Woolhouse M E
Centre for Tropical Veterinary Medicine, University of Edinburgh, Easter Bush, Roslin, Midlothian, UK EH25 9RG.
Parasitol Today. 1998 Oct;14(10):428-34. doi: 10.1016/s0169-4758(98)01318-0.
A characteristic relationship between infection and host age, with levels of infection reaching a peak in particular age classes, has been reported for many parasites. However, several field studies have shown that this relationship is not invariant: if age-infection data are compared across host populations, the peak level of infection is higher and occurs at a younger age when the transmission rate is high, and is lower and occurs at an older age when it is low. This pattern is called the ;peak shift'. Here, Mark Woolhouse reviews the evidence for and the implications of the peak shift. The peak shift is consistent with the predictions of mathematical models that assume gradually acquired protective immunity, and this interpretation is supported by experimental studies using animals. This agreement between theory, experimental evidence and field studies strongly suggests that acquired immunity has a major impact on epidemiological patterns not only for parasites such as malaria, where the importance of acquired immunity is not in doubt, but also for many parasitic helminths, where the role of acquired immunity is less widely accepted.
许多寄生虫都存在感染与宿主年龄之间的特征性关系，即感染水平在特定年龄组达到峰值。然而，一些实地研究表明这种关系并非一成不变：如果比较不同宿主种群的年龄-感染数据，当传播率高时，感染峰值水平更高且出现在更年轻的年龄，而当传播率低时，感染峰值水平更低且出现在更年长的年龄。这种模式被称为“峰值转移”。在此，马克·伍尔豪斯回顾了支持峰值转移的证据及其影响。峰值转移与假设逐渐获得保护性免疫的数学模型预测一致，并且这种解释得到了动物实验研究的支持。理论、实验证据和实地研究之间的这种一致性有力地表明，获得性免疫不仅对疟疾等寄生虫的流行病学模式有重大影响（在疟疾中获得性免疫的重要性毋庸置疑），而且对许多寄生蠕虫也有重大影响（在寄生蠕虫中获得性免疫的作用不太被广泛接受）。
