What is the recommended treatment for intestinal parasites?

Treatment of Intestinal Parasites

The recommended treatment for intestinal parasites depends on the specific parasite identified, with albendazole 400 mg as a single dose being the most broadly effective first-line agent for common intestinal nematodes including hookworm, ascariasis, and pinworm. 1

Common Intestinal Nematodes

Hookworm (Ancylostoma duodenale/Necator americanus)

• Albendazole 400 mg orally daily for 3 days is the recommended treatment 1, 2
• Alternative regimens include mebendazole 500 mg as a single dose, mebendazole 100 mg twice daily for 3 days, or ivermectin 200 μg/kg as a single dose 2
• For patients with prolonged exposure in endemic areas and negative stool tests, treat empirically with albendazole 400 mg plus ivermectin 200 μg/kg as a single dose due to high false-negative rates 2
• Address iron-deficiency anemia with iron supplementation in heavy infections, as hookworm causes significant blood loss 2, 3
• In areas with documented mebendazole resistance, use ivermectin 200 μg/kg as a single dose 2

Ascaris lumbricoides (Roundworm)

• First-line treatment options include albendazole 400 mg, mebendazole 500 mg, or ivermectin 200 μg/kg, all as a single oral dose 4
• All three regimens show comparable efficacy for uncomplicated ascariasis 4
• Monitor for intestinal or biliary obstruction, which may require surgical intervention in addition to anthelmintic therapy 4

Enterobius vermicularis (Pinworm/Threadworm)

• Albendazole 400 mg as a single dose is recommended 1
• Alternative: mebendazole 100 mg as a single dose 1
• Repeat treatment in 2 weeks to address auto-reinfection 1
• Treat all household contacts simultaneously to prevent reinfection 1

Trichuris trichiura (Whipworm)

• Mebendazole 100 mg twice daily for 3 days in combination with ivermectin 200 μg/kg once daily for 3 days is recommended 1
• Combination therapy is superior to monotherapy, particularly in heavy infections where single-agent cure rates are low 1

Strongyloides stercoralis (Threadworm)

• Ivermectin 200 μg/kg daily for 2 days is the treatment of choice 5
• Ivermectin shows 64-100% cure rates and is significantly more effective than albendazole 5
• At least three stool examinations should be conducted over three months following treatment to ensure eradication, as recrudescence can occur up to 106 days post-treatment 5
• Use concentration techniques (Baermann apparatus) for follow-up stool examinations due to low larval counts 5

Intestinal Cestodes (Tapeworms)

Taenia species (Beef/Pork Tapeworm)

• Praziquantel 5-10 mg/kg as a single dose is the standard treatment 1
• Consider cysticercosis serology if the infecting species is T. solium, as neurocysticercosis may coexist and requires treatment with steroids and albendazole 1

Hymenolepis nana (Dwarf Tapeworm)

• Praziquantel 25 mg/kg as a single dose is recommended (higher dose than for other tapeworms) 1
• Alternative: niclosamide 2 g once daily for 7 days 1

Intestinal Protozoa

Giardia lamblia

• Metronidazole is the treatment of choice for giardiasis 6, 3
• Albendazole 400 mg daily for 5 days shows 95% cure rates and may be used as an alternative, particularly when treating concurrent helminth infections 7
• Single-dose albendazole (600-800 mg) shows moderate efficacy (62-75%) and may be useful in mass treatment programs 7

Entamoeba histolytica

• Metronidazole is indicated for treatment of acute intestinal amebiasis (amebic dysentery) and amebic liver abscess 6
• Therapy does not obviate the need for aspiration or drainage of pus in liver abscess 6
• Use both luminal and tissue amebicides to attack both life-cycle stages 3

Cystoisospora belli (formerly Isospora belli)

• Trimethoprim-sulfamethoxazole 960 mg twice daily for 7 days is recommended for prolonged symptoms or immunocompromised patients 1
• Immunocompetent individuals with symptoms resolving within 5 days require only supportive care 1

Special Situations

Trichinellosis (Trichinella species)

• Albendazole 400 mg once daily for 3 days in mild disease 1
• In severe disease with myositis, facial edema, or systemic complications: albendazole 400 mg twice daily for 21 days with prednisolone 40-60 mg once daily 1
• Seek specialist advice; intensive care management may be needed for severe presentations 1

Cutaneous Larva Migrans

• Ivermectin 200 μg/kg as a single oral dose is the treatment of choice 2
• Alternative: albendazole 400 mg once daily for 3 days 2
• Topical corticosteroids or systemic antihistamines may be used for symptomatic relief in severe pruritus 1

Gnathostomiasis

• Ivermectin 200 μg/kg daily for 2 days is recommended 1
• Alternative: albendazole 400 mg twice daily for 21 days 1
• Treatment may need to be repeated; monitor for relapse 1

Critical Pitfalls and Caveats

Drug resistance is emerging in hookworms, Trichuris trichiura, possibly Ascaris lumbricoides, and Giardia species 8. In areas with documented resistance, switch to alternative agents as outlined above.

Prolonged albendazole use (>14-28 days) carries risk of liver toxicity and myelosuppression 8. Monitor liver function and complete blood count when extended treatment courses are necessary 1.

Microsporidia treatment varies by species: albendazole is effective for Encephalitozoon intestinalis but not Enterocytozoon bieneusi 1. Nitazoxanide may be used for E. bieneusi in HIV-infected adults 1.

In mixed aerobic and anaerobic infections, antimicrobials appropriate for aerobic pathogens should be used in addition to metronidazole for anaerobic coverage 6.