Eosinophils and Parasitic Infections

Background: Eosinophils dysregulate immune responses associated with malignancies, allergic and parasitic diseases especially helminthic infections, though it is infrequently observed with protozoan diseases. Objective: The aim of the present study was to evaluate and compare the percentage of eosinophils in different parasitic diseases at Baqiyatallah Hospital, Tehran, Iran. Materials and Methods: One hundred and 72 samples were obtained from 74 and 98 patients with helminthic and protozoan diseases respectively and evaluated. Direct wet mount and formalin ether concentration were used for intestinal parasites identification. Scotch tape test and serological methods were utilized for diagnosis of Enterobius vermicularis and tissue parasites respectively. Eosinophils were counted and six or more percentages were considered as eosinophilia. Results: In general, in 34 out of 74 helminthic infections (45.9%) and 5 out of 98 protozoan infections (5.1%), an eosinophil level equal or more than 6% was observed. The rate of eosinophilia in helminthic infections were 13/18 (72.2%), 7/11 (63.6%), 3/10 (30%), 2/3 (66.7%), 1/9 (11.11%), 5/13 (38.5%), 3/4 (75%) in the patients with fasciolosis, strongyloidiasis, hymenolepiasis, hookworm infection, enterobiasis, echinococcosis, and trichostrongyliasis, respectively. Concerning the protozoan infections, 3/26(11.5%) and 2/20(10%) of the individuals suffering from giardiasis and blastocystosis showed an eosinophil level higher than normal range, respectively. Conclusion: As expected, helminthic infections especially fasciolosis and strongyloidiasis were the most important infections correlated with eosinophilia. According to available reports, eosinophilia higher than normal range in giardiasis and blastocystosis is not unexpected.