Dream about killing parasites is a clue for trouble, loss and overwhelming grief. You may be feeling emotionally wounded and are trying to cover/shield your hurt from others. You are not letting anyone stand in the way of your goals. Your dream is a premonition for feelings of hopelessness about some situation or circumstance. You need to relinquish your worries and let go of your old problems.
Killing parasites dream is a metaphor for firm and concrete ideas or plans that are being set into motion. A person cannot change who they are no matter how hard they may try. You are not being understood or someone is not understanding you. This dream is a metaphor for repressed desires and unexpressed emotions that are on the verge of exploding or bursting if not dealt with soon. There is a void in your life.
If you dreamt about killing parasites:
Join up with those who are on a positive, upward track instead of getting dragged down by the naysayers who only see the potential pitfalls of a plan and who continue to be overly critical of your work. If this means changing jobs, then do so.