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Test for Ascaris

Intestinal parasites are common in parts of the world where sanitation is poor. Ascaris lumbricoides, a roundworm, infects humans through the consumption of contaminated food and drink. While the signs and symptoms may be no more than some abdominal pain, heavy infestations in children may cause developmental problems. As with any infection, proper diagnosis leads to proper treatment. Diagnosing ascaris infections depends on the proper testing and experience of the lab technician who analyzes it.

  1. Intestinal Parasites

    • Parasites are life forms that live along or within larger hosts. Parasites do not benefit the host, rather they rely on the host for shelter and nutrition. Certain types of parasites affect humans. Blood parasites, such as malaria, live within red blood cells. Skin parasites, such as fungal infections, live on the surface of the skin, eating skin gland secretions. Intestinal parasites, such as ascaris, live within the intestines, feeding off the food in the intestine or the blood from nearby blood vessels.

    Ascaris lumbricoides

    • Ascaris lumbricoides infects humans when they consume food or water contaminated with the fertilized eggs of the roundworm. Once the eggs hatch within the small intestine, the worms travel to the lungs through the circulatory system. In the lungs, they break through the lung walls and crawl to the throat, where they are swallowed. The worms will then mature in the intestine and be excreted in feces to start their life cycle all over again.

    Signs and Symptoms

    • According to the Centers for Disease Control and Prevention (CDC), infection with ascaris is usually asymptomatic. In a few people, high numbers of worms in the intestines may cause abdominal pain or discomfort. In children, infestation with the worms may stunt the child's growth. Some people exhibit respiratory difficulty, such as a cough or spitting up blood, when the worms break through the lungs. According to the CDC, ascaris is found worldwide; in the U.S. rural areas of the southeast are the most affected in the country.

    Testing

    • Laboratory diagnosis usually includes identifying the roundworm's eggs in fecal samples. The samples are collected and then fixed in formalin. The lab technician then views the sample under the microscope to see the eggs. In some cases, adult worms may be passed in feces, making identification of the parasites easier. Other times, the worms can be found in samples from the stomach or when they are coughed up.

    Experience Counts

    • Because diagnosis of ascaris infections depends so heavily on finding the eggs in a fecal sample through the use of a microscope, the experience of the laboratorian is key. Experienced lab technicians can differentiate between the eggs of ascaris and the eggs of other intestinal parasites. They can also identify the larvae or mature roundworms. Nevertheless, if the number of parasites is very low, the eggs may not be viewable in the sample.

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