Hymenolepis diminuta: The effect of serum on different ages of worms in vitro

Abstract Hymenolepis diminuta : The effect of serum on different ages of worms in vitro . International Journal for Parasitology 16: 447–453. Newly excysted and 2-day-old Hymenolepis dimmuta were lysed completely in 50% fresh rat serum starting from the posterior end. In older worms, 4- to 10-day-old, lysis started in the groove between proglottides at the anterior end of the strobila. The scolex and neck often survived as a destrobilated worm, and in older worms a small amount of the tail-end also avoided lysis. Destrobilation in vitro of worms of increasing age resulted in destrobilated worms of increasing length. Worms which had destrobilated in vivo were either lysed completely or further decollated in fresh rat serum. When 50% fresh rat serum was further diluted with heat inactivated serum, the mean time of lysis of newly excysted worms increased from about 2 min at titer 2 to 40 min at titer 16, where 72% of the worms were lysed. The rest of the worms and worms in titres higher than 16 survived for 24 h. It is suggested that complement could be the effector arm of the host defence system whether specific or not in destrobilation and killing of H. diminuta in its hosts.