ARE YOU SURE IT IS AMOEBIASIS AND NOT GIARDIASIS ?
Hon. Visiting Physician, Jaslok Hospital and Bombay Hospital, Mumbai, Ex. Hon. Prof. of Medicine, Grant Medical College and JJ Hospital, Mumbai 400 008.
There are many aspects common between amoebiasis and giardiasis. I am quite convinced that the doctors are overdiagnosing amoebiasis and underdiagnosing Giardiasis. Many patients who are treated as amoebiasis are actually suffering from giardia and respond to the so called "treatment". This is because the drugs used are same and the dose and duration of treatment for giardia is much less. For example the dose of tinidazole in a strip of four tablets of "Fasigyn" is enough to get r"f from giardiasis, while the same dose continued for three days is effective for amoebiasis.
The following discussion will be self explanatory:
Few years back 'giardia lamblia' was discovered by VanLeeuwenhoek in his own stool, with his own miscroscope. Since then infestation has been recognised all around the world. But in many developing countries, giardiasis is so common, that most, if not all, village children become infested during early childhood (this often permits an efficient immunity to develop which is lacking in many adults living in aristocratic societies in the big cities).
Unlike amoebiasis, the mode of infection in giardiasis is not always faeco-oral route. It can really be compared to the life cycle of the thread worm which is of the nature of an auto infection.
More the reason, that as in the case of thread worms, the whole family should be treated at the same time. Unfortunately, the ideal drug for giardiasis is 'mepacrine'. This is not available and is slightly toxic to be used by the present day standards. (It was routinely used in the treatment of malaria in the past). The parasite sets up colonies in the duodenum and upper small intestines, and with the poor sanitation, (by the faeco oral route even with good sanitation) the infection persists.
Giardiasis is more notorious than arnoebiasIs for causing decreased levels of disaccharides such as maltose, sucrose and lactose. This causes symptoms of milk intolerance and foul flatus.
Finally a word about the diagnosis of 'giardiasis'. Presence of trophozoite form or cystic form of giardia in the stools (former easy to find in freshly passed diarrhoeal stool) is diagnostic. Unfortunately stool examination is often negative. As in amoebiasis, it is necessary to examine several stool samples over a few days to detect the cysts of Giardia, which is difficult in private practice.
The other investigations are costly, and invasive. For example duodenal intubation to detect the parasites, or peroral jejunal biopsy lead to a more accurate diagnosis.
In practice we can only look forward to days when serological tests for giardia serum antibodies (IgM) will be available. But that will not solve all the problems because the diagnostic titres will have to be established in immune persons. Or if the early reports of antigen detection in giardiasis come true, the diagnosis will certainly be facilitated.
To Section TOC