What is the treatment for Endolimax nana cysts and trophozites?

Treatment for Endolimax nana Cysts and Trophozoites

Metronidazole at a dose of 2 g/day for 10 days is the recommended treatment for Endolimax nana infections causing symptoms. 1

Understanding Endolimax nana

Endolimax nana is a commensal protozoan typically found in the human colon. While often considered non-pathogenic, it can cause clinical symptoms in some cases, particularly in immunocompetent individuals:

• Common symptoms include:
  • Chronic diarrhea
  • Abdominal pain
  • Weight loss
  • Flatulence
  • Nausea
  • Anorexia

Diagnostic Considerations

Before initiating treatment, confirm the diagnosis through:

• Multiple stool examinations (at least three) to identify cysts or trophozoites
• Rule out co-infections with other parasites such as Blastocystis hominis, which commonly co-occurs with E. nana 2

Treatment Algorithm

1. First-line treatment:

   • Metronidazole 2 g/day divided into doses for 10 days 1

2. Alternative regimens:

   • Albendazole 400 mg twice daily (800 mg/day) with meals for 3-5 days 3
   • Ivermectin 200 μg/kg as a single dose (may be more effective in some cases) 3

3. For persistent infections:

   • Consider a second course of metronidazole after a brief interval 1
   • Alternatively, switch to albendazole if metronidazole was used initially

Monitoring and Follow-up

• Perform follow-up stool examinations 2-4 weeks after completing therapy
• At least three negative stool samples indicate successful eradication
• Monitor for resolution of clinical symptoms
• If using albendazole for more than 14 days, monitor for hepatotoxicity and leukopenia 4

Special Considerations

• In immunocompromised patients, more aggressive or prolonged therapy may be required
• When treating with albendazole, administer with food to improve absorption 3
• For patients with persistent symptoms despite negative follow-up stool examinations, consider alternative diagnoses

Treatment Efficacy

Case reports have demonstrated successful eradication of E. nana and resolution of symptoms following metronidazole treatment 1, 2. In a documented case, a patient with chronic urticaria, abdominal pain, and diarrhea associated with E. nana infection experienced complete symptom resolution after two courses of metronidazole (2 g/day for 10 days each) 1.

Clinical Pearls

• E. nana is often overlooked as a potential cause of gastrointestinal symptoms
• Multiple stool samples increase the likelihood of detecting the parasite
• Consider treatment when symptoms are present and other causes have been ruled out
• Co-infection with other intestinal parasites is common and may require broader antiparasitic therapy

While E. nana is traditionally considered non-pathogenic, mounting evidence suggests it can cause clinical symptoms in both immunocompetent and immunocompromised individuals, warranting appropriate treatment when identified in symptomatic patients.