Tuberculosis and smoking - a lethal combination

I recently succumbed, in the Oxfam book department, to four hefty volumes of The People’s Physician, written in the mid 1930s. As I staggered up the street clutching them to my chest, I briefly regretted my purchase. However they are providing a mine of interesting insights into health and illness when today’s 90 year olds were children. The issues were very different then compared to those we worry about today. Pulmonary tuberculosis (TB) was the second biggest cause of adult death (after cancer) and its victims were predominantly in the earlier part of adult life rather than old age. It is a horrible way to die as lung tissue is slowly destroyed.

TB is unique in the way it interacts with the immune system because many of those infected never develop the full-blown illness. Instead, the bacillus slowly creates a small focus of infection, destroying lung tissue, before the immune system gains the upper hand and literally walls off the area of infection. This virtually eliminates the chances that the infected person will pass TB to others. The immune system, in this instance, consists primarily of immune cells known as macrophages. These large “white blood cells”, patrol the cavities of the lungs engulfing bacteria. The way they interact with TB is complex. They may hold the line, ensuring that the dormant (or latent) stage of TB lasts a lifetime. In other patients a dip in their performance allows the disease to break out and proceed on its destructive path.The BCG vaccination gives only partial protection from infection.

Recently a team of immunologists in Dublin has expanded understanding of how the macrophages interact with TB and how smoking impairs their performance and does so in a number of specific ways, disturbing on the fine balance of resistance to this unusual disease.This serves to remind us that smoking has multiple damaging effects in cells throughout the body. 

In the 1930s the causes of TB were thought to be to be lack of fresh air, infected milk and poor nutrition along with overcrowded housing, which made transmission more likely.  

The only treatments were rest, preferably in a room awash with fresh air, and, if possible, exposure to plenty of sunshine. Sufferers from affluent families were sometimes sent to alpine sanatoria, where semi-clad exercise in the sunshine was a key feature of the regime. In the People’s Physician there are photos of boys wearing only underpants, skiing, ice-skating and sitting at their desks outdoors and girls (in knickers and bonnets) exercising on sunny alpine meadows.

In the 1940s antibiotics became available and streptomycin proved to be an effective cure for TB. I have a relative who received the new drug in the nick of time and, with only half a lung remaining, went on to lead a long, active life. It is still the case though, that a very long course of antibiotic treatment is required to bring about a complete cure.

Although TB is now quite rare in wealthier nations it still kills around 1.5 million people a year, mainly in poorer parts of the world, making it the biggest bacterial killer of our time. There are some 9 million new infections every year. 

It is common knowledge that the damage inflicted on the immune system by HIV is one of the driving factors of this slow-burn epidemic. Drug resistant TB is on the rise, which also contributes to the spread of infection. It was news to me that smoking, too, significantly increases the chances that an infection will become active rather than lying dormant which means that this also makes a contribution to the spread of this horrible illness.

An Indian statistical study predicts that the effects of smoking on those infected will result in an additional 40 million deaths from TB between 2010 and 2050.

Back in the mid 1930s smoking was not considered damaging to health. It was considered as normal as eating and drinking. We now know that it causes lung and other cancers and that it contributes to coronary heart disease. TB, it seems, is yet another way in which tobacco claims victims. As smoking declines in the more wealthy parts of the world it is increasing in many poorer regions, where TB is also common. If drug resistant TB spreads, and there is no reason to suppose that it will not, we could see it returning to Europe as a frequent and indiscriminate killer. This is yet another reason why governments around the world need combat the use of cigarettes with all the determination they can muster.

Here’s the link to more information about the Dublin research:

http://bit.ly/1xKmXIH

And the Indian modeling:

http://bit.ly/11rOYbn