Strongyloides stercoralis infection complicating the central nervous system.

Strongyloides stercoralis is a nematode endemic in humid tropical regions. The life cycle of this parasite is complex and unique due to its capacity to cause autoinfection, resulting in chronic infections. Innate and adaptive immune responses are responsible for clearing the parasite. Many risk factors have been described, but the most important is living in or having visited an endemic area. The clinical presentation of strongyloidiasis is varied and ranges from asymptomatic chronic infection to hyperinfection syndrome. Hyperinfection syndrome is more common in patients with immunosuppresion due to therapy with corticosteroids, coinfection with human T-lymphotropic virus type I (HTLV-1), transplant patients, or patients receiving chemotherapy. Multiplication and migration of large parasite numbers cause worsening of the initial symptoms and leads to a high mortality rate. CNS involvement in strongyloidiasis has only been seen in patients with hyperinfection syndrome. Meningitis is the most common form of CNS involvement and gram-negative bacteria are the more frequent etiology. Repeated stool samples with concentration methods have a good sensitivity and specificity. In patients that are not from endemic areas serum antibody tests may be useful in the diagnosis. Treatment with a single dose of ivermectin is recommended for most patients. In severe or hyperinfection cases repeated doses may be needed.