According to the World Health Organization (1971),World Health Organization. (1971). Mass health examinations. Public Health Papers NO 45. Geneva: World Health Organization. screening is a "medical investigation that does not arise from a patient’s request for advice for specific complains. The term covers all types of examination and does not refer to their speed or accuracy." Similarly Harford et al. (1978)Harford, E. R. (1978). Impedance Screening for Middle Ear Disease in Children: Proceedings of a Symposium Held in Nashville, Tennessee, June 20–22, 1977. Grune & Stratton. states, "screening is a process by which individuals are identified who may have disease or disorders that are otherwise undetected" and which many have "findings of asymptomatic cases" (Haggard & Hughes, 1991).Haggard, M. P., & Hughes, E. (1991). Screening children's hearing: a review of the literature and the implications of otitis media. HM Stationery Office. When considering an appropriate screening program for a developing, or developed, country, Wilson and Jungner (1968)Wilson, J. M. G., & Jungner, G. (1968). Principles and practice of screening for disease. World Health Organization. Public Health Paper, (34). recommend the following ten basic principles that screening program should observe:
