Volume 2:  Issue 1

MARCH 2001

TRAVELLERS! - BEWARE OF THE FELLOW TRAVELLER--GIARDIA LAMBILIA
PROF. IQBAL AKHTAR KHAN, MBBS, DTM, PhD, FACTM

5% cases of TD but now the figure has risen to 83%; as documented in the largest reported travel related outbreak of giardiasis occurring in residents of United Kingdom who became infected while staying in a resort hotel in Greece [2]. The resulting incapacitating diarrhoea can become a memorable component of a trip to destinations in developing countries by disturbing the tight schedule of a well organized tour, spoiling the pleasure and sometimes even the purpose of the trip.

Giardia lamblia is the main parasitic triggering factor of the "homing diarrhoea" which affects children of emigrants coming back from a trip to their country of origin and may become serious enough to cause death secondary to dehydration or septicaemia [3]. Infection with Giardia lamblia may add to the miseries of other infections. In a previously healthy Japanese traveller acquiring paratyphoid fever after a trip to India, the concomitant infection with Giardia lamblia was found to exacerbate the paratyphoid fever [4]. Similarly, in a study on returning travellers, cryptosporidiosis was found to be seven times more frequent in patients with Giardia lamblia than in others [5].

Is a giardiasis- free trip possible?
Travel related imported cases of giardiasis introduce into the community the disease about which the residents may have little awareness and in most cases, the possibility of which did not exist in the minds of the local family physicians. It becomes, therefore, imperative that necessary measures should be taken to block importation of Giardia lamblia. There is no chemoprophylaxis or immunoprophylaxis available. The only safe and reliable tool in the hands of the travellers is behavioural modification. Pre-travel counselling of the travellers especially of those to area of endemicity is highly rewarding exercise. Routine and rigorous hand washing (most preferably with a liquid soap) before food intake, after changing a soiled diaper; and before feeding a child should be the priorities of personal hygiene.

Water is the most important vehicle of transmission. Hikers, campers and back packers who ingest untreated surface water, inlanders who drink untreated ground water and

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Introduction
Giardia lamblia, the aetiological agent of giardiasis, is a fascinating organism with a long and venerable history. This highly communicable and the most common enteric protozoan parasite, occurring from the tropics to Arctic prevalence Greenland with a global prevalence of up to 30%, is now ranked as one of the ten major parasites of humans, resulting in significant morbidity. The tremendous increase in international travel, and rapid and convenient means of transportation have facilitated the spread of Giardia lamblia from one destination to another. Whereas the travellers need passport, visa and tickets, Giardia lamblia does not.

Transmission and risk determinants
Although the parasite is ubiquitous, most of the infections occur in tropical settings and developing countries, where the standards of hygiene are less than ideal. One acquires giardial infection by ingesting viable cysts through contaminated water or food. The environmental pollution by unhealthy living conditions, overcrowding, unsafe drinking water, unsafe food and unsafe sewage disposal is the mainstay in the continuity of the endemicity of the disease. The host factors include mode of travel (air, road, caravanning, camping, backpackers), younger age (4-5 times more common in children), dietary mistakes (consumption of raw vegetables, salads, reconstituted juices and traditional drinks in tropical settings), an impaired gastric acid barrier (those with previous gastro - intestinal surgery, those on antacids, H₂ receptor antagonists and proton pump inhibitors) and immune deficiency (congenital, acquired, immunosuppressive therapy). In travellers to Nepal falling prey to giardiasis, consumption of cannabis has been found to play an important role. It induces hypochlorhydria, possibly lowers the infective dose for Giardia and produces a more voluminous diarrhoea [1].

Magnitude of the problem
Giardia lamblia is now considered to be the most frequent parasitic cause of travellers' diarrhoea (TD) in travellers originating from United States, United Kingdom, Italy, Germany, Austria, Netherlands, Switzerland, Sweden and Japan. In previous studies, it was held responsible for up to