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Title: Patterns and consequences of coinfection in humans : consequences for treatment and health
Author: Griffiths, Emily
ISNI:       0000 0004 2738 0189
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2013
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Coinfection by multiple species of parasite, including viruses, bacteria, protozoa, fungal pathogens, and helminths, affects hundreds of millions of people. Despite the potential for significant health effects, and important implications for treatment of infections, relatively little is know about the structure of coinfecting communities, the processes responsible for this structure, and the consequences for host health. This lack of knowledge limits the extent to which treatment of infection can account for coinfection. The four original research chapters of this thesis include collation and analyses of large databases of coinfection information collected from published papers, analyses of coinfection data in a large database of death certificates, and analyses of the behaviour of a theoretical model of two coinfecting parasites. Coinfection information in previously published literature indicates that coinfection tends to enhance parasite abundance and harm human health. The same literature shows that interactions among coinfecting parasites are likely to involve shared resources, as opposed to being mediated via the immune system. Analysis of death certificates showed that the proportion of deaths attributed to coinfection was greatest in early adulthood, and that, positive associations between pairs of coinfections on death certificates were more common than negative associations. The theoretical model of two coinfecting parasites revealed that indirect effects of treatment on untreated parasites may be predictable given information about the direction of interspecific interactions among parasites. In sum, these findings indicate that coinfection in humans involves hundreds of different species combinations, that these communities are likely to be structured by bottom-up rather than top-down processes, and that coinfection can present a serious health risk. Furthermore, a better understanding of interspecific interactions among parasites could be used to improve treatment outcomes. Further research could show where specific treatments indirectly suppress more parasites than currently estimated.
Supervisor: Warren, Philip Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available