The life cycle of the parasite and the consequent human disease manifestations are reviewed in Chapter 1. Chapter 2 describes the drug trial in Papua New Guinea which provides most of the data for the dissertation. Chapter 3 demonstrates that data on two aspects of the vector-human interface - density dependence of microfilarial survival, and comparisons of mosquito catching methods - have in the past been manipulated in ways which simplified analysis by reducing the influence of extreme values, but at the cost of unjustified conclusions. Chapter 4 analyses the mean and aggregation of human microfilarial density as functions of age and sex. In particular, data from demographic surveillance are used to investigate the hypothesis that a drop in intensity among women of reproductive age is the result of pregnancy-associated changes. In addition, spatial heterogeneity is shown to be an alternative explanation for intra-family associations which have previously been attributed to <I>in utero</I> effects. The distributions of acute and chronic disease are characterized in Chapters 5 and 6, in order to select statistical models which can accommodate heterogeneity and determine risk factors for the different types of morbidity. Geographical patterns are visualized using satellite mapping techniques, and autoregressive spatial models are used to check that the maps are not unduly dominated by counts with high sampling variability because of small denominators. Chapter 7 returns to the vector to consider possible effects on other mosquito-borne diseases of mass anti-filarial chemotherapeutic control programmes. Chapter 8 provides a concluding synthesis of the work. Overall, this research demonstrates that heterogeneity arises in lymphatic filariasis through a network of factors - including vector contact, innate and acquired host characteristics, and geographical variability - which must be recognized and distinguished in order to properly quantify the epidemiology of the disease.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:595423 |
| Date | January 1998 |
| Creators | Alexander, N. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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