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:
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 .
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 . CDC makes use of specific DNA probes in the identification of Giardia intesinalis.
Dehydrated patients may benefit from intravenous fluids and plasma expanders. Antibiotic therapy is still the gold standard in the treatment .
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.
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:
The clinical infection in giardiasis is caused by the ingestion of the Giardia intestinalis cysts . 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 .
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 . 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 . 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 . 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 .
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 .
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.
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.
Giardiasis is caused by a flagellated protozoan called Giardia intestinalis (G. lamblia as its old name).
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.