Some sexually transmitted diseases (STDs) can affect the white blood cell count. For example, infections such as HIV or syphilis can cause changes in the white blood cell count. HIV, specifically, attacks and destroys CD4+ T cells, which are a type of white blood cell involved in immune responses. This can lead to a decrease in the white blood cell count, particularly the CD4+ T cell count. Syphilis, on the other hand, can cause an increase in white blood cells, particularly during the early stages of infection. However, it is important to note that not all STDs directly affect the white blood cell count, and individual responses to infections can vary. Proper diagnostic testing is necessary to accurately diagnose and monitor STDs.