PROTOZOAN PARASITES

Several micro-organisms are well known to cause acute symptoms of gastro-enteritis (sickness and diarrhoea as in the case of infection with Salmonella or Campylobacter). However, other parasites are also capable of causing chronic or recurrent problems. These may not be readily identified in ordinary hospital laboratory tests.

Protozoan parasites, including Blastocystis hominis, Dientamoeba fragilis, Endolimax nana and others, as any amoebas, are single cell parasites, which for years were thought to be harmless or merely “incidental” findings in stool microscopy and culture. Many people carrying them are actually oblivious of any digestive symptoms. However, during the last 10-12 years a number of medical reports have associated these parasites with various problems including irritable bowel and chronic fatigue. It is interesting that a significant proportion (25-30%) of people with irritable bowel have amoebic parasites but only 5% of the normal population. Some of the patients seen in our clinics have a history of acute infection of the digestive system while in the tropics or travelling in countries with poor hygiene. These days many people get such parasites while in the UK.

Parasitology Screen
The detection of these parasites is difficult, because they disintegrate soon after they leave the intestine, unless the stool sample is immediately placed in special container with fixative. In the U.K. there are only three specialist laboratories equipped to detect them with more in Europe and the USA. The test is thorough. Although recommended by some experts, in our day-to-day practice we have not seen significant difference between purged or non-purged samples.

Treatment
A number of common antibiotics available in the U.K. today have been used for the treatment of the above parasites (e.g Erythromycin, Metronidazole or Doxycycline) but they appear to be less effective than some anti-parasitic agents imported from abroad. Safety is high, providing that courses of these medications are given only for a 2-3 weeks. Sometimes more than a single course of treatment in required for a successful eradication.

Confirm Eradication
It is important to repeat the parasitology test about four weeks after the end of treatment, to confirm clearance. Earlier tests might miss the parasites during their reproductive phase. Protozoan parasites are the third most common causative factor in irritable bowel, after food intolerance and abnormal intestinal fermentation (See relevant sections in this website).

Outcomes
Most people notice the difference when they successfully treat such parasites but one should bear in mind that others experience no improvement, if other underlying factors remain active.

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