Giardiasis 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. Epidemiology Global epidemiology Giardia is a common cause of gastrointestinal disturbance in both high- and low- income countries . 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% . 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: 2004-2010
Between 2004 and 2010, there were between 2,903 and 3,751 laboratory confirmed cases of Giardia lamblia in England, Wales and Northern Ireland
(EWNI) each year .The proportion of reported travel-associated infections was 8% on average each year. It should be noted that the presence of a travel history is often used as a criterion for testing for Giardia and it is possible that because of this, cases acquired in the UK may be under reported. As Giardia is prevalent throughout the world, countries of travel for most travel-associated cases of Giardia lamblia tend to reflect regions and countries of the world where
hygiene and sanitation facilities are less robust. India and Egypt are commonly reported countries for Giardia lamblia acquired abroad [Table 1].
Table 1. Top 20 most reported countries of travel for travel-associated Giardia lamblia, England, Wales and Northern Ireland: 2010 and 2009 Country of travel 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 cases, the risk increases with the duration of travel . A systematic review of studies from 1973-2004 found that Giardia was the causative organism in 1.3%, 1.6%,
6.2% and 5.7% of studies from Latin America and Caribbean, Africa, South Asia and Southeast Asia respectively . However, a study of acute diarrhoea in returned European travellers presenting to 16 EuroTravNet clinics in 2010 found 16% of cases were due to Giardia . Giardia was the cause of 11% of travellers’ diarrhoea presenting to a clinic in Nepal . 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 .
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.
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 . Diarrhoea can persist for several days or weeks and be accompanied by weight loss and lactose
intolerance . Severe cases can be associated with malabsorption. Less common are vomiting and fever. Urticaria is seen rarely. Symptoms often last for more than 10 days and sometimes longer than a month
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 albendazole, metronidazole or tinidazole [10,11] Lactose intolerance and an irritable-bowel like syndrome can occur following infection and need to be distinguished from relapse of infection. Prevention There is no vaccine or chemoprophylaxis for Giardia. Travellers should be advised to observe carefuld 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.
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. Giardia lamblia 2010 Travel and Migrant Health Section, HPA. January 2013 [Accessed 25 June 2013]. Available at: 5. CDC. Giardiasis. Health Information for International Travel. 2012. Atlanta. 2012:169-170-1. [Accessed 25 June 2013]. Available at: http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-
related-to-travel/giardiasis.htm . Global etiology of travelers' diarrhea: systematic review from 1973 to the presen09 Apr;80(4):609-14. 7. P Gautret P, Cramer JP, Field V et al. Infectious Diseases among travellers
and migrants in Europe. EuroTravNet 2010. Eurosurveillance 2012;17:26. 16-26. 8. Travelers' diarrhea in Nepal: an update on the pathogens and antibiotic resistance. 2011 Mar-Apr;18(2):102-8.
9. Okhuysen PC. Traveler’s diarrhoea due to intestinal protozoa. Clin Infect Dis 2001;33:110–4.
10. Gardner TB, Hill DR. Treatment of giardiasis. Clin Microbiol Rev 2001;14:114-28. Available at
11. al. Drugs for treating giardiasis. 12 Dec 12;12.
Field VF, Ford L, Hill DR, eds.Health Information for Overseas Travel. NaTHNaC, London, UK, 2010 Updated June 2013
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