Giardiasis, also known as beaver fever in layman terms is a chronic intestinal infection that is caused by the flagellate protozoan Giardia lamblia, or Giardia duodenalis or Giardia intestinalis. Mostly causing acute diarrhoeal illness, the infection is commonly seen in children and quite often leads to epidemics. Also Read: Diarrhoea: Causes, Symptoms and Treatment


The Giardia parasite exists in two forms which are the dominant and active trophozoite and the inactive cyst. The active trophozoite sticks to the intestinal lining using a hook-like ‘sucker’ which is usually responsible for causing the various signs and symptoms of giardiasis. Although active, the trophozoite cannot live outside of the human body for long, therefore it confines itself in a hard-shelled cyst. This inactive cyst, on the other hand, can exist for longer duration outside the body and is the one responsible for contaminating food and water particles. When the contaminated food or water is consumed, the inactive cyst becomes active and transforms itself into the disease-causing trophozoite and starts the entire cycle.

Generally, people travelling to unhygienic contaminated places where the infection is common, or changing baby diapers, touching contaminated surfaces like bathroom handles, or eating uncooked food are at the risk of getting this infection. It also spreads through intake contaminated water from ponds, lakes and wells while swimming or playing or consuming contaminated food or from direct person to person contact.

Although giardiasis may not be a fatal infection, it might leave a long-term effect on the patient and in some chronic cases, lead to malnutrition, dehydration and lactose intolerance. Also Read: Dehydration: Causes, Symptoms And Treatment


Although some people have the parasite in them, they don't show any signs and symptoms but can spread the infection onto others. For people where the trophozoite is active, symptoms usually develop 1-2 weeks after getting Infected by the parasite and last for 2-6 weeks. The common symptoms include:

  • Foul-smelling watery diarrhea
  • Greasy stools
  • Abdominal cramps and bloating
  • Loss of appetite
  • Headache
  • Gas or flatulence
  • Fatigue or malaise
  • Nausea or vomiting
  • Weight loss
  • Dehydration
  • Dizziness or confusion

Diagnosis and Treatment

It is advisable to consult a doctor if you notice any of the above-mentioned symptoms like loose stool or abdominal pain. The gastroenterologist usually does a thorough physical checkup and acknowledges the patients past medical history and travel history to understand from where the infection has been picked up followed by the following tests which are blood test stool test to check for the parasite.

Although people suffering from an acute form gets well on their own, but a chronic condition requires proper prescribed medications to kill the parasite and provide relief from the symptoms.

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The infection can very well be prevented by following a few preventive measures like:

  • Washing the hands with a soap before eating any food
  • While travelling, use only packaged drinking water
  • Avoid drinking stagnant water from wells, ponds and rivers
  • Try not to intake any water while swimming in pools and lakes which you think might be contaminated