My Account
About Us
Contact us
الواجهة العربية
Medical News Medical News
Aricles Articles
Events Events
Guidelines Guidelines
Videos Library Videos Library
Diseases Diseases
Follow us : facebook twitter Digg Linkedin Boxiz

Please select the categories you are intersted in:
News Articles Guidelines Events Videos Journals' abstracts

Latest Subscribers
Advanced Search »

Giardia infection (giardiasis)


Disease: Giardia infection (giardiasis) Giardia infection (giardiasis)
Category: Infectious diseases

Disease Definition:

The intestinal infection that is characterized by abdominal cramps, nausea, bloating and watery diarrhea is called giardia infection. This condition is caused by a parasite that is found worldwide, particularly in areas with unsafe water and poor sanitation.


Mostly, these parasites are found in backcountry streams and lakes, in addition to swimming pools, spas and municipal water supplies. This infection could be transmitted through person-to-person contact and food.


Generally, within six weeks, the infection will clear up. However, long after the parasites are gone, a person could have recurrent episodes or have intestinal problems. Prevention is the best defense in the case of this condition. Despite the fact that there are several drugs that are generally effective against giardia parasites, however, they don't work for everyone.


Work Group:

Symptoms, Causes


Some people could carry the parasite and spread it to others through their stool despite the fact that they never develop signs or symptoms. However, if people do experience signs and symptoms, they will occur one or two weeks after the exposure and include:


  • Fatigue
  • Nausea
  • Bloating and abdominal cramps
  • Weight loss, which could be as much as 10% of the body weight.
  • Watery and in some cases, foul-smelling diarrhea, which could alternate with soft and greasy stools.


Although in some people the signs and symptoms of giardia could become chronic and linger for months or years, however, most of the time they go away in two to six weeks.



This disease is caused by the parasite called Giardia intestinalis, which is also known as Giardia lamblia. There are two forms of the giardia parasite:


This form of giardia lives in the intestines of an infected human or animal.

Inactive cyst:

This form could survive for months in the environment.


In case a person ingests inactive cysts, the hard shells of the cysts break down in the person's stomach, releasing the parasite. Then, the parasites attach to the wall of the small intestine, reproduce by the millions and damage the intestinal wall. This could lead to diarrhea and weight loss because it interferes with the ability to absorb food.


These parasites detach from the small intestine in time and transform back into cysts, which are shed in the person's feces. Until they are ingested by another host, they could survive in soil or water for long periods.



These are the three most common ways through which a person picks up the parasite:

Direct contact:

In case someone's hands become contaminated with fecal matter, they could become infected with giardiasis. People especially at risk are parents changing a child's diapers in addition to children in child care centers and child care workers. This parasite could also spread through anal sex.


The main source of giardia infection is water. Some of the places that these parasites are found include lakes, rivers, streams and ponds worldwide, along with wells, municipal water supplies, water parks, swimming pools, spas and cisterns. These parasites have also been found in touch tanks in museums and aquariums. Agricultural runoff and wastewater discharge could contaminate ground and surface water. Water could also become contaminated from animal feces because giardiasis also affects small rodents, a variety of birds, muskrats, beavers, fish and reptiles. Pools and spas could be accidentaly contaminated by people with diarrhea and children in diapers. In case someone accidentally swallows water from a tainted pool or spa, if they drink from streams or lakes that contain the parasites or if they drink contaminated tap water at home or abroad, they could also become infected.


In case food handlers don't wash their hands or if raw produce is irrigated or washed with contaminated water, this parasite could also be transmitted through food. However, food is a less common source of infection than water, particularly in industrialized countries because cooking food kills giardia. However, outbreaks could occur through infected food service workers and ice.



In industrialized countries, infection with the giardia parasite is almost never fatal. However, it could cause lasting symptoms and some serious complications, particularly in children under the age of five and infants. Some of the most common complications of giardia infection include:

Failure to thrive:

Children's physical and mental development could be harmed due to chronic diarrhea from giardia infection. It could also cause malnutrition.

Skin rash:

This infection could cause hives or a skin rash in some rare cases.


When a person's body does not have enough water to carry out its normal functions, dehydration occurs usually as a result of severe diarrhea.

Lactose intolerance:

Many people with giardia infection are unable to properly digest milk sugar, a condition known as lactose intolerance. This problem could linger long after the infection has cleared, which could cause weight loss and malabsorption.


Usually, children and adults who have giardia infection with no symptoms don't need treatment unless it is likely that they could spread the parasites. Usually, people that are experiencing problems get better in a few weeks on their own. Giardiasis is usually treated with antibiotics such as metronidazole or tinidazole in case the signs and symptoms are severe or if the infection persists. Although tinidazole requires a shorter course of treatment, but both of the drugs are effective. A person should avoid alcohol while taking these drugs. Nausea, vomiting and a metallic taste are some of the side effects of both of these medications. Because these medications could lead to birth defects, pregnant women shouldn't use them during the first trimester. Some doctors may prefer not treating pregnant women at all, or they may consider using the less toxic, but also less effective drug called paramomycin. In extreme cases, when the signs and symptoms are severe, metronidazole could be considered.


Not available

Expert's opinion

Expert's Name:
Specialty: -

Expert's opinion:

For Specialists

Clinical Trials:

Not available


Latest Drugs:




Forgot your password

sign up

Consultants Corner

Dr. Tahsin Martini

Dr. Tahsin Martini Degree status: M.D. in Ophthalmology

Dr. Samer Al-Jneidy

Dr. Samer Al-Jneidy Pediatrician

Samir Moussa M.D.

Samir Moussa M.D. ENT Specialist

Dr . Dirar Abboud

Dr . Dirar Abboud Hepatologist – Gastroenterologist

Yaser Habrawi , F.R.C.S.Ed

Yaser Habrawi , F.R.C.S.Ed Consultant Ophthalmologist

Dr. Faisal Dibsi

Dr. Faisal Dibsi Specialist of Otolaryngology - Head and Neck Surgery

Dr. Talal Sabouni


Dr. Hani Najjar

Dr. Hani Najjar Pediatrics, Neurology

Which of the following you are mostly interested in?

Cancer Research
Mental Health
Heart Disease & Diabetes
Sexual Health
Obesity and Healthy Diets
Mother & Child Health

Disclaimer : This site does not endorse or recommend any medical treatment, pharmaceuticals or brand names. More Details