Giardiasis is an intestinal infection caused by the parasite Giardia lamblia that affects an estimated 200 million people globally each year. Although it's traditionally been considered a tropical disease, giardiasis is becoming more common in the developed countries, especially among children. Nearly 2 per cent of adults and 6 to 8 per cent of children are reportedly infected with the microorganism in devel-oped countries worldwide. Yet, the true figures are likely to be much higher, as many cases have been mis- or undiagnosed (see Facfile A).
Antibiotics such as metronidazole are the usual treatment of choice, but drug resistance is an increasing problem, with laboratory studies showing that Giardia parasites are now resistant to the currently available antigiardial drugs (Expert Opin Drug Saf, 2003; 2: 529-41). Metronidazole, in particular, is associated with clinicalresistance prevalence levels as high as 20 per cent and recurrence rates as high as 90 per cent (Altern Med Rev, 2003; 8: 129-42).
There's also the issue of safety. In some cases, metronidazole can cause serious neurological side-effects such as seizures, peripheral neuropathy (nerve damage causing numbness and pain in the extremities) and encephalopathy (disordered brain function and/or structure) (J Med Case Reports, 2011; 5: 63). More common side-effects include vomiting, diarrhoea, upset stomach and loss of appetite, which ironically are the symptoms of giardiasis itself.
Happily, there are safer, more effective ways to manage the infection. Herbal medicine has great potential to influence the course of giardiasis. Combined with simple dietary changes, it may be the best natural weapon we have against this common waterborne parasite.
A qualified medical herbalist can prescribe the best herbs for you based on your symptoms. The following appear to be most useful, based on scientific studies.
- Garlic (Allium sativa). Garlic has a long history of use as an antiparasitic and antimicrobial agent, and research suggests that both whole raw garlic and some of its constituents possess antigiardial activity (Microbiology, 2000, 146: 3119-27). In one clinical trial, 26 children infected with Giardia took either 5 mL of fresh garlic blended with distilled water or a commercial garlic preparation (two 0.6-mg capsules), twice a day for three days. In all cases, their clinical symptoms subsided within 36 hours. By the end of the study, stool samples revealed that the children were free of the parasite (J Egypt Soc Parasitol, 1991; 21: 497-502).
- Indian long pepper (Piper longum). This herb is used in Ayurvedic medicine to treat intestinal disorders. In test-tube studies, extracts of P. longum have shown total Giardia-killing activity. In mice, the herb was found to reduce the number of intestinal trophozoites-the active form of the parasite-by 75 per cent after five days (Phytother Res, 1999; 13: 561-5). These results, however, may not apply to humans.
- Pippali rasayana (PR). Prepared from P. longum and Butea monosperma ('Flame of the Forest' or 'palash' tree), PR is a traditional Ayurvedic remedy for chronic dysentery and worm infestations. In a randomized controlled trial of 50 giardiasis sufferers, half were given 1 g of PR three times a day, while the other half took a placebo.
After 15 days, stool samples showed the complete disappear-ance of Giardia in 92 per cent of the PR group vs 20 per cent with the placebo. Moreover, the general signs and symptoms of ill health and abdominal discomfort were significantly reduced in those taking PR (J Ethnopharmacol, 1997; 56: 233-6).
Laboratory studies suggest that PR has no direct antigiardial activity. Instead, it appears to work by enhancing the immune system and other mechanisms responsible for clearing infection from the body (Altern Med Rev, 2003; 8: 129-42).
- Oregano (Origanum vul-gare). In the lab, this common culinary herb demonstrated antigiardial activity superior to that of tinidazole, an antibiotic often used to treat giardiasis (Rev Invest Clin, 1994; 46: 343-7). More recently, among 18 tested essential oils, oregano oil was one of the most active against Giardia trophozoites (Nat Prod Commun, 2010; 5: 137-41).
- Berberine-containing herbs. Berberine is a compound found in several plants, including barberry, Oregon grape and goldenseal. According to test-tube studies, berberine salts and extracts can inhibit the growth of Giardia trophozoites (Tokai J Exp Clin Med, 1990; 15: 417-23).
In a controlled clinical trial, 40 giardiasis sufferers were given either berberine, metro-nidazole or vitamin B-complex syrup (as a placebo) for six days. Although berberine wasn't as effective as metronidazole at reducing parasite-positive stools (68-per-cent vs 100-per-cent reduction), berberine appeared to be superior for reducing gastrointestinal symptoms. It was also better than the placebo (associated with a 25-per-cent reduction in Giardia-positive stools). The researchers believe that an increase in dose or longer duration of treat-ment would increase berber-ine's treatment success (Altern Med Rev, 2003; 8: 129-42).
- Propolis. Although not strictly a herb, propolis-the sticky substance made by bees from plant resins-is often used in herbal medicine to treat infections.
In a trial of 138 adults and children with giardiasis, the participants received a five-day regimen of either tinidazole or propolis. The children were given a 10-per-cent propolis solution, whereas adults took either a 20-per-cent or 30-per-cent solution.
Cure rates were 52 per cent in the propolis-treated children, 40 per cent in the adults taking the 20-per-cent propolis and 60 per cent in those taking the 30-per-cent propolis-with no side-effects. On the other hand, a 40-per-cent cure rate was reported for the tinidazole group (Acta Gastroenterol Latinoam, 1988; 18: 195-201).Beneficial nutrition
Dietary changes can also help get rid of Giardia infection. According to one scientific review, consum-ing a whole-food, high-fibre, low simple-carbohydrate and low-fat diet can help to reduce symptoms, boost the body's defence mechan-isms and even prevent the growth of trophozoites (Altern Med Rev, 2003; 8: 129-42). Specifically, the follow-ing foods are recommended.
- Probiotics. These micro-organisms can directly inhibit Giardia growth and trigger innate immunological anti-giardial mechanisms. The Lactobacillus johnsonii strain La1, for instance, inhibited the growth of Giardia in test-tube studies and enhanced levels of immunoglobulin A (IgA, an antibody that plays a crucial role in protecting mucosal surfaces) immune responses (Appl Environ Microbiol, 2001; 67: 5037-42; Altern Med Rev, 2003; 8: 129-42).
The L. acidophilus strain La5 and L. rhamnosus strain GG also appear to enhance immune responses, which may help to encourage intestinal clearance of Giardia. Try eating half a cup of low-fat yoghurt containing one or more of these strains (with guaranteed levels of viable bacteria at a minimum of 106/mL), or take a probiotic supplement.
- Wheat germ. This contains an agent (agglutinin) shown to inhibit the growth of Giardia trophozoites in the laboratory (J Clin Invest, 1994; 94: 2283-8).
In a double-blind, placebo-controlled trial, 63 giardiasis sufferers, 25 of whom had no symptoms, consumed wheat germ (2 g or 1 tsp three times daily) or a placebo for 7-10 days. The 38 participants with symptoms were also given metronidazole.
The results showed that, in the asymptomatic patients, giardial cyst and trophozoite numbers were reduced by 60 per cent with wheat germ compared with a placebo, with a significant reduction seen within 24 hours. In the symptomatic patients, a trend towards more rapid resolution of symptoms was noted in the wheat-germ group (Am J Trop Med Hyg, 2001; 65: 705-10). It may be that a larger amount of wheat germ (1-2 tbsp three times a day) is necessary for a significant effect (Altern Med Rev, 2003; 8: 129-42).
- Fibre. Animal studies suggest that a diet high in insoluble fibre may protect against Giardia. Gerbils fed a low-fibre diet were significantly more likely to present with giardiasis after inoculation of Giardia cysts than gerbils on a high-fibre diet. When the infected animals on the low-fibre diet were switched to a high-fibre diet, trophozoites were cleared from the small bowel (Am JTrop Med Hyg, 1989; 41: 512-20). However, these results may not apply to humans. Good sources of insoluble fibre include beans, brown rice, oats and lentils.
Factfile A: Symptoms and prevention
Giardiasis can cause a range of symptoms including diarrhoea, abdominal pain, bloating, loss of appetite, weight loss and fatigue. Because the symptoms overlap with many other disorders, such as irritable bowel syndrome (IBS) and coeliac disease, giardiasis is often misdiagnosed and patients may suffer for years without proper treatment. In up to 50 per cent of cases, however, there are no symptoms at all.
Giardiasis can occur by ingesting water or food contaminated by faeces from infected humans or animals, or through person-to-person contact. Giardia is protected by an outer shell, called a 'cyst', which allows it to survive outside the body for long periods of time.
A person only needs to pick up a few of these cysts for the infection to develop. So, to prevent giardiasis:
- wash your hands after going to the toilet, changing a nappy, and before handling and eating food;
- use bottled water when travelling in parts of the world where the water supply is likely to be unsafe;
- keep your mouth closed when swimming in pools, lakes or streams.
Factfile B: The gallbladder connection
Medical herbalist Susan Koten-founder of the Willow Herbal Centre in Romford, Essex-has been successfully treating patients with giardiasis for some 20 years. She estimates that, in about 60 per cent of cases, the gallbladder is affected and must be addressed in addition to the intestinal infection.
Susan uses a combination of herbs, including fringetree (Chionanthus virginicus), Leptandra virginica and barberry (Berberis vulgaris) to flush out the gallbladder, and a fresh tincture of sweet wormwood (Artemisia annua) to clear the Giardia infection.
One patient, a 78-year-old woman, had been suffering for years with IBS-like symptoms-mainly, loose stools, abdominal pain and lethargy. Using muscle testing, Susan diagnosed Giardia in the small intestine and gallbladder, and prescribed sweet wormwood along with a 'gallbladder mix'. By her second visit, the patient's bowel movements had returned to normal, her energy had improved and she was no longer experiencing abdominal pain.
For more information, contact the Willow Herbal Centre (www.willowherbalcentre.co.uk; tel: 01708 381 478).
WDDTY 22 no 7, October 2011