What is the recommended treatment for a patient with suspected strongyloidiasis, particularly those with a history of travel to tropical or subtropical regions or weakened immune systems, such as Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) or those taking immunosuppressive medications?

Treatment of Strongyloidiasis

First-Line Treatment

For uncomplicated strongyloidiasis, treat with ivermectin 200 μg/kg orally for 2 consecutive days, which achieves cure rates approaching 100% with excellent tolerability. 1, 2, 3

Standard Dosing Regimen

• Administer ivermectin 200 μg/kg orally on 2 consecutive days for immunocompetent patients 1, 2
• Take tablets on an empty stomach with water to optimize absorption 2
• The 2-day regimen achieves 100% cure rates compared to 77% with single-dose therapy 3

Dosing by Body Weight

• 15-24 kg: 1 tablet (3 mg) 2
• 25-35 kg: 2 tablets 2
• 36-50 kg: 3 tablets 2
• 51-65 kg: 4 tablets 2
• 66-79 kg: 5 tablets 2
• ≥80 kg: 200 μg/kg 2

Immunocompromised Patients

For immunocompromised patients, use ivermectin 200 μg/kg on days 1,2,15, and 16 to prevent treatment failure. 1

High-Risk Populations Requiring Extended Treatment

• Patients receiving corticosteroids, especially >20 mg prednisone daily 4
• Those on anti-TNF therapy, calcineurin inhibitors, or chemotherapy 4
• HIV/AIDS patients with CD4 counts <200 2
• HTLV-1 infected individuals 5, 6
• Organ transplant recipients 7

Critical Warning for Immunosuppressed Patients

• Never initiate corticosteroid therapy without first treating strongyloidiasis, as this precipitates potentially fatal hyperinfection syndrome 1, 4, 2
• Discontinue all immunosuppressive medications if hyperinfection syndrome develops 4
• Multiple treatment courses at 2-week intervals may be required, and cure may not be achievable in severely immunocompromised hosts 2
• Consider suppressive therapy (ivermectin once monthly) for patients who cannot achieve cure 2

Hyperinfection Syndrome Management

For hyperinfection syndrome, initiate parenteral ivermectin immediately and stop all immunosuppressive therapy if clinically feasible. 4

Recognition of Hyperinfection

• Suspect in any immunosuppressed patient from endemic areas presenting with pneumonia, gastrointestinal bleeding, sepsis, or meningitis 1, 4
• Note that severe hyperinfection may paradoxically lack eosinophilia despite 70% of cases showing elevated eosinophils 4
• Paralytic ileus, respiratory failure, and gram-negative sepsis are hallmark features 5, 7

Treatment Approach

• Administer ivermectin 200 μg/kg daily until clinical improvement, then continue for at least 2 weeks after parasite clearance 4, 2
• Use parenteral formulation if available, or consider rectal administration if oral route compromised 4
• Repeated courses may be necessary given high mortality rates 4, 2

Pre-Treatment Screening Requirements

Screen all patients from endemic areas (tropics, subtropics, Southeast Asia, Latin America, sub-Saharan Africa) before initiating immunosuppressive therapy. 8, 4

Screening Algorithm

• Obtain serological ELISA testing with recombinant antigens as primary diagnostic method (sensitivity >80%) 8
• Perform stool microscopy using concentration techniques on multiple samples, though sensitivity remains limited 8, 4
• Repeat testing 8-10 weeks after return from endemic areas if initial screening negative 8
• Consider empiric treatment for high-risk patients even without confirmed diagnosis given low test sensitivity 1, 4

Mandatory Screening Populations

• Long-term travelers (>1 month) returning from endemic areas 8
• Patients about to receive corticosteroids, chemotherapy, or other immunosuppression 1, 8
• Individuals with unexplained eosinophilia and appropriate exposure history 5, 8

Alternative Treatment Options

Albendazole 400 mg daily for 3 days is an alternative but significantly less effective option, with cure rates of only 38-63% compared to ivermectin's 77-100% 1, 9

When to Consider Albendazole

• Ivermectin contraindicated or unavailable 9
• Pregnancy (though safety data limited for both agents) 2
• Patient intolerance to ivermectin 9

Thiabendazole No Longer Recommended

• Thiabendazole 25 mg/kg twice daily for 3 days achieves only 78% cure rates 3
• Causes frequent gastrointestinal side effects (16% of patients) including asthenia, epigastralgia, and disorientation 3, 9
• Ivermectin demonstrates superior tolerability with fewer adverse events (RR 0.31,95% CI 0.20-0.50) 9

Post-Treatment Monitoring

Perform repeated stool examinations to document parasite clearance, though sensitivity remains poor even with multiple specimens 4, 2

Follow-Up Protocol

• Examine three stool samples collected on alternate days beginning 2 weeks after treatment completion 2, 3
• Persistent eosinophilia after treatment correlates with treatment failure (77% not-cure rate) 3
• Repeat treatment if larvae detected or eosinophilia persists 3
• For immunocompromised patients, continue monitoring for months as relapse common 2, 10

Clinical Manifestations to Recognize

Larva Currens

• Itchy, linear, urticarial rash that moves 5-10 cm per hour around trunk, upper legs, and buttocks 5, 1
• Pathognomonic for strongyloidiasis and indicates active infection 5

Löffler's Syndrome

• Fever, urticaria, wheezing, dry cough, and migratory pulmonary infiltrates from larval lung migration 5, 8
• Occurs days to weeks after initial infection 5
• Larvae may be detected in sputum or bronchoalveolar lavage, though rare 8

Gastrointestinal Symptoms

• Nonspecific abdominal pain, diarrhea, bloating, or constipation 5, 7
• Many patients remain asymptomatic for decades 7

Critical Pitfalls to Avoid

• Do not rely on single-dose ivermectin in immunocompromised patients—this has resulted in fatal relapses 4
• Do not exclude loiasis before treatment if patient has traveled to West or Central Africa, as co-infection can cause severe encephalopathy with ivermectin 5, 2
• Do not assume negative stool microscopy excludes strongyloidiasis—sensitivity is poor even with multiple specimens 8
• Do not wait for diagnostic confirmation before treating high-risk patients about to receive immunosuppression 1, 4