October 2007

Giardiasis

• Introduction
• Epidemiology
• Risk for travellers
• Transmission
• Signs and symptoms
• Treatment
• Prevention
• References
• Reading list
• Links

Introduction

Giardiasis is a diarrhoeal illness seen throughout the world. It is caused by a flagellate protozoan parasite, Giardia intestinalis, also known as G. lamblia and G. duodenalis.

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Epidemiology   

Global epidemiology

Giardia is a common cause of gastrointestinal disturbance in both high- and low-income countries [1]. The incidence of Giardia is generally higher in low-income countries (e.g. many countries of Africa, Asia, and South and Central America) where access to clean water and basic sanitation is lacking. Nearly all children in this setting will acquire Giardia at some point in their childhood, and the prevalence of the parasite in young children can be as high as 10%-30% [1]. In areas such as Western Europe and the United States of America, Giardia infection is associated with ingestion of contaminated water, person-to-person spread, recent foreign travel, and recreational swimming [1-3]. Giardia may be a cause of 2%-5% of cases of diarrhoea in high-income countries.

Giardiasis in travellers from England, Wales, and Northern Ireland

Laboratory reports of Giardia by travel history, England, Wales, and Northern Ireland: 1994 to 2005

 

Since 2002, there have been approximately 3,000 cases of giardiasis reported each year in England, Wales, and Northern Ireland [4]. This is a decline since the mid 1990s [Figure]. The percent of cases for which a travel history was available has also declined and was around 10% in 2005. As Giardia is prevalent throughout the world, there are a range of countries for travel-associated giardiasis cases, although the Indian sub-continent remains the most common region of travel for cases of giardiasis (Table below).

Laboratory reports of Giardia lamblia by country of travel, England, Wales, and Northern Ireland: 2004 and 2005

Country of travel	2004	2005	2004-05
India	86	60	146
Pakistan	28	28	56
Turkey	7	12	19
Egypt	15	8	23
Africa	4	8	12
Kenya	11	8	19
Spain	12	8	20
Nepal	8	7	15
France	8	7	15
Thailand	8	6	14
South Africa	7	4	11
Mexico	5	4	9
Bangladesh	5	4	9
Bulgaria	1	4	5
The Gambia	3	4	7
Malaysia	1	4	5
Dominican Republic	2	3	5
Cyprus	2	3	5
Greece	2	3	5
Guyana	-	3	3
Sub total - top 20	215	188	403
Other countries	87 (N=41)	72 (N=33)	159
Country not stated	19	14	33
Total	321	274	595

 

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Risk for travellers

Giardia is prevalent throughout the world, including temperate, high-income countries, such as the UK and the United States. Several studies have examined acquisition of giardiasis in international travellers. For travel-associated case, the risk increases with the duration of travel [5]. A study of German travellers from 1994 and 1997 found that 2.6% (352 of 13,566 persons presenting to an infectious diseases clinic) had giardiasis without another infection [6]. Infection was more common among those visiting the Indian sub-continent or West Africa, although this may have reflected travel patterns. A study of those staying at resort hotels in Jamaica found that 1.2% of travellers reporting to medical units had diarrhoea caused by Giardia [7]. In Tasmania, the prevalence of Giardia infection was as high as 11% in refugees, immigrants, and returned travellers [8], and in an Austrian study the rate of infection was highest amongst trekkers [9]. Ten percent of travellers to Nepal with diarrhoea of 14 days duration or less, and 27% of those with diarrhoea of more than 14 days duration, were infected with Giardia [10].

Length of stay, activities that expose travellers to contaminated water, and sanitation standards in the host country are factors associated with the acquisition of intestinal protozoa such as Giardia [11].

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Transmission

Giardia can be found in humans and many non human mammalian reservoirs such as sheep and cattle. The role of non-human mammals in transmission of Giardia to humans remains unclear.

Infection is acquired via the faecal-oral route [1, 5], often through the ingestion of Giardia cysts from faecally-contaminated water. Person-to-person transmission occurs in conditions of poor faecal-oral hygiene, particularly in low-income settings amongst children, between young children in day care facilities, and amongst men who have sex with men. Transmission of Giardia via food is uncommon.

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Signs and symptoms

Most cases of giardiasis are asymptomatic. In those that do experience clinical illness, the incubation period is usually between 1 and 2 weeks [1, 5]. Therefore symptoms may begin after a traveller has returned home. The most common symptoms are a gradual onset of nausea, anorexia and diarrhoea, accompanied by abdominal cramps, bloating and flatulence [1]. Diarrhoea can persist for several days or weeks and be accompanied by weight loss and lactose intolerance [1]. Severe cases can be associated with malabsorption. Less common are vomiting and fever. Urticaria is rarely seen.

Symptoms often last for more than 10 days and sometimes longer than a month and may come and go.

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Treatment

Persons who have appropriate risk factors and symptoms such as prolonged diarrhoea and weight loss should be suspected of having giardiasis. A diagnosis can be confirmed by a stool examination for ova and parasites or a stool antigen detection assay.

Giardiasis responds promptly to treatment with metronidazole or tinidazole [12] Lactose intolerance and an irritable-bowel like syndrome can occur following infection and need to be distinguished from relapse of infection.

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Prevention

There is no vaccine or chemoprophylaxis for Giardia. Travellers should be advised to observe careful food, water and personal hygiene.

Giardia intestinalis parasites are moderately resistant to chlorine levels found in drinking water, and if there has been a faecal accident in a swimming pool, swimmers may become infected. Travellers should therefore be advised to avoid swallowing water whilst swimming and refrain from using swimming pools if experiencing diarrhoea.

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References      

1. Hill DR, Nash TE. Intestinal Flagellate and Ciliate Infections. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical Infectious Diseases. Principles, Pathogens & Practice. 2nd ed. Elsevier, Philadelphia. 2006:984-8.

2. Copue S, Delabre K, Pouillot R et al. Detection of Cryptosporidium, Giardia and Enterocytozoon bieneusi in surface water, including recreational areas: a one year prospective study: FEMS Immunol Med Microbiol. 2006; 47:351-9.

3.Stuart JM, Orr HJ, Warburton FG, et al. Risk Factors for Sporadic Giardiasis: A Case-Control Study in Southwestern England. Emerg. Infect Dis. 2003; 9, 2

4. Health Protection Agency. Food poisoning and travellers’ diarrhoea. In: Foreign travel-associated illness, England, Wales and Northern Ireland – 2007 report. 2007:28-9.

5. CDC. Giardiasis. Health Information for International Travel. 2008. Atlanta.        2007:150-1. Available at: http://wwwn.cdc.gov/travel/yellowBookCh4-Giardiasis.aspx

6. Jelinek T, Löscher T. Epidemiology of giardiasis in German Travellers. J Trav Med 2000;7:70- 3. Available at: http://www.blackwellsynergy.com/doi/pdf/10.2310/7060.2000.000

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7. Paredes P, Campbell-Forrester S, Mathewson JJ, et al. Etiology of travelers’ diarrhea on a Caribbean island. J Trav Med 2000;7:15-8.

8. Kettlewell JS, Bettiol SS, Davies N, et al. Epidemiology of giardiasis in Tasmania: a potential to residents and visitors. J Travel Med 1998;5:127-30.

9. Reinthaler F, Feierl G, Stünzner D et al. Diarrhea in returning Austrian tourists: Epidemiology, etiology, and cost analyses. J Travel Med 1998;5:65-72.  

10. Taylor DN, Houston R, Shlim DR et al. Etiology of diarrhea among travellers and foreign residents in Nepal. JAMA 1988;260:1245-8.

11. Okhuysen PC. Traveler’s diarrhoea due to intestinal protozoa. Clin Infect Dis 2001;33:110–4. 

12. Gardner TB, Hill DR. Treatment of giardiasis. Clin Microbiol Rev 2001;14:114-28. Available at http://cmr.asm.org/cgi/content/full/14/1/114.

Reading list

Ericsson C, DuPont H, Steffen R. Travelers’ Diarrhea. 2003. BC Decker Inc. Ontario.

Links

Health Protection Agency:

www.hpa.org.uk/infections/topics_az/giardia/menu.htm

Centers for Disease Control and Prevention:

http://www.dpd.cdc.gov/dpdx/HTML/Frames/GL/Giardiasis/body_

Giardiasis_page1.

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