The Herbal Approach
Susan Koten

GIARDIASIS was originally called Cercomonas intestinalis by Lambi in 1859, and renamed Giardia lamblia by Stiles in 1915, in honour of Professor A Giard of Paris and Dr. F. Lambi of Prague

GIARDIA LAMBLIA (synonymous with Lamblia intestinalis and Giardia duodenalis) is a flagellated protozoan parasite that colonises and reproduces in the small intestine causing giardiasis. The giardia parasite attaches to the epithelium by a ventral adhesive disc and reproduces via binary fission. Giardia trophozoites absorb their nutrients from the lumen of the small intestine and are anaerobes. If the organism is split and stained, it has a very characteristic pattern that resembles a familiar "smiley face" symbol.


Although species of Giardia inhabit the intestinal tracts of virtually all classes of vertebrates G Duodenalis is the only species found in humans and most other animals including dogs cats cattle pigs sheep and horses and birds

The common occurrence of Giardia in pet dogs and cats is of public health significance because of the potential for zoonotic transmission. This was highlighted in a study by Bugg et al which found that dogs from multi-dog households were more commonly infected with Giardia than dogs in single-dog households emphasizing the potential ease with which Giardia can be spread to in-contact animals and therefore presumably humans. In Germany 16.5% of pet dogs were infected with Giardia

G duodenalis has a global distribution and is the most common intestinal parasite of humans in developed countries.

G Lamblia is the most common intestinal parasite in humans worldwide and Giardiasis has been ranked in the top ten parasitic diseases of man .

In Asia, Africa and Latin America, about 200 million people have symptomatic giardiasis and some 500,000 new cases reported each day (WHO 1996) It is also a frequently encountered parasite of domestic animals especially livestock, dogs, cats and numerous species of wild mammals have been documented as hosts of Giardia.

Giardia infection can occur through ingestion of dormant cysts in contaminated water, food or by the faecal-oral route through poor hygiene practices. The Giardia cyst can survive for weeks to months in warm water and therefore can be present in contaminated wells and water systems and even clean looking mountain streams. They may also occur in city reservoirs and persist after water treatments as the Giardia cysts are resistant to conventional water treatment methods such as chlorination and ozonolysis. Zoonotic transmission is also possible, and therefore Giardia infection is a concern for people camping.

As well as waterborne sources, faecal-oral transmission can also occur i.e. in day care centres, where children may have poor hygiene practices. Those who work with children are also at risk of being infected, as are family members of infected individuals. Not all Giardia infections are symptomatic and many people can unknowingly serve as carriers of the parasite.

Life Cycle of Giardia

The life cycle begins with a noninfective cyst being excreted with the faeces of an infected individual. The cyst is hardy, providing protection from various degrees of heat and cold, desiccation and infection from other organisms. Once ingested by a host the trophozoite emerges to an active state of feeding and motility. After the feeding stage, the trophozoite undergoes asexual replication through longitudinal binary fission. The resulting trophozoites and cysts then pass through the digestive system in the faeces. While the trophozoites may be found in the faeces only the cysts are capable of surviving outside of the host.

Life cycle of Giardia is in two stages, namely the flagellated trophozoite and the cyst. Trophozoites divide by binary fission within the intestinal lumen. Trophozoites may be stimulated to form cysts by bile secretion in the upper small intestine. Upon ingestion by a new host the cyst stage is stimulated by H+ (Hydrogen ion) to undergo excystation and liberate new trophozoites establishing infection in a new host.

H+ is likely derived from gastric acid secretion or from bicarbonate secretion in the small intestine and this serves as the trigger to initiate excystation of ingested Giardia cysts.

Giardia cysts do not have any mechanism to adhere to intestinal epithelium and therefore are shed in faecal material, thereby serving to propagate infections to new hosts by the spread of cysts through faecal-oral contact or ingestion of shed cysts through intake of food or water.

Upon stimulation of excystation, the filamentous cyst wall undergoes a general weakening and vigorous activity of trophozoite flagella within the cyst appears to mediate rupture of the cell wall. The irregularly shaped trophozite, now containing four nuclei, emerges from the cyst as an ovoid shaped cell with two pairs of flagella that undergo cytodifferentiation and finally completion of cytokinesis to give rise to two new trophozoites, each new trophozoite has four pairs of flagella.

Binary fission of trophozites usually requires 6-8 hrs or longer in some cases.

The formation of cysts has been shown to require about 14-16hrs and involves two stages.

Stage 1 involves stimulation of trophozites with high levels of bile and leads to intracellular formation of cyst wall product that requires about 10-12 hrs before it is secreted and detectable

Stage 11 involves extracellular formation of the filamentous cyst wall

Process of excystation (emerging from cyst) takes less than 20 mins. Once activation has occurred these four stages could be completed within less than10 mins.

Stage 1 activation of cyst by H+ which includes changes in appearance of cyst wall Stage 11 Rupture of cyst wall liberating fluid Stage 111 emergence of undivided trophozite from the cyst Stage 1V the cytodifferentiation of the two daughter cells


Colonisation of the gut results in inflammation and villous atrophy, reducing the guts absorptive capability. In humans, infection is symptomatic only about 50% of the time, and whether to treat asymptomatic individuals is controversial. Symptoms of infection include diarrhoea, malaise, excessive gas (often flatulence or a foul or sulphuric-tasting belch, which has been known to be so nauseating in taste that it can cause the infected person to vomit) stetorrhoea (pale, foul smelling, greasy stools) epigastric pain, bloating, nausea, diminished interest in food, possible (but rare) vomiting which is often violent, and weight loss. Pus, mucus and blood are not commonly present in the stool.

Infection can be prolonged in patients who are immunocompromised or who have decreased gastric acid secretion.

People with recurring Giardia infections particularly those with a lack of Iga, may develop chronic disease.

Lactase deficiency may develop in an infection with Giardia however this usually does not persist for more than a few weeks and a full recovery is the norm.

The pathophysiological process responsible for small intestinal malabsorption and diarrhoea in giardiases appear to share similarities with those observed in other disorders such as bacterial enteritis, chronic food anaphylaxis, Chrohn's disease, and celiac disease.


Gardia lamblia infection in humans is frequently MISDIAGNOSED Accurate diagnosis requires an antigen test or if that is unavailable an ova and parasite examination of stool. Multiple stool examinations are recommended since the cysts and trophozoites are not shed consistently. Also the trophozotes are unstable and may disintegrate before it can be seen. Given the difficult nature of testing to find the infection, including many false negatives some patients should be treated on the basis of empirical evidence TREATING BASED ON SYMPTOMS

Effects on epithelial ultrastructure and function

In studies on human patients the most commonly reported small intestine abnormalities associated with infection have been disaccharidase deficiencies. Giardia has also been shown to impair other digestive enzymes, including trypsin, lipase, and amylase.

In giardiasis, brush border enzyme deficiencies may or may not be associated with villus atrophy. Studies have demonstrated that brush border enzyme abnormalities result from a diffuse shortening of brush border microvilli along the entire villus axis at site of trophozoic attachment as well as in other areas. Together findings from these studies indicate that infection with Giardia causes a diffuse loss of brush border microvillus length which in turn causes epithelial maldigestion and malabsorbtion of electrolytes, nutrients and water, factors which combined contributes to the production of diarrhoea.

So the loss of microvillus height rather than villus atrophy appears to act as the injury responsible for impairment of brush border digestive enzyme activities and reduction of active epithelial absorption in giardiasis.

Role of parasitic products

Giardia causes epithelial injury without invading the mucosa. However an ever increasing number of reports indicate that secretory-excretory products of Giardia are responsible for at least part of the intestinal epithelial abnormalities seen in giardiasis.


Metronidazole (Flagyl) used to treat giardiasis can cause nausea, headaches, disorientation, and can leave a metallic taste in the mouth. It can also encourage yeast growth.

The parasite expert Dr Louis Parish has warned of the misconception that "treatment with a single course of metronidazole is 90% effective" Twenty five years that may have been the case but the protozoa rapidly became resistant.. Today the single cure rate is less than 5%. The ability of parasites to adapt is actually quite remarkable. Like bacteria parasites can use their encysted or resting periods to toughen their cell walls to a nearly impermeable state.

Giardiasis is associated with a wide spectrum of clinical signs which varies in severity from being asymptomatic to severe gastrointestinal illness. The immune status of the host has been shown to influence the susceptibility and the severity of the infection, therefore immunocompromised hosts are vulnerable to severe and chronic infection i.e. diarrhoea, motility disorders (abdominal pain, cramps, bloating), vomiting, anorexia, growth retardation, and allergic disease.


Antiparasitical action of herbs are usually bitter and/or pungent.
Bitters include Wormwood, Neem, Oregan Grape
Pungent herbs include Bayberry, Clove, Garlic

Allium Sativum (garlic)

Whole garlic is an effective inhibitor against Giardia intestinalis. In one study, using visible light microscopy, viable3 Giardia has a distinct shape like a tear drop, they reflect light and are mobile, swimming in a distinct spiral pathway. Often they attach to the glass slide and the mition of the flagella of Giardia can be observed. Addition of whole garlic preparation resulted in a loss of adherence to the glass slide, a loss of motility and flagellar movement. There was also a decrease in cell numbers and an increase in the proportion of swollen misshapen cells.

Artemisia Annua (sweet wormwood) Qing huo

This herb is renowned for its use in treating malaria where its effectiveness is confirmed in both historical data and modern pharmacology. Accordint to WHO (World Health Organisation 1.5 million malaria patients in South East Asia and Latin America were treated with artemisin, a constituent of Qing Huo. In China Falciparum plasmodium resistance to chloroquine is 84.6% but only 2.2-2.4% to artemisinin. Thus a remisinin has completely replaced chloroquine and quinine as drugs of choice fror treatment of malaria. However, it is important to keep in mind that while it is effective as a drug for treatment it is not effective as a casual prophylactic agent.

Qing huo has shown few adverse reactions in toxicology studies. In chronic toxicology studies no abnormalities were reported in heart, liver, kidneys, and other vital organs following long term administration. (Ref Chinese Herbology and Pharmacology by John and Tina Chen)

Dose 3 - 10 grms in decoction. The herb should only be cooked for a short period of time as heat may make it less effective. i.e no more than 15 mins, Tincture: 7.5 - 10 ml per day 1.2 tincture

Kidney herbs

Couch Grass (agropyron repens) Parts used the rhizome
A good diuretic and its demulcent properties is good for irritation and inflammation of the kidneys. Useful in removing kidney stones and gravel

Gravel Root (Eupatorium purpureum) Parts used Rhizome and root
Primary use for kidney stones and gravel

Hydrangea (Hydrangea arborescens) Parts used Dried roots and rhizome
Good in a kidney combination formulae

Parsley Piert (Aphanes arvensis) Parts used Aerial parts A potent diuretic and good for painful urination. Commonly used for kidney and urinary stones and gravel. Also good for water retention due to kidney and liver problems.

Alisma (Alisma orientalis) Parts used Rhizome
Has a potent function to regulate water circulation and resolve fluid accumulation. A good diuretic

In all kidney problems the above combination is a base formulae. The dose is 20ml per herb per week to equal 100ml and this can be doubled to give a stronger dose.


BALMONY (Chelone glabra) Parts used Dried aerial. From the North American Indians it has a long history as a curative remedy for liver and gallbladder problems. Used for gallstones and inflammation of gallbladder.

FRINGETREE (Chionanthus virginicus) Parts used The root bark Specific for all liver and gallbladder problems. Gallstones and inflammation of gallbladder

BARBERRY (Berberis vulgaris) Parts used bark of root or stem. Excellent for stimulating bile flow and correcting liver function. Gallstones and inflammation of gallbladder

BOLDO (Peumos boldo) Parts used Dried leaves. Specific for gallbladder problems. Gallstones and inflammation of gallbladder

WAHOO (Euonymus atropurpureus) Part used Root bark. Primary liver herb and used for pain due to congestion of stones. Inflammation of gallbladder.

The Merck Manual Fifteenth Edition
Giardia the Cosmopolitan Parasite by B.E. Olson and P.M Wallis
WDDTY Vol 17 No 3
WDDTY Vol 8 No.5
WDDTY Vol 15 No 1
Guess What Came to Dinner by Ann Louise Gittleman
The Parasite Menace by Skye Weintraub
The Cure for all Diseases by Hulda Clark
Chinese Medical Herbology and Pharmacology by John K. Chen and Tina T. Chen
The Herb Users Guide by David Hoffman
Power vs Force The Hidden Determinants of Human Behavior bt David Hawkins