Even with investment, a usable vaccine is still a decade away. Photograph: Marco Longari/Getty Images.
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Underground epidemic: the tuberculosis crisis in South Africa's gold mines

South Africa's gold mining industry has suffered a number of setbacks in recent years. Repeated union strikes have resulted in bloody clashes between workers and police. Economic pressure has increased after a recent fall in the price of gold. However, there is another major problem blighting the South African gold mining industry - one which rarely makes international headlines: the seemingly unstoppable tuberculosis (TB) epidemic, which has spread through the majority of the workforce.

Pulmonary TB is a known killer in many countries, but nowhere is it thought to be more prolific than deep underground in South Africa’s gold mines. Statistics provided by non-profit biotech company Aeras, which works to advance TB research and development and is this month heading up a TB and mining awareness campaign, states that of the 2.3 million new cases of TB reported in Africa last year, 760,000 – almost a third – were connected to mining in sub-Saharan Africa. According to Aeras, nine out of ten gold miners in South Africa are latently infected with TB and one mine worker with active TB can spread the disease to between 10 and 15 other people.

“The [South African] mining industry, in particular gold and platinum, has some of the highest rates of TB in the world, if not the highest,” says Aeras Vice President of External Affairs, Kari Stoever.

“TB is a major risk in this occupation [mining] that is providing a livelihood for over a million people in just the South African region.”

One of the biggest gold miners in the region, AngloGold Ashanti, said the company recognises the scale of the problem: “We are certainly cognisant of the gravity of the TB problem in South Africa as a whole, and therefore also in the gold mining industry. Over the past decade we have intensified our efforts to address this issue,” said a representative.

HIV infection and exposure to silica dust in ultra-deep mines, along with close working and living conditions predispose South African gold miners to TB, according to a study published in The New England Journal of Medicine in January.

Results of the large-scale, five-year study of 78,744 miners in 15 gold mines from 2006 to 2011, showed that intervention treatment did not reduce the incidence of TB. Although it did show a reduced incidence of TB during treatment, 12 months after the study, researchers did not find any difference in the number of cases of TB in those who had preventative therapy and those who didn’t.

Stoever says the problem may not be isolated to South Africa, but other African mining nations as well, such as the Democratic Republic of Congo, where TB is endemic, and Ghana, but it is impossible to know for sure because the data isn’t being collected.

The infectious and often fatal disease, which attacks the lungs and is spread through the air, is having a huge affect on miner’s health, as well as that of their families and their finances. It’s also costing mining companies heavily in lost productivity and costly treatment and in turn the general economy because the mining industry makes up 18 per cent of South Africa’s Gross Domestic Product.

According to Aeras, the TB epidemic results in miners losing $320 million per year in lost wages. TB treatment is reported to cost the South African government and mining industry more than $360 million per year.

Stoever says the total economic toll of TB in South Africa is estimated to be about $1.3bn per year. “South Africa went from being number one in production of gold to sixth in the world but they are number one for cost,” she adds.

However, there is no straight-forward solution to the problem. Treating TB isn’t cheap and it can be complicated due to increasing drug resistance or the presence of HIV. Stoever says treatment for straightforward TB is six months of antibiotics followed by ensuring the individual is not infectious before returning down the mine. For drug-resistant TB, treatment is a combination of highly toxic drugs for up to two years. In some mine treatment centres this can cause a sanatorium-type lockdown until the workers' sputum clears. Drug resistance is also a huge concern which, if it worsens, which is entirely possible, could be “catastrophic” says Stoever.

Currently there is no vaccine for TB in adults, but there is a common misconception that the Bacillus Calmette-Guérin vaccine (BCG) given to school children around the world can protect against adult respiratory TB , but it is much less effective in protecting adults against pulmonary TB than it is children.

Mining companies, particularly the bigger ones, have largely been addressing the TB epidemic head-on. Stoever, speaking after visiting hospitals run by both AngloGold Ashanti and Anglo American Platinum, two of the biggest gold miners in South Africa, said both companies are doing an  “outstanding" job of finding TB cases and ensuring miners are getting the appropriate treatments but adds that she is sure “some [companies] have better practises than others”.

AngloGold Ashanti say it has had some success in reducing the incidence rate of TB, reducing the incidence rate [percentage of employees who develop TB during the year] in its South African operations from 4.3 per cent in 2006 to 1.8 per cent in 2012. It added that all patients remain in employment throughout the course of their treatment. Despite these positive results the company recognises that “more challenges remain.”

In the wake of the disappointing trial results published in The New England Journal of Medicine in January, Aeras is currently in discussion with the Chamber of Mines in South Africa and many mining executives to find an alternative long-term solution.

Stoever says Aeras wants to create a “virtuous cycle” related to the markets.

She explains: “If we could somehow look at gold  as a commodity, gold as a natural resource, gold as a big driver of economic development in the South Africa region… and figure out a way to create this virtuous cycle where we then put money into the health system to fight infectious diseases like TB and HIV both with our current tools, which have their limitations, but also in research and development, where we really have  our best bet in potentially eliminating TB and HIV with vaccines in the future.”

“This isn’t an act of charity; this is a real bottom line business for families and communities,” she adds.

Anglo-Gold Ashanti also recognise that any long-term solution must be a collaborative one. It says: “The fight against TB is a collective responsibility of all the role players in society – people in their individual capacity, organised business, organised labour and other organs of civil society.”

It adds that it is “willing to partner with like-minded stakeholders to find durable solutions.”

Right now a vaccine seems to be the only viable long-term solution, but Stoever admits that although research and development has improved from no TB vaccine candidates in 2000 to 13 today, six of which Aeras is working on, a usable vaccine is still likely a decade away. The key, as Aeras knows, is keeping up thorough and rigorous treatment of TB and convincing mining companies and the government that a vaccine is worth investing in. No one should have to risk repeated TB infection just from going to work.

Heidi Vella is a features writer for Nridigital.com

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.