CD4 and syphilis: While some studies have indicated that syphilis infection leads to a decline in CD4+ T cell counts in HIV-infected individuals (9, 11) and that HIV/syphilis co-infection hampers immune recovery and antiretroviral effectiveness (30), others, such as Wang et al. (31) have reported that patients at different stages of disease progression experience an increase in CD4 + T cell counts of more than 200 cells/μL after treatment.