As discussed in Chapter 1, in 1998 ZL began administering ART in Haiti based on patients’ clincal status alone. Since CD4 testing has become available in central Haiti, initiation of treatment has been guided by CD4 count as well as by the clinical status of the patient. The WHO has also used both clinical staging and total lymphocyte count as surrogate markers for immune suppression. Under the WHO guidelines, the total lymphocyte count is calculated by multiplying WBC count per high-powered field by the patient’s percentage of lymphocytes. Protocol 3.1^* provides an overview of both the laboratory and syndromic approaches to initiating ART; for a discussion of when to initiate ART in HIV-positive pregnant women, also see Sections 2.5.2 through 2.5.5 and Protocol 2.3.