Mid-week Medical: Tuberculosis (TB)
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If you’ve missed our Chief Medical Officer on his weekly slot on Wednesday afternoon on FM100, don’t worry because we’ve got the highlights for you right here.
What is TB?
TB is an infectious disease caused by various strains of Mycobacteria, usually Mycobacterium tuberculosis, causing serious illness and often death. TB typically attacks the lungs but can also affect other parts of the body i.e. the pleura (Tuberculosis pleurisy), CNS (Tuberculosis meningitis), lymphatic system (Scrofula of the neck), the genitourinary system (urogenital tuberculosis) and bones and joints (Pott disease of the spine).
Although TB has been present in humans since antiquity it was only identified as a single disease in 1820 and only named Tuberculosis in 1839 by JL Schonlein
The bacillus causing tuberculosis was identified by Robert Koch in 1882. He received the Nobel Prize in physiology and medicine in 1905 for this discovery.
The first genuine success in immunization against TB came in 1906. It was called bacilli Calmette-Guerin (BCG) and was first used in humans in 1921.
One third of the world population is currently infected with the Tuberculosis bacillus. Nine million new cases are diagnosed each year and 1.5 million people die from it.
PNG has one of the highest TB rates in the Western Pacific region, second only to Cambodia. The three provinces with the highest infection rates are Western province, Gulf province and NCD.
TB is one of the top three diseases in terms of hospital admissions. 25,000 new cases are diagnosed every year with a death rate of about 10%.
DR-TB is a big problem and accounts for 4.5% of new cases and 24% of retreatment cases.
Challenges in tackling TB in PNG
- limited diagnostic capacities
- access to medical care (85% of the population lives in remote areas)
- high rate of “lost to follow-up”
- emerging threat to DR-TB
- lack of awareness of TB.
TB is spread from person to person by:
Touching a person or sharing eating utensils are harmless.
Signs and symptoms
- cough lasting more than two weeks
- chest pains when coughing
- blood-stained sputum
- night sweats
- constant tiredness/fatigue
- loss of appetite
- weight loss
About 90% of those infected with Mycobacterium Tuberculosis however do not have symptoms. This kind of infection is called Latent TB. 10% of these patients will progress to active disease and if untreated 50% will die from it.
- chest x-ray
- multiple sputum cultures for acid-fast bacilli.
- mantoux tuberculin skin test for screening people at high risk
- interferon gamma release assays are recommended in those patients with a positive Mantoux test.
New onset TB
- Six months with a combination of antibiotics (Rifampicin, Isoniazid, pyrazinamide and Ethambutol)
- treated with a single antibiotic
- needs AB sensitivity tests before treatment is commenced
- treatment with at least four effective AB for 18 – 24 months
- DR-TB = Resistance to Rifampicin & Isoniazid
- XDR-TB = Resistance to three or more of the six classes of second line drugs
- Totally DR-TB = Resistant to all currently used drugs
- HIV – 10% of people infected with Tuberculosis develop active disease. In contrast 30% of those co-infected with HIV develop active disease.
- chronic lung disease – Silicosis increases risk 30-fold
- smoking – 2-fold
- Diabetes Mellitus – 3-fold
- greater public awareness
- effective treatment and screening programs
- vaccination of infants (BCG).
- fear of transmission
- links between poverty and AIDS
- decrease stigma through education programs and “TB clubs”.