What is the relationship between immunosuppression and Strongyloides (strongyloidiasis) infection?

From the Guidelines

Patients with strongyloidiasis who require immunosuppression should receive ivermectin treatment before starting immunosuppressive therapy to prevent potentially fatal hyperinfection syndrome, as recommended by the most recent guidelines 1. The recommended regimen is ivermectin 200 μg/kg orally once daily for 2 consecutive days, with repeat treatment after 2 weeks in cases of chronic strongyloidiasis. For patients already immunosuppressed with suspected strongyloidiasis, treatment should be extended to ivermectin daily for 5-7 days. Some key points to consider when managing strongyloidiasis in immunosuppressed patients include:

• Screening for strongyloidiasis is essential before initiating immunosuppression in patients from endemic areas (tropical and subtropical regions) or with risk factors such as rural residence, agricultural work, or walking barefoot.
• Serologic testing is preferred for screening due to its higher sensitivity compared to stool examination, as noted in the guidelines 1.
• The danger lies in the strongyloides parasite's unique autoinfection cycle, which can accelerate dramatically during immunosuppression, particularly with corticosteroids, leading to hyperinfection syndrome with mortality rates exceeding 60% 1. This condition involves massive parasite proliferation, widespread migration throughout the body, and potential gram-negative sepsis from intestinal bacteria carried by the migrating larvae. It is also important to note that immunosuppressive therapy can increase the risk of strongyloidiasis, and therefore, screening and treatment should be considered before starting immunosuppressive therapy, as suggested by the guidelines 1.

From the FDA Drug Label

In immunocompromised (including HIV-infected) patients being treated for intestinal strongyloidiasis, repeated courses of therapy may be required Adequate and well-controlled clinical studies have not been conducted in such patients to determine the optimal dosing regimen. Several treatments, i.e., at 2-week intervals, may be required, and cure may not be achievable. Control of extra-intestinal strongyloidiasis in these patients is difficult, and suppressive therapy, i.e., once per month, may be helpful.

Immunosuppression and Strongyloides: In immunocompromised patients, including those with HIV, repeated courses of ivermectin therapy may be required to treat intestinal strongyloidiasis. The optimal dosing regimen has not been established, and cure may not be achievable. Suppressive therapy may be necessary to control extra-intestinal strongyloidiasis in these patients 2.

• Key points:
  • Repeated courses of therapy may be required
  • Optimal dosing regimen not established
  • Cure may not be achievable
  • Suppressive therapy may be necessary
  • Difficulty in controlling extra-intestinal strongyloidiasis

From the Research

Immunosuppression and Strongyloides

• Immunosuppressed individuals are at a higher risk of developing life-threatening clinical syndromes associated with strongyloidiasis, such as hyperinfection syndrome (HS) or dissemination 3, 4.
• The risk of strongyloidiasis is particularly high in immunocompromised patients, especially those receiving chemotherapy or corticosteroid treatment 5.
• Strongyloidiasis can lead to severe disseminated disease in immunocompromised people, making it essential to screen for the infection before starting immunosuppressive therapies in patients from endemic areas 6.

Diagnosis and Treatment

• The diagnosis of strongyloidiasis can be challenging due to the low sensitivity of stool examination and the limited specificity of serology in high-prevalence populations 6.
• Ivermectin is the first-line treatment for strongyloidiasis, with an estimated efficacy of about 86% and excellent tolerability 7.
• Albendazole has a lower efficacy than ivermectin but can be used when ivermectin is not available or not recommended 7.
• Moxidectin might be a valid alternative to ivermectin, with the advantage of being a dose-independent formulation 7.

Management of Strongyloidiasis in Immunocompromised Patients

• Immunocompromised patients may require multiple doses of ivermectin, and repeated doses are recommended up to 2 weeks after clearance of larvae from biological fluids, with close monitoring and further dosing based on review 7.
• Subcutaneous ivermectin can be used in cases of impaired intestinal absorption or paralytic ileus 7.
• A risk-benefit assessment should be considered for each case when using ivermectin in pregnant or lactating women, as there is limited available data on its safety in these populations 7.