GENETIC DEPENDENT TRANSMISSION OF EIMERIA SEPARATA FROM RATTUS TO THREE STRAINS OF MUS MUSCULUS, AN ABNORMAL HOST

We examined susceptibility of several strains of mice to Eimeria separata. Mice of the following coat-color genotypes were inoculated with 2 X 104 sporulated oocysts of E. separata isolated from Rattus norvegicus: random-bred (aabbCC and A-bbCC), Balb/C (AAbbcc), Balb/Gw (AABBcc), Z/Gw (aaBBcc), and Swiss NLW (cc). Allele designations are A = agouti, a = nonagouti, B = black, b = brown, C, c = albino. Eimeria separata completed its life cycle with oocyst production in all male and female random-bred (aabbCC), Balb/ Gw and G/Gw mice. The reproductive index of E. separata in Balb/Gw mice was significantly lower (P < 0.05) than that of the other mouse strains. Among the random-bred mice, E. separata had a significantly lower (P < 0.05) mean reproductive index in male than in female hosts. Patent period and oocyst length/width indices remained constant irrespective of host genus. This is the first documentation that genetic factors play a role in susceptibility of mice to the rat coccidium, E. separata.