Strongyloidiasis
Strongyloidiasis is an intestinal infection caused by the parasitic nematode Strongyloides stercoralis. Strongyloidiasis is common in the wet tropics of South America. The complex parasite has a dual life cycle involving both parasitic and free living stages. Strongyloidiasis is typically acquired when the infective filariform larvae penetrate the skin during contact with contaminated soil, although ingestion of filariform larvae via the fecal-oral route can also result in infection. The larvae are transferred through the circulation to the lungs. From the lungs, they ascend to the glottis via the bronchi and are subsequently swallowed. In the duodenum and jejunum, the larvae burrow into the mucus membrane, where, after molting, the female worm produces eggs by parthenogenesis, which yields noninfective rhabditiform larvae. These larvae can be passed in the stool and become infective filariform larvae, or they can develop into adults in the external environment and produce rhabditiform larvae.Adult worms can survive and reproduce both in the small intestine of man and in the soil, giving rise to a variety of possible routes for infection. During direct development, adult eggs hatch in the intestine into rhabditiform larvae, which are passed in the stool.Under favourable conditions they mature in the soil into filariform (infective) larvae that are capable of penetrating the skin of humans.The rhabditiform larvae also have the ability to develop into free living adult worms that exist in the soil independently of humans--this is known as indirect development.
Once the infective larvae have penetrated the skin, they travel to the lungs via the circulatory system, where they migrate up the airways, reach the oesophagus, and are swallowed back down to the intestine where mating occurs, completing the cycle. Some rhabditiform larvae convert within the intestine to infectious filariform larvae that immediately reenter the bowel wall, short-circuiting the life cycle.Sometimes filariform larvae are passed in stool and reenter through the skin of the buttocks and thighs. Autoinfection can result in extremely high worm burdens (hyperinfection syndrome) and explains why strongyloidiasis persists for many decades. Hyperinfection usually occurs in patients taking corticosteroids or with impaired cell-mediated immunity, particularly those infected with the human T-lymphotropic virus 1 (HTLV-1). Hyperinfection may represent activation of a previously asymptomatic or newly acquired Strongyloides infection. However, disseminated strongyloidiasis is less common than might be predicted among patients with AIDS, even those living in areas where Strongyloides is highly endemic.
Causes of Strongyloidiasis
Common causes of Strongyloidiasis
- Parasitic nematode.
- Hyperinfection syndrome.
- Chimpanzees.
- Baboons.
- Hookworm.
- HIV-1 infection
- Corticosteroids.
- Diabetes mellitus.
- Neoplasms.
Symptoms of Strongyloidiasis
Common symptoms of Strongyloidiasis
- Abdominal pain.(upper pain)
- Vomiting.
- Diarrhea.
- Weight loss.
- Rash.
- Constipation.
- Anemia.
- Periodic appearance of red hive-like appearing lesions near the anus.
- Wheezing.
- Eosinophilia.
- Epigastric pain.
- Tenderness.
- Hemoptysis.
- Dyspnea.
- Fever.
- Confusion.
Treatment of Strongyloidiasis
Common Treatment of Strongyloidiasis
- Treatment is to eliminate the worms with anti-worm medications (anthelminthics) such as ivermectin or thiabendazole.
- Provide supportive treatment as indicated (eg, intravenous fluids if volume depletion, blood transfusion if gastrointestinal or alveolar hemorrhage, mechanical ventilation if respiratory failure).
- Perform surgery in patients with acute abdominal symptoms (peritonitis due to bowel perforation or infarction) in the context of severe strongyloidiasis.
- Administer anthelmintic therapy.
- The antihelminth drug thiabendazole was the only treatment available for many years.
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