Do many people have the sickle cell trait but don't even know it?

Yes: Over 2 million americans have sickle cell trait. Approximately 1 in 12 african americans have sickle cell trait. Many patients are diagnosed during routine newborn screening. However, not all patients know or remember the results. Other ethnic groups that are at risk include people with ancestors from south america, cuba, central asia, saudi arabia, india, turkey, greece, italy, etc.