What harm does roundworm cause?

Roundworms are intracavitary parasites that live in the intestines of humans and other animals. They do a lot of harm to their owner:

1) The larva from the intestine enters the lungs, and then is swallowed again and already develops into a worm. During migration, it makes a hole in the intestine, which is already dangerous. While moving through the bloodstream, it can destroy some of the blood cells.

2) The worm uses the resources of the host for feeding. It removes many nutrients that do not have time to be absorbed in the intestines, and the host develops weakness, lack of nutrients, and weight decreases.

3) In the process of life, roundworms secrete metabolites that poison the host.