There are at least three distinct HPV natural history patterns that are observed globally, likely linked to different levels of immunologic control of HPV infections: a) immunocompetent populations are characterized by lower HPV prevalence in mid-adult women between the ages of 30 and 49 years, when screening is optimal; this pattern is characteristic of the Americas, Europe, and parts of Asia and the Middle East/Northern Africa; b) partially immunodeficient populations that do not have a high burden of HIV but appear to have reduced cell-mediated immunity (for instance, due to chronic parasitoses) show higher HPV prevalence at optimal screening ages; this pattern is characteristic particularly in sub-Saharan Africa; and c) HIV-infected women, with pronounced immunodeficiency in controlling HPV infections, leading to continuous high prevalence across screening ages. The graphs display the prevalence of any hrHPV (green lines) and HPV16/18 (red lines).