Reducing the impact of the next influenza pandemic using household-based public health interventions.
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BACKGROUND: The outbreak of highly pathogenic H5N1 influenza in domestic poultry and wild birds has caused global concern over the possible evolution of a novel human strain [1]. If such a strain emerges, and is not controlled at source [2,3], a pandemic is likely to result. Health policy in most countries will then be focused on reducing morbidity and mortality. METHODS AND FINDINGS: We estimate the expected reduction in primary attack rates for different household-based interventions using a mathematical model of influenza transmission within and between households. We show that, for lower transmissibility strains [2,4], the combination of household-based quarantine, isolation of cases outside the household, and targeted prophylactic use of anti-virals will be highly effective and likely feasible across a range of plausible transmission scenarios. For example, for a basic reproductive number (the average number of people infected by a typically infectious individual in an otherwise susceptible population) of 1.8, assuming only 50% compliance, this combination could reduce the infection (symptomatic) attack rate from 74% (49%) to 40% (27%), requiring peak quarantine and isolation levels of 6.2% and 0.8% of the population, respectively, and an overall anti-viral stockpile of 3.9 doses per member of the population. Although contact tracing may be additionally effective, the resources required make it impractical in most scenarios. CONCLUSIONS: National influenza pandemic preparedness plans currently focus on reducing the impact associated with a constant attack rate, rather than on reducing transmission. Our findings suggest that the additional benefits and resource requirements of household-based interventions in reducing average levels of transmission should also be considered, even when expected levels of compliance are only moderate. (+info)
Estimating in real time the efficacy of measures to control emerging communicable diseases.
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Controlling an emerging communicable disease requires prompt adoption of measures such as quarantine. Assessment of the efficacy of these measures must be rapid as well. In this paper, the authors present a framework to monitor the efficacy of control measures in real time. Bayesian estimation of the reproduction number R (mean number of cases generated by a single infectious person) during an outbreak allows them to judge rapidly whether the epidemic is under control (R < 1). Only counts and time of onset of symptoms, plus tracing information from a subset of cases, are required. Markov chain Monte Carlo and Monte Carlo sampling are used to infer the temporal pattern of R up to the last observation. The operating characteristics of the method are investigated in a simulation study of severe acute respiratory syndrome-like outbreaks. In this particular setting, control measures lacking efficacy (R > or = 1.1) could be detected after 2 weeks in at least 70% of the epidemics, with less than a 5% probability of a wrong conclusion. When control measures are efficacious (R = 0.5), this situation may be evidenced in 68% of the epidemics after 2 weeks and 92% of the epidemics after 3 weeks, with less than a 5% probability of a wrong conclusion. (+info)
Preparation of animals for research--issues to consider for rodents and rabbits.
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This article provides details to consider when preparing to use animals in biomedical research. The stress of transport and receipt of animals into a new environment mandate the need for a period of stabilization and acclimation. This allotment of time often occurs in conjunction with the quarantine period and permits a stress "recovery" period. Discussions in the article include specific effects of the environment on the animal, such as housing and environmental enrichment. Suggestions are offered regarding how to minimize the effects of procedures and equipment through the use of preconditioning techniques. Guidelines for these techniques and for acclimation should be instituted by the institutional animal care and use committee. Stress and distress are placed in perspective as they relate to the preparation of laboratory animals for research. (+info)
Selection, acclimation, training, and preparation of dogs for the research setting.
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Dogs have made and will continue to make valuable contributions as animal models in biomedical research. A comprehensive approach from time of breeding through completion of in-life usage is necessary to ensure that high-quality dog models are used in studies. This approach ensures good care and minimizes the impact of interanimal variability on experimental results. Guidance related to choosing and developing high-quality laboratory dogs and managing canine research colonies is provided in this article. Ensuring that dogs are healthy, well adapted, and cooperative involves good communication between vendors, veterinarians, care staff, and researchers to develop appropriate dog husbandry programs. These programs are designed to minimize animal stress and distress from the postweaning period through the transfer and acclimation period within the research facility. Canine socialization and training programs provided by skilled personnel, together with comprehensive veterinary health programs, can further enhance animal welfare and minimize interanimal and group variability in studies. (+info)
A 'small-world-like' model for comparing interventions aimed at preventing and controlling influenza pandemics.
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BACKGROUND: With an influenza pandemic seemingly imminent, we constructed a model simulating the spread of influenza within the community, in order to test the impact of various interventions. METHODS: The model includes an individual level, in which the risk of influenza virus infection and the dynamics of viral shedding are simulated according to age, treatment, and vaccination status; and a community level, in which meetings between individuals are simulated on randomly generated graphs. We used data on real pandemics to calibrate some parameters of the model. The reference scenario assumes no vaccination, no use of antiviral drugs, and no preexisting herd immunity. We explored the impact of interventions such as vaccination, treatment/prophylaxis with neuraminidase inhibitors, quarantine, and closure of schools or workplaces. RESULTS: In the reference scenario, 57% of realizations lead to an explosive outbreak, lasting a mean of 82 days (standard deviation (SD) 12 days) and affecting 46.8% of the population on average. Interventions aimed at reducing the number of meetings, combined with measures reducing individual transmissibility, would be partly effective: coverage of 70% of affected households, with treatment of the index patient, prophylaxis of household contacts, and confinement to home of all household members, would reduce the probability of an outbreak by 52%, and the remaining outbreaks would be limited to 17% of the population (range 0.8%-25%). Reactive vaccination of 70% of the susceptible population would significantly reduce the frequency, size, and mean duration of outbreaks, but the benefit would depend markedly on the interval between identification of the first case and the beginning of mass vaccination. The epidemic would affect 4% of the population if vaccination started immediately, 17% if there was a 14-day delay, and 36% if there was a 28-day delay. Closing schools when the number of infections in the community exceeded 50 would be very effective, limiting the size of outbreaks to 10% of the population (range 0.9%-22%). CONCLUSION: This flexible tool can help to determine the interventions most likely to contain an influenza pandemic. These results support the stockpiling of antiviral drugs and accelerated vaccine development. (+info)
Where do pets fit into human quarantines?
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Currently, there are over 400 viral zoonoses in the world. In addition, there are numerous bacterial zoonoses. Of the emerging diseases, <75% are zoonoses. The potential for household transmission through pets is now being considered in any new disease when information is incomplete regarding potential hosts, and the risk for interspecies transmission is unknown. The possible role of household pets in disease transmission in community-based quarantines has previously been overlooked. (+info)
Risk assessment for invasive species produces net bioeconomic benefits.
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International commerce in live organisms presents a policy challenge for trade globalization; sales of live organisms create wealth, but some nonindigenous species cause harm. To reduce damage, some countries have implemented species screening to limit the introduction of damaging species. Adoption of new risk assessment (RA) technologies has been slowed, however, by concerns that RA accuracy remains insufficient to produce positive net economic benefits. This concern arises because only a small proportion of all introduced species escape, spread, and cause harm (i.e., become invasive), so a RA will exclude many noninvasive species (which provide a net economic benefit) for every invasive species correctly identified. Here, we develop a simple cost:benefit bioeconomic framework to quantify the net benefits from applying species prescreening. Because invasive species are rarely eradicated, and their damages must therefore be borne for long periods, we have projected the value of RA over a suitable range of policy time horizons (10-500 years). We apply the model to the Australian plant quarantine program and show that this RA program produces positive net economic benefits over the range of reasonable assumptions. Because we use low estimates of the financial damage caused by invasive species and high estimates of the value of species in the ornamental trade, our results underestimate the net benefit of the Australian plant quarantine program. In addition, because plants have relatively low rates of invasion, applying screening protocols to animals would likely demonstrate even greater benefits. (+info)
Quarantine Activity Reporting System (QARS).
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This poster describes the Quarantine Activity Reporting System (QARS), a new web based,secure electronic system which enables tracking the presence of ill persons on inbound flights and vessels and at land border crossings, infectious disease threats, or actions related to imported pathogens. (+info)