The relationship between CD4+ T-lymphocyte cell count and opportunisticinfections such as Cryptosporidium has been widelyreported.42,44,45 The number of T-lymphocyte ≤100 cells/mm3 or between101 and 200 cells/mm3 indicates a high risk of parasitic infection, whilecryptosporidiosis was also reported to be closely related to low CD4+counts in several studies. Here, CD4 is linked to parasitic infectious disease.