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Giardia (Giardiasis)

Basic Information

An intestinal infection, giardia is caused by a parasite. This parasite is responsible for destroying the lining of the intestines which can often result in malabsorption (the poor absorption of food). The protozoal parasite known as giardia lamblia usually causes an infection of the upper bowel area.

This parasite is a common worldwide problem and is a contaminant of surface waters. It is spread through contaminated water or food and fecal-oral contact. Thus it can be regarded as a sexually transmitted disease (STD).

There is a frequent occurrence of outbreaks, especially in day care children, and as day care centers become increasingly utilized giardia is more commonly diagnosed. It is believed that 35% of children in day care centers are infected at some point. While the exact incidence is not known it is generally believed that in the United States 4% of the population at some point becomes infected with this parasite which seems to infect males and females alike.

Sexually active gay men form a risk group as well especially those between 20 and 40 years of age. Giardia is spread by fecal-oral contact. If you have been diagnosed with this sexually transmitted disease please do not have sexual contact until your health care provider informs you that you no longer have this parasite. Additionally your health care provider may wish to test you for other sexually transmitted diseases such as gonorrhea, syphilis, hepatitis and herpes since when you are diagnosed with an STD there is a likelihood that you could have another sexually transmitted disease. Also a discussion about HIV may be important and indicated.

Worldwide the greatest number of giardia infections are water-borne. Cases have decreased with the coming of better sanitation and water treatment but still when the water treatment plants are not well maintained or there is area flooding the incidence of exposure to these organisms is greatly increased. Giardia remains active for nearly five weeks in cold or lukewarm water and are resistant to chlorine. The majority of parasites are removed from our drinking water supply by filtration. However, small numbers may still be found in tap water. Besides water the parasites can be acquired from food, sexual or person-to-person contact. It is also believed that domestic animals such as cats and dogs pose a risk to humans. Also at risk are those patients with immuno-deficiency. Neonatal infection is considered rare.

Symptoms

Up to 25% of patients have no symptoms. Patients who are symptomatic usually have at least one off the following symptoms:

  • dehydration
  • diarrhea (can be explosive with frequent stools)
  • bloating
  • nausea
  • fever
  • cramps
  • malaise
  • flatulence

More severe symptoms, which can last for weeks either chronically or intermittently, can include:

  • weight loss
  • malabsorption
  • chronic diarrhea

It is not usual to experience GI bleeding.

It takes one to three weeks for the inflammation to start to cause symptoms.

Diagnosis/Treatment

The most effective and widely used diagnostic tool for giardiasis is stool examination. It is usually recommended that three stool samples be taken to exclude day-to-day variances. In this way also your health care provider can rule out other causes of infective diarrhea such as amoeba, shigella, salmonella, etc. Sometimes a duodenal aspirate is recommended for microscopic examination to exclude other pathogens. Lab tests that record Vitamin B12 levels and stool fat and lactose intolerance may also be recommended. It is thought that a large number of patients with chronic gastrointestinal complaints are infected with giardia. It is important to consider this parasite in the early evaluation of these patients so that unnecessary costly procedures may be avoided. It is important to remember that barium in the stool may cloud or prevent detection of the parasite.

Treatment with medicines such as metronidazole, quinacrine or paromomycin may be prescribed for treatment of giardia. However, you must take your medication in the dosage that is prescribed and follow-up treatment by medication with your health care provider. Side effects of these medicines could include dizziness, a metallic taste, headache and nightmares. Do not under any circumstances substitute medications or take someone else's medication and under no circumstances should alcohol be consumed while taking these medications. Alcohol can give acute adverse side effects. Do not try to medicate yourself for cases of diarrhea alone. Medications for diarrhea have been known to regularly mask or hide symptoms and will not cure the problem. Should you have a high grade fever once you are taking treatment or cannot tolerate the side effects of the medication please see your health care provider immediately.

Dehydration is considered the most widely seen complication resulting from this parasitic infection. Be on the alert for signs of dehydration which include a decrease in urination, dry or wrinkling skin and a coated tongue. Your health care provider may at the very least recommend your fluid intake be increased and may even recommend a liquid diet especially if upset stomach persists. Treatment will speed up the recovery period.

As mentioned previously children especially in day care centers are vulnerable to becoming infected with this parasite. It may be wise to keep the child at home until the infection goes away. Caregivers are at risk from this parasite and must remember to wash hands thoroughly before eating or drinking. The patient as well should wash hands before eating or drinking .

If you are traveling to areas in Third World countries or the wilderness it is important to remember to boil water. Parasites are killed by temperatures over 50 degrees Celsius. If boiling water is not an option, taking halogenated water purification tablets is recommended. It is a good idea to avoid drinking the water from streams and lakes or eating uncooked foods that may have been rinsed or washed in these streams or lakes.

It is important to be tested a few months after your treatment is completed and infection is gone as reinfection is possible. Sexual partners or family members should be tested for parasites as well.

Your health care provider may wish to refer you to a gastroenterologist if you have suffered weight loss and/or malabsorption which have not resolved with treatment. If you feel you have giardia please see your health care provider promptly.

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