Methotrexate exposure and risk of strongyloidiasis

Rheumatologic disease patients receiving immunomodulating drugs such as methotrexate (MTX) have increased infection rates. Strongyloides, a global endemic intestinal parasite, can cause significant or fatal disease in immunocompromised patients. The risk of serious Strongyloides infection with MTX dosed for rheumatologic disease is unknown.

We performed a systematic literature review searching EMBASE, Medline and Web of Science databases. All studies reporting humans exposed to MTX and tested for Strongyloides were reviewed. Exclusion criteria were bone marrow transplantation, intrathecal route and MTX exposure completed >1 year prior to clinically apparent Strongyloides disease.

After excluding duplicates, 294 articles were reviewed. Of these, 29 cases were described in 27 papers. Twenty cases (69%) had an underlying rheumatologic or dermatologic disease, the rest had a haematologic disease. Hyperinfection or dissemination was found in 59% of cases (52% low-dose MTX; 75% high-dose MTX). Death occurred in 34% of cases (19% low-dose MTX; 75% high-dose MTX, P < 0.01). All eight patients on high-dose MTX received other immunosuppressants. Corticosteroids were taken in 18/21 patients on low-dose MTX. One of the three patients on MTX monotherapy had hyperinfection syndrome. None had disseminated Strongyloides.

Serious Strongyloides infection can occur with low-dose MTX particularly when given with other immunosuppression. Global travel and greater awareness of rheumatologic conditions in low- to middle-income countries will increase the exposure of individuals prescribed MTX (with or without corticosteroids) to Strongyloides. Strongyloides screening and treatment should be considered for individuals receiving low-dose MTX therapy, particularly if combined with additional immunosuppression.