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What is Giardiasis?

Giardiasis is an infection caused by the parasite Giardia lamblia. You can develop giardiasis from being exposed to infected people or animals and by consuming contaminated food or water.

The condition is more common in overcrowded developing countries with poor sanitation and a lack of clean drinking water.


Giardiasis is caused by a parasite. You may become infected with giardiasis if you:

  • Drink water from untreated water sources such as lakes, streams, or wells
  • Eat undercooked or raw food that is contaminated with giardiasis
  • Are exposed to someone with giardiasis
  • Travel to places where giardiasis is common
  • Touch contaminated surfaces such as changing tables, bathroom handles, or toys, and then eat without washing your hands.


Symptoms usually show up 1 or 2 weeks after exposure. Some of the common symptoms include:

  • Diarrhea
  • Greasy stools
  • Fatigue
  • Nausea
  • Loss of appetite
  • Vomiting
  • Bloating and abdominal cramps
  • Excessive gas
  • Headaches
  • Weight loss
  • Pain in the abdomen


Your doctor diagnoses giardiasis by testing stool samples. Procedures such as enteroscopy, or visualization of the bowel with a scope, may be performed to examine your digestive tract and collect tissue samples for further analysis.


Giardiasis may not require any treatment if there are mild or absent symptoms and may go away on its own. However, anti-parasitic drugs may be recommended by some doctors. For severe symptoms or for prolonged cases your doctor may prescribe antibiotics. Side-effects of antibiotics can include nausea, a metallic taste in the mouth, and reaction to alcohol. For pregnant women, treatment should not be started until after delivery as the drugs are not safe for an unborn child.


You can prevent giardiasis by:

  • Purifying all pond, stream, lake, well, or river water before drinking. You can purify water by boiling, treating it with iodine, or filtering
  • Daycare workers or workers in institutions should follow good hygiene practices such as washing hands frequently
  • Practicing safe sex such as using condoms
  • Wash or peeling fresh fruits and vegetables before eating