LONG-TERM SURVIVAL OF DAMAGED NIPPOSTRONGYLUS-BRASILIENSIS ADULT WORMS IN THE TESTOSTERONE-TREATED INDIAN SOFT-FURRED RAT, MILLARDIA-MELTADA

When testosterone-treated female Millardia meltada were infected with Nippostrongylus brasiliensis, adult worms persisted for over seven wee ks. The kinetics of faecal egg counts showed a biphasic pattern having a transient decline at around two weeks post infection (p.i.). Thus t he status of N. brasiliensis adult worms surviving in the small intest ines of testosterone treated M. meltada was examined, The fecundity an d maturity of eggs in the uteri of female adult worms were examined at one, two, three and seven weeks p.i. Both the fecundity and maturity of eggs transiently decreased at two and three weeks p.i. and then com pletely recovered by seven weeks, Adoptive transfer of N. brasiliensis adult worms into naive recipients can discriminate the status of worm s. Those obtained from the stable phase of a primary infection ('norma l' worm) can establish and survive in the recipients, whereas those ob tained at the time of expulsion ('damaged' worm) are rapidly expelled Therefore, 300 each of N. brasiliensis adult worms collected from the testosterone-treated female M. meltada at one, two and seven weeks p.i . were transferred intraduodenally into normal rats to determine their status. Those collected at one week p.i. persisted for eight days ind icating that they were still 'normal'. In contrast, worms collected at two and seven weeks p.i. were expelled within four days, indicating t hat they had already been 'damaged', Moreover, when the 'damaged' worm s obtained from rats were intraduodenally transferred into testosteron e-treated female M. meltada, they were not expelled, suggesting that t estosterone-treatment affected the final expulsive step, but not the d amaging process, of the mucosal defence of M. meltada against N. brasi liensis adult worms.