OBJECTIVE:To evaluate tuberculosis (TB) incidence rates and trends over a period of 20 years (1991-2010) and assess the impact of the National TB Control Program (NTP) on incidence trends.METHODS:This is a retrospective study of TB surveillance data reported by the Ministry of Health. We evaluated TB incidence data by nationality, age, and region of the country and assessed incidence trends over 20 years of study. Chi-squared test was used to assess trend change and its significance.RESULTS:There were a total of 64,345 reported TB cases over the study period. Of these 48% were Non-Saudis. TB annual incidence rate ranged between 14 and 17/100,000. For Saudis, the rate ranged between 8.6 and 12.2/100,000. Non-Saudis had 2-3 times higher incidence. Disease trend was rising over the first 10 years of the study period then it started to fall slightly. The incidence increased with age, but only people older than 45 years showed a declining trend. Regional variations were observed. Makkah and Jazan regions had the highest incidence rates. Disease trends were rising over the last 10 years in Makkah and Central regions.CONCLUSION:TB control seems to be facing some challenges in several regions of the Kingdom. NTP needs to evaluate and improve TB control strategies in order to reduce disease incidence to elimination levels.

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Latent tuberculosis infection (LTBI) is often diagnosed by the tuberculin skin test (TST). The latter has several limitations with regard to its sensitivity and specificity. It may be positive in people with prior bacille Calmette-Guérin (BCG) vaccination or exposure to nontuberculous mycobacteria. False negative TST results frequently occur in patients with impaired T-cell function. Therefore TST results have to be interpreted taking into consideration the pretest risk of TB infection or reactivation. Recently, interferon gamma release assays (IGRA) were introduced for the diagnosis of LTBI. These include the T-SPOT-TB and the QuantiFERON®-TB Gold tests.These tests measure interferon gamma released in response to T-cell stimulation by specific Mycobacterium tuberculosis antigens. These tests have been shown to be more specific than the TST as they are not affected by BCG vaccination. Their sensitivity was similar to that of the TST and in some studies they correlated better with the degree of exposure. In immune-compromised patients their sensitivity was better than that of the TST. IGRA tests were shown to have better predictive value for the development of active disease among individuals with LTBI. These tests are expensive. Their most cost-effective utilization is as confirmatory tests in patients with positive TST results, particularly in areas with high rates of BCG vaccination.

A case-control study was conducted in Saudi Arabia, where the same strain of BCG has been used and surveys had shown that up to 88% of vaccinated children remain tuberculin negative. Active cases were obtained by surveying the seven tuberculosis centers in 1 yr. Control subjects were obtained from a nationwide survey of normal individuals. Vaccination in both groups was ascertained by history and BCG scar. Relative risk of contracting active tuberculosis in the vaccinated versus unvaccinated and protection was calculated. Protection was as follows: age group 5 to 14 yr, 82% (55 to 93%); age group 15 to 24 yr, 67% (55 to 77%); and age group 25 to 34 yr, 20% (-6 to 37%). We document the uninterrupted record of protection by BCG administered in the neonatal period and discuss the significance of vaccination timing. We concur with other studies that protection lapsed after about 20 yr. More importantly, this is the first large study that documents a lack of tuberculin sensitivity despite protection. This challenges the view that sensitization is essential for protection and supports the "two-pathway" theory that BCG vaccination could trigger either protective (Lister type) or antagonistic (tuberculin or Koch type) reactions and that the most protective vaccines would have little tuberculin-sensitizing effect because the two pathways are competitive.

The findings in 44 patients with back pain and brucellosis are described. Radiological changes tended to occur in older patients with a longer duration of disease. The younger patients more often experienced an acute arthritis with sacroiliitis resembling a reactive disease. Bone scanning was more sensitive than radiographs, particularly in detecting acute sacroiliitis and hip involvement. The lumbar spine was the most frequently involved site although no part of the spine was spared. Extensive destruction of a vertebral body with little involvement of the adjacent vertebrae, lower lumbar spondylolysis and spondylolisthesis, and discitis with calcification were striking radiological findings hitherto undescribed in brucellosis. Computerized axial tomography (CAT) scanning revealed vertebral-arch destruction in three cases of spondylolisthesis. Circumferential sclerosis of the vertebral bodies was another CAT-scan finding.