Nevada is the only US state in which commercial sex is legal. Since 1971, counties of fewer than 400000 people have been able to elect to legalize brothels. At present, there are 32 legal brothels employing about 300 licensed prostitutes. Licensed brothel sex workers undergo weekly state-mandated medical examinations for gonorrhea, herpes, and venereal warts and monthly blood tests for syphilis. In March 1986, the Nevada Board of Health began requiring a negative initial human immunodeficiency virus (HIV) antibody test and negative monthly tests thereafter as a condition of employment. If a brothel worker or applicant is found to be seropositive, her employment is immediately terminated or denied.