The ADA covers only long-term disabilities, not those from acute illnesses or injuries that affect the worker for less than six months. The ADA specifically exempts illegal drug use, drunkenness, sexual preference (homosexuality, bisexuality, and transvestism), and pregnancy from the definition of disability. Beyond these specific exemptions, it provides that the employee’s physical or mental condition cannot be considered except as directly relevant to job performance. This follows the existing law that limits educational testing to qualifications that are directly related to job performance. Employers may not use a calculus test to screen applicants for janitorial jobs, Griggs v. Duke Power Co., 401 U.S. 424 (1971). and they may not use blood sugar testing to screen potential secretaries.