Tuberculosis is an infectious disease caused by the Mycobacterium tuberculosis germ, which has existed since ancient times. Fragments of the spinal column from Egyptian mummies show evidence of TB more than 4,000 years ago.
In Hong Kong, TB became a notifiable disease in 1939. The city's rate of infection - about 70 per 100,000 people last year - is said to be many times higher than that of other Western developed countries. About one in 13 people in Hong Kong will develop TB at some stage in their life, according to the Health Department's Tuberculosis and Chest Service.
The airborne disease is transmitted through small droplets expelled when a TB patient coughs or sneezes. Prolonged exposure is usually required for the disease to be transmitted.
It typically affects the lungs, but can also attack other organs such as lymph nodes, bones, joints, spinal column, brain and kidneys. Symptoms include persistent cough, blood-stained sputum, weight loss, afternoon fever and night sweating. Sometimes, patients may have no symptoms. The usual tests used to diagnose TB include examination of chest X-ray and sputum.
The Bacilli Calmette-Guerin (BCG) vaccine is the most widely used and given to all Hong Kong babies. The degree of protection is not 100 per cent, and it's effective in children but not adults.
Most TB patients can be cured with drug treatment, provided by the Health Department free of charge. The usual course of treatment, introduced in 1979, lasts six months and involves four drugs.
To mark World TB Day this Saturday, test your knowledge of the disease.
1. By what name was TB known in earlier times?
2. In which country was the first TB vaccine developed?
3. How is TB transmitted from person to person?
a. Airborne droplets
b. Direct touch
c. Sexual contact
4. Which part of the human body is not affected by TB?
a. Hair and nails
Answers: 1. b; 2. c; 3. a; 4. c