ACCRA, Ghana — At Kaneshie Polyclinic, a health center in a hardscrabble neighborhood of Accra, the capital of Ghana, there is a rule. Every patient who walks through the door — a woman in labor, a construction worker with an injury, a child with malaria — is screened for tuberculosis. This policy, a national one, is meant to address a tragic problem; two-thirds of the people in this country with tuberculosis don’t know they have it. Tuberculosis, which is preventable and curable, has reclaimed