Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario, Canada.
Ann Intern Med. 2011 May 3;154(9):593-601. doi: 10.7326/0003-4819-154-9-201105030-00334. Epub 2011 Mar 7.
Haiti is in the midst of a cholera epidemic. Surveillance data for formulating models of the epidemic are limited, but such models can aid understanding of epidemic processes and help define control strategies.
To predict, by using a mathematical model, the sequence and timing of regional cholera epidemics in Haiti and explore the potential effects of disease-control strategies.
Compartmental mathematical model allowing person-to-person and waterborne transmission of cholera. Within- and between-region epidemic spread was modeled, with the latter dependent on population sizes and distance between regional centroids (a "gravity" model).
Haiti, 2010 to 2011.
Haitian hospitalization data, 2009 census data, literature-derived parameter values, and model calibration.
Dates of epidemic onset and hospitalizations.
The plausible range for cholera's basic reproductive number (R(0), defined as the number of secondary cases per primary case in a susceptible population without intervention) was 2.06 to 2.78. The order and timing of regional cholera outbreaks predicted by the gravity model were closely correlated with empirical observations. Analysis of changes in disease dynamics over time suggests that public health interventions have substantially affected this epidemic. A limited vaccine supply provided late in the epidemic was projected to have a modest effect.
Assumptions were simplified, which was necessary for modeling. Projections are based on the initial dynamics of the epidemic, which may change.
Despite limited surveillance data from the cholera epidemic in Haiti, a model simulating between-region disease transmission according to population and distance closely reproduces reported disease patterns. This model is a tool that planners, policymakers, and medical personnel seeking to manage the epidemic could use immediately.
海地正处于霍乱疫情之中。用于制定疫情模型的监测数据有限，但此类模型有助于了解疫情进程并帮助确定控制策略。
利用数学模型预测海地霍乱疫情的区域顺序和时间，并探讨疾病控制策略的潜在影响。
允许人际和水源传播霍乱的房室数学模型。模拟了区域内和区域间的疫情传播，后者取决于人口规模和区域质心之间的距离（“重力”模型）。
海地，2010 年至 2011 年。
海地住院数据、2009 年人口普查数据、文献中得出的参数值和模型校准。
疫情爆发和住院日期。
霍乱基本繁殖数（R(0)，定义为无干预措施的易感人群中每个原发性病例的继发性病例数）的合理范围为 2.06 至 2.78。重力模型预测的区域霍乱暴发的顺序和时间与实际观察结果密切相关。对随时间变化的疾病动态的分析表明，公共卫生干预措施已极大地影响了这一疫情。在疫情后期提供的有限疫苗供应预计将产生适度影响。
模型简化了假设，这对于建模是必要的。预测基于疫情的初始动态，这可能会发生变化。
尽管海地霍乱疫情的监测数据有限，但根据人口和距离模拟区域间疾病传播的模型密切再现了报告的疾病模式。该模型是规划者、政策制定者和寻求管理疫情的医务人员可以立即使用的工具。
