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 PDT

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Giardiasis, also known as beaver fever or giardial infection is an infection of the digestive system, caused by giardia lamblia, a single-celled organism (parasite). According to the US CDC (Centers for Disease Control and Prevention), there are approximately 20,000 cases in the USA each year. However, the true incidence is probably in the millions. The National Health Service (NHS), UK, says there are about 3,000 identified cases annually. As the organism also infects other mammals apart from humans, it is very hard to eradicate.

Giardiasis occurs all over the world. It is more common in areas with poor sanitation, among individuals engaged in ano-oral sex, and institutions.

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.

Giardiasis occurs when infective cysts enter the body. Transmission can be from person-to-person, through water supplies, and venereal (transmitted by sexual intercourse). Poor handwashing can accelerate the spread of infection, for example, if an infected person does not wash their hands after going to the toilet and then shakes other people's hands, contaminates surfaces, handles food, etc.

Food-borne epidemics can occur through food contamination by infected food handlers.

Infected babies can transmit infection if diaper changing is done with inadequate handwashing.

Even in developed nations, modes of transmission vary. While in the USA water-borne transmission is common, in the UK it is not.

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.

If symptoms do appear, they will usually do so about 7 days after the person becomes infected - it can take longer.

Not every infected person has symptoms, even though they can still spread it to others. If symptoms do occur they may include:

• Slight fever
• Abdominal bloating
• Foul flatus - strong smelling wind
• Dehydration - in extreme cases
• Abdominal cramps
• Abdominal pain
• Burping
• Fatigue
• Heartburn
• In some cases Lactose intolerance may occur
• Indigestion
• Loss of appetite
• Malaise
• Nausea
• Upset stomach
• Halitosis - foul smelling breath
• Watery, sometimes foul-smelling diarrhea. Stools usually eventually become greasy, but do not contain blood. Watery diarrhea may cycle with soft stools and constipation.
• Weight loss, which can be severe

The majority of patients improve within a couple of weeks, some may take up to six weeks, and others even longer. Medications can help speed up recovery.

What are the causes of giardiasis?

There are two types of Giardia, the active form which exists in the gut of the infected person/animal, or the inactive cyst form which can remain dormant in the environment for several months.

The microscopic parasite is called giardia lamblia or giardia intestinalis.

Most infected individuals are unaware because they do not have any symptoms. The WHO (World Health Organization) estimates that up to nearly one third of some countries' populations are infected. It is widespread in sub-Saharan Africa, south and southeast Asia, Central America, western parts of South America, Russia, Turkey, Romania, and Bulgaria.

Parasites can leave their host's body when a person/animal passes a stool. Outside, they form a hard protective shell and become a giardia cyst where they can survive for several months in the environment.

The infection spreads most commonly when people drink water that has been tainted by infected feces - a common occurrence in countries with poor sanitation.

The infection can also spread if infected people do not wash their hands after going to the toilet, and then handle food and eating utensils.

Streams and lakes may be contaminated.

Touching the anus of an infected person significantly increases the risk of developing giardiasis.

Swimming pools - infected babies who are placed in a pool wearing their diapers can potentially contaminate that swimming pool. Anybody who swims there is at risk of becoming infected.

Wind can pick up the parasite cysts from infected manure on farmland and blow it in any direction.

Diagnosis of giardiasis

A stool sample is taken and sent to the lab to check for giardia cysts. Sometimes several samples are needed, because an infected person does not expel cysts every time they go to the toilet.

Complications of giardiasis

Dehydration - diarrhea can lead to dehydration. If the water loss is severe it can be serious, especially for children and babies. It is important to consume plenty of fluids, preferably water.

What are the treatment options for giardiasis?

Metronidazole (Flagyl) - a very effective medication for the treatment of giardiasis. The adult dosage is 250 mg three times daily for 5 days. The pediatric dosage is 5mg per kilogram of body weight per dose, 3 times daily for 5 days. Side effects are very rare, but may include convulsions, confusion, hallucinations, a rash, nausea, dark/cloudy urine, vomiting and drowsiness. Metronidazole inhibits aldehyde dehydrogenase - a substance which breaks down alcohol - so, avoid alcohol when on this medication.

Other possible medications: Tinidazole (Fasigyn) - adult dosage 2g (taken once), pediatric dosage 50mg per kilogram of body weight (taken once, max 2g).
Nitazoxanide - adult dosage 500mg two times daily for 3 days, pediatric dosage, 103 years 100mg every 12 hours for 3 days, 4-11 years 200mg every 12 hours for 3 days.

Prevention of giardiasis

Handwashing - wash your hands before and after going to the toilet, before and after eating, before and after changing a diaper, before and after handling food (cooking or preparing food).

Drinking water - beware of water in rivers and lakes. If you are camping make sure you have brought your own water supply or some means of boiling it.

Travelling abroad - if you are in a part of the world where clean water is scarce, only use purified bottled water. Avoid ice (you do not know what type of water was used to make it). If you drink straight from the bottle wipe the rim with a tissue before you start drinking. Avoid eating raw foods. Brush your teeth with purified water. Keep your hands spotlessly clean.

Written by Christian Nordqvist


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