It is established that more than half of the patients may harbor the Giardia trophozoites and pass out the cysts without any symptoms at all.

In cases of symptomatic giardiasis that occurs after a mean 9 day average of incubation, the following system-wise presentation may be seen in most patients:

• General appearance: Patients may appear anorexic and nauseated due to electrolyte imbalance and impending dehydration. Some may appear undernourished or malnourished due to malabsorption problems of the gut.
• Head and neck: Infants may present with sunken fontanels during massive diarrhea. Tongue may appear dry and eyes will appear sunken with dehydration. 
• Chest and heart: Tachycardia and shallow breathing may be observable in dehydrated patients.
• Abdomen: Abdominal cramps may present due to the uncontrolled presynaptic release of cyclic AMP in the abdominal muscles due to the enterotoxins effect. The passage of malodorous flatus and stools are due to intestinal malabsorption. Watery diarrhea is a product of the increased endothelial permeability of the intestines. 
• Extremities: Thread-like pulses may be appreciated in dehydrated patients. 
• Neurologic: Decreased mental development may be evident in severely malnourished infants. 

• Weight Loss

  Chronic small bowel diarrhea can also result, with weight loss and signs of malabsorption. [medical-dictionary.thefreedictionary.com]

  Substantial weight loss and fatigue may occur. Chronic giardiasis occasionally causes failure to thrive in children. [msdmanuals.com]

  Usual symptoms of the acute infection are diarrhea, abdominal pain, nausea, and weight loss. Children are more frequently affected than adults. Various extra-intestinal manifestations have been reported, among which are arthritis and arthralgia. [ncbi.nlm.nih.gov]

  Infection with Giardia lamblia causes a chronic diarrheal disease called giardiasis that is characterized by steatorrhea (fatty stools), abdominal cramps, bloating, frequent loose stools, fatigue and weight loss. [ehagroup.com]

• Pain

  Other associated symptoms were abdominal pain (100%), abdominal distension (70%), flatulence (50%), less consistent stools (50%), anemia (30%), and increased erythrocyte sedimentation rate (60%). [ncbi.nlm.nih.gov]

  Other symptoms include foul-smelling and greasy feces, stomach pains, gas and bloating, loss of appetite, nausea and vomiting. [medical-dictionary.thefreedictionary.com]

• Asymptomatic

  Symptoms and Signs of Giardiasis Many cases of giardiasis are asymptomatic. However, asymptomatic people can pass infective cysts. Symptoms of acute giardiasis usually appear 1 to 14 days (average 7 days) after infection. [msdmanuals.com]

  Abstract The aim of this study was to evaluate carbohydrate absorption in well-nourished children with asymptomatic giardiasis. [ajtmh.org]

  CAPC guidelines suggest that asymptomatic dogs and cats may not need treatment. [cliniciansbrief.com]

  See Giardia lamblia. gi·ar·di·a·sis ( jē'ahr-dī'ă-sis ) Infection with the protozoan parasite Giardia lamblia, sometimes asymptomatic but often manifested by diarrhea, dyspepsia, and malabsorption. [medical-dictionary.thefreedictionary.com]

• Camping

  Water supply varied between camps: in some camps water was provided by the municipal water ducts, in others there were individual tanks for each house. Municipal water (piped water) was the major source of drinking water and was used in 15 camps. [bmcpublichealth.biomedcentral.com]

  Travel-related cases (both international and domestic) were more likely to go camping or kayaking, and consume untreated water compared to endemic cases. [ncbi.nlm.nih.gov]

  When travelling, camping or hiking or a “boil water” advisory has been issued, bring the water to a full boil for 1 minute. [algomapublichealth.com]

  When camping: Bring bottled water for drinking, cooking, and brushing teeth. Purify untreated water before using—boil, filter, or sterilize. Thoroughly wash or peel raw fruits and vegetables before eating. [cancercarewny.com]

  Avoid drinking improperly treated water, for example, when camping or during foreign travel. Municipal water supplies with filtration are usually safe. Keep children with diarrhea out of swimming pools. [phpa.health.maryland.gov]

• Malaise

  They are usually mild and include watery malodorous diarrhea, abdominal cramps and distention, flatulence, eructation, intermittent nausea, epigastric discomfort, and sometimes low-grade malaise, fatigue, and anorexia. [msdmanuals.com]

  Up to one half of symptomatic cases progress to chronic disease, with continued loose stools, stomachache, malaise, weight loss, and malabsorption. [clinicaladvisor.com]

  […] attach to the brush border and may cause local damage with ↓ of brush-border enzymes Clinical Acute, intermittent or chronic diarrhea unresponsive to conservative management; foul smelling, greasy stools; occasionally fever and vomiting; otherwise, malaise [medical-dictionary.thefreedictionary.com]

• Diarrhea

  Chronic small bowel diarrhea can also result, with weight loss and signs of malabsorption. [medical-dictionary.thefreedictionary.com]

  In clinically affected animals, diarrhea can be mucoid, pale, and soft and have a strong odor; steatorrhea may be present. Mild to moderate discomfort from abdominal inflammation can occur with diarrhea. [cliniciansbrief.com]

  Symptoms Acute giardia infection causes abdominal cramping and diarrhea, both sometimes quite severe. Some children get chronic giardiasis and have diarrhea and cramps for a long time. Such children lose weight and grow poorly. [healthcentral.com]

  10-CM Diagnosis Code R19.7 Diarrhea, unspecified 2016 2017 2018 2019 Billable/Specific Code Applicable To Diarrhea NOS Type 1 Excludes functional diarrhea ( K59.1 ) neonatal diarrhea ( P78.3 ) psychogenic diarrhea ( F45.8 ) Giardia lamblia A07.1 giardial [icd10data.com]

• Nausea

  Other symptoms include foul-smelling and greasy feces, stomach pains, gas and bloating, loss of appetite, nausea and vomiting. [medical-dictionary.thefreedictionary.com]

  There are many prescription medications available for treating this infection including antibiotics and medications to relieve nausea and vomiting. [news-medical.net]

  They are usually mild and include watery malodorous diarrhea, abdominal cramps and distention, flatulence, eructation, intermittent nausea, epigastric discomfort, and sometimes low-grade malaise, fatigue, and anorexia. [msdmanuals.com]

  Side effects from some of the medicines used to treat giardia are: Metallic taste in the mouth Nausea Severe reaction to alcohol In most pregnant women, treatment should not start until after delivery. [nlm.nih.gov]

• Abdominal Cramps

  The main symptoms are abdominal cramping and diarrhea. People may have abdominal cramping, gas, belching, diarrhea, and nausea and feel tired. [msdmanuals.com]

  Infection with Giardia lamblia causes a chronic diarrheal disease called giardiasis that is characterized by steatorrhea (fatty stools), abdominal cramps, bloating, frequent loose stools, fatigue and weight loss. [ehagroup.com]

  Symptoms Acute giardia infection causes abdominal cramping and diarrhea, both sometimes quite severe. Some children get chronic giardiasis and have diarrhea and cramps for a long time. Such children lose weight and grow poorly. [healthcentral.com]

  Infection may be asymptomatic or may cause nausea; abdominal cramps; foul-smelling, greasy diarrhea; fatigue; and weight loss. Treatment is metronidazole or tinidazole, furazolidone, or paromomycin. It is treated with flagyl. [medical-dictionary.thefreedictionary.com]

• Vomiting

  Sameerna syrup acts to (i) wards off vomiting and sensation of tendency to vomit. (ii) create anti cholera atmosphere in intestines and digestive parts. (iii) control abdominal and renal colic boosts mental and physical health of children. [medium.com]

  Symptoms include diarrhea, abdominal pain, bloating, nausea, and vomiting. In chronic giardiasis the symptoms are recurrent and malabsorption and debilitation may occur. [web.archive.org]

  Another is furazolidone (Furoxone), which comes in liquid form and sometimes causes nausea and vomiting. This is rarely used in the U.S. A third is paromycin (Humatim), which is safe, but not as effective as the other two. [healthcentral.com]

  However, many dogs infected with Giardia do not get diarrhea, vomiting, or any other signs of illness. What happens when Giardia is untreated? Some dogs can get quite sick. These could show variable levels of dehydration, vomiting and diarrhea. [wellesleyanimalhospital.ca]

  Immediately remove and wash any clothes or bedding contaminated with vomit or diarrhoea using soap and hot water. Thoroughly clean and disinfect contaminated surfaces with a bleach-based household cleaner immediately after any episode of vomiting. [healthywa.wa.gov.au]

• Abdominal Pain

  Other associated symptoms were abdominal pain (100%), abdominal distension (70%), flatulence (50%), less consistent stools (50%), anemia (30%), and increased erythrocyte sedimentation rate (60%). [ncbi.nlm.nih.gov]

  Symptoms include diarrhea, abdominal pain, bloating, nausea, and vomiting. In chronic giardiasis the symptoms are recurrent and malabsorption and debilitation may occur. [web.archive.org]

• Urticaria

  Review of the world literature shows an association between giardiasis and urticaria. Other allergic phenomena, such as angioedema and possibly arthropathy, also might be associated with this infection. [ncbi.nlm.nih.gov]

  Anthelmin syrup neutralizes the toxicity and side effects caused by external and internal toxins of worms present in the body such as : (i) Low continuous fever (ii) Flatulence (iii) Diarrhea (iv) Urticaria (v) Difficult breathing (vi) Nervine convulsions [medium.com]

  Other complications include: long-term, non-specific gastrointestinal problems chronic fatigue Studies have also suggested that it may lead to a higher risk of: eye problems muscular complications allergy symptoms, such as urticaria Some reports have [medicalnewstoday.com]

  Giardiasis causing urticaria in a child. Am. J. Dis. Child. 137 :761–763. PubMed Google Scholar Harter, L., F. Frost, G. Grunenfelder, K. Perkins-Jones, and J. Libby. 1984. Giardiasis in an infant and toddler swim class. Am. J. [link.springer.com]

• Headache

  Harmful outcomes were uncommon, and 5-NIs were associated with lower risk of abdominal pain, and higher risk of both bitter or metallic taste and headache. [ncbi.nlm.nih.gov]

  Other symptoms include: Abdominal gas or bloating Headache Loss of appetite Low-grade fever Nausea Weight loss and loss of body fluids Some people who have had a giardia infection for a long time continue having symptoms, even after the infection is gone [nlm.nih.gov]

  The primary symptoms include: diarrhea, abdominal cramps, headaches, nausea, vomiting, and low-grade fever, which can lead to weight loss and dehydration. [water-research.net]

• Lethargy

  Diarrhea may last one or more weeks, accompanied by one or more of the following: headache, fatigue, nausea, vomiting, abdominal pain, stomach cramps, dehydration, lethargy, gas, watery stool, bloating, or swelling. [healthcommunities.com]

  Destroying of feathers, plucking them out feverishly to get at the itch Loss of appetite Weight loss Diarrhea that features mucus and is foul smelling Your bird may itch a lot, scratching and preening Yeast infections that keep reoccurring Depression Lethargy [wagwalking.com]

  Some signs are vomiting, diarrhea, lethargy, dehydration, weight loss, fatigue, and stomach cramps. You are not guaranteed to have any or all of these signs, but they are typically associated with Giardia. [wikihow.com]

The most common diagnostic modality is the direct identification of the Giardia cysts and trophozoites from stools and upper gastrointestinal tract washings under the light microscopy methodology. Direct light microscopy yield is operator dependent and may not be as specific as the immune assays in Giardia intestinalis identification [7].

The more sensitive antigenic test may involve enzyme immune-assays to identify the antigens. Studies have demonstrated that only 10% of the positive yield in Giradia intestinalis antigenic tests can be spotted in direct microscopy [8]. CDC makes use of specific DNA probes in the identification of Giardia intesinalis.

• Giardia Lamblia

  Keywords: giardia lamblia; protozoa; flagellate; intestine; waterborne References Aldeen WE, Carroll K, Robison A, Morrison M and Hale D (1998) Comparison of nine commercially available enzyme‐linked immunosorbent assays for the detection of Giardia lamblia [els.net]

  Who is more susceptible to infection from Giardia lamblia? All individuals are susceptible to infection with Giardia. [ehagroup.com]

  Etiology Pathogen : Giardia lamblia ; (also known as Giardia intestinalis or duodenalis ), a protozoan Transmission Waterborne: from drinking of recreational water (e.g., lakes, rivers, ponds, swimming pools) Fecal-oral (e.g., through food handlers, people [amboss.com]

• Colitis

  (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic) K52.9 - see also Enteritis ICD-10-CM Diagnosis Code K52.9 Noninfective gastroenteritis and colitis, unspecified 2016 2017 2018 2019 Billable/Specific Code Applicable To Colitis NOS Enteritis [icd10data.com]

  カテゴリ 感染症 階層分類 感染症疾患 [BR: jp08401 ] 寄生虫感染症 その他の原生動物による感染症 H00362 ジアルジア症 ICD-11 による疾患分類 [BR: jp08403 ] 01 Certain infectious or parasitic diseases Gastroenteritis or colitis of infectious origin Protozoal intestinal infections 1A31 Giardiasis H00362 ジアルジア [kegg.jp]

  Two to 3 months prior to admission to the hospital, he had undergone evaluation elsewhere that revealed hypogammaglobulinemia, a depressed CD4 cell count, CMV colitis, and giardiasis. [doi.org]

Dehydrated patients may benefit from intravenous fluids and plasma expanders. Antibiotic therapy is still the gold standard in the treatment [9].

Giardiasis is treated with oral metronidazole and tinidazole in adults while nitazoxanides are usually given to pediatric patients. Furazolidone and quinacrine have been also used for but have become less popular due to relative toxicity. Metronidazole and tinidazole are contraindicated with pregnancy.

The prognosis of patients with giardiasis is particularly good. Majority of the cases remains silent and asymptomatic while symptomatic cases are usually self-limiting. Mortality do rarely occur among immunocompromised hosts like premature infants, malnourished children and adults suffering severe dehydration. 

Complications

A number of cases are asymptomatic while symptomatic cases may resolve spontaneously and may cause persistent dysfunctions and complications. The following are the most common complications found in Giardia intestinalis infection:

• Dehydration results from excessive watery diarrhea that damages the cell’s normal functionality.
• Failure to thrive in children with diarrhea may lead to malnutrition and result in permanent mental and physical retardation.
• Milk intolerance occurs due to the progressive flattening of the intestinal villi and malabsorption may predispose patients to lactose intolerance.

The clinical infection in giardiasis is caused by the ingestion of the Giardia intestinalis cysts [2]. Humans are easily affected because of its relatively low infective doses which only range from 10 to 25 cysts to cause a clinically significant disease process.

World epidemics especially in the United States are usually due to waterborne transmission of the Giardia cysts. Food transmission of this intestinal protozoan via food contamination has also been observed among infected food handlers [3].

In the United States, Giardia lamblia has been responsible for at least 90 diarrheal outbreaks between the periods of 1964 to 1984 afflicting more than 23,000 of the population. These were all associated to inadequately treated surface water system in the Western mountain regions of the country where G. lamblia remains endemic up to this date.

Giardiasis has an endemic occurrence in the months of July to October due to increased outdoor activities like recreational camping and mountain climbing [4]. Giardiasis predominantly affects children below the age of five and young adults between the ages 25 and 39 years old. The average prevalence of giardiasis in the United States climbs to as high as 23.5 cases per 100,000 population especially during the endemic months.

The worldwide prevalence of this enteropathogen ranges from 4 to 42% in both temperate and tropical countries. Giardia intestinalis has been implicated in epidemic childhood diarrhea with an infection rating of 15-20% among those below 10 years old [5]. Giardia has also been dubbed as the most common intestinal parasite in United Kingdom and Eastern Europe.

The highest prevalence rating of G. intestinalis reaching 73.4% is found in Nepal. Giardiasis may occur more common among males than females. It affects all ages but age-specific incidence is described to rise from infancy and wanes down during adolescence [6]. The Centers for Disease Control (CDC) identifies children between the age 1 to 9 years old and adults with ages 35 to 44 are most prone to the infection.

The Giardia cysts entry to human gut is notably more common via oral-fecal route or waterborne transmission. Although a great majority of the human population in endemic areas pose as a Giardia carrier, a great majority of the cases remains asymptomatic.

Symptomatic patients generally present the infection within a mean average of 9 days of incubation and convey the whole natural clinical course from 3 to 10 weeks.

There are a number of postulated mechanisms that explain the pathophysiology of Giardia intestinalis in humans.

The most common of which is the adhesion of the Giardia trophozoite to the intestinal villi which flattens the intestinal brush borders causing increased endothelial permeability to cause watery diarrhea. The flattening of the villi has been closely associated with malabsorption syndromes among patients.

Giardia has also been identified to release an enterotoxin that damages the villi and contributes to the symptomatology.

Giardiasis is effectively prevented by water treatment of public water sources with iodine and chlorine containing purifying compounds. Food handlers are encouraged to hygienically prepare food products to avoid fecal-oral route of transmission.

Water may be chlorinated and boiled at home for safety. Some fine filtration systems has been proven to remove Giardia intestinalis cysts from water sources. The proper pasteurization of milk products from dairy farm may prevent infections through zooanthroponotic transmissions [10].

Giardiasis is a clinical disease caused by a flagellated parasitic protozoan Giardia intestinalis (new name of Giardia lamblia) which is revered to be the most common intestinal protozoan parasite in the world [1].

Giardiasis is an ubiquitous intestinal infestation with predilection to poor sanitation and dirty water supply worldwide. Patients will usually complain of abdominal bloating, cramps, nausea and multiple bouts of diarrhea.

Giardiasis may be transmitted through oral-fecal route or from host person to another. The disorder is often times self-limiting but intestinal complication may persist with time. Although antiprotozoal medications provide adequate coverage for giardiasis, good sanitary awareness and clean hygienic practices are paramount to its prevention.

Definition

Giardiasis is a very common intestinal infestation that occurs anywhere in the world which is more endemic in regions with poor health sanitation and dirty water supply.

Cause

Giardiasis is caused by a flagellated protozoan called Giardia intestinalis (G. lamblia as its old name).

Symptoms

Abdominal cramping, pain, malodorous flatus and stools, and watery diarrhea occurs. 

Diagnosis

Giardiasis is diagnosed by direct light microscopy and immune fluorescence assay.

Treatment and follow-up

Patients diagnosed with Giardiasis will benefit from antiprotozoal agents like metronidazole and tinidazole. Patients suffering from dehydration may be given fluid and plasma expanders. Patients must practice proper hygiene and sanitation to prevent its recurrence.

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3. Robertson LJ, Forberg T, Hermansen L, Gjerde BK, Langeland N. Molecular characterisation of Giardia isolates from clinical infections following a waterborne outbreak. J Infect. Jul 2007; 55(1):79-88.
4. Fort GG, Mikolich DJ, Policar M. Giardiasis. In: Ferri FF. Clinical Advisor. 3rd ed. Philadelphia, PA: Mosby, An Imprint of Elsevier; 2009:358.
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10. Dixon B, Parrington L, Cook A, Pintar K, Pollari F, Kelton D, Farber J. The potential for zoonotic transmission of Giardia duodenalis and Cryptosporidium spp. from beef and dairy cattle in Ontario, Canada. Vet Parasitol. 2011; 175(1-2):20-6