Approach

The goal of therapy is to eradicate all organisms. Presumptive treatment of the disease is required in immigrants from endemic areas who have unexplained eosinophilia or who require immunosuppressive therapy as part of the treatment of another condition. Otherwise, treatment is only given once the diagnosis is established. All diagnosed patients should be treated, including those who are asymptomatic, due to the risk of hyperinfection.[1]

Standard precautions (e.g., wearing gloves and gowns, hand hygiene) are recommended in hospitalized patients.

Presumptive treatment in immigrants from endemic areas

When unexplained eosinophilia is detected in any person who has migrated from an endemic area, screening for strongyloides infection is required. In the US, asymptomatic refugees who did not receive overseas presumptive ivermectin therapy for strongyloides may be presumptively treated upon arrival, or screened (using strongyloides IgG serology) if there are contraindications to presumptive treatment (e.g., concomitant Loa loa infection) or if ivermectin is unavailable.[37] Stool ova and parasite exam should not be used to rule out infection as it lacks sensitivity for Strongyloides infection. Refugees who have lived in Loa loa-endemic countries should be tested for Loa loa microfilariae before being treated with ivermectin in order to prevent complications including encephalopathy. Presumptive treatment for pregnant women is not recommended.[37]

Risk of life-threatening hyperinfection is primarily related to immunosuppression, particularly the iatrogenic introduction of corticosteroid (or other immunosuppressive) therapy for a comorbid disorder.[20][21]  Empiric treatment with ivermectin is most likely necessary with iatrogenic immunosuppression, although serologic screening for infection can be pursued if time allows before immunosuppression commences. Presumptive treatment with ivermectin is recommended for people who have migrated from endemic areas and who require urgent corticosteroids for acute conditions (e.g., asthma), especially in the presence of eosinophilia.[11]

For planned future immunosuppression, such as anticipated organ or bone marrow transplantation, screening should be performed as part of the pretransplant evaluation.

Initial therapy for confirmed infection

Ivermectin is considered the treatment of choice (regardless of resource setting) due to superior efficacy over albendazole.[1][38] [ Cochrane Clinical Answers logo ] [Evidence B]​​ A single dose of ivermectin is approximately 85% to 90% effective.[39][40][41] Two doses are approximately 85% to 95% effective.[42][43][44][45][46] Albendazole is considered a suitable alternative if ivermectin is not available, although the efficacy compared with ivermectin is very low.[1] Thiabendazole is also recommended in countries where it is available, but it has a high rate of nausea (thiabendazole is no longer available in the US). Moxidectin is another possible alternative that has been approved in the US for onchocerciasis by the US Food and Drug Administration (FDA). It has a long history of use in veterinary medicine and may be used off-label for strongyloides. Moxidectin had a 94% cure rate for strongyloides in one randomized trial, which was similar to the 95% cure rate of ivermectin.[47] As it has a long half life in tissue, a single dose is effective. It has not been studied in children aged <12 years. If ivermectin is unavailable, moxidectin may be the preferred alternative as albendazole is clearly inferior to ivermectin.

Anthelmintics are most effective against adult worms and are not very effective against migrating larvae. Thus, repeated therapy may be necessary to eradicate any residual strongyloides adults that have developed from migrating larvae in the interim.

Various treatment regimens exist and local guidance should be consulted. The US Centers for Disease Control and Prevention (CDC) recommends 1-2 doses of ivermectin administered on consecutive days.[36]​ However, some regimens recommend the second dose to be given 2 weeks after the first dose, regardless. The efficacy of one dose of ivermectin has been directly compared with two doses separated by 2 weeks in a randomized trial without any difference found.[46]

Ivermectin may very rarely precipitate encephalitis in people who have concomitant heavy infection with Loa loa, due to the mass killing of microfilariae in the central nervous system. This is becoming more of a theoretical concern due to the success of the ongoing river blindness (onchocerciasis) eradication programs led by the Carter Center, which use ivermectin. However, should current eradication programs break down (e.g., in situations such as long-term war), people should then be screened for filariasis by blood smear collected between 10 a.m. and 2 p.m., before receiving ivermectin.[28]

In critically ill people with hyperinfection or disseminated strongyloidiasis unable to take oral medications, ivermectin has been administered successfully by subcutaneous, intravenous, or rectal routes. No FDA-approved formulations for these routes of administration are available for any of the strongyloides therapy options. However, veterinary formulations of ivermectin are available for subcutaneous, intravenous, and rectal use, and have been used successfully in life-threatening hyperinfection. For critically ill people, ivermectin is given daily for a duration of 7-14 days. Alternatively, ivermectin and albendazole have been administered together for this indication.[48] Involvement of a tropical medicine specialist is recommended.

If the patient is pregnant, the risks and benefits of treatment should be carefully considered. In chronic strongyloides infection, deferring treatment until after pregnancy is reasonable; however, in hyperinfection or disseminated strongyloidiasis, therapy should be given immediately. Data on ivermectin and albendazole use in pregnancy is sparse, but no increased teratogenicity has been reported with inadvertent use in the first trimester during lymphatic filariasis eradication programs.[49] Specialist advice should be sought if corticosteroids are required to accelerate fetal lung development. Treatment should be supervised by a tropical medicine specialist.

Children are treated with the same medications as adults. The safety of ivermectin in children who weigh <15 kg has not been determined; however, mass prevention campaigns recommend its use in children who are ≥90 cm tall, and in children aged <3 years at a reduced dose. Albendazole has been used in children as young as 1 year old in mass prevention campaigns.[36]​ Generally, children tolerate treatment better than adults. Of note, these drugs are unavailable as a suspension or syrup but tablets can be crushed.

Poor response to initial therapy

People not completing a treatment course, whether due to intolerance, noncompliance, or other reasons, should be given retreatment. Two doses of ivermectin are generally well-tolerated.

Treatment failure is the most probable cause of eosinophilia persisting beyond 4-6 months after treatment.[11][33] Persistent eosinophilia requires retreatment with ivermectin and consideration of screening for human T-cell lymphotropic virus type-1 (HTLV-1) infection.[23] In immunosuppressed people, such as those with HTLV-1 infection or HIV/AIDS, multiple 14-day treatment courses may be necessary, separated by 2-week intervals. Follow-up stool ova and parasite exams verify eradication of strongyloides at 3 and 6 months. Alternatively, serology could be followed.[50] In 65% to 80% of people, the quantitative serology will decrease by 40% or become negative after 6 months.[51] Less than 40% decrease in quantitative serology after 6 months, or an increase in titer, prompts retreatment.[52]

Use of this content is subject to our disclaimer