Generally, there is malabsorption of nutrients, especially fatty foods. Many parasites affect the nervous system and give rise to sleep disorders, such as insomnia. In children, hyperactivity is common, but adults may have symptoms ranging from depression to anxiety. Some parasites affect the brain and memory. It is extremely easy to contract a parasite infection.
Contaminated water is one source of infection.
Improperly washed or undercooked food is a common means of infection. Transmission from pets is another. Contact with another infected person is also a common route of infection. Travel can escalate the risks. Antibiotics pose another problem because they interfere with the normal intestinal flora.