Parasite transmission in size-structured host populations Pubblico

Abstract

Parasite infection success can depend on host characteristics such as size, age, or genotype. Transmission theory that ignores variation and treats hosts as uniform individuals with identical infection risk matches data poorly and cannot address critical themes in disease ecology, such as superspreading and parasite aggregation. For the host snail Biomphalaria glabrata and its obligate parasite Schistosoma mansoni, larger snails experience higher rates of exposure to parasites but are less susceptible to infection. These size-dependencies are known for individual hosts in isolation, but their effects within size-structured populations remain unknown. To assess this relationship, I created mathematical models that can predict transmission dynamics at the population-level and test the strength of these models using experimental data. My results show that size-dependent models accounting for differences in both exposure and susceptibility with host size outperformed current or null models and were able to predict differences in population prevalence amongst different size-structures. Understanding how variation in host traits drives transmission is critical for increasing our ability to predict disease dynamics. Incorporating host body size in population-level parasite transmission models may enable researchers to improve decision making surrounding human schistosome risk in endemic areas.

Table of Contents

1.    Introduction……………………………………………………………………………1

2.    Methods……………………………………………………………………...………...3

a.    Snail Maintenance………………………………………………………..……4

b.    Experimental Design……………………………………………………...…...4

c.    Infection Diagnosis……………………………………………………………5

d.    Model Creation and Parameterization…………………………………...……5

e.    Model Competition……………………………………………………………6

3.    Results…………………………………………………………………………….…...7

a.    Experimental Results………………………………………………………….7

b.    Model Results…………………………………………………………………7

4.    Discussion…………………………………………………………………………….8

5.    Figures……………………………………………………………………………......11

a.    Figure 1………………………………………………………………………11

b.    Figure 2………………………………………………………………………12

c.    Figure 3………………………………………………………………………13

d.    Figure 4………………………………………………………………………14

e.    Figure 5………………………………………………………………………15

f.     Table 1……………………………………………………………………….16

6.    References……………………………………………………………………………17

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Biology, Parasitology Biology, Ecology
Parola chiave	size structure Schistosomiasis parasite transmission
Committee Chair / Thesis Advisor	David Civitello, Emory University
Committee Members	Michal Arbilly, Emory University Julie Clennon, Emory University

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