Koelle Katia, Pascual Mercedes, Yunus Md
The Department of Ecology and Evolutionary Biology, 2019 Kraus Natural Science Building, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA.
Proc Biol Sci. 2006 Nov 22;273(1603):2879-86. doi: 10.1098/rspb.2006.3668.
Interest in understanding strain diversity and its impact on disease dynamics has grown over the past decade. Theoretical disease models of several co-circulating strains indicate that incomplete cross-immunity generates conditions for strain-cycling behaviour at the population level. However, there have been no quantitative analyses of disease time-series that are clear examples of theoretically expected strain cycling. Here, we analyse a 40-year (1966-2005) cholera time-series from Bangladesh to determine whether patterns evident in these data are compatible with serotype-cycling behaviour. A mathematical two-serotype model is capable of explaining the oscillations in case patterns when cross-immunity between the two serotypes, Inaba and Ogawa, is high. Further support that cholera's serotype-cycling arises from population-level immunity patterns is provided by calculations of time-varying effective reproductive rates. These results shed light on historically observed serotype dominance shifts and have important implications for cholera early warning systems.
在过去十年中，人们对于理解菌株多样性及其对疾病动态的影响的兴趣与日俱增。几种共同流行菌株的理论疾病模型表明，不完全交叉免疫为群体水平上的菌株循环行为创造了条件。然而，对于疾病时间序列，尚未有能明确体现理论预期菌株循环的定量分析。在此，我们分析了来自孟加拉国的40年（1966 - 2005年）霍乱时间序列，以确定这些数据中明显的模式是否与血清型循环行为相符。当两种血清型（稻叶型和小川型）之间的交叉免疫程度较高时，一个数学双血清型模型能够解释病例模式中的振荡现象。时变有效繁殖率的计算进一步支持了霍乱血清型循环源于群体水平免疫模式这一观点。这些结果揭示了历史上观察到的血清型优势转移情况，对霍乱早期预警系统具有重要意义。
