Abstract
M.Tech. (Biomedical Technology)
TB continues to be one of the major causes of morbidity
and mortality in developed and developing countries, (Mauch, 1993),
despite the development of drugs and vaccines. Today, TB is one of the
most serious health problems not only in South Africa, but worldwide. The
transmission rate for TB for the population of Cape Town is 3% per year,
while the transmission rate in gold mineworkers is estimated at 10% per
year (Churchyard and Corbett, 2001). Tubercle bacilli have the ability of
evading the immune system by entering a dormant phase while in the
human host, and are able to reactivate at a later stage. Little is known
about the mechanisms of this reactivation. TB remains a global
emergency because of our lack of understanding of the details of its
pathogenesis (Rook and Zumla, 2001).
Since radioactive minerals are found in mines, it was postulated that
radioactivity may be the reason for pulmonary cancers, a fact which is now
well established. The biologic effects of radiation have been shown to
produce irreparable deoxyribonucleic acid double-strand breaks or singlestrand
breaks, or create structural changes by damaging the nucleus.
Although no studies have shown toxic effects resulting from long-term,
low-dose radiation exposure, risks are still assumed, (Herscovici and
Sanders, 2000), and research concerning the mutagenic affects of lowdose
radiation exposure is necessary.
All the risk factors for pulmonary tuberculosis (PTB) in mineworkers are
not known, although many have been identified, such as age and mining
occupation. This study aimed to determine if long-term, low-dose exposure
to ionizing radiation has an effect on the reactivation of dormant tubercle....