Medical Q&As

Parasites - blood test?

Are there any blood tests available to confirm a parasitic infection?

The answer to your question really depends on which type of human parasitic infection you are thinking of. For example if you were concerned with the possibility of an intestinal parasite being present a blood test might reveal an eosinophilia, which means an increase in the number of eosinophils in the blood. An eosinophil is a particular type of white blood cell that is normally present in the blood and the lining of the gut. If hookworms, pinworms or roundworms were present in the gut this could give rise to an increase in the number of eosinophils in the blood, which would be detectable with a blood test. However, eosinophilia is not specific to parasitic infection and can happen for other reasons. Therefore this test would be suggestive of parasites being present without being diagnostic. Also the test would not give you any indication of which type of parasite was present. On the other hand if you were concerned about a specific parasite such as toxoplasma gondii, which causes toxoplasmosis, it would be possible to test specifically for the presence of that particular parasite. It really is necessary to know the clinical context that forms the basis for your question. Finally it is not the usual practice to perform blood tests to check for the presence of intestinal worms since they are usually visible in the stools or in the area surrounding the anus.