infectious diseases
Strongyloidiasis
Pathophysiology of Strongyloidiasis
 adult worms live in the mucosa and submucosa of the duodenum and jejunum. Released eggs hatch in the bowel lumen, liberating rhabditiform larvae. Most of the larvae are excreted in the stool. After a few days in soil, they develop into infectious filariform larvae. Like Hookworm Infection , Some rhabditiform larvae convert within the intestine to infectious filariform larvae that immediately reenter the bowel wall, short-circuiting the life cycle (internal autoinfection). Sometimes filariform larvae are passed in stool; if the stool contaminates the skin (eg, of the buttocks or thighs), larvae can reenter through the skin (external autoinfection). Autoinfection explains why strongyloidiasis can persist for many decades and helps account for the extremely high worm burden in the hyperinfection syndrome and disseminated strongyloidiasis. Hyperinfection syndrome may result from a newly acquiredStrongyloidesinfection or from activation of a previously asymptomatic one. In either case, it can result in disseminated disease in which organs that are not usually part of the parasite’s normal life cycle (eg, central nervous system [CNS], skin, liver, heart) are affected. Hyperinfection typically occurs in people who have impaired Th2 type cell-mediated immunity including those taking corticosteroids or immunosuppressive biologics, receiving immunosuppressive therapy for solid organ or hematopoietic stem cell transplants, or infected with the human T-lymphotropic virus 1 (HTLV-1). Hyperinfection has also been associated with alcoholism and malnutrition. However, hyperinfection and disseminated strongyloidiasis are less common than might be predicted among patients with HIV/AIDS, even those living in areas whereStrongyloidesis highly endemic. Patients with undiagnosed strongyloidiasis may progress to hyperinfection or disseminated disease if corticosteroid therapy is initiated, including patients with COVID-19 receiving 1.Stauffer WM, Alpern JD, Walker PF: COVID-19 andDexamethasone: A potential strategy to avoid steroid-relatedStrongyloideshyperinfection.JAMA324(7):623-624, 2020. doi:10.1001/jama.2020.13170 