Definition

Giardiasis is a digestive tract infection caused by Giardia duodenalis parasites, also known as Giardia lamblia or Giardia intestinalis. These parasites are so small that they are hard to see with the naked eye. Giardiasis is the most common parasitic infection of the digestive tract found worldwide, particularly in countries with low sanitation and polluted water. This infection affects 8% of children and almost 2% of adults in developed countries, while approximately 33% of the population in developing countries has been infected by it.

Giardiasis is usually asymptomatic, making it challenging to identify in most cases. However, if symptoms occur, they may include abdominal cramps, bloating, vomiting, and diarrhea.

Causes

Giardia is a parasite that lives in the intestines of humans and animals. Before infecting a host, the parasite is protected by a hard shell or cyst, allowing it to survive outside the body for several months. If an animal or human swallows the Giardia cyst, the protective shell dissolves, and the parasite is released to infect the intestine. Giardia cysts are commonly found in murky water and contaminated food.

Giardiasis can be transmitted through various means, including:

• Swallowing water or food contaminated by Giardia can be present in lakes, rivers, or swimming pools.
• Close contact with individuals with giardiasis, such as through handshakes when hands are dirty.
• Traveling to low sanitation areas.
• Exposure to feces of giardiasis patients or engaging in sexual contact (primarily anal) with giardiasis patients.
• Accidentally swallowing Giardia parasites by touching contaminated surfaces, such as bathroom door handles, tablecloths, used diapers, or toys.
• Contact with animal feces or areas of infected animals. While this transmission method is rare because the route of Giardiasis infection to humans differs from that to animals, infected animals can potentially spread it to other animals.

Risk factor

Giardiasis is more common in children because they have a higher risk of coming into contact with feces, especially if they are still using diapers or are in daycare. Children's natural curiosity makes them more prone to touching dirty surfaces. Individuals who work in daycare or with children also face an elevated risk of giardiasis.

Giardiasis is also more prevalent in areas with low hygiene standards or inadequate clean water provision. Locations with the highest risk are rural areas and open natural settings. Activities like swimming in pools, hot springs, lakes, or water bodies with murky water pose a higher risk of swallowing contaminated water and becoming infected by Giardia.

Certain risk factors can further increase the likelihood of giardiasis, such as engaging in sexual contact with affected individuals, visiting areas with a high incidence of giardiasis or low sanitation, and having a weakened immune system.

Symptoms

Symptoms of giardiasis can manifest around 1-3 weeks after infection and may last for 2-6 weeks. Almost half of those infected do not exhibit symptoms but can still transmit the infection. Common symptoms include:

• Smelly diarrhea
• Feeling sluggish
• Abdominal cramps and bloating
• Vomiting and nausea
• Weight loss
• Dehydration
• Fever (seldom occurs)

Diagnosis

The diagnosis is determined by assessing the primary concern, symptoms experienced, dietary and drinking habits, and travel history, along with additional examinations. If necessary, the doctor may request a fecal examination to identify the microbe causing the disease. Typically, the doctor will require three samples of feces from different days because the parasite may not appear in all samples. Giardia parasites can be detected through microscopic tests. Some laboratories can also identify giardiasis antigen using Nucleic Acid Amplification Tests (NAAT).

Management

Children and adults infected by Giardia may not always show symptoms, but they still have the potential to transmit it to other people. Some individuals with mild symptoms will recover after a few weeks.

For severe giardiasis symptoms or symptoms that persist after a few weeks, anti-parasite medication is recommended. It's important to consume the medicine according to the instructions to ensure the parasite is fully addressed. If the affected individual is dehydrated, intravenous fluids may be necessary to manage fluid balance.

While Giardia can infect people of all ages, pregnant women and babies can experience severe dehydration after infection. However, anti-parasite drugs can be risky for pregnant women. If they have mild symptoms, doctors may recommend delaying therapy until the second or third trimester. It's essential to consult with a doctor if pregnant.

Complications

Untreated giardiasis symptoms can lead to severe complications, particularly in children and babies. The most common complications include:

• Dehydration

Prolonged diarrhea and vomiting can cause dehydration and a shortage of fluids, disrupting the normal functioning of the body.

• Failure to grow

Chronic diarrhea due to giardiasis can lead to malnutrition, affecting the growth and development of children.

• Lactose intolerance

Individuals who have been infected by giardiasis may develop lactose intolerance, affecting their ability to digest milk products. This condition can persist for an extended period, even after the infection has been cured.

Prevention

There are no medications or vaccines for giardiasis. Taking care of your hygiene and avoiding exposure to parasites, as well as preventing the transmission of infection from others, are the main ways to prevent getting giardiasis. These methods include:

• Wash hands with water and soap for at least 20 seconds after using the toilet, changing diapers, or before preparing food. If water and soap are not available, hand sanitizer can be used, although it may not be as effective as handwashing with soap and water.
• Properly processing drinking water. Avoid consuming water from shallow wells, rivers, lakes, direct springs, or fish ponds unless it has been boiled for 10 minutes at 70 degrees Celsius. 
• Washing food ingredients before processing them. Fruits and vegetables need to be washed with clean water and decontaminated before eating. Avoid consuming raw fruits and vegetables in unfamiliar areas.
• Drinking water from certified providers and from unopened or unbroken containers.
• Practicing safe sex, such as using condoms

When to see a doctor?

Consult and see a doctor if you or others around you experience symptoms such as diarrhea, abdominal cramps, bloating, nausea, and vomiting that last for a few weeks. Ignoring these symptoms can lead to dehydration. Inform the doctor if you have been exposed to giardiasis risk factors, such as working or entrusting children in daycare, traveling to areas with a high incidence of giardiasis, or consuming water from high-risk sources like lakes or rivers.

Consult and see a doctor if you or others around you experience symptoms such as diarrhea, abdominal cramps, bloating, nausea, and vomiting that last for a few weeks. Ignoring these symptoms can lead to dehydration. Inform the doctor if you have been exposed to giardiasis risk factors, such as working or entrusting children in daycare, traveling to areas with a high incidence of giardiasis, or consuming water from high-risk sources like lakes or rivers.