The Essential Guide to Giardiasis: Symptoms, Causes, Treatments, and Natural Approaches

The waterborne Giardia parasite is the most common of its kind in the United States and causes a diarrheal infection called giardiasis. The Epoch Times

Approximately 7.15 million waterborne illnesses occur in the United States each year. The Giardia intestinal parasite is the most common of its kind found in humans in the United States. Found worldwide, this waterborne parasite causes diarrheal infections called giardiasis. In 2018, there were 15,579 cases of giardiasis in the United States, of which nearly 97 percent were confirmed.

Giardia can enter a person’s gastrointestinal (GI) system through water, soil, or feces. It is an enteroparasite, meaning it grows in the small intestine of humans and other vertebrates, such as beavers and birds. A Giardia infection, giardiasis, can wreak havoc on the human digestive system, causing diarrhea, malabsorption, and possible long-term effects.

What Are the Symptoms and Early Signs of Giardiasis?

The symptoms of giardiasis are varied. This illness is most often acute, developing over three weeks. Symptoms may depend on the state of the person’s immune system, age, nutritional status, or the existence of other GI infections. Common symptoms of giardiasis include:

• Diarrhea
• Malabsorption
• Bloating
• Abdominal pain
• Fatigue
• Weight loss

Giardiasis may also be asymptomatic. The condition may be chronic or acute, and it may be persistent.

What Causes Giardiasis?

Giardiasis is acquired through a fecal-oral route. The parasite Giardia creates cysts that are excreted in feces. Cysts are infectious as soon as they are excreted. They can survive on surfaces, fruits, vegetables, and water for weeks to months. Ingestion of Giardia cysts results in giardiasis.

Giardia parasites change the environment of the intestines. According to a 2013 review published in the World Journal of Gastroenterology (WJG), the parasites attach to the small intestine’s lining by an adhesive disk. This causes a severe disruption in the barrier function of the intestine wall, upsetting the microbiota, or normal bacteria, of the small intestine and producing diarrhea. Other substances produced during this adhesion further harm the intestines.

A 2020 review published in Parasite confirmed this disruption to the microbiota of the small intestine. However, any lasting effects on the gut wall after the parasite is gone need further investigation.

Once ingested via feces, Giardia cysts mature and infect the small intestines, where the parasites disrupt the healthy microbiota. The Epoch Times

Where Can I Get Infected?

This waterborne pathogen does not survive well in the water systems of developed countries. However, modern challenges create the chance of infection in these areas. These include aging infrastructure, chlorine-tolerant and biofilm-related pathogens, and recreational water use.

It’s possible to get giardiasis from drinking water. For example, aged pipes in a building or water from a private well may contain the parasite.

Giardiasis infection is also possible while enjoying water parks and other water entertainment facilities. According to a case-control study published in Epidemiology & Infection, the chlorine-tolerant pathogen can reside in these recreational waters and plumbing.

Who Is More Likely to Develop Giardiasis?

Awareness of giardiasis risk factors can help prevent the parasite’s spread. People most at risk are:

• Young children or infants
• International travelers
• Hikers who drink water from a river, lake, stream, or spring
• People who swim in natural bodies of water
• People who engage in anal sex
• Caregivers who come in contact with diapers or children wearing diapers
• People taking antibiotics
• People with a chronic GI condition, such as Crohn’s disease, irritable bowel syndrome (IBS), and celiac disease

According to the case study, people with chronic GI conditions may be more susceptible to giardiasis. However, these people may simply be more likely to become symptomatic.

What Are the Tests to Detect Giardiasis?

If you have symptoms of giardiasis and visit a health care provider, be prepared to provide as much information as possible. The provider may need a history of symptoms for a diagnosis if stool samples are negative for giardiasis. Without a Giardia-positive stool sample, a record of your stools and diet may help determine a diagnosis.

Collected stool samples will be sent to a lab for a Giardia antigen test. Specifically, an enzyme-linked immunoabsorbent assay (ELISA) test will be used to identify Giardia antigen presence in stool samples.

Giardiasis May Be Missed

Giardiasis can sometimes be missed. An infection may be misdiagnosed because its symptoms are similar to other GI infections, such as IBS or lactose intolerance.

When testing for giardiasis, you may be asked for several stool samples. Giardia cysts are not excreted out of every stool. Unless cysts are present in the sample, a diagnosis of giardiasis can’t be confirmed.

If the diagnosis is still strongly suspected, a fluid sample is sometimes obtained from the first portion of the small intestine (the duodenum) via an upper endoscopy. These samples are called duodenal aspirate cultures.

However, confirmation of the presence of cysts is not required for treatment. Sometimes a provider will treat a patient for giardiasis based on symptoms and the patient’s history.

What Are the Complications of Giardiasis?

Giardiasis can have lasting effects on a person’s GI system. The effects can be different for adults and children. According to the WJG review, some long-term consequences for adults include:

• Eye conditions
• Anorexia and poor nutritional status
• Inflammatory arthritis
• Myopathy
• Hives
• Chronic fatigue syndrome (CFS)
• Post-infection IBS
• Functional dyspepsia (impaired digestion)

Eye Conditions

In some cases, giardiasis has caused iridocyclitis—inflammation of the iris and eye muscles. It may also cause choroiditis, which is retina inflammation, and choroid and retinal hemorrhage.

Arthritis

Arthritis may occur post-infection, according to the WJG review. It generally appears two to four weeks after giardiasis has been cleared. Though rates of arthritis are relatively low, when arthritis does occur, it can be present in the limbs, knees, and ankles.

Myopathy

Myopathy is weakness and dysfunction of the muscles. Myopathy can occur when there are low levels of potassium in the body. Diarrhea can decrease the amount of potassium in the body. For this reason, the WJG review posits that the prevalence of myopathy in people with giardiasis is relative to their number of bouts of diarrhea. Myopathy rarely occurs, but when it does, it most often happens in older people and women.

Lasting Effects on Children

Giardiasis can leave lasting effects on children differently than on adults. These may be:

• Iron deficiency
• Micronutrient deficiencies
• Protein-energy malnutrition
• Cognitive deficiencies
• Failure to thrive

There have also been instances of chronic giardiasis causing problems in the pancreas. The presence of Giardia in tumoral masses in the pancreas has led to questions about the carcinogenic mechanisms of giardiasis, according to the WJG review. However, the correlation between cancer and giardiasis has yet to be established.

Another lasting effect that giardiasis may have on the GI system is reducing the risk of a person having moderate-to-severe diarrhea post-infection.

What Are the Treatments for Giardiasis?

Giardiasis is treatable but can become chronic. It is most often treated with pharmaceuticals. The infection generally clears within two to three weeks when treated this way.

Medications

While giardiasis is most successfully treated with pharmaceuticals, it should be noted that there has been an increase in parasite drug resistance. If your symptoms are severe, your doctor might prescribe an antiparasitic antibiotic to kill the parasite.

The most common class of drugs used to treat giardiasis is nitroimidazole antibiotics. These include metronidazole and tinidazole. Treatment with these drugs is 80 to 90 percent effective, according to a 2019 study published in the International Journal for Parasitology: Drugs and Drug Resistance.

Possible side effects of nitroimidazoles are:

• Nausea
• Fatigue
• Malaise
• Vomiting
• Weakness
• Headaches

Studies like the 2019 one performed on aminoguanidines, such as robenidine, show promise in treating resistant giardiasis. These in vitro studies have demonstrated that robenidine affects Giardia’s adherence to the intestine. In addition, complete inhibition of the parasite was also observed. However, further research is needed to understand the actions of robenidine on Giardia.

Another area of study is anti-giardial drugs, as mentioned in the 2020 Parasite review. Sirtuins are another possibility for treating giardiasis, but further research is needed.

How Does Mindset Affect Giardiasis?

Giardiasis is generally easy to treat. However, symptoms can become overwhelming when prolonged, and giardiasis becomes chronic. This prolonged experience with symptoms can impact a person’s quality of life and lead to feelings of despair.

The despair felt with chronic or prolonged giardiasis can manifest as stress. Stress can disrupt gut-brain communication. As stress increases, the intensity of pain, bloating, and discomfort can also increase. Stress can then thin the protective layer of the intestines and allow bacterial growth. Thus, it could worsen giardiasis. Stress also affects how quickly food moves through the digestive system, sometimes resulting in diarrhea.

The recurrence of symptoms can also be due to post-infectious irritable bowel syndrome (PI-IBS) (pdf). Depression is a risk factor for IBS. However, psychological factors do not seem to impact PI-IBS as they do chronic fatigue present after a giardiasis infection. Further studies are needed to understand the psychological impact of PI-IBS.

Chronic giardiasis can result in vitamin A, B12, and folate deficiencies. Studies have shown that supplementation of vitamin B12 and folate can decrease symptoms of depression. In addition, supplementing with vitamin A may prove beneficial in protection from giardiasis, though excessive vitamin A has been shown to impact cognitive function negatively.

What Are the Natural Approaches to Giardiasis?

More research should be done on treating giardiasis with herbal or natural remedies. The general approach is to use nutrition and plants or herbs in combination for intervention.

Nutritional approaches are used to address the acute symptoms of giardiasis. Eating whole foods, foods high in fiber and low in fat, and avoiding foods high in lactose and refined sugar may minimize symptoms. Introducing probiotics and wheat germ into your diet may also help eliminate the parasite.

Garlic and other herbs containing berberine have been the most studied in their effects on giardiasis. They show they may help treat the infection, but much research is needed to confirm these claims.

The Epidemiology & Infection case study mentioned that an association has been shown between people who consume raw fruits and vegetables and a decrease in their odds of getting giardiasis. But, again, more research is needed.

How Can I Prevent Giardiasis?

The best way to prevent giardiasis is with behavior modification. Be sure to:

• Wash your hands after touching a child in diapers or shaking another person’s hand.
• Wash after swimming in a natural or manmade body of water.
• Wash after swimming in a water park or other water entertainment facility.
• Avoid swimming in suspect bodies of stagnant water, such as gravel pits.

If you are planning an international trip:

• Bring and use hand sanitizer.
• Drink bottled water or boil water from the tap before you drink or cook with it.
• Eat only food that is washed and cooked thoroughly.

Medically reviewed by Beverly Timerding, MD.