Using a multiple stage age of infection model, we derive an expression for the basic reproduction number, Ro. We apply this method to find Ro in analogous treatment models. We find, in the model without treatment, Ro depends only on the mean infective period, and not on the infective distribution. In treatment models, Ro depends on the mean infective and mean treatment period, as well as the distribution of the infective period, but not on the distribution of the treatment period. With an explicit formula for Ro and the final size relation, we provide a practical alternative to evaluating the effect of treatment and other control measures. We compare our models to previous models of SARS and TB.

Orthokeratology (OK) is a specialty contact lens procedure that involves the overnight wear of lenses to reshape the corneal tissue resulting in clear vision upon lens removal. Currently it is the only way of achieving clear vision without having to wear spectacles or contact lenses during the day or undergoing refractive surgery. This thesis investigated the effects of this procedure on the corneal epithelium and the potential increase in risk of microbial infection in an animal model. The cat was first established as an appropriate animal model in a pilot study to examine OK epithelial changes. Initial findings of epithelial thickness changes similar to those found with human myopic and hyperopic OK clinical studies led to the further development of this animal model to better mimic human lens wear for the remaining studies undertaken. Histological studies were used to examine epithelial effects of overnight myopic OK lens wear. Repeatable and differential effects on epithelial thickness and morphology across the cornea were found, including thinning of the central and peripheral epithelium and thickening of the mid-peripheral epithelium. Central thinning was attributed to compression of cells and was less in overnight wear compared to continuous wear. Mid-peripheral thickening was due to increased cell layers and peripheral thinning was attributed to cellular compression. Recovery of epithelial morphologic and thickness changes commenced one day after ceasing lens wear and was complete within one week. Minimal changes to keratocyte populations in regions adjacent to epithelial thickness changes were found. Microbiological studies investigated the effect of epithelial changes on corneal susceptibility to bacterial infections by exposing OK-treated corneas to large amounts of Pseudomonas aeruginosa. The hypothesis that OK lenses increased susceptibility to infection (within the time tested) was rejected as no infections were produced in any animals (except the positive scratch control). Length of OK treatment, duration and quantity of bacterial exposure, lens wearing schedule and bacterial strain type did not affect susceptibility to infection. The epithelium is a major contributor to OK-induced corneal changes. These epithelial changes are reversible and do not appear to predispose to infection provided corneal integrity is maintained.

Thesis (M.S. - Nutrition and Food Science)--University of Arizona, 1986. / Includes bibliographical references (leaves 34-36).

Thesis (Ph. D. - Microbiology and Immunology)--University of Arizona, 1985. / Includes bibliographical references (leaves 134-143).

Thesis (Ph. D. - Microbiology and Immunology)--University of Arizona, 1985. / Bibliography: leaves 142-161.

Thesis (Ph. D. - Microbiology and Immunology)--University of Arizona, 1985. / Includes bibliographical references (leaves 118-127).

Diss. (sammanfattning) Göteborg : Univ. , 2007. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available in print.

Diss. (sammanfattning) Stockholm : Karol. inst.

Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 2001? / Errata sheet has been pasted onto the front end-paper. Bibliography: leaves 208-217.