Intestinal parasites in the body are commonly caused by poor sanitation and hygiene, as well as international travel to locations where parasite infections are common. In some cases, worms may be spread through sexual intercourse when anal and oral sexual contact occur, according to Planned Parenthood. The two most common internal parasites are Helminths and protozoa. Both are worms and can live inside the human body for years without causing any symptoms. However, a variety of symptoms can be identified to diagnose a worm infection in the human body.
Roundworms may travel to the lungs through a person's blood stream or lymphatic system. According to the Mayo Clinic, symptoms are similar to a person suffering from pneumonia or asthma. A person has difficulty breathing and shortness of breath. Coughing and wheezing may be present. The clinic adds that the worms may spend between six to 10 days in the lungs until a person coughs them up, and then swallows them—they then travel to the intestine where they live the remainder of their life cycle.
Abdominal cramps or pain frequently occur with mild intestinal worm infections. Many roundworm larvae live in the small intestines until they die, according to the Mayo Clinic. Diarrhea and blood in a person's stool is common. A person may have recurring episodes of nausea and vomiting.
A person suffering from pinworms may have episodes of anal itching or discomfort. A person experiences the symptoms as the female pinworm lays her eggs. Symptoms lead to difficulty sleeping and restlessness. Some people suffering from pinworms may not experience this symptom.
A person suffering from a severe internal worm infection may constantly feel tired, despite getting plenty of rest. Slow growth and weight loss are common. Diarrhea may continue, growing more severe and chronic. Worms may be visibly present in stool, or exiting through the nose or mouth, according to MedlinePlus. Worms may causes blockage in the intestines or biliary tract obstruction. Blockage causes severe pain, disturbance of sleep, restlessness and episodes of vomiting.