Reaction to tuberculin testing in Saudi Arabia

Abstract

An epidemiological study of tuberculosis infection in the Kingdom of Saudi Arabia was conducted, between January 1987 to February 1990. A proportional to population size sampling method was used for the whole country, and 1933 subjects were screened. A pre- designed questionnaire was used to collect details of BCG scar, age, sex, residence area, nationality, education, occupation and tuberculosis test. The relative importance of these factors was assessed by using Logistic Regression Analysis. The extent to which these factors affected the severity of tuberculosis was also examined. A number of statistically significant association were found between positive tuberculin test (> 10mm) and age (p < 0.0001), sex (p = 0.018), nationality (p = 0.009), residence area (p = 0.05) and occupation (p = 0.0003).

PIP: During January 1987-February 1990, a tuberculosis (TB) survey was conducted to determine risk factors associated with TB in Saudi Arabia. The health professionals used the tuberculin test (Mantoux test) to screen 11,933 individuals over 5 years old from throughout Saudi Arabia. The researchers excluded the 4212 individuals whose BCG history was not known. A positive tuberculin test (induration of =or 10 mm on the forearm) was associated with age (peaking in 15-24 year age group at 17%; increasing trend with age; p = 0.0001), sex (males more likely infected than females; p = 0.0187), nationality (non-Saudis; p = 0.009), residence (p = 0.0504), and occupation (p = 0.0003). All individuals who had a BCG history in all age groups, except the 65 and older group, were more likely to have a positive Mantoux reaction than those who had not been vaccinated with BCG (p = 0.0001). Based on these findings, the investigators concluded that screening all foreign labor within four weeks of entering Saudi Arabia for active TB should continue until the TB prevalence rate falls to 2%, that administration of BCG vaccination in the first few weeks of life should continue until the percentage of reactors to the tuberculin test falls to 2%, and that a similar study should be conducted in another five years to compare its findings with these findings. A second BCG vaccination should be administered to all persons at the age of leaving school to reduce the proportion of positive reactors in this age group (15-24) from its current rate of 17%.