Kenyan Prostitute Jacinta Kerabu 42 Advertises For Custom Outside Her Home-based Brothel in the Majengo Slum of Nairobi Kenya Friday 19 May 2006 Kerabu Has Been a Sex Worker For Over Two Decades and Estimates That in the Course of Her Career She Has Probably Had Sex More Than 50 000 Times - Yet She Has Never Contracted Hiv and Every Credible Study of Her Case Points Towards Her Being Immune to It Researchers Have Been Studying Kenyan Sex Workers Like Kerabu For Over 20 Years in a Quest to Find the Secret of Their Immunity in the Hope That It May Lead to a Vaccine