The protozoan Giardia lamblia, also known as Giardia intestinalis. Is a flagellated protozoan that infect and reproduces in the small intestine, cau

sing beaver fever also known as Giardiasis. This protozoan attaches it’s self  to the walls of the small intestine by a ventral adhesive disc, and  is able to asexually reproduce via binary fission.

The infection, Giardiasis does not spread through the bloodstream and other parts of the gastrointestinal tract, but has an affinity for the lumen of the small intestine.Giardia’s trophozoite is anaerobe and obtains their nutrients from the lumen of the small intestine.

Microscopically, if this protozoan is split and stained, its characteristic pattern resembles the familiar “smiley face” symbol or a clown face and the motile trophozoite with a leaf-like  movement.

The Chief pathways of human infection include ingestion of untreated sewage, contaminated food or drinking contaminated water. The contamination of natural waters also occurs in watersheds where intensive grazing occurs. Giardiasis occur worldwide, but  is the most commonly intestinal parasite in the United States and Canada among children in day care centers, hikers, family members, homosexual male partners and immunocompromised adults. It is also more common in overcrowded developing countries that lack sanitary conditions and water quality control. Domestic pets such as dogs and cats also frequently contract giardiasis.

Transmission of Giardia lamblia

This infection can occur through ingestion of giardia lamblia cysts in contaminated water or food, or by the fecal–oral route (through poor hygiene practices). The cyst form can survive for weeks to months in cold water, so can be present in stagnant water, contaminated wells and water systems, It can also be found on surfaces, soil, food, or water that has been contaminated with feces from infected humans or animals. The cysts are very resistant to conventional water treatment methods, such as chlorination and ozonolysis hence difficult to deal with.

Transmission by animals (Zoonotic) is also possible, so Giardia’s infection is a concern for people camping in the wilderness or swimming in contaminated streams or lakes, especially the artificial lakes formed by beaver dams’ reason why it is also known as beaver disease.

Fecal oral transmission will also occur, where there is a poor hygiene practice. People working with children are also at risk of the infection with Giardia lamblia, it goes with the family members of infected individuals.

Not all Giardia infections are symptomatic, and many people can unknowingly serve as carriers of this parasite.

Life Cycle of Giardia Lamblia

This begins with a non-infective cyst excreted in the feces of an infected individual. This cyst stage can survive well in a variety of environmental conditions such as the acidity of the stomach therefore allowing it to pass through to the small intestine where it can replicate and cause clinical illness. Giardia lamblia cysts are then formed and passed through the feces to complete its life cycle and spread to other hosts.

Signs and symptoms

Giardia infection symptoms vary from none to severe diarrhea with mal-absorption of nutrients that eventually leads to

• fatty stools
• weight loss
• fatigue
• difficulties in adsorbing Vitamin A,
• Folate acid
• Vitamin B12
• Flatulence
• abdominal cramps
• nausea or vomiting
• headache
• loss of appetite

One of the most common and prominent symptom is chronic diarrhea which can occur for 4 days or up to a months if untreated. Diarrhea is often greasy (steatorrhoea) and fouls smelling, with a tendency to float due to the presence of fat. Itchy skin, hives, and swelling of the eyes and joints are less common symtoms.

These symptoms develop 9–15 days after exposure but may also occur as early as one day.Some patient turn to be lactose intolerance that may become temporal to permanent.

Laboratory Diagnosis of Giardia Lamblia

Giardia lamblia can be seen microscopically in stool samples when performing stool wet mount. Macroscopic examination should be carried out to check the stool consistency, color and obvious the smell.

Under a normal compound light microscope. Giardia often looks like a “clown face”, with two nuclei outlined by adhesive discs above dark median bodies that form the “mouth” .The motile trophozoite has a falling leaf-like  movement.

Cysts are oval, with four nuclei, and have a retracted cytoplasm.

Prevention of Giardiasis

• Hand-washing and avoiding potentially contaminated food and untreated water.
• Boiling suspected water for one minute before drinking to kill microorganism.
• Chemical disinfectants or filters may be used to maintain sanitary
• Proper handling of infected feces. 
• Venereal transmission happens through fecal-oral contamination. Additionally, diaper changing and inadequate hand washing are risk factors for transmission from infected children.
• Food-borne Giardiasis has developed through the contamination of food by infected food-handlers. Hence proper handling and storing of food.
• Homosexual are advice to use condom

Treatments for giardiasis

In most cases, giardiasis are self limited meaning clearing up on it own. But in case of severe or prolonged infections,The following antiparasitic drugs are recommended

• Metronidazole

• Tinidazole is as effective as metronidazole, mostly the drug of choice.
• Nitazoxanide is a popular option for children because it’s available in liquid form and only needs to be taken for three days.
• Paromomycin

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Reference:

Giardia lamblia Wikipedia

Giardiasis Wikipedia

Giardiasis Healthline