CD4 and Blastocystis infectious disease: Interestingly, our study revealed that the prevalence of Blastocystis in HIV/AIDS cases with high HIV virus load and low CD4+ T cell count was much higher than that in other groups, implying that Blastocystis infection among HIV/AIDS subjects was not only association with HIV virus load and CD4+ T cell count, but also depended on the interaction effect between these two variables.