjects selected 2735 completed the initial interview. If the diastolic blood pressure was greater than 89 mm Hg in three readings, up to two further visits were made. The prevalence rate of hypertension in the sample was estimated to be 115/1000. Only 5.1% of the hypertensive subjects were unaware of their condition, and 5.4% were aware but not receiving treatment. In 16.9% the hypertension was treated but uncontrolled, while in 72.6% it was treated and controlled. The prevalence rate was significantly higher in the older subjects (p < 0.0001). Control was better in the women and the older subjects. The results indicate that physicians in Middlesex County are detecting and treating most patients with hypertension; screening programs are thus not needed. Control of hypertension could be further improved by determining why the condition in those receiving treatment is not being controlled.     

Translational control in influenza virus-infected cells

Influenza virus type A has been shown to establish a translational control system such that during infection there is a dramatic inhibition of host cell protein synthesis and viral mRNAs are selectively and efficiently translated. The following review summarizes the complex strategies employed by influenza to accomplish these goals. These include: (i) preventing newly made cellular mRNAs from entering the cytoplasm of infected cells; (ii) inhibiting the initiation and elongation steps of translation of preexisting cellular mRNAs; (iii) possessing RNAs with structural features which enhance translation; (iv) encoding mechanisms to downregulate the interferon induced protein kinase thus allowing overall protein synthesis levels to remain high.     

Current status for influenza control

Influenza viruses are responsible for respiratory illness with significant morbidity and mortality. To curb the disease, two-pronged attack on the virus, therapeutic and prophylactic, is being actively pursued. The therapeutic use of existing anti-influenza drugs, such as amantadine and rimantadine, is limited by their significant adverse side effect, emergence of resistant viral strains, and lack of activity against influenza B virus. A new class of antiviral agents designed to inhibit influenza neuraminidase are currently under active development for use in the prophylaxis and treatment of influenza A and B virus infections. Two of these compounds, zanamivir (GG167) and GS4104 have reached clinical trials. Limitations in the effectiveness and application of inactivated vaccines have stimulated development of alternative approaches to influenza immunization. One such approach is a live, intranasally administered vaccine, attenuated by cold-adaptation of a master strain with subsequent genetic reassortment with circulating wild-type strains. Recently developed reverse-genetics techniques have made it possible to use RNA viruses as vector. Besides DNA viral vectors, live influenza virus vectors may emerge as a useful alternative for the vaccination against different pathogens.     

Disease mitigation measures in the control of pandemic influenza

The threat of an influenza pandemic has alarmed countries around the globe and given rise to an intense interest in disease mitigation measures. This article reviews what is known about the effectiveness and practical feasibility of a range of actions that might be taken in attempts to lessen the number of cases and deaths resulting from an influenza pandemic. The article also discusses potential adverse second- and third-order effects of mitigation actions that decision makers must take into account. Finally, the article summarizes the authors' judgments of the likely effectiveness and likely adverse consequences of the range of disease mitigation measures and suggests priorities and practical actions to be taken.     

The challenges of avian influenza virus: mechanism, epidemiology and control

Early 2009, eight human infection cases of H5N1 highly pathogenic avian influenza (HPAI) virus, with 5 death cases, were reported in China. This again made the world alert on a possible pandemic worldwide, probably caused by     

The role of health care workers and antiviral drugs in the control of pandemic influenza

Until a vaccine against the new strain becomes available, the response to newly emerged pandemic influenza will consist of the use of antiviral drugs and measures that limit exposure to infectious individuals. These first-line defence measures include isolating cases upon diagnosis, reducing close contacts, the use of personal protective equipment and hygiene, and using antiviral drugs for treatment and prophylaxis. There are significant 'costs' associated with control measures, so to justify such interventions it is important to assess their potential to reduce transmission. In this paper, we determine the effect that a number of different antiviral interventions have on the reproduction number of infectives and the probability that an imported infection fades out, and determine parameter scenarios for which these interventions are able to eliminate an emerging pandemic of influenza. We also assess the role that health care workers play in transmission and the extent to which providing them with antiviral prophylaxis and personal protective equipment modifies this role. Our results indicate that this class requires protection to avoid a greatly disproportionate contribution to early infective numbers, and for the maintenance of a stable health care system. Further, we show that the role children play in increasing transmission is moderate, in spite of closer mixing with other children.     

The new face of health care in Ontario

Canada is experiencing a dramatic increase in the number of older people in its population. Adopting strategies that involve physician actions, a societal approach and individual participation may substantially improve the health of senior citizens. This article presents ways to improve the quality of life and reduce the risk of premature death through manoeuvres that can be initiated by physicians in the context of the periodic health examination. The authors highlight the role of evidence in choosing the most appropriate interventions, speculate on areas of future importance and emphasize a societal approach to population health.