Ngoma- The National TB control programme under the Ministry of Health has started a nationwide population based national TB prevalence survey.  The survey was launched in Rukumberi sector, Ngoma district on Tuesday.According to medical experts, the parameters to be investigated include bacteriological prevalence of tubercle bacilli in sputum, radiological prevalence of chest abnormalities associated with tuberculosis in adults, and hypersensitivity to tuberculin in children.