Lack of basophilia in human parasitic infections.

While basophilia is often found in animal models of parasitic infection, it has not yet been established whether it occurs in parasite-infected humans. We investigated the relationship between basophilia and parasitic infections in humans by reviewing charts from 668 patients with confirmed parasitic infection (472 with only helminths, 146 with only protozoa, and 50 with both helminth and protozoan infections) and from 50 patients without parasitic infections. Basophilia (> 290 cells/mm3 ) occurred in only four of the 668 parasite-infected patients (0.6%), and there were no statistically significant differences in the percentages of patients with basophilia or in the absolute basophil counts among either the helminth-infected, protozoa-infected, or uninfected populations. Analysis with regard to relative basophil levels revealed that basophils constituted more than 3% of the peripheral white blood cell population in only four patients. Thus, basophilia occurs only rarely in human parasitic infections and is consequently not a useful clinical marker in the evaluation of suspected parasitic disease.