Giardiasis - Causes, Symptoms, Diagnosis, Prevention & Treatment
Health Education

Protect Yourself from Giardiasis: Intestinal Infection

Dr.Dilip Todi profile Authored by Dr.Dilip Todi on 18 Mar 2015 - 11:56.


Giardiasis is an intestinal infection caused by Giardia lamblia (a single-celled microscopic parasite) that typically affects the intestines causing abdominal cramps, nausea, swelling and diarrhoea. This organism is often prevalent in areas with poor sanitation. Usually, unsafe water is the medium through which Giardiasis spreads in the community.

However, contaminated food and close contact with an infected person may also contribute to spread of this infection.  It may take up to a week to clear up the Giardiasis infection, but intestinal discomfort may last longer, even if the causative pathogen is no more in the body. 

When a person is infected by the microscopic parasite Giardia lamblia, it resides in human intestine and causesa variety of symptoms. In the intestine, these parasites become encased within cysts and then get released through stools of an infected person. The cysts help the parasites to survive outside the body. When these shelled parasites enter a healthy human body through contaminated water or food, cysts (hard shell) get dissolved and parasite is released, causing symptoms. This cycle repeats and infection spread in the community.

Mediums of infection spread: Infection may spread from person-to-person via the following ways:

  • Consuming contaminated water (especially from pond, swimming pools, wells, spas, etc.) 
  • Eating contaminated food  
  • Handling children (especially their diapers) with Giardiasis
  • Anal sex
  • Handling animal waste
  • Eating uncooked food that contains Giardia organisms
  • Having contact with someone who is ill with giardiasis

People infected with Giardiasis may or may not develop any sign or symptoms. Those who develop the symptoms usually experience them after about two weeks of exposure to the pathogen and may last for two to four weeks or longer. Common signs and symptoms may include:

  • Acute or chronic diarrhoea (watery and/ or greasy stool)
  • Tiredness
  • Abdominal cramps (that often worsens with eating)
  • Bloating (abdominal swelling with fluid or gas)
  • Nausea
  • Unexpected weight loss
  • Belching gas with foul taste
  • Constipation
  • Burps
  • Occasional headaches

Most often patients get cured with proper treatment, but may recur in some patients.

When to see a doctor?

If you are experiencing multiple symptoms mentioned above, some of the following alarming signs, you must visit your doctor:

  • Feeling dehydrated
  • Diarrhoea (6 times in 24 hours)
  • Exposed to poor sanitation
  • Exposed to contaminated water or food
  • Fever (more than 100.4 F)
  • Illness lasting more than two days


Diagnosis of Giardiasis may involve a series of tests and examinations. These may include:

  • Stool exam to test giardia cysts in the stool.
  • String test is done by collecting the mucus and secretion from the intestine.
  • Aspiration and biopsy: A tissue sample from the intestine examined. 

Research about Giardiasis Parasite to Create a Vaccine

The Giardia parasite hides from the immune system by changing disguises, in the form of a protein on its surface.The intestinal parasite Giardia lamblia changes outfits frequently. With more than 200 protein coats, this parasite, changes its form every instant making the body's immune cells go off track.

Hugo Luján, a Howard Hughes Medical Institute international research scholar, in an advance online publication in the journal, Nature Medicine on April 25, 2010, showed that Giardia parasites engineered to express all their surface proteins worked as vaccines enabling prevention or mitigation of future infections. Luján believes Giardia's hardy surface proteins, that enable the parasite thrive in the harsh, acidic environments of the stomach and upper intestine, may actually be used to deliver vaccines not only against Giardia but for parasites causing malaria too. "These proteins help the parasite survive but we're planning to use that armor to make new, oral vaccines." This vaccine could help save lives and money on treatment.



Complications: Poorly managed Giardiasis may lead to severe complications, especially in children. These may include:

  • Severe dehydration (loss of excess water)
  • Malnutrition 
  • Altered physical and mental growth 
  • Failure to digest milk (lactose intolerance)

Asymptomatic patients do not need any treatment unless they are likely to spread infection in the community. Most of those who develop symptoms often get recovered on their own in a few weeks, while those with severe symptoms may need medical management. Treatment of Giardiasis may include:

Drugs and medications: These may include:

  • Antibiotics such as Metronidazole and Tinidazole are used to treat the infection. Alcohol must be avoided while taking this medication.
  • Nitazoxanide: is a liquid form usually given to children with giardiasis.
  • Quinacrine pillsare given for five days and is believed to be a very effective.
    (Note: As with any other treatment drugs and medicines may also cause several side effects. Talk to your doctor about dealing with the adverse effects.)

Treating Giardiasis during pregnancy :

As some of the medicines may harm the baby and the mother, treatment is usually postponed (in case of mild infection) until after delivery. In severe cases, when the treatment can’t be postponed, paromomycin and metronidazole (after first trimester) may be given.

Some tips to eating right:

  • Drink a lot of water
  • Prefer drinking fluids free of caffeine e.g. Soups, fruit juices, sports drinks, etc.
  • Avoid tea, coffee or carbonated beverages.
  • Suck ice chips if feeling thirsty, but can’t drink water due to stomach fullness or any other reason.
  • Prefer eating plane foods such as boiled vegetables, cooked rice, potatoes, noodles, etc.
  • Avoid spicy and deep fried foods and also unhygienically prepared food.
  • Avoid milk for several weeks post the giardiasis infection.




Prevention is the best remedy to stay away from communicable infections like Giardiasis. Here are the tips:

  • Wash your hands frequently
  • Use alcohol-based sanitizer in work place or schools
  • Drink purified water (purify the water by filtering it or boiling it for 10 minutes)
  • Cover your mouth in crowded places
  • Keep your mouth closed in the swimming pool
  • Use bottled water while travelling
  • Avoid using ice
  • Do not eat raw and unwashed fruits and vegetables
  • Avoid anal/ oral sex or practice safe sex using condom.
*Disclaimer This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.