FAQ: Frequently Asked Questions

Giardia Lamblia is a protozoan parasite.  Protozoan means one cell.  

There is an adult form of Trophozoite (if you looked at a picture it looks like a smiling face and tail).  That form has the flagellin and moves around and is what makes a person sick.

The Trophozoan can form a cyst, (it’s little and oval shaped – it’s smaller than the Trophozoite and has a shell around it).  It also is one cell and you can only be seen under a microscope.  The cysts of giardia can live outside the body, but the Trophozoites will die quickly if outside of a dog or a human.  The cysts can live on surfaces up to 15 days.  

For example, a bathroom doorknob, handle or faucet can have cysts, which come from drinking water.  The giardia cysts are also found in streams and rivers due to sewage contamination or delivered via beavers and other animals. People who backpack in the wilderness need to treat all water for giardia.

People can start to get sick within three to ten days.  However, a person doesn’t necessarily feel the impact of major symptoms because of the low load of giardia cysts; however, the parasite starts growing when signs of stress appear in other areas of the body.

The most common way a person gets infected is by consuming food or water that is contaminated.  A food handler can contaminate the food.  Sometimes giardia is spread within families because someone has giardia and is the person preparing the food for their family.

Public restroom facilities

Open salad bars are a perfect example of a situation in which raw food sitting on an open table with many different people handling the food with tools.  A reporter, who noticed people’s behavior around open salad bars, documented this example.

Sex, especially oral sex.

Household pets (dogs and cats) can carry giardia.  If you are cleaning up after your pets, the cysts of giardia can get on your hands.  Pets are grooming themselves and are licking their skin (the perianal and genital areas of skin).  Just handling your pet may transfer giardia.

Children going to daycare centers. As many as 30% of daycare staff are infected with giardia annually, especially in infant centers because of the diaper changing.  Horizontal surfaces at infant care centers carry giardia and need to be carefully wiped with Clorox to help get rid of it.

1. Acute diarrhea, gas, bloating, nausea and fatigue

A lot of people acquire and have no symptoms at all.  An asymptomatic giardia carrier can spread giardia to someone else and that person can become symptomatic.  There are different strains of giardia, so it is possible that some are pathogenic while others are not. In some family situations, it is clear that their is one person who had no symptoms who brought the infection into the family but only other family members got sick so they must have gotten sick with same strain.  

In general, women tend to be more prone to contracting giardia than men, which possibly has to do with hormones.

2. Chronic: constipation may be more prominent then diarrhea, gas, bloating, fatigue nausea, abdominal pain, and an intolerance of specific foods (fruit in particular).

When you treat giardiasis, food problems will resolve slowly.  There are other unusual symptoms associated with giardia that do not depend on a compromised immune system and they are probably due to the nature of the immune response triggered by giardia, including skin rashes, hives and joint pains.

Giardia can also cause an overgrowth of bacteria and yeast in the small intestine.  The bacteria and yeast that overgrow may ferment food to produce substances that have toxic effects.  Some people have neurological effects (brain fog and spaciness related to eating) when infected. 

It means symptoms have been going on for more than a few months. According to Dr. Leo Galland, once treated properly, people with symptoms present for more than 25 years could be cured within a year.

Irritable Bowel Syndrome, Chronic Fatigue Syndrome, or depression.  As far as hormones come into play, since women tend to be more affected than men and some women find the symptoms are cyclic and relate to their menstrual cycle, there are definitely hormonal influences on the symptoms.

Any kind of chronic infection can disrupt a person’s hormones, but it is still undecided if giardia does that more than any other kinds of infections.

The main effect of a compromised immune system is that it increases susceptibility to acquiring giardia and makes it much harder to get rid of. 

The concept of a compromised immune system is very tricky.  The damage that’s associated with giardia in the intestines is actually due to your own immune system.  

There was a study done on animals that had certain aspects of their immune system disabled and their intestines were not damaged by giardia.  It’s the immune system itself that damages the intestines and produces symptoms like hives and arthritis with giardia. You need a strong immune system to get rid of giardia and not get sick.  However, when you do get sick, the disturbed immune system contributes to symptoms. 

The immune system is such a complex set of reactions (it’s really like an orchestra, not a radio that you turn the volume up or down).  There are all these different parts that interact in different ways to produce the desired outcome to fighting an infection.  There are many people in whom this modulation does not occur properly for many reasons, one being related to different kinds of stress. It’s been well documented that someone can be a carrier of giardia and not have any symptoms and then get really stressed, whether psychological or an acute infection, or given steroids to treat something and giardia becomes active, because whatever is going on (in particular the steroids) dampen down the immune response in such a way that giardia gets activated.  AIDS is a situation in which people are prone to giardia and other intestinal parasites.  Another example that is not a direct effect of the immune system but that increases susceptibility to giardia, is lack of stomach acid so people taking drugs like proton pump inhibitors to treat heartburn may increase your susceptibility.

Any doctor can order this test but you want a laboratory that specializes in tropical medicine or Parasitology.  There are doctors who specialize in that as well.

Several different drugs are used to treat giardiasis.  The original antibiotics prescribed were Flagyl or Metronidazole (although found there are resistant strains to Metronidazole now).  

There is a newer drug related to Metronidazole called Tinidazole or Tindamax.  This medicine is shown to be superior to Flagyl and causes fewer side effects.  

The newest drug available is Alinia, which is Nitazoxanide.  It’s easy to take, has fewer side effects and seems to be more effective.  Albenza is mostly used to treat worms, but when used in conjunction with Alinia or Tinidazole, it enhances the effect of the drug.  Doctors may use a combination of Alinia or Albendazole to treat giardiasis, especially in chronic cases or if the person has failed previous treatments.  

There are some things that can enhance the effectiveness of the drugs.  One that’s studied most is a yeast, called Saccharomyces Boulardii, which is available under the trade name, Florastor.  It’s been shown in a study of children in Bangladesh to cure giardia by itself without any drugs.  It’s helpful for preventing antibiotic induced diarrhea and enhances effectiveness of anti parasitic drugs (when its administered with them) and these drugs do not kill Florastor because it is a yeast, not a bacterial probiotic.  

There are a number of herbs that may be used occasionally or as follow-up to antibiotics but haven’t been tested in same control trials that antibiotics have been studied.  They include: grapefruit extract, citrus seed extract and Berberine, which were derived from several different kinds of herbs.  Berberine and Artemisia or its extract called Artemisnin, is mostly used in treating Malaria but has been helpful in treating giardia especially in combination.  Some doctors use the three herbs especially as follow-up to antibiotics.  

Side effects depend on the medication.  Metronidazole can produce a metallic taste in your mouth, abdominal pain, fatigue, numbness, tingling in your arms and legs, mood changes and confusion.  Not a good first choice.  Tinidazole may produce all of the same symptoms but much less likely to do so.  Side effects with Alinia and Albenza are quite rare and mostly cause abdominal pain, which is also true with Florastor.  Some people who are allergic to yeast will break out in skin rashes and it tends to be constipating.

This varies greatly from case to case.  Sometimes a person can be better while on a drug within a few days.  Often it can take a week or so before noticing improvement because the drugs are so rough.  Occasionally, improvement doesn’t manifest itself for at least a few weeks.  Some people may feel better in the beginning of treatment but then can backtrack and feel worse again.  There may not be stable improvement for several weeks or even a few months after treatment is complete.  

Dr. Leo Galland studied a phenomenon called Leaky Gut Syndrome, which is measured by doing a test for Small Intestinal Permeability.  Results to this test usually show up abnormal in those who have giardiasis because there is a lot of inflammation in the small intestine.  In some cases, after the person is cured it can take between 6 to 9 months to feel normal.

If after treatment you still have intestinal symptoms or any symptoms, its possible that you have a bacterial or yeast overgrowth in the intestines that wasn’t covered by the medication prescribed. If this is the case, it needs to be treated.

Diet may have a significant impact on your symptoms.  It may take months, a year or even longer before you are able to eat a normal diet after having giardia.  People who have giardia or who have had giardia are often sensitive to sugar.  Sugar in fruits as well as in sweets, alcohol and wheat.  Eliminating the foods is worthwhile once you find out if eating them aggravates your symptoms.  Since giardiasis is often associated with bacterial or yeast overgrowth, further dietary changes may help.  One is a yeast and mold avoidance diet and the other is Fructose Malabsorption Diet. You can even go to the extreme with the FODMAPS Diet.  It came from Australia and is related to the diet of the Fructose Malabsorption. 

There may also be Nutritional Supplements that are needed because people with giardia can get deficient in Vitamin A and B12.  If you’ve been treated for giardia and appear to be cured but some symptoms still exist, one of the important things to consider is getting tested for Small Intestinal Bacterial Overgrowth.  Family members should be tested as well.