Parasite Primer

Roundworms and Hookworms, cont'd

• Trichinella (Trichinella spiralis) infection is often due to eating undercooked pork. Worms travel from the intestines into the muscles of the chest, diaphragm, jaws, and upper arm. Symptoms include diarrhea, nausea, severe muscle pain, facial swelling, difficulty breathing or chewing, and enlarged lymph nodes.
  

3. Tapeworms Tapeworms are flat, segmented and shaped like ribbons. Tapeworms are the largest intestinal parasites and can grow to up to several feet in length. Tapeworm larvae can be found in undercooked meat or fish. From larvae, worms develop in the body and attach to the small intestine. It survives here by absorbing nutrients from ingested foods. Tapeworm infection is often symptomless.

• Taenia solium (pork tapeworm) infection most commonly occurs after eating undercooked pork, smoked ham, or sausages containing larvae. Adult worms attach to the intestines. Symptoms are similar to infection with beef tapeworm. Larvae can travel to subcutaneous tissue, muscle, the central nervous system, and/or the eye, where they eventually form cysts to which the person infected responds with an inflammatory response which can happen after 4 or 5 years. It can develop into blindness, seizures, neurological deficits, and hydrocephalus (swelling of the head).
  
• Taenia saginata (beef tapeworm) infection occurs most commonly after eating undercooked beef containing the larvae. It can live in the intestines for up to 25 years and grow to a length of eight feet. It is usually symptomless, although occasionally presents as abdominal discomfort, loss of appetite, weight loss and diarrhea. Segments can crawl out of the anus.
  
• Diphyllobothrium latum (fish tapeworm) infection is most commonly due to eating freshwater fish containing larvae. Fish tapeworm can grow to 15 meters in length. Symptoms are nonspecific abdominal symptoms, such as loss of appetite, heartburn, diarrhea, and nausea. Vitamin B12 deficiency can also occur, leading to macrocytic anemia and neurological symptoms such as muscle twitches.
  
• Clonorchis sinensis is another worm transmitted by eating raw fish. The worms live in the gallbladder area, so complications can include bile duct stomes, gallbladder stones, and other gallbladder disease.
  

4. Flukes
Flatworms are leaf-shaped worms that attach to the host using abdominal suckers. It usually begins its life cycle as snails, then as larvae they infect fish, vegetation, or humans. Flatworms can travel to lungs, intestines, heart, brain, and the liver. Eggs can cause inflammation by releasing toxins that damage tissues.

• Intestinal Fluke (Fasciolopsis buski) - these worms live in the small intestines. They can cause intestinal ulcers and allergic reactions. Common symptoms are vomiting, diarrhea, nausea, and stomach pain. Intestinal fluke contamination comes from eating infected water vegetables, such as water chestnuts, bamboo shoots, watercress.
  
• Oriental Lung Fluke (Paragonimus westermani) is found predominantly in Asian countries. These worms can penetrate the intestines and travel to the brain or lungs. Symptoms of infection include irrepressible coughing fits and bloody sputum. Sources of these worms include undercooked crabs and crayfish.
  
• Sheep Liver Fluke (Fasciola hepatica) is most commonly transmitted from fresh watercress. The worm attaches to the gallbladder and bile ducts, causing inflammation and local trauma. Symptoms include jaundice, fever, coughing, vomiting, and abdominal pain.
  
• Blood Flukes are transmitted by swimming in contaminated water. They burrow into the skin and migrate to the heart, lungs, liver, or bladder. They can live in the body for up to 30 years.