 In each service investigated, each health care professional participating in the study held an information register. Each page of the register had two parts, one with a detachable section specifying the correspondence between the identity of study patients and their identity number, and an anonymous one describing the main characteristics of eligible patients. During each consultation day, the health care professional listed in the register all eligible patients, their gender, age group, if the patient had worked at least one day in the previous month, a health indicator last CD4 count for HIV patients, last alanine transaminase ALT level for patients with hepatitis B, the fact of consulting in this facility for the first time for patients in the reference group, and participation in the survey participant, not offered participation, refusal. 