As the world commemorates the 2015 edition of the World TB Day, we reflect on the Occupational Health and Safety Institute in relation to its work of controlling pulmonary tuberculosis (PTB) among miners in Zambia.

It is common knowledge that Zambia is one of the leading copper mining countries in the world.

As of 2013, statistics ranked Zambia seventh among copper mining countries, Chile being first, followed by Japan, Peru, United Sates of America (USA), Austria and then Russia.

Besides these seven, 43 other countries are engaged in industrial (commercial) copper mining, with Saudi Arabia and Colombia being the least copper producers.

However, copper mining is also a major migration issue in that it causes movement of labour from non-copper rich regions within and outside the country to the mines.

Many migrants who prefer to work in the mines travel from all over the country as well as from other parts of the world to work in the mines.

However, the migrant labour in the mines comes with its own benefits and challenges that affect host communities.

Not only that, exposure of miners to toxic or infectious substances in the mining environment has the potential of spreading to the outside world, beyond the affected mine, and put lives of people in host communities and beyond at risk.

Therefore, the establishment of the Occupational Health and Safety Institute is important because besides safeguarding the lives of miners, it helps them access medical services especially in relation to the management of TB.

The Occupational Health and Safety Institute was established in the 1940s after a case of silicosis was suspected among miners.

Started as a pneumoconiosis research bureau, the institute was mandated to carry out medical examinations in people seeking employment in the mines (initial examination), those who are already in employment to determine their fitness for continued work in the mines (periodical examination), those who are exiting the mines (exit examination) and those who have retired from the mines.

The main purpose of the institute is to detect the occupational diseases associated with silica dust-pneumoconiosis and pulmonary tuberculosis (TB) and forward their names for compensation.

The institute also advises the removal of such persons from scheduled areas once certified and gives statistics to the Mine Safety Department as an indicator for dust control if the cases are high.

The institution is mandated to carry out post-mortem as well. It is the only institution of its kind in the country.

Pulmonary tuberculosis (PTB) associated with crystalline silica dust exposure is an occupational disease caused by mycobacterium tuberculosis in employees who have been exposed to silica at the work place.

The problem of diagnosing PTB in silica exposure is sometimes difficult. This is because most of it tends to be sputum negative more especially in HIV positive miners.

It may be difficult to differentiate between CXR picture of military tuberculosis and nodulations of silicosis.

Exposure to silica dust and silicosis increases the risk of PTB approximately four fold.

The combined effect of silicosis and Human Immunodeficiency Virus (HIV) increase the risk multiplicatively.

However this healthy worker effect tends to disappear after five years of exposure to silica. As a result of this and other factors in long serving miners, PTB prevalence tends to be higher in miners than in the general population.

Pulmonary tuberculosis associated with silica dust exposure is presumed to be work related: firstly, if the affected employee has silicosis attributable to silica dust exposure (silico-tuberculosis);

secondly, if the affected employee has been exposed to free crystalline silica in the work place for more than a year in absence of radiological evidence of silicosis; and thirdly, if the affected employee develops tuberculosis within one year of leaving employment.

Diagnosis may be confirmed by: isolation of mycobacterium tuberculosis, by culture of sputum or body fluids or tissue; or positive sputum smear and relevant clinical/radiological picture; or two positive sputum smears; or three negative sputum smears and a relevant clinical, radiological picture and response to tuberculosis treatment.

Current legislation (on TB) in Zambian mines is twofold: all those found with PTB or give a history of PTB at initial examination are disqualified to work in certain high risk sections of the mines; and those found with PTB during periodical medical examination are removed from scheduled areas and discharged eventually.

Because of the above legislation, there is a tendency by some miners of avoiding mine hospitals and going to other facilities so as to keep their jobs. That affects statistics.

In terms of the disease burden, there were 1,627 cases of PTB among miners who were certified at Occupational Health and Safety Institute from 1945 -2002.

There was a prevalence of 1,693 cases of PTB per 100,000 among in-service copper miners in 2004.

Then later, a prevalence of 16 per cent of PTB was found among retired mine workers in 2013.

The following is a random sample of some of the trends of PTB incidences among in-service copper miners from the institute’s records.

Currently the national TB prevalence is 400 per 100,000 (this includes both children and adult population).

The incidences of PTB may seem low compared to other neighboring mining nations like South Africa, with more than 3,000 per 100,000.

This is partly because of the following reasons: Firstly, only those who have worked as periodicals are certified. Secondly, recurrent initials are not certified. This system is common among contractors.

Thirdly, diagnosis is mainly by history, clinical picture, chest x-ray sputum microscopy examination and response TB treatment possibility of under diagnosis since the institute has no facility to culture sputum or any other body fluids.

Fourthly, miners at times go to alternative facilities for fear of losing employment once certified; and finally, the system of keeping records makes it difficult at times to follow up retirees.

Among challenges being faced by the institute are the following: Lack of more sensitive methods of TB diagnosis-strengthening the diagnosis laboratory; rigid legislations on tuberculosiss; limited manpower as the institute has less than ten doctors have to cover the whole country in occupational disease surveillance.

Others are: hard copy record keeping which makes it difficult to follow up retired miners.

There is need for electronic record management system; the need for training of manpower; the need for resources for research especially in the areas of those already certified with TB to show how great is the risk of relapse when one is kept in silica dust after treatment compared to one who gets certified and is removed from silica dust.

Finally, the institute requires resources for sensitization on the risk factors of TB to the miners and the community at large.

News Reporter