A MODEL FOR VARIATIONS IN SINGLE AND REPEATED EGG COUNTS IN SCHISTOSOMA-MANSONI INFECTIONS

被引:88
作者
DEVLAS, SJ [1 ]
GRYSEELS, B [1 ]
VANOORTMARSSEN, GJ [1 ]
POLDERMAN, AM [1 ]
HABBEMA, JDF [1 ]
机构
[1] LEIDEN UNIV,FAC MED,PARASITOL LAB,2300 RC LEIDEN,NETHERLANDS
关键词
SCHISTOSOMA-MANSONI; EGG COUNTS; WORM LOAD DISTRIBUTIONS; STOCHASTIC MODEL;
D O I
10.1017/S003118200006371X
中图分类号
R38 [医学寄生虫学]; Q [生物科学];
学科分类号
07 ; 0710 ; 09 ; 100103 ;
摘要
Faecal egg counts are often used to measure Schistosoma mansoni infection, but the considerable variation between successive counts complicates their interpretation. The stochastic model described in this paper gives a description of observed egg counts in a population and can be used as a tool to gain an insight into the underlying worm load distribution. The model distinguishes between two sources of variation in egg counts: (1) variation caused by the difference in worm load between individuals, and (2) the variability of egg counts for an individual with a given worm load. Empirical data, single and repeated measurements, from surveys in five villages in Burundi and Zaire have been used to fit and validate the model. We have discussed possible mechanisms that explain the differences in estimated values between the villages. The model indicates that the expected number of eggs in a stool sample per S. mansoni worm pair is lower than suggested by autopsy data and that, possibly as a consequence of immunity, the inter-individual variation in worm loads decreases with age.
引用
收藏
页码:451 / 460
页数:10
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