CD4 and infection: The HIV cohort allowed us to quantify the overall incidence of dissemination at 1.5 per 100 person-years [48]; however, when stratifying on CD4 counts, the incidence rate exceeded 10 per 100 person-years for persons with less than 50 CD4 per mm3 [49], and there were seasonal fluctuations in incidence, peaking during the dry season, which emphasized that cases were probably often new infections [50].