FATE OF INFECTIVE LARVAE OF BRUGIA-MALAYI IN THE PERITONEAL-CAVITY OFMASTOMYS-NATALENSIS AND MERIONES-UNGUICULATUS

The fate of intraperitoneally inoculated infective third-stage larvae (L-3) of the nematode Brugia malayi Lichtenstein and the status of the peritoneal macrophage function were investigated in the susceptible r odent hosts Mastomys natalensis Roberts and Meriones unguiculatus Miln e-Edwards (jird). Jirds and M, natalensis were inoculated intraperiton eally with 125 and 250 L-3 and the worm burden and peritoneal macropha ge function in the two species were compared at different days post-in oculation (DPI), None of the infected M, natalensis had adult worms in the peritoneal cavity; very few degenerating L-3 surrounded by perito neal cells were recovered 7 and 15 DPI. In contrast, all the infected jirds showed the parasite in different stages of development and the w orm burden at different days PI was more in 250 L-3 dose group than in 125 L-3 dose group, The phagocytic function of peritoneal macrophages of normal M. natalensis was twice higher than that of jirds. This fun ction was found significantly suppressed in both host species at 15 DP I; at 35 DPI, the activity was still at this low level in the jird, wh ile that in M. natalensis reverted to uninfected age-and sex-matched c ontrol levels, These findings demonstrate that the peritoneal environm ent of M. natalensis is not conducive to the development of B. malayi and this is probably related to high macrophage activity in the perito neum of this host compared to that found in the jird.