Parasitic worms, such as tapeworms, roundworms and pinworms, can cause infection within the human body if they are accidentally ingested. These worms can enter your body if you consume contaminated food products, such as undercooked beef (tapeworms), or if you do not wash your hands before eating (pinworms).
Stomach Upset
Humans who are infected by parasitic worms most commonly develop stomach-related symptoms. You can experience nausea, vomiting or abdominal pain due to irritation caused by intestinal worms. Some people also experience diarrhea, a condition that causes frequent bowel movements that lead to the excretion of watery or loose stools. You may also experience abdominal pain, bloating or gas, due to recurrent bouts of diarrhea.
If the worms within your intestine cause significant irritation, you may notice the appearance of blood within your stools. Worms that are left undetected or untreated can become very large and may cause intestinal obstruction, warns the Food Safety and Inspection Service of the United States Department of Agriculture.
Weight Loss
Appetite loss or decrease can also occur in conjunction with stomach upset and can lead to significant weight loss in some patients infected by worms.
Jaundice
Certain types of worms, such as tapeworms, can form fluid-filled cysts within your liver, kidney, brain or lungs. Cysts that form on the liver can put pressure on this organ and may cause liver damage. If this occurs, you can develop jaundice, a medical condition characterized by yellowing of the eyes or skin.
Fever
If you have been infected with a parasitic worm, you can develop a fever in response to this invader. A fever is part of the body's natural immune response and helps to prevent the growth and spread of parasites throughout the body. Fever may be accompanied by additional symptoms, including body aches, weakness, fatigue or headache.
Skin Irritation
Some types of roundworms---especially hookworms---can cause significant skin irritation to develop in an infected human. Your skin can develop a rash that may appear dry or flaky. These skin patches can become severely itchy and may occur on any region of your body, explain health professionals at the State of California---Health and Human Services Agency. Pinworms, which exit your body through your bowel movements, can severely irritate the skin surrounding your anus. This can cause your buttocks to itch and may lead to vaginal inflammation in females.
