Further studies on the development of Wuchereria bancrofti in laboratory animals.

In an attempt to obtain a small animal laboratory model for Wuchereria bancrofti Mongolian gerbils and hamsters were infected with third-stage larvae of strains of the parasite from Indonesia and China. Gerbils were necropsied at 7 to 591 days and larvae recovered up to 219 days. The third molt occurred on or before 10 days and worms found after 14 days were in the fourth stage. More worms were recovered early in the infection (7 to 30 days) than in older infections. The worms were usually recovered from the testes, pelt and carcass and heart and lungs. An adult male worm was recovered on one occasion from the lung of a gerbil at 92 days. The parasite was also found to develop in hamsters with results similar to those in gerbils. Gerbils and hamsters were given antithymocyte sera before and after infection and more worms were recovered and the worms larger in size in some treated animals. Continued studies with geographic strains of W. bancrofti in various animals should be encouraged in order to find a small laboratory animal model for the parasite.

Repeated infections of Brugia pahangi in the jird, Meriones unguiculatus.

Male jirds, Meriones unguiculatus, were subcutaneously inoculated in the groin with 1 to 5 doses of infective-stage larvae of Brugia pahangi at weekly or monthly intervals. When a dose of either 25 or 75 larvae or 4 weekly doses of 25 larvae were given, 15-16% of the larvae were recovered as adults approximately 4 to 7 months post inoculation. Only 8-10% of the larvae were recovered if 4 weekly or 5 monthly doses of 75 larvae each were given. After an inoculation of 75 larvae, 25% of the worms were recovered at 30 days. The 30 day-old population consisted of an average of 10 female and 8.8 male worms. Jirds previously inoculated with 4 weekly or 5 monthly doses were challenged with an additional 75 larvae 30 days prior to necropsy. An average of only 4.5 thirty day-old female worms were recovered in these cases, presenting a 55% decrease as compared to the single inoculation situation. There was some decrease in the mean length of female worms in multiply-inoculated jirds, but no difference in the mean lengths of the male worm population from singly or multiply-inoculated jirds was observed. No differences in prepatent periods or in patterns of microfilaraemia were observed in singly or multiply-inoculated jirds.