Meeting Abstract

P3.109  Tuesday, Jan. 6  Tapeworm Co-infection Alters Life History and Distribution of the Nematode Heligmosomoides bakeri WARD, W. Timothy*; KRISTAN, Deborah; California State University San Marcos; California State University San Marcos ward033@csusm.edu

In nature, most hosts harbor more than one parasite species concurrently. When different parasite species occupy the same site in the host, there may be direct and indirect effects of one parasite on the other. We investigated if an established infection with the bile duct tapeworm (Rodentolepis microstoma) influenced life-history (survival, sex ratio) and habitat selection (location along the small intestine) of the nematode Heligmosomoides bakeri. Laboratory mice (Mus musculus) were infected with either 0 (control), 4 (low-intensity group) or 12 (high-intensity group) R. microstoma cysticercoids. At 21 days post-R. microstoma infection, the same mice were inoculated with 300 infective stage H. bakeri larvae. Mice were euthanized 6 days post-H. bakeri infection and the following variables were measured for fourth stage H. bakeri larvae: total number of worms, sex ratio, and location of larvae along the small intestine. We also determined the number and mass of R. microstoma, bile duct mass, and circulating alkaline phosphatase in mouse plasma. Alkaline phosphatase is elevated during bile duct obstruction associated with liver disease but has not been tested during bile duct obstruction due to parasite infection. We found that, during tapeworm co-infection, 57% fewer H. bakeri larvae established (p < 0.0001) and larvae were located more distally along the small intestine (p < 0.0001) compared to mice with nematode only infection. There was no effect of R. microstoma on H. bakeri sex ratio (p = 0.55). R. microstoma infection increased bile duct mass more than two-fold (p = 0.02), but there was no change in serum alkaline phosphatase (p=0.19), regardless of the number of adult R. microstoma (p=0.34).