**Roundworms** are worm species under the phylum Nematoda. They are unsegmented having pseudocoeloms and digestive systems that are composed of two openings (anus–posterior opening and mouth- anterior opening).

Parasitic worms include trichinosis-causing worm, filarial worm (thread-like worm that dwell in blood stream), ascarid worm (lives in intestine of hosts), and hookworm (can multiply very quickly and harm the host).

See explanation.

***Ascaris lumbricoides*** are parasitic roundworms that infect humans and other vertebrate organisms. This worm is the culprit for the emerging malnutrition worldwide. They are very successful in invading the host’s small intestine and absorbing the nutrients that come from the food intake of the host.

*A. lumbricoides* are usually spread by eating contaminated fecal-contaminated food materials that are not washed properly. Examples of these are fruits, vegetables, and raw meat.

Hookworms are parasitic organisms that usually invade the intestine of their host organisms. As their name implies, hookworms contain a hook-like structure that is being used by them to attach to the intestinal walls of the host.

Hookworms enter the human body by poking the skin of the unprotected foot and then migrate into the bloodstream via many processes. Once they are inside the bloodstream, they get their nutrients by exploding the red blood cells.

Scientists have already discovered *C. elegans*’ life cycle, starting from a single cell to a fully mature adult, not to mention the complete sequence of its DNA. They wished to find out the relationship between the DNA sequences and their behavior and their interesting life cycle. That way, they will be able to apply to other organisms with similar DNA, as well.

In order to prevent a disease, you have to know its nature of that disease. **Elephantiasis** is caused by insect bites. So, people should wear clothes to cover the maximum area of skin and put on insect-repellent that is environmentally friendly. The government should establish a group to control the insect population so that they won’t grow exponentially in ponds and lakes.