Tuberculosis Cough Sneeze Talk Spit Dormant For Years Biology Essay

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What is Tuberculosis or TB? Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis. When infected people cough, sneeze, talk or spit, they propel TB germs, known as bacilli, into the air. A person needs only to inhale a small number of these to be infected.

Left untreated, each person with active TB disease will infect on average between 10 and 15 people every year. But all people infected with TB bacilli will not necessarily become sick with the disease. The immune system "walls off" the TB bacilli which, protected by a thick waxy coat, can lie dormant for years. When someone's immune system is weakened, the chances of becoming sick are greater.


March 24th commemorates the day in 1882 when Dr Robert Koch announced that he had discovered the cause of Tuberculosis. This was the pathogen Mycobacterium tuberculosis also known as the TB bacillus. At the time of Koch's announcement in Berlin, TB was raging through Europe and the Americas, causing the death of one out of every seven people.

A century after Dr. Koch's announcement, the first World TB Day was sponsored by the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD).


World TB Day is meant to focus attention on TB; to build public awareness that tuberculosis today remains a global epidemic causing the deaths of several million people each year, mostly in developing countries.

TB Facts


TB remains a threat to the health and well-being of people around the world. At any given moment, more than 13 million people around the world are suffering from an active infection. (Source Global TB Alliance)

TB kills someone approximately every 20 seconds - nearly 4,700 people every day, or 1.7 million in 2009 alone. (Source Global TB Alliance)

Among infectious diseases, TB remains the second leading killer of adults in the world, with more than 2 million TB-related deaths each year.

Overall, one-third of the world's population is currently infected with the TB bacillus.

5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB. Nearly half a million TB-related deaths occur every year in the S.E. Asia region alone.

WHO estimates that the largest number of new TB cases in 2008 occurred in the South-East Asia Region, which accounted for 35% of incident cases globally.

TB will rob the world's poorest countries of an estimated $1 to $3 trillion over the next 10 years

In some countries, loss of productivity attributable to TB approaches 7% of GDPTB will rob the world's poorest countries of an estimated $1 to $3 trillion over the next 10 years. (Global TB Alliance)


India has more new TB cases annually than any other country. India is the highest TB burden country accounting for one fifth of the global incidence (Global annual incidence estimate is 9.4 million cases out of which

It is estimated that 1.98 million cases are from India). India is 17th among 22 High Burden Countries in terms of TB incidence rate (Source: WHO global TB Report 2009)

About 40% of Indian population is infected with TB bacillus. Unfortunately, TB appears to have a tendency to infect those who are in the optimally productive age group.

India and China alone account for an estimated 35% of TB cases worldwide. There are estimated 35% of TB cases worldwide.

The countries that ranked first to fifth in terms of total numbers of MDR-TB cases in 2007 were India (131 000), China (112 000), the Russian Federation (43 000), South Africa (16 000) and Bangladesh (15 000).

Current Drug/Diagnostics scenario

TB Vaccine/ Drug Development Milestones

1921 BCG Vaccine first used on humans

1944 | Streptomycin

1949 | P-Aminosalicylic Acid

1952 | Isoniazid

1954 | Pyrazinamide

1955 | Cycloserine

1962 | Ethambutol

1963 | Rifampicin

TB drug regimen takes months to administer and the long regimen often leads to non-compliance, which in turn leads to drug resistant TB. Strains that are resistant to a single drug have been documented in every country surveyed. Strains of TB resistant to all major anti-TB drugs have emerged. Drug-resistant TB is caused by inconsistent or partial treatment, when patients do not take all their medicines regularly for the required period. Multidrug-resistant TB (MDR-TB), is caused by TB bacilli resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. Drug-resistant TB requires up to two years of treatment with second-line anti-TB drugs which are more costly than first-line drugs, and which often produce adverse drug reactions. The emergence of extensively drug-resistant (XDR) TB, particularly when TB patients are also infected with HIV, is another serious threat.


One of the biggest challenges in drug discovery is the building of a robust pipe- line of projects at various stages of discovery to account for the high rate of attrition expected at each step of the path. This is even more challenging in the case of Tuberculosis drug discovery because of the paucity of well validated targets. This is compounded by the limited basic biology knowledge available.

Urgently needed:

Quicker diagnosis

More effective drugs/vaccines that will need shorter regimens

Stronger and more affordable healthcare systems.


The healthcare needs of the poor and vulnerable populations must be effectively addressed. Directly Observed Treatment, Short course (DOTS), the TB control approach launched by WHO in 1995, has, since its launch, brought 41 million patients under its services. This system must be given more teeth with better, more -effective drugs.

In terms of population coverage, India now has the second largest DOTS programme in the world. However, India's DOTS programme is the fastest expanding programme, and the largest in the world in terms of patients initiated on treatment, placing more than 100,000 patients on treatment every month.

Millennium Development Goals of the WHO hopes to have halted and begun to reverse incidence of TB by 2015.

(Briefing for 24th March)

Towards new diagnostics, drugs and vaccines

The Open Source Drug Discovery Project is CSIR led Team India consortium with global partnerships with the vision to provide affordable healthcare to the developing world. It was launched in 2008.

OSDD has independent biologists freely sharing their work through the internet. As a first phase, drugs against Mycobacterium tuberculosis including drug resistant and latent tuberculosis is being undertaken with the following major objectives:

• Development of a web-based portal for data deposition, exchange, evaluation and tabulation for analysis

• Collaborative sharing of know-how for the entire spectrum of processes in drug discovery-- ranging from identification of drug-able nontoxic targets, in vitro and in vivo validation, in-silico screening of small molecules, lead optimization, pre-clinical toxicity and clinical trials

• Creation of a comprehensive Systems Biology approach for drug discovery

• Establishment of an International Collaborative Centre for Affordable Health (ICCAH), which will operate with Government, International and Philanthropic funding.

OSDD has already delivered via its Connect to Decode project the re-annotated genome of Mycobacterium tuberculosis.

The Metabolome map i.e. the complete map of all the metabolic reactions that take place in the cell of Mycobacterium tuberculosis. This map is important because these interaction pathways / metabolic reactions can provide to choke points to exploit vulnerabilities as drug targets.