Tuberculosis from animals: Why is it a forgotten agenda?

Tuberculosis is a major public health problem in India, accounting for one-fifth of the global TB cases. Each year nearly 2 million people in India develop TB, of which around 0.87 million are infectious cases. It is estimated that annually around 3,30,000 Indians die due to TB. Currently, TB kills more people in India than any other country. India has an estimated 40 per cent of the world’s cases, killing approximately one person every minute.

It strikes deep at the very economy of the family and the country as well. Having taken note of this in 1962, the National Tuberculosis Control Programme was launched by the government of India with great fanfare and enthusiasm. But even after 49 years after the launch and the TB programme having undergone several changes, both in name and content, there does not seem to any signs of abetting. On the contrary fresh problems seem to be cropping up.

For instance the TB problem has been compounded with the problem of HIV/AIDS and in addition the major setback because of drug resistance has also become a cause for concern. With all this previous experiences one wonders if it is necessary to take a re-look at this huge major public health problem. For that we need to look into the nature and history of the disease and also as to how it was almost eradicated in several developed countries. What is that magic wand that made the TB to disappear from these countries, while we in India continue to struggle with it. Has our strategy itself been wrong?

Interestingly it was on March 24, 1882, that Robert Koch discovered the tiny germ that causes deadly disease and named it Mycobacterium tuberculosis. He thus revolutionised the scientific understanding of the disease. He received the Nobel Prize in 1905 for this discovery.

Koch did not believe that bovine (cattle) and human tuberculosis were similar but later it was proved that tuberculosis can spread from animals and that too cattle.
The understanding of this particular point seems to have been a major cornerstone for eradication of much of tuberculosis in developed countries especially the United Kingdom and other European nations. These countries selectively identified and isolated cattle that harboured the TB germ. This detection of TB bacteria in the animals was done by simple test known as Mantoux test (Also called Tuberculin Sensitivity Test, Pirquet test, or PPD test for Purified Protein Derivative).

It is a diagnostic tool for tuberculosis and if the animal is positive then it is totally isolated (around 2 km away from human life) or sent to the abattoir. During its isolation there is a separate staff and exclusive set of instruments that take care of all these animals, until they die natural death and then to be buried away.

Century-old findings

The Royal Commission on Tuberculosis (1907) established the common identity of the disease in man and cattle under the British ministry of agriculture and food. Under the direction of this commission in 1929, over 15,000 cattle were slaughtered under the Tuberculosis Order. So it is obvious that it was done in a massive scale and followed up systematically every year until TB ceased to be a major public health problem. The same history of the TB disease can be observed from other European countries as well.

WHO recognised way back in a seminar titled ‘Advances in the control of zoonoses’ that it conducted in the year November 1952 that prevention and eradication of zoonoses in human beings can be accomplished in large part by control of these diseases in animals, so that it is natural for public-health officials to give every assistance — moral, financial and scientific to agricultural authorities in carrying out animal-disease-control programmes.

Recent literature in 1998 by WHO reaffirms that in humans the vast majority of cases of tuberculosis are caused by Mycobacterium tuberculosis. However, TB can be caused by a number of other bacteria, of which Mycobacterium bovis, causing so-called ‘bovine tuberculosis’ is one of the more prevalent and has the widest host range of all TB bacteria.

Knowing the close relation of the animals to humans in our villages, it is obvious that TB is endemic and that it is spreading from animals; though more scientific studies need to be done to look at this possibility in the Indian context. While slaughter of cows and other animals are big political issues in India and more so in Karnataka but the government seems to have totally missed the bus on this issue of zoonotic transmission of the TB and further its prevention.

While political parties and leaders seem to be dancing to fancy agendas of the multinational drug companies by pumping more drugs to treat TB, we seem to be totally oblivious to the fact that the TB disease that is rampant in cows and other animals can be an important source of the spread of the disease to humans. One wonders if there are other compulsions to look away from the facts just as the ostrich does.