Giardiasis - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Giardiasis is a waterborne disease found worldwide, especially in places with poor sanitation and contaminated water. Swallowing contaminated or recreational water from lakes, rivers, or pools is the most common cause of the disease.

What Is Giardiasis?

Giardiasis is a parasitic infection that affects the small intestine. Giardia is the causative organism of the disease, which can spread through direct person-to-person contact or by consuming contaminated food and water. The infection is marked by diarrhea, stomach cramps, nausea, and vomiting.

What Is the Cause of Giardiasis and How Does It Spread?

Giardiasis is caused by a microscopic parasite Giardia that infects the intestine and is found in human and animal feces and can contaminate anything. Once the parasite enters a person’s body, it lives in the intestine and is passed in stools. However, Giardia can live outside the body for an extended time, for weeks or months.

Giardiasis can be spread by:

• Consuming food contaminated by Giardia.

• Drinking unsafe water.

• Person-to-person contact (being in close contact with a person infected by the parasite).

• Traveling to places with poor sanitation.

• Having unprotected anal sex with an infected person.

• Touching surfaces that may be contaminated with Giardia (like doorknobs, diaper changing tables, stair rails) and then touching the mouth.

• Being in close contact with animals that may have been infected.

What Are the Risk Factors?

Giardiasis is a common illness and can affect anybody; however, some are at a higher risk of contracting the disease.

• Children are at the most risk of giardiasis, as they are likely to come in contact with feces, especially in a child care center.

• Parents and caretakers who change diapers.

• People who stay in places without access to safe drinking water; giardiasis spreads in places with poor sanitation and without access to safe water.

• Travelers and backpackers travel to different places and may not have access to safe water and food.

• People who engage in unprotected anal or oral-anal sex

What Is the Pathophysiology of Giardiasis?

The life cycle of Giardia occurs in two stages. These include:

• Trophozoite: This stage is considered the active feeding stage of the parasite. The parasite resides in the human’s small intestine.

• Cyst: This stage is considered the dormant and hardy stage that is passed into the environment.

It was noticed that intermediate hosts are not necessary for the Giardia lifecycle. When the water and foods that are contaminated with cysts are ingested, the cysts enter the stomach and duodenum. In this environment, these cysts undergo excystation triggered by exposure to acid and pancreatic enzymes. Within a few minutes of infection, the trophozoites appear in the duodenum. These trophozoites multiply fast in the small intestine. When these reach the large intestine, due to a neutral pH environment and with secondary bile components, the encystation occurs. After this, the cysts are released into the environment and start the cycle again.

The exact mechanism regarding the symptoms of giardiasis is not clear. It was thought that trophozoites have a ventral disk that can be used to attach themselves to the intestinal epithelium. Researchers have found that these protozoa tend to disrupt the small intestine epithelial cell junctions and brush border enzymes. This leads to altered gastrointestinal motility among infected persons. The protozoa tend to release thiol proteinases and lectins. These were found to have cytopathic effects. The combination of all these effects tends to increase the permeability and impair the processing of saccharides.

What Does Giardiasis Do to the Affected Person?

Giardiasis does not cause noticeable symptoms, but it can cause symptoms. Some symptoms are caused by the parasite, and others are caused by the body's reaction to removing the parasite. For example, the parasite can engulf most of the nutrients ingested and make the person tired. Diarrhea, swelling, and skin reactions are caused by the immune system's response.

The symptoms resolve when the infection goes away. They are short-lived, but if the infection remains for a long period and keeps coming back often, it causes more damage, which lasts for the long term. The reason for this type of damage is weakened immunity caused by preexisting health conditions. This status may make the person more vulnerable to suffering complications of giardiasis.

What Are the Symptoms and Signs of Giardiasis?

The clinical symptoms of a person depend on many factors, including the person’s parasite load and the immune response. Some people may not show symptoms. Symptoms may appear one to two weeks after the infection and may last two to six weeks. However, for people with weaker immunity, it may last longer.

The symptoms include:

• Diarrhea.

• Weakness.

• Stomach cramps.

• Headache.

• Gas or flatulence.

• Nausea and vomiting.

• Greasy stools that float.

• Anorexia (an eating disorder represented by abnormally low body weight).

• Low-grade fever.

• Weight loss.

• Dehydration.

• Itchy skin.

• Swelling of eyes and joints.

Over time, giardiasis can also prevent the body from absorbing nutrients that are necessary for the body.

How Is Giardiasis Diagnosed?

The diagnosis of giardiasis is made by testing the person’s stool sample. However, not all samples might contain Giardia; hence, multiple stool tests are done. The doctor may also perform an endoscopy, where a thin, flexible tube is placed through the mouth to inspect the small intestine, followed by obtaining a tissue sample from the small intestine for biopsy.

What Are the Treatment Options Available for Giardiasis?

Most people do not require treatment as the infection subsides in a few weeks unless they are likely to spread the disease. The doctor would advise antiparasitic medication for mild cases of giardiasis. However, antibiotics like Metronidazole, Tinidazole, and Nitazoxanide may be prescribed in case of severe symptoms. One must follow the healthcare provider’s instructions and take the medications in time. If the medication is not taken properly or stopped abruptly, this may lead to another infection as the previous one was not cleared and the second course of medication may have to be taken.

Can Giardia Go Away on Its Own?

Yes. Giardia goes off on its own. If the symptoms appear to be mild, a healthcare provider may advise not to take treatment, and the symptoms may resolve on their own. If frequent antibiotics are taken, antibiotic resistance may develop. The same is happening in the case of giardiasis. If the infection is left to heal on its own, antibiotic resistance may be avoided.

It was noticed that the infection cannot heal on its own for some individuals and for some, it may be very persistent. If the symptoms remain for more than six weeks, the healthcare provider must be consulted. Healthcare providers help identify if the symptoms are due to giardiasis or due to the after-effects of the infection.

What Happens if Giardia Is Left Untreated?

If the giardiasis is left untreated, it resolves on its own. If the infection is not resolved, it may lead to complications related to the digestive system and the immune system. The antibiotics prescribed must be taken according to the instructions to avoid rebounding the infection.

What Are the Complications of Giardiasis?

Giardiasis symptoms usually go away after a few weeks of the infection; however, some serious complications linger even after the infection subsides:

• Dehydration: This results from severe diarrhea when the body does not have enough water to function normally.

• Malnutrition: Severe and chronic diarrhea due to giardiasis can lead to malnutrition in children and harm their mental and physical development.

• Lactose Intolerance: Some people develop lactose intolerance following a giardiasis infection.

What Is the Long-Term Outlook for Giardiasis?

Giardiasis usually subsides two to six weeks after the infection and may subside with appropriate medications in severe cases. However, a few complications, like lactose intolerance, may linger.

Can Pets Get Giardiasis?

Animals can acquire the disease from feces or another infected animal. Still, the chances of a pet spreading it to a person are relatively small, as the type of Giardia that infects humans is often different from the one in animals.

How to Prevent Giardiasis?

Currently, no medications can prevent giardiasis, but some simple precautions can save one from giardiasis.

• Washing Hands Often: Washing hands often can protect one from giardiasis and most infections. Wash hands with soap after a diaper change, using the toilet, before preparing food, and before eating. Alcohol-based sanitizers can also be used, if necessary, instead of soap and water.

• Avoid Drinking Unsafe Water: Do not directly drink water from rivers or lakes; these may be contaminated. Make sure to drink filtered, boiled, or treated water only.

• Avoid Swallowing Water While Swimming: Avoid swallowing water in pools, hot tubs, splash pads, etc. when swimming, and keep your mouth closed.

• Wash Fruits and Vegetables: Wash all produce well before consuming or using them to prepare food.

• Practice Safe Sex: Use condoms and perform only safe and protected sex.

Conclusion

Giardiasis is an infection that affects the small intestine caused by and causes diarrhea, stomach cramps, nausea, vomiting, malaise, etc. Most symptoms tend to subside a few weeks after the infection and are more likely to require no treatment. However, in severe cases, antibiotics are prescribed. The disease has never been fatal and has often been resolved by taking appropriate treatment as prescribed by the doctor.