Entamoeba histolytica Antigen, Stool (EHAS)

Price: 15 د.ا

The EHAS test is a non-invasive laboratory assay designed to detect Entamoeba histolytica antigens in stool samples. E. histolytica causes amoebiasis, an intestinal infection that can, in severe cases, spread to the liver, lungs, or brain.

How It Works

• Antigen Detection: Uses specific antibodies to capture parasite-derived proteins (antigens) present in the stool.
• Sample Processing: A fresh stool specimen is collected and analyzed via enzyme-linked immunosorbent assay (ELISA) or rapid immunochromatographic methods.
• Interpretation:
  • Negative: No detectable E. histolytica antigen; infection unlikely.
  • Positive: Antigen detected; confirms active infection.

Clinical Presentation

• Intestinal Amoebiasis
  • Watery or bloody diarrhea
  • Abdominal pain and cramping
  • Fever and malaise
• Extraintestinal Spread (in complicated cases)
  • Amebic liver abscess
  • Pulmonary or cerebral involvement

Indications for Testing

• Persistent or recurrent diarrhea
• Presence of blood in stool
• Travel to or residence in endemic areas
• Unexplained fever with hepatic symptoms

Diagnostic Comparison

Method	Sensitivity	Specificity	Notes
Microscopy	60%–80%	80%–90%	Operator-dependent; cannot distinguish species
EHAS (ELISA)	95%–99%	>95%	High accuracy; detects active infection
Serology	Variable	Variable	May reflect past exposure; not species-specific

Treatment & Prevention

• First-Line Therapy: Metronidazole or tinidazole to eradicate the parasite.
• Prevention:
  • Drink treated or boiled water
  • Practice strict hand hygiene
  • Thoroughly wash and cook food

Frequently Asked Questions

1. How does EHAS compare to stool microscopy?
   EHAS (ELISA) is more sensitive and specific, detecting low-level or chronic infections that microscopy may miss.
2. Can EHAS detect asymptomatic carriers?
   Yes—because it identifies parasite antigens, it can pick up infections even without overt symptoms.
3. Is the test species-specific?
   Yes—EHAS targets Entamoeba histolytica antigens and does not cross-react with non-pathogenic Entamoeba species.
4. Do I need any special preparation before the test?
   No dietary or medication restrictions are required; simply provide a fresh stool sample.
5. When should the test be repeated after treatment?
   A follow-up EHAS is recommended 2–4 weeks post-therapy to confirm parasite clearance.

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