Oocyst output, periodicity, and immunity of two deer mouse (Peromyscus maniculatus) eimerians (Eimeria arizonensis and Eimeria delicata).

We compared the life histories of 2 eimerians (Eimeria arizonensis and Eimeria delicata), which co-occur in the deer mouse (Peromyscus maniculatus). Laboratory-reared deer mice were given 10(3), 10(4) (E. delicata), or 10(3), 10(4), or 10(5) (E. arizonensis) oocysts by stomach intubation. Eimeria arizonensis infections lasted longer (11-13 days) than E. delicata infections (9-10 days). Eimeria arizonensis infections also produced more oocysts for each oocyst ingested at both levels compared. Both parasites exhibited periodicity in oocyst output at all levels compared. However, peaks in E. arizonensis output occurred at approximately 20-24-hr intervals, whereas peaks in E. delicata output occurred at 12-16-hr intervals. Finally, deer mice developed immunity to both eimerians after only 1 inoculation at all levels tested. Based on these parameters, we expect E. arizonensis to have a greater reproductive potential than E. delicata in free-living deer mice.