What is the recommended treatment regimen for filariasis using Diethylcarbazine (DEC)?

Diethylcarbamazine (DEC) Treatment Regimen for Lymphatic Filariasis

For lymphatic filariasis, diethylcarbamazine (DEC) should be administered at 6 mg/kg in 3 divided doses daily for 14 days, plus doxycycline 200 mg daily for 6 weeks. 1

Pre-Treatment Evaluation

Before initiating DEC therapy, it is essential to:

• Rule out co-infections:

  • Exclude onchocerciasis and loiasis if the patient has traveled to co-endemic areas 1, 2
  • Perform skin snips and slit lamp examination to rule out onchocerciasis 2
  • Determine Loa loa microfilarial load if applicable 2

• Assess microfilarial load:

  • Nocturnal blood microscopy (10 pm to 2 am) using 4x citrated blood bottles (20 ml total volume, not refrigerated) 1

Treatment Algorithm Based on Microfilarial Load

For patients with no microfilariae detected:

• DEC can be given without steroid cover 1
• Standard DEC regimen can be initiated

For patients with microfilariae >1000/ml:

1. Screen for strongyloidiasis first 1
2. Start prednisolone for steroid cover 1
3. Administer albendazole 200 mg twice daily for 21 days 1
4. Check day blood microscopy at day 28 1
5. Repeat albendazole course as needed until microfilarial level <1000/ml 1
6. Then initiate DEC with prednisolone cover 1

Standard DEC Regimen

The recommended escalating DEC dosing schedule is:

• Day 1: 50 mg single dose
• Day 2: 50 mg three times a day
• Day 3: 100 mg three times a day
• Day 4: 200 mg three times a day
• Days 5-21: Continue 200 mg three times a day 1

Alternative Regimen

For areas where a simplified regimen is needed, the following is recommended:

• DEC 6 mg/kg in 3 divided doses daily for 14 days 1
• Plus doxycycline 200 mg daily for 6 weeks 1

Follow-up Monitoring

• Repeat day blood examinations at 6 and 12 months after the last negative sample to monitor for relapse 1
• Monitor for adverse reactions during treatment, including fever, headache, myalgia, and pruritus 2
• Severe reactions such as encephalopathy may occur in patients with high microfilarial loads 2

Special Considerations

• Contraindications: DEC is contraindicated in patients with onchocerciasis due to risk of severe reactions, including blindness 2

• Alternative treatments for patients with contraindications:

  • Ivermectin 150-200 μg/kg plus albendazole 400 mg 2

• For co-infections:

  • In cases of onchocerciasis or loiasis co-infection, seek expert advice 1
  • For patients with high Loa loa microfilarial loads (>8000/ml), albendazole with corticosteroid coverage is preferred over DEC due to risk of encephalopathy 2

While multi-dose DEC/albendazole combinations have shown greater efficacy in clearing microfilaremia compared to single-dose regimens (99.6% vs 85.7% reduction) 3, the current guidelines still recommend the standard 14-day DEC regimen with doxycycline for optimal treatment of lymphatic filariasis.