Parameters Influencing the Susceptibility of Neonate Mice to Infection with Brugia pahangi

Abstract

A total of 307 young mice between less than 1 day (neonate) and 4 wk after birth were inoculated either subcutaneously or intraperitoneally with infective larvae of Brugia pahangi to determine the best protocol for the establishment of patent infections. For both male and female neonates, i.p. infection produced higher adult worm burdens than did s.c. infection. Although the numbers of adult worms harbored by male and female mice were not statistically different, male mice were more prone to develop a patent infection; no neonate female mice became microfilaremic , whereas seven of 113 i.p.-infected male mice developed microfilaremia. More female adult worms were recovered, on the average, than were male worms, regardless of the age of mice used for infection. However, the younger the mice were at infection, the higher were the numbers of male worms recovered. A high number of gravid female worms were recovered from amicrofilaremic mice. Adult female and male worms harvested from amicrofilaremic mice, implanted into the peritoneal cavity of jirds (Meriones unguiculatus), did not produce microfilariae although approximately 50% of the jirds contained gravid female parasites. Jirds implanted with worms from microfilaremic mice did, however, contain peritoneal microfilariae. It appeared that amicrofilaremic mice irreversibly damaged female worms to the extent that worms could survive and appear healthy, but could not release microfilariae.