Epidemiology of tuberculosis

Tuberculosis "Tap Dik" or TB as it is commonly referred to is a common and at times fatal infectious disease caused by the Acid Fast Bacterium "Mycobacterium tuberculosis".

History of Tuberculosis

Believed to have been transferred to humans from Bovines thousands of years ago.

Skeletal remains show that prehistoric humans (4000 BC) had tuberculosis. Tubercular decay has been found in the spines of Egyptian mummies.

In 460 BC Hippocrates identified it as the most common disease of the times.

The bacillus causing tuberculosis, Mycobacterium tuberculosis, was identified and described on 24 March 1882 by Robert Koch. He received the Nobel Prize in physiology or medicine in 1905 for this discovery.

Albert Calmette and Camille Guérin achieved the first genuine success in immunization against tuberculosis in 1906, using attenuated bovine-strain tuberculosis. It was called bacillus of Calmette and Guérin (BCG). The BCG vaccine was first used on humans in 1921 in France.

In 1993 WHO declared TB a global emergency in developing countries.

tuberculosis by the numbers

Tuberculosis (TB) is second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent.

In 2012, 8.6 million people fell ill with TB and 1.3 million died from TB.

Roughly one-third of the world's population has been infected with M. tuberculosis, with new infections occurring in about 1% of the population each year. However, most infections with M. tuberculosis do not cause TB disease, and 90–95% of infections remain asymptomatic

In 2012, about 80% of reported TB cases occurred in 22 countries, referred to as High Burden Countries.

The TB death rate dropped 45% between 1990 and 2012. An estimated 22 million lives saved through use of DOTS and the Stop TB Strategy recommended by WHO.

tuberculosis in pakistan

Pakistan ranks 5th amongst the 22 HBCs and
4th among 27 MDR high burden countries in
the world.

Estimated prevalence of all types is 350/100000.
42000 new TB cases emerge annually out of which 4000 are drug resistant. (Incidence of sputum positive cases: 80/100000 per year).

TB is responsible for 5.1% of total national disease burden. It causes substantial impact on socio-economic status as 75% of TB cases fall in productive age group (15-45 years old).

About 68000 people die annually because of TB despite an increase in treatment success rate, from 77% in 2001 to 91% in 2007-09.

natural history of tuberculosis

Agent

source of infection

• Humans (Sputum + for M. Tuberculosis)
• Bovine, infected milk (unboiled)

communicability

• Patients are infective as long as they remain untreated.

Host factors

• AGE: affects all ages
• SEX: more in males
• HEREDITY: no
• NUTRITION: malnutrition predisposition
• IMMUNITY: no inherited immunity, acquired 

Social Factors

• Poor quality of life
• Poor housing and overcrowding
• Population explosion
• Undernutrition
• Lack of Education

risk factors

• HIV: 13% of all TB cases are also HIV+
• Chronic Lung Disease
• Silicosis: 30 fold increase in risk
• Smoking: twice the risk versus non-smokers
• Others

Untitled Slide