Butterworth A E, Fulford A J, Dunne D W, Ouma J H, Sturrock R F
Molteno Laboratories of Parasitology, Department of Pathology, University of Cambridge, U.K.
Philos Trans R Soc Lond B Biol Sci. 1988 Oct 31;321(1207):495-511. doi: 10.1098/rstb.1988.0105.
A major difficulty in understanding the epidemiology of human schistosomiasis has been to distinguish between acquired immunity and reduced exposure as possible reasons for an observed decline, in older individuals, of levels of superinfection or of reinfection after chemotherapy. A series of studies of Schistosoma mansoni infections in Kenya has been undertaken to approach this problem, by investigation of intensities of reinfection after treatment of individuals whose levels of contact with contaminated water is subsequently observed. Intensities of reinfection are highest among younger children, thereafter declining sharply. This decline can be attributed only in part to age-related changes in the duration and nature of exposure; there is also evidence for the development of an acquired resistance to reinfection that is dependent both on age and on previous experience of infection, and that may be immunologically mediated. Evidence has been obtained that the slow development of this acquired immunity with age may be associated with the early development and subsequent slow decline of inappropriate immune responses that 'block' the effect of potentially protective responses. Implications of these findings for immunological intervention through vaccination are discussed.
在理解人类血吸虫病流行病学方面的一个主要困难在于，难以区分获得性免疫和接触减少这两种因素，它们都可能是导致观察到的老年个体化疗后再感染或重复感染水平下降的原因。为了解决这个问题，在肯尼亚开展了一系列关于曼氏血吸虫感染的研究，通过调查那些接触受污染水源程度随后被观测到的个体在治疗后的再感染强度来进行研究。再感染强度在年幼儿童中最高，之后急剧下降。这种下降只能部分归因于与年龄相关的接触持续时间和性质的变化；也有证据表明，对再感染产生了获得性抵抗力，这种抵抗力既取决于年龄，也取决于先前的感染经历，并且可能是由免疫介导的。有证据表明，随着年龄增长这种获得性免疫的缓慢发展可能与不适当免疫反应早期的发展以及随后的缓慢下降有关，这些不适当的免疫反应“阻碍”了潜在保护性反应的作用。文中讨论了这些发现对通过疫苗接种进行免疫干预的意义。
