Strongyloidesis a disease caused by the intestinal roundworm, or nematode, Strongyloides. Over 40 species of Strongyloides exist that can infect birds, livestock, and other animals, but the S. stercoralis species causes most Strongyloides infections in humans.
Strongyloides can be most commonly in the tropics, subtropics, and warm temperate regions. The disease is also more common in rural areas and among institutionalized populations. The Center for Disease Control& Prevention (CDC&P) estimates that between 30 and 100 million people are infected worldwide. The disease is rare in the United States but can be found in the southeastern states.
Here are some of the most commonly asked questions about the diagnosis, treatment, and prevention of Strongyloides.
- How do you get Strongyloides? People contract Strongyloides when their skin comes into contact with soil contaminated with roundworm larvae. Young Strongyloides worms are invisible to the naked eye and can pass through a person’s skin into the bloodstream to the lungs and throat; from the throat, they are then swallowed into the stomach and move into the small intestine, where they attach to the intestinal walls. Roundworm eggs are then passed through the stool.Because Strongyloides is contracted from the soil, several activities increase a person’s chance of getting the disease. Risk factors for Strongyloides include walking with bare feet in contaminated areas, farming, coal mining, and engaging in activities that bring you into contact with human waste or sewage. People with weakened immune systems are also at higher risk of contracting Strongyloides and of developing a more serious case of the disease; people with Human T-Cell Lymphotropic Virus-1 (HTLV-1) have been found to be particularly liable to Strongyloides infection.
- What are the symptoms of Strongyloides? In around 50% of cases, strongyloidiasis causes no symptoms. If Strongyloides symptoms appear at all, they will include abdominal pain (particularly in the upper abdomen), diarrhea, vomiting, weight loss, cough, and rash. In rarer cases, life-threatening forms of the disease called hyperinfection syndrome and disseminated strongyloidiasis can occur; in such cases, people will become critically ill and should go to the hospital immediately. As mentioned previously, these severe cases are more common in people with suppressed immune systems.
- How is Strongyloides infection diagnosed? The most common way to diagnose Strongyloides infection is with a stool sample, which is then examined under a microscope to detect roundworm larvae. Blood tests can also be used to detect Strongyloides antigens. In some cases, a duodemal aspiration will be conducted, in which a small amount of tissue from the small intestine is removed and tested for larvae.
- How is Strongyloides infection typically treated? Strongyloides treatment centers on oral de-worming medications, including Ivermectin and Albendazole. The dosage and duration of treatment will depend on the severity of the Strongyloides infection. People with hyperinfection syndrome and disseminated strongyloidiasis will often require several rounds of treatment. After treatment, a follow-up stool sample should be collected within 2-4 weeks to ensure that the infection has cleared.
- How can I prevent Strongyloides infection? Practicing good personal hygiene is the best way to prevent Strongyloides infection. Always wash your hands thoroughly with warm water and soap after using the toilet or changing a diaper. Properly dispose of waste and sewage, and wear shoes when walking in soil.
- What are the different types of Strongyloides tests? Standard serial stool examinations are often the first line of diagnostic testing; however, these can be insensitive and require multiple tests. Serologic testing for Strongyloides uses enzyme-linked immunosorbent assays (ELISA) like the IVD Strongyloides Serum Antibody Detection Microwell ELISA test kit.
Center for Disease Control (CDC). “Parasites – Strongyloides.” Available at
Medline Plus. “Strongyloides Fact Sheet.” Available at