The biology of NippostrongyLus brasiliensis in SPF rats

When maintained under SPF (specific pathogen free) conditions, Wistar rats had low and variable counts of adult Nippostrongylus brasiliensis. Worm counts were increased if rats were kept in solid rather than wire-bottom cages, if rats were maintained under non-SPF conditions, or if SPF rats were orally inoculated with gut contents from non-SPF rats. It is concluded that gut flora in SPF wistar rats directly or indirectly affects the numbers of larvae establishing as adult worms.