A CORE GROUP MODEL FOR DISEASE TRANSMISSION
A CORE GROUP MODEL FOR DISEASE TRANSMISSION
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DOI：
10.1016/0025-5564(94)00066-9
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发表时间：
1995-07-01
影响因子：
4.3
通讯作者：
CASTILLOCHAVEZ, C
中科院分区：
文献类型：
--
作者：
HADELER, KP;CASTILLOCHAVEZ, C
性传播疾病的模型一般假定核心群体的规模是固定的。关于疾病流行率的公开信息可能会影响性行为高度活跃人群招募新的合格者。假设核心人群的招募率较低，而疾病流行率较高，核心群体成员仅相互混合，核心群体以外的疾病水平可以忽略不计，一些核心群体成员通过使用部分有效的疫苗或免疫抑制剂来降低风险。建立了一个核心人口与非核心人口之和为常数的人口-传染病模型。一个更简单的版本模拟了在教育计划和降低易感性的措施的影响下，规模恒定的孤立核心人群中的流行病。确定了地方性感染的阈值条件。即使在简化的版本中，也可以观察到向后分叉，多个感染性定态和滞后现象。疾病流行水平的突然变化可能由疾病管理参数的微小变化引起，在没有这样的计划的情况下不会发生。总体结论是，部分有效的疫苗接种或教育计划可能会增加病例总数，同时降低核心组病例的相对频率。这项研究对繁殖数量与消除尝试的关系提出了一些新的看法。它表明，虽然繁殖数确定了疾病在易感人群中传播的阈值，但在计划消除现有流行病时，它的价值有限。
Models for sexually transmitted diseases generally assume that the size of the core group is fixed. Publicly available information on disease prevalence may influence the recruitment of new susceptibles into highly sexually active populations. It is assumed that the recruitment rate into the core population is low while disease prevalence is high, core group members mix only with each other, disease levels outside the core are negligible, and some core group members reduce their risk through the use of a partially effective vaccine or prophylactics. A demographic-epidemic model is formulated in which the combined size of the core and non-core population is constant. A simpler version models the epidemic in an isolated core population of constant size under the influence of educational programs and measures that reduce susceptibility. The threshold condition for an endemic infection is determined. Backward bifurcations, multiple infective stationary states, and hysteresis phenomena can be observed even in the simplified version. Abrupt changes in disease prevalence levels may result from small changes in the disease management parameters and do not occur in the absence of such a program. The general conclusion is that partially effective vaccination or education programs may increase the total number of cases while decreasing the relative frequency of cases in the core group. The study throws some new light on the role of the reproduction number in connection with elimination attempts. It shows that although the reproduction number defines the threshold for the spread of the disease in a susceptible population, it is of limited value when elimination of an existing epidemic is planned.