What Is Giardiasis? What Causes Giardiasis?

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Main Category: GastroIntestinal / Gastroenterology
Also Included In: Infectious Diseases / Bacteria / Viruses;  Tropical Diseases;  Pediatrics / Children's Health
Article Date: 12 Oct 2009 - 11:00 PST

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Giardiasis is an infection of the digestive system. It is caused by a parasite that is found all over the world called giardia intestinalis. It is one of the most common waterborne diseases and is frequent in areas with poor sanitation and unsafe water.

According to Medilexicon's medical dictionary, Giardiasis is: "Infection with the protozoan parasite Giardia; G. lamblia may cause diarrhea, dyspepsia, and occasionally malabsorption in humans."

The parasites are found in streams and lakes, but also in municipal water supplies, swimming pools and spas. The infection can also be transmitted by drinking contaminated water, eating food washed with contaminated water, person-to-person contact, or when an infected person does not wash their hands properly after using the toilet and handles food that is then eaten by others.

The symptoms of this intestinal infection are abdominal cramps, bloating, nausea and diarrhea.

Infections usually clear up within six weeks. But there may be recurrent episodes or intestinal problems long after the parasites are gone.

It occurs at any age but is common in young children. It is a serious problem for poor children who live in poorer countries because the symptoms of diarrhea can quickly make them dehydrated and malnourished. This can be fatal.

In general, several drugs are effective against giardia parasites. Prevention is the best defense.

What are the signs and symptoms of giardiasis?

A symptom is something the patient feels or reports, while a sign is something other people, including a doctor, may detect. For example, a headache may be a symptom, while a rash may be a sign.

Some people with giardia infection never develop signs or symptoms. However, they still carry the parasite and can spread it to others through their stool. This is known as asymptomatic giardiasis.

Signs and symptoms usually appear one to two weeks after exposure. They may include:

• A low-grade fever (for example a temperature of 37-38ºC (98.6-100.4ºF))
• Abdominal bloating
• Abdominal cramps
• Abdominal pain
• Burping
• Fatigue
• Indigestion
• Loss of appetite
• Nausea
• Upset stomach
• Watery, sometimes foul-smelling diarrhea
• Weight loss (as much as 10 percent of your body weight)
• Malaise
• Heartburn
• In some cases Lactose intolerance may occur
• In acute or severe cases, signs of dehydration or malnutrition

Those symptoms usually resolve within two weeks, although in a few cases diarrhea can persist for several months or even years. However, this chronic (long-lasting) form of giardiasis is rare in people who have received medical treatment for the condition.

In some unusual cases there can be allergic manifestations such as urticaria, erythema multiforme, bronchospasm, reactive arthritis, and biliary tract disease.

What are the causes of giardiasis?

There are two types of Giardia:

• Active form. It lives in the intestines of an infected animal or human.
• Inactive cyst form. It can survive for months in the environment.

When ingesting the inactive cysts, their hard shells break down in the stomach, releasing the parasites. The parasites then stick to the wall of the small intestine. They eventually reproduce by the millions and damage the intestinal wall. This interferes with the ability to absorb food, leading to diarrhea and weight loss.

After some time the parasites detach from the small intestine, transform back into cysts and are shed in the feces. They can survive in soil or water for long periods until they are ingested by another host.

There are three different ways of developing giardiasis:

• Water. It is the main source of giardiasis. The parasites are found in lakes, ponds, rivers and streams worldwide, municipal water supplies, wells, cisterns, swimming pools, water parks and spas. Ground and surface water can become contaminated from agricultural overflow and wastewater discharge. This most commonly occurs in countries that have poor sanitation and limited access to clean water.
  
  Water can also become contaminated from animal feces, because giardiasis affects beavers, muskrats, small rodents and a variety of birds, reptiles and fish. In Canada giardiasis is nicknamed 'Beaver fever'. There have been a number of cases where hikers and campers have contracted giardiasis after drinking contaminated water from streams and lakes. It is not recommended to drink untreated water that has not been boiled or chemically treated, even if it looks clean.
  
  Small children using diapers and people with diarrhea may accidentally contaminate pools and spas. Infection can take place after drinking contaminated tap water at home or abroad, accidentally swallowing water from an infected pool or spa.


• Food. Giardia parasites can be transmitted through food. Raw produce is irrigated or washed with contaminated water. Another way is when food was handled by someone with giardiasis who did not wash their hands. Because cooking food kills giardia, food is a less common source of infection than water is, especially in industrialized countries. However, outbreaks can occur through ice and infected food service workers.


• Direct contact. If hands become contaminated with fecal substance, for example, parents changing a child's diapers are especially at risk. So are child care workers and children in child care centers. The giardia parasite can also spread through anal sex.

What are the risk factors of giardiasis?

Anyone can pick up giardia parasites but some people are especially at risk:

• Children. Giardiasis is far more common in children than it is in adults. Children are more likely to come in contact with feces, especially if they wear diapers, are toilet training or spend time in a child care center.

Children also tend to put their hands or other objects in their mouths. They may swallow lake or pool water, and can be careless about hand washing.

• Child care workers and parents. Adults who are in contact with young children, especially in schools and child care centers. Parents of infants and toddlers are at risk of infection.


• People without access to safe drinking water. Giardiasis is more typically found in places where sanitation is inadequate or water is not safe to drink.


• Travelers. When traveling to places where giardiasis is common, it is advised to be careful with food and drink. The risk increases with the amount of time spent in a region and is greatest in rural or wilderness areas.


• Hikers and campers. In the United States, giardia parasites may inhabit mountainous areas where lakes and streams have become contaminated.


• People who drink from shallow wells. According to the Environmental Protection Agency, all surface water in the United States contains giardia parasites.


• People who have anal sex. Having anal sex without using a condom increases the risk of giardia infection and other serious sexually transmitted diseases.

Diagnosis of giardiasis

If diarrhea disappears within a week or less, it probably is not giardiasis.

It is recommended to seek medical advice when there is abdominal bloating, loose stools, dehydration and nausea lasting two weeks or more. Giardiasis can be easily overlooked because the signs and symptoms resemble those of other gastrointestinal diseases. It is important to mention during a medical examination if there is a child in child care, a recent excursion to an endemic area, or if there was swallowing of water from a lake or stream.

Giardiasis can be diagnosed by checking stool samples for giardia cysts. This is usually done in a laboratory. Several stool samples may need to be checked over a period of several days, because giardia cysts are not always present in the stools. Stool tests may also be used to monitor the effectiveness of the received treatment.

Complications of giardiasis

In industrialized countries Giardia infection is almost never fatal. However, it can cause lasting symptoms and serious complications, especially in infants and children under five. The most common complications include:

• Dehydration. Often a result of severe diarrhea, dehydration occurs when the body does not have enough water to function properly. Dehydration can be very serious. A substantial loss of water is dangerous to the human body because it loses key minerals, such as salt and potassium. It is essential to drink plenty of water, particularly after each bout of diarrhea.


• Dehydration in children: Young children are at particular risk from dehydration because their bodies are smaller and contain a smaller amount of fluids. They should drink plenty of fluids. It is important to be aware of the symptoms of dehydration in children because it is potentially more serious than the giardiasis infection itself. Symptoms of dehydration include:
  
  
  • Deep, fast breathing
  • Dry mouth and eyes
  • No tears are produced when the child cries
  • Sunken appearance of the eyes
  • Urinating infrequently
  • Weakness and sluggishness
  
  The most effective treatment for dehydration is oral rehydration solution (ORS). It typically comes in sachets that are available without prescription (over-the-counter, OTC) at the local pharmacy. They dissolve in water and help to replace salt, glucose, and other important minerals that a child loses through dehydration.


• Failure to thrive. Chronic diarrhea from giardia infection can lead to malnutrition and harm children's physical and mental development.


• Lactose intolerance. Some people may develop lactose intolerance which is the inability to properly digest milk sugar. The problem may persist long after the infection has cleared.


• Skin rash. In rare cases, giardia infection may cause a skin irritation.

What are the treatment options for giardiasis?

Children and adults who have giardia infection but no symptoms usually do not need treatment unless they are likely to spread the parasites.

When signs and symptoms are severe or the infection persists, giardiasis can usually be successfully treated with antibiotics, such as metronidazole or tinidazole. They are equally effective, but tinidazole requires a shorter course of treatment. Both can cause side effects, such as a metallic taste, nausea and vomiting. Avoid drinking alcohol during treatment.

Pregnant women should not use these drugs during the first trimester, because they may lead to birth defects. Pregnant women may be treated with the less toxic and less effective drug paramomycin. Metronidazole may be considered only in extreme cases where signs and symptoms are severe.

If an individual is diagnosed with giardiasis, other members of the household may be advised to have treatment with metronidazole. This may be recommended as a precautionary measure in case they have also been infected.

Prevention of giardiasis

Common-sense precautions help reduce the chances of becoming infected or spread the infection to others.

• Washing hands. This is the simplest and best way to prevent most kinds of infection. Wash hands after using the toilet or changing diapers and before eating or preparing food. Scrub hands vigorously with soap and warm water for at least 15 seconds. Make sure that both the front and back of hands are clean. Rinse thoroughly, and then dry hands with a disposable paper towel. When soap and water are not available, alcohol-based sanitizers containing at least 60 percent alcohol are an excellent alternative. Children should be encouraged to wash their hands regularly.


• Purify water. If the water is not safe to drink, it can be purified using one of these methods:
  
  
  • Heating or boiling water to at least 158 F (70 C) for ten minutes.
  
  
  • Using a water filter. The Center for Disease Control and Prevention recommends a filter with a pore size of 1 micron or smaller in order to be effective for cyst removal.
  
  
  • It is not recommended to rely on chlorine or iodine water purification tablets as they are not always effective against giardia parasites.


• When camping, bury your waste. Without access to a toilet, bury your waste and your pet's at least 6 inches (15 centimeters) deep and 150 feet (about 46 meters) from a water source.


• Try not to swallow water when swimming in pools, lakes or streams.


• Be careful with tap water. Water can become contaminated if standard treatments are not effective or natural events, such as flooding overwhelm treatment systems. If an outbreak of giardia infection occurs locally, it is advised to buy bottled water or boil or filter tap water before using it.


• Traveling. In parts of the world where the water supply is likely to be unsafe, it is recommended to drink and brush your teeth with bottled water. Do not use ice, and avoid raw fruits and vegetables.


• Safe sex. If engaging in anal sex, use a condom every time.

If you are infected, keep others safe by following these measures:

• Wash your own hands. Scrub your hands with soap and warm water for at least 15 seconds after using the toilet and before handling food. It is important to keep in mind that parasites can spread for several weeks after symptoms have stopped.


• Stay out of the water. Avoid all types of recreational water (pools, hot tubs, whirlpool spas, lakes and streams) for at least two weeks after the diarrhea has stopped. The spread of infection can continue after the symptoms have disappeared.


• Avoid sharing utensils or towels.


• It is recommended that the infected individual stay away from work or college until completely freed from symptoms for 48 hours.


• Safe-sex. Avoid having any kind of anal or oral-anal sex until free from infection.

Travelling abroad

It is recommended to drink bottled water when travelling to countries where giardiasis is widespread and sanitation is poor. Make sure that the bottle is properly sealed.

Also, avoid eating raw fruit or vegetables because these may have been handled by somebody with giardiasis.

Places where giardiasis is widespread include:

• Bulgaria
• Central America
• Countries of the former Yugoslavia
• Romania
• Russia
• South and southeast Asia
• Sub-Saharan Africa (all the countries south of the Sahara Desert)
• Turkey
• Western parts of South America

Written by Stephanie Brunner (B.A.)
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today