EPIDEMIOLOGY OF GASTROINTESTINAL PARASITE INFECTIONS IN A WILD HERBIVORE

Open Access
Author:
Perry, Georgia L
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Isabella Cattadori, Thesis Supervisor
  • Gong Chen, Honors Advisor
Keywords:
  • Trichostrongylus retortaeformis
  • gastrointestinal parasite
Abstract:
Host mediated-effects and parasite density-dependence can greatly impact the rate of growth and fecundity of parasitic helminths in a seasonal environment. Trends in nematode development and fecundity can provide quantitative data regarding infection dynamics, host immunity, and regional climatic conditions over time. The purpose of this study was to examine the development and fecundity of the gastrointestinal nematode Trichostrongylus retortaeformis (TR) in wild European rabbit (Oryctolagus cuniculus) and make predictions on the processes affecting parasite dynamics of infection. Nematode length and number of eggs in uterus were quantified using a digitalized system of a camera connected to a microscope and a computer; two years of monthly data were processed. A number of clear patterns were observed in this study. First, there was a positive linear relationship between the numbers of eggs in utero and nematode length. Secondly, a distinct exponential decrease was noted when comparing the lengths and the number of eggs present in the nematodes with host age. Finally, the number of eggs steadily increased throughout the spring and summer peaking in June and then continued to steadily decrease in the fall and winter. The peak correlates to when the offspring are born. These trends appear to be directly attributed to host immune responses; however, parasite density dependent processed may have also contributed to the pattern observed. Further research using laboratory rabbits is needed to reveal more clearly how parasite density-dependent constraints, host-mediated effects and the seasonal environment impact the course of an infection.