Given Algeria’s young population, policy favors preventive health care and clinics over hospitals. In keeping with this policy, the government maintains an immunization program. However, poor sanitation and unclean water still cause tuberculosis, hepatitis, measles, typhoid fever, cholera, and dysentery. In 2003 about 0.10 percent of the population aged 15–49 was living with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). The poor generally receive health care free of charge, but the wealthy pay for care according to a sliding scale. Access to health care is enhanced by the requirement that doctors and dentists work in public health for at least five years. However, doctors are more easily found in the cities of the north than in the southern Sahara region.