Step 1: Define risk category for disseminated strongyloidiasis based on epidemiologic and clinical factors.

Epidemiologic risk category for Strongyloides exposure/Infection	Clinical risk factors for disseminated Strongyloides
	• HTLV-11 infection • Glucocorticoid2 therapy • Immunomodulatory agent3 • Hematologic malignancy	• No known defects in cell-mediated immunity
Birth or residence or long-term travel4 in Southeast Asia, Oceania, Sub-Saharan Africa, South America, Caribbean	High	Moderate
Birth or residence or long-term travel4 in Mediterranean countries, Middle East, North Africa, Indian sub-continent, Asia	Moderate	Low
Birth or residence or long-term travel4 in Australia, North America5 or Western Europe	Very low	Very low

¹ HTLV-1 = Human T-lymphotropic virus

² Equivalent to 20 mg/day of prednisone for ≥2 weeks.

³ Includes: alkylating agents, antimetabolites, immunosuppressive or immunomodulatory agents used in the management of solid-organ transplant and multiple sclerosis, tumor necrosis factor (TNF), Interleokin 1 (IL-1) and adhesion blocking agents, lymphocyte depleting agents.

⁴ Defined as cumulative six-month exposure in rural or beach areas, or contact of skin with sand or soil in a risk area even during shorter-term travel (8-10). If significant re-exposure accumulates, consider re-screening if initially negative.

⁵ Areas of North America that may be higher than low risk include Florida, Kentucky and Virginia. Aboriginal Australians are at elevated risk of strongyloidiasis.