Strongyloidiasis
Strongyloidiasis is an infectious disease caused by the parasitic worm Strongyloides stercoralis, primarily affecting the gastrointestinal tract, skin, and lungs, but potentially impacting other organs as well. The worm thrives in soil found in tropical and subtropical regions, including parts of the southeastern United States, Europe, Australia, and Japan. Infection typically occurs when individuals walk barefoot on soil contaminated with feces, allowing larvae to penetrate the skin and migrate through the body. Although many infected individuals remain asymptomatic, those with weakened immune systems may experience severe complications, including infections of vital organs.
Diagnosis involves identifying larvae in stool samples or detecting specific antibodies in the blood. Mild cases are usually treated with medications like ivermectin or albendazole, while those with more severe or disseminated infections may require additional antibacterial treatments. Prevention strategies emphasize the importance of wearing protective footwear in endemic areas and screening at-risk individuals, particularly before immunosuppressive therapies are initiated. Overall, while effective treatments exist, the prognosis for individuals with disseminated infections can be grave, highlighting the importance of awareness and preventive measures in affected communities.
Strongyloidiasis
- ANATOMY OR SYSTEM AFFECTED: All (primarily gastrointestinal tract, skin, and lungs, but can disseminate to other organs)
Definition
Strongyloidiasis is a disease caused by the worm Strongyloides stercoralis. This worm species lives in the soil of tropical and subtropical regions, the southeastern United States, and parts of Europe, Australia, and Japan. Many people from endemic areas are chronically infected.
Causes
Larvae infect people who walk barefoot on fecal-contaminated soil. The larvae migrate to the small intestine, invade blood vessels, and migrate to the lungs, where they are swallowed. Adult worms attach to the small intestine, producing larvae that pass into the stool.
Risk Factors
Recreational and occupational activities expose people to fecal-contaminated soil in endemic areas, increasing the risk of strongyloidiasis. In temperate climates, strongyloidiasis is more common among alcoholics, Caucasians, males, and people of low socioeconomic status. Cancer, impaired bowel activity, being immunocompromised, low stomach acid content, diabetes mellitus, and medications that weaken the immune system predispose persons to severe infection.
Symptoms
Most people with strongyloidiasis do not have symptoms of infection. After larvae enter the skin, a local skin reaction may develop. Cough and breathing problems occur after several days if larvae migrate to the lungs. Abdominal pain, nausea, and diarrhea occur after several weeks if larvae are swallowed. People with weakened immune systems may develop an infection of the brain, lungs, heart, kidneys, or liver.
Screening and Diagnosis
Larvae can be seen in stool under the microscope or by smearing stool onto culture media. People with strongyloidiasis have positive antibodies against Strongyloides even if the stool examination is negative. People with weakened immune systems may have noticeable changes on their chest X-rays. Bronchoscopy, in which a fiber optic scope is inserted into the airways, can obtain specimens for culture that identify Strongyloides on special growth media.
Treatment and Therapy
Mild Strongyloides infection is treated with ivermectin, albendazole, or thiabendazole. Antibacterial drugs are also used to treat people with weakened immune systems and disseminated infections. After treatment, stool should be examined for larvae to ensure eradication. Despite treatment, many people with disseminated infections die.
Prevention and Outcomes
People who live in endemic areas should wear proper footwear when walking on fecal-contaminated soil. People with risk factors for developing strongyloidiasis should be screened with antibody testing before starting medications that weaken the immune system.
Bibliography
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Keiser, Paul, and Thomas Nutman. "Strongyloides stercoralis in the Immunocompromised Population." Clinical Microbiology Reviews, vol. 17, no. 1, Jan. 2004, pp. 208-217.
Lam, C. S. "Disseminated Strongyloidiasis: A Retrospective Study of Clinical Course and Outcome." European Journal of Clinical Microbiology and Infectious Diseases, vol. 25, no. 1, Jan. 2006, pp. 14-18.
Maguire, James. "Intestinal Nematodes (Roundworms)." Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John F. Bennett, and Raphael Dolin. 7th ed., Churchill Livingstone/Elsevier, 2010.
Seladi-Schulman, Jill, and Jacquelyn Cafasso. "Strongyloidiasis." Healthline, 31 July 2018, www.healthline.com/health/strongyloidiasis. Accessed 30 Oct. 2024.
"Strongyloidiasis." Cleveland Clinic, 2 Feb. 2023, my.clevelandclinic.org/health/diseases/14074-strongyloidiasis. Accessed 30 Oct. 2024.
"Symptoms of Strongyloidiasis." CDC, 16 Feb. 2024, www.cdc.gov/strongyloides/symptoms/index.html. Accessed 30 Oct. 2024.
Weller, P. F., and T. B. Nutman. "Intestinal Nematodes." Harrison’s Principles of Internal Medicine, edited by Joan Butterton. 17th ed., McGraw-Hill, 2008.