Under the Weather Climate, Ecosystems, and Infectious Disease (2001) / Chapter Skim
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Towards the Development of Disease Early Warning Systems
Towards the Development of Disease Early Warning Systems
Pages 86-102
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From page 86... ...
In some instances, "sentinel" animals are placed in high-risk locations and monitored for evidence of infection, since infections among these animals will typically presage human cases. These "surveillance and response" approaches provide fairly high predictive certainty of an impending disease outbreak but often leave public health authorities with little advance notice for mobilizing actions to prevent further spread of the disease agent.
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From page 87... ...
A benefit of this multi-staged early warning approach is that response plans can be gradually ramped up as forecast certainty increases. This would give public health officials several opportunities to weigh the costs of response actions against the risk posed to the public.
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From page 88... ...
The focus must be not only on improving hazard monitoring and prediction but also on improving coordination among relevant parties, such as the scientific organizations that forecast hazard events, the national and local management agencies that assess risk and develop response strategies, and the public communication channels used to disseminate warning information.
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From page 89... ...
Climate forecasts and information from ongoing epidemiological surveillance and environmental observations may be used as input for predictive models that generate watches or warnings about an impending disease risk. This information is then coupled with vulnerability assessments to determine which segments of a population are most likely to face harm from an impending hazard and risk analysis to determine the likely impact of the impending hazard on these groups.
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From page 90... ...
Yet risk analysis is still fundamentally static in character in many places, often because cartographic and census information is so out of date that it bears little relationship to real risk levels. A priority must be to build the capacity to monitor dynamic changes in risk patterns at a high level of spatial and temporal resolution, in order to provide accurate information on the likely impact of a specific hazard event in a given area.
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From page 91... ...
Response plans that contradict the accepted coping strategies of a vulnerable group are not likely to be implemented effectively. The actions taken to prevent or mitigate disease outbreaks can often carry significant costs and, in particular, can pose a major burden on resources in poor countries.
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From page 92... ...
Implementation Issues Early warning systems are only as good as their weakest link, and they can fail for a number of reasons: the hazard forecast or risk scenarios generated may be inaccurate; there may be a failure to communicate warning information in sufficient time or in a way that can be usefully interpreted by people exposed to a hazard; appropriate response decisions may not be made due to a lack of information, opaque decision-making procedures, or perceived political risks; or intervention actions may incur unacceptable costs for the community. One potentially key barrier in effectively implementing an early warning system is lack of clear decision-making protocols among the relevant institutions.
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From page 93... ...
· National level: Scientific teams working within national public health agencies or other organizations can use climate forecasts together with information from vulnerability assessments and surveillance networks to assess the disease risks posed to specific communities. National governments and scientific agencies can also help strengthen the basic infrastructure for epidemiological and environmental surveillance systems.
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From page 94... ...
. It also demonstrates the challenges of coordinating response actions among various government agencies and public health officials, and effectively communicating about a new disease risk to the public.
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From page 95... ...
To manage the potential spread of West Nile virus, the New Jersey Department of Health and Senior Services developed a preparedness plan that included the following components: · Human, animal, and mosquito surveillance to detect whether and where the virus is present, including sentinel chicken flocks. · Continued comprehensive mosquito control activities to suppress the emergence of mosquito populations.
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From page 96... ...
It has been previously described in Central Europe, the Middle East, and sub-Saharan Africa, with some evidence that it may be spread by bird migration between Europe and Africa (Watson et al., 1972; Miller et al., 2000~. West Nile virus is endemic in temperate areas and was probably brought to New York through international transport of an infected bird, mosquito, or human.
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From page 97... ...
In some instances, investigators have begun developing models that use environmental observations to predict disease outbreaks (such as Rift Valley fever and hantavirus, discussed earlier) , but thus far these models have only been used to make such "predictions" retroactively.
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From page 98... ...
They also determined the average profit for each nitrogen application rate over all years and the average profit based on each phase of the ENSO cycle (Stone et al., 1996~. Comparing results of the fixed strategy and the tactical strategy (considering the forecast ENS O phase)
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From page 99... ...
Short-term weather forecasts are used in the course of a forest fire, and resource dispatch centers do sometimes use medium term forecasts (10-30 days) to determine what kinds of resources to have on standby.
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From page 100... ...
The evacuations issued in 1999 during Hurricane Floyd for the coast of South Carolina are a good example of the problem of false positives, since the hurricane did not make landfall where forecast, and of inadequate evacuation planning, which led to massive traffic congestion. Some of the lessons learned from forecasting and responding to hurricanes that might be applicable to a disease early warning system include: · the need to prepare the population for the possibility of false-positive forecasts; · the challenge of educating populations that have not previously been exposed to the hazard in question; and · the need to assess the vulnerability of different populations within one region.
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From page 101... ...
FEWS provides regional and country-specific analyses, monthly bulletins integrating forecast information, and vulnerability assessments. These assessments are typically carried out in conjunction with local institutions, and the analyses and conclusions are shared with the host governments.
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From page 102... ...
FEWS offers perhaps the most relevant example of an early warning system for the public health community to consider. In fact, since malnutrition and susceptibility to disease are closely linked, it could be highly advantageous for a disease early warning system to build on the infrastructure and personal networks that FEWS has already established in many regions.
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