Giardiasis: Symptoms

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Symptoms

Many children and adults infected with Giardia lamblia have no symptoms of giardiasis, even though they are infected and the parasite is present in their feces. These people can pass the infection to others.

The most common symptoms of giardia include:

• Diarrhea, usually lasting 7 to 10 days. It can last longer but can also get better within 2 to 4 days. There first may be a large amount of watery diarrhea followed later by greasy, foul-smelling stools that may float. This is a sign that fat is not being digested properly and instead is being passed from the body in the stool.
• Abdominal cramps or tenderness.
• Nausea and loss of appetite.
• Passing more gas or having more bloating than usual.
• Fatigue.

People often do not seek treatment for these symptoms. In most cases, the symptoms gradually get better on their own. But if giardiasis is not treated during the first episode of symptoms, the illness may become a long-term (chronic) problem.

People with chronic giardiasis have bouts of diarrhea that come and go along with the other common symptoms of giardiasis. These episodes alternate between periods of constipation and normal bowel movements, and they last only a few days at a time. Because of this, many people do not seek treatment. Other symptoms of chronic giardiasis include:

• Loose, soft, greasy stools (not always watery or liquid). Sometimes the stools may be foul-smelling or foamy and are often passed in small amounts.
• Discomfort in the abdomen or pit of the stomach that is often worse after a meal.
• Belly cramps, bloating, or pain.
• Passing more gas than usual.
• Persistent bad breath or belching that sometimes smells of sulfur.
• Occasional headaches.
• Weight loss.
• General feeling of discomfort or illness (malaise), weakness, or fatigue.

Symptoms in children

Young children with giardiasis may show no symptoms other than a failure to grow and gain weight normally. If a child does have other symptoms, they may include:

• Pale, foamy, foul-smelling diarrhea.
• Weight loss or lack of appetite.
• Belly pain, nausea, or vomiting.
• Nutritional deficiencies caused by not being able to absorb certain nutrients.

Breast-feeding is thought to help protect infants from giardia infection. Breast milk contains nutrients that may kill the parasite.¹

The symptoms of giardiasis are common to numerous other intestinal infections. The duration of the symptoms and a test to detect the parasite may be the only ways to distinguish between these diseases.

Last updated:	October 16, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	E. Gregory Thompson, MD - Internal Medicine, W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Editors:	Susan Van Houten, RN, BSN, MBA, Pat Truman, MATC