The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is Giardiasis?

Giardiasis is an infection in the intestines caused by a protozoan parasite (an organism consisting of a single, complex cell) called Giardia, usually, a particular species of Giardia called Giardia lamblia (also called Giardia duodenalis or Giardia intestinalis). The main symptom is diarrhea, usually consisting of loose, foul-smelling, greasy stool. Other symptoms that you may experience include flatulence, tummy cramps, bloating, fatigue, nausea, anorexia (lack of appetite), and weight loss. Giardiasis can be an acute case, consisting of symptoms that begin 7 – 14 days after you become infected and that also last about 7-14 days.  Alternatively, you can have chronic giardiasis, in which the condition persists several months after the infection and the symptoms come and go.

How common is Giardiasis during pregnancy?

Giardiasis afflicts about 2 percent of adults in developed countries and is the most common parasitic disease in the United States affecting humans. In developing countries, almost 33 percent of people have suffered from giardiasis at some point in life. The following are the main risk factors that put people at risk, including pregnant women:

  • Traveling in a country where giardiasis is common
  • Childcare
  • Being in contact with someone who has had giardiasis
  • Drinking water thats contaminated with Giardia parasites, or Giardia eggs. In particular, this includes people who drink untreated water from lakes or rivers while hiking or camping.
  • Contact with non-human animals that are infected. This includes your dog or cat, even though they typically are infected with a different species of Giardia than usually infects humans.

How is Giardiasis diagnosed?

The main way to diagnose giardiasis is by using a microscope to examine a sample of the patients stool for the mature parasite’s cells and eggs of Giardia. To have this done, your doctor would order an O and P (ova and parasites) on a stool sample. Tests that use antibodies to reveal Giardia also are conducted in some cases. When analysis of repeated stool samples comes out negative, yet there is a strong suspicion that the patient has giardiasis, the next step is to obtain a sample from the duodenum, the first region of the small intestine, as this is where the concentration of the parasites would be highest in an infected person. The classic way to obtain such a sample is a non-invasive technique called the strong test, in which the patient swallows a gelatin capsule that is attached to a string. This brings the capsule end of the string through the stomach and into the duodenum as the gelatin dissolves. The string is then pulled out through the mouth, along with contents from the duodenum that have adhered to the string. These contents can be examined for Giardia cells and eggs. Although not routine, a more complex procedure called endoscopy can be performed to obtain better duodenal samples, in event that the simpler tests come out negative.

Does Giardiasis cause problems during pregnancy?

Along with the discomfort of diarrhea and gas, which can be particularly bad during pregnancy given the growing womb, giardiasis can dehydrate you if the diarrhea is excessive.

Does Giardiasis during pregnancy cause problems for the baby?

Potential harm to the developing baby is not the direct consequence of the parasitic infection but is instead from the dehydration that can occur if diarrhea continues and the lost fluid is not replaced. Dehydration can decrease the amount of amniotic fluid, which can interfere with the baby’s growth, plus it can trigger premature labor and delivery.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the giardiasis
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat Giardiasis during pregnancy?

A handful of medications are available to treat Giardia infections. The most commonly used drug is called metronidazole. It can be taken during the second and third trimesters if needed, but not during the first as it can harm the developing baby. However, a drug called paromomycin (belonging to a group of drugs called aminoglycosides) is also effective against Giardia, plus it is considered safe throughout pregnancy since it is not absorbed through the gastrointestinal tract. There have been some reports of strains of Giardia that are resistant to the usual drugs. These are susceptible to the drugs quinacrine and furazolidone, neither of which is available in the United States. Generally, pregnant women who have only mild symptoms of giardiasis, or who are infected with Giardia but have no symptoms at all, are not given medication, but otherwise, paromomycin is the choice.

Who should NOT stop taking medication for Giardiasis during pregnancy?

Women who suffer moderate to severe symptoms of giardiasis are better off getting medication than not getting it.

What should I know about choosing a medication for Giardiasis during pregnancy?

You may find Pregistrys expert reports about the individual medications used to treat giardiasis here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for my Giardiasis when I am breastfeeding?

Since paromomycin is not absorbed through the gastrointestinal tract, it does not enter the mothers blood or her breastmilk, so it is considered safe in a nursing mother.

What alternative therapies besides medications can I use to treat Giardiasis during pregnancy?

When diarrhea is severe enough to disrupt fluids and electrolytes of the person, the management of fluids and electrolytes (by giving fluid and appropriate chemicals intravenously) becomes an important component of treatment.

What can I do for myself and my baby when I have Giardiasis during pregnancy?

Do all that you can to remain hydrated. This means continuing to take in fluids by mouth.

Resources for Giardiasis in pregnancy:

For more information about giardiasis during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or check the following links:


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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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