Giardia Infection – Diagnosis and Treatment

Overview

Giardia infection is a common cause of intestinal illness caused by the protozoan parasite known as Giardia lamblia (also called Giardia intestinalis).

This parasite spreads through water, food, or surfaces contaminated with feces from infected people or animals. Outbreaks are often linked to untreated water in lakes, streams, and sometimes swimming pools.

Symptoms and Signs:

• Watery or greasy diarrhea
• Abdominal pain, cramps, or bloating
• Gas, belching, and flatulence
• Nausea, vomiting, and loss of appetite
• Dehydration and weight loss
• Fatigue and low-grade fever

Some people may have giardiasis without any symptoms (asymptomatic), but they can still spread the germs. In young children or infants, symptoms may also include failure to thrive.

Diagnosis

Reviewing Medical History and Symptoms

A healthcare provider will often begin by asking about recent travel, water exposure, and symptoms such as diarrhea, stomach cramps, or nausea.

They might also inquire about close contacts who are sick. This information helps guide which tests may be needed.

Examining Stool Samples for Parasites

To look for Giardia, a common test involves examining one or more stool (poop) samples under a microscope.

Ova and Parasite Exam is the standard process, where the sample is checked for Giardia cysts or trophozoites.

Sometimes, samples must be collected over several days because the parasite may not appear in every sample.

Using Other Tests to Find Giardia Proteins

In some cases, clinics use special tests that check for Giardia proteins, called antigens, in the stool. These tests can include enzyme-linked immunosorbent assay (ELISA) or direct fluorescent antibody (DFA) tests.

Such methods can provide quicker and sometimes more accurate results than traditional stool exams.

Treatment

Medicines Prescribed to Get Rid of the Parasite

To treat giardia infections, doctors usually prescribe antiparasitic drugs. These medications work to destroy or inhibit the parasite causing the illness. They are typically taken by mouth, either as tablets or liquids.

The table below summarizes common types of treatment based on their drug action:

Medicine Name	How It’s Taken	Usual Use Time
Nitroimidazole-class antiparasitic	By mouth	5–7 days or single dose
Thiazolide-class antiparasitic	By mouth	Around 3 days
Benzimidazole-class antiparasitic	By mouth	Typically 5 days

A doctor will choose which drug is best based on age, health, and how strong the infection is.

Treatment in Kids

Treating giardia in children may need some changes. Doctors often select medicines and doses that are safe for a child’s age and weight. Some kids might get liquid forms of medicine if they can’t swallow pills.

Caregivers should make sure the child drinks enough fluids, as diarrhea can cause dehydration. If a child has a weak immune system or certain health problems, the doctor may need to use a different treatment plan.

What Side Effects Can Happen With These Medicines

Most people handle giardia medicine well, but there can be some side effects. Common issues include:

• Nausea
• Upset stomach
• Headache
• Bitter or metallic taste in the mouth

Rarely, people might have allergic reactions or feel dizzy.

If someone feels very sick after taking the medicine or has any unusual symptoms, they should contact their doctor for advice. Doctors will explain what to expect and what to do if problems come up.

Home Remedies and Lifestyle Changes

Changing What You Eat While Sick

When someone has a Giardia infection, it helps to eat foods that are gentle on the stomach. Soft foods, like plain rice, bananas, and toast, are easy to digest and can help reduce stomach upset.

Eating smaller meals more often may also make it easier for the body to manage symptoms, such as nausea or diarrhea.

Staying Well Hydrated

Keeping up with fluids is important because diarrhea from Giardia infection can cause the body to lose water quickly.

Drinking water, diluted juice, or oral rehydration solutions can help replace fluids and important electrolytes. Sipping fluids slowly throughout the day is often easier for the stomach.

What to Avoid and What to Choose

Foods to Avoid	Foods to Choose
Fatty or fried foods	Plain rice
Spicy snacks	Bananas
Dairy products	Applesauce
Caffeinated drinks	Toast or crackers
Sugary items	Cooked carrots

People should avoid foods that are hard to digest, like greasy meals, spicy snacks, and most dairy products, as these can make symptoms worse.

It helps to pick simple foods that are low in fat and easy to digest until symptoms improve.

Steps to Reduce the Risk of Giardia Infection

Cleanliness and Personal Care Habits

• Wash hands often, especially after using the bathroom, changing diapers, or handling pets.
• Use soap and water for at least 20 seconds.
• Clean surfaces like bathroom fixtures, countertops, and doorknobs often to avoid spreading germs.

Guidelines for Safe Drinking Water

• Drink water from wells, city supplies, or bottled sources whenever possible.
• Boil water for at least one minute when unsure if it is clean, especially in areas without reliable treatment.
• Use water filters labeled as effective against parasites like Giardia.

Water Source	Is it Safe Without Treatment?	What to Do
Tap (treated/city)	Often	Use as is
Well	Sometimes	Test or boil
River/Lake/Stream	No	Boil or filter
Bottled	Yes	Use as is

Tips for Staying Safe When Visiting Other Places

• Do not drink local tap water in areas where water treatment is uncertain.
• Avoid eating fresh fruits or vegetables washed with unsafe water.
• Use bottled water for brushing teeth and making ice.
• Avoid swallowing water in pools, lakes, or rivers.

Taking basic steps can help protect against Giardia and reduce the risk of infection.

Getting Ready for Your Appointment

Before seeing a provider, write down your symptoms, when they started, and how severe they are. Make a list of any recent travel or possible contact with untreated water, since these details can help with diagnosis.

Tips for your visit:

What to Bring	Why It Helps
List of symptoms and their duration	Helps the provider understand your case.
Notes on recent travel or water use	Identifies possible sources of infection.
A record of all medications taken	Prevents problems with treatment choices.
Any questions about your condition	Makes sure you get the information needed.

Being prepared helps your visit go smoothly and allows your provider to plan the best treatment for your situation.