Introduction
Tuberculosis remains a leading cause of death, second to the Human
Immunodeficiency Virus. The risk of latent tuberculosis infection and active
tuberculosis disease is a known occupational hazard. In South Africa, a high
tuberculosis burden country, the potential of Mycobacterium tuberculosis
transmission to health care workers is high. This includes diagnostic
radiographers and other radiology staff working in radiology departments.
Purpose of the Study
This study aimed to investigate the association of demographic and
occupational factors with latent tuberculosis infection in radiology staff in public
sector hospitals of the eThekwini Health District.
Methodology
This cross-sectional study was conducted from 26 February 2013 to 07 June
2013. Quantitative methods were used to test for associations of demographic
and occupational factors with latent tuberculosis infection in participants. A
sample size of 181 participants for an estimated population of 340 radiology
staff was recommended at the proposal stage. The study consisted of two
phases; the questionnaire survey (phase one) and the administration of a twostep
tuberculin skin test (phase two).
Data was obtained with regard to demographics, occupational history, social
behaviours, medical history; and family and home histories. Demographic and
occupational associations with latent tuberculosis infection were made in
relation to the size of the first tuberculin skin test induration. Frequency
distributions were developed to describe data categories. Pearson’s and
Spearman rho’ correlation coefficients were used to test for correlations
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between the independent variables. The chi-square test was used to determine
associations between the categorical independent variables and the dependent
variable. Bivariate analyses were performed using these tests. The multivariate
analysis was performed using logistic and linear regression on the dependent
variable.
Results
A total of 182 questionnaires were returned from approximately 280 radiology
staff. At the outset, all doctors working in the radiology department had to be
excluded due to numerous failed attempts to enlist their participation. Fifty-three
(29.12 percent) participants were excluded from phase one of the study and a
further thirteen participants were excluded from phase two. The total sample
was 116 participants. Of the 116 participants, 86.2 percent tested positive for
latent tuberculosis infection at the first step of the two-step testing method used.
One (0.86 percent) participant went on to convert at the second step, testing
positive at this level.
Demographic associations with latent tuberculosis infection included age (older)
as an associated factor. A significant demographic association with latent
tuberculosis infection was the use of alcohol (p-value 0.033 on the multivariate
analysis). Occupational associations with latent tuberculosis infection included
longer durations of employment. The annual income (higher income earners)
displayed significant associations with latent tuberculosis infection (p-value
0.048 on the multivariate analysis). It is necessary in this study to note that
participants include support personnel (lower income earners) making up 37.8
percent of the study, diagnostic radiographers making up 48.3 percent; and
radiography managers/assistant managers (highest income earners) making up
13.8 percent of the study.
Conclusion and recommendations
The risk of transmission of Mycobacterium Tuberculosis to health care workers
is a known occupational hazard. This study has described the prevalence of
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latent tuberculosis infection in radiology staff, at district and regional hospitals
within the eThekwini Health District. With 23.62 percent of all participants
already having active TB disease and 86.2 percent of the tested group
displaying positive results for latent tuberculosis infection, using the tuberculin
skin tests, the need for tuberculosis screening is essential. The findings of this
study will be used as a health improvement mechanism for stakeholders, having
identified potential gaps in medical screening in healthcare in Kwa-Zulu Natal.
This study makes recommendations for the early detection of active
tuberculosis infection and the monitoring of health care workers that are latently
infected, thus assisting in reducing the rate of conversion of latent tuberculosis
infection to active tuberculosis disease in radiology staff. This reduces long-term
exorbitant costs related to health care associated infections, such as
tuberculosis. It also reduces rates of transmission and cross infection to both
co-workers and already immunocompromised patients, helping to curb the
overall epidemic in South Africa.