Tuberculosis (TB)

Introduction

Tuberculosis (TB) is an infectious disease caused by a bacteria known as Mycobacterium tuberculosis that usually affects the lungs, although it can affect any part of the body like bones, joints, genito-urinary, intestines, skin, tuberculous meningitis and others.

TB is one of the major global public health challenges and is a re-emerging infectious disease. WHO estimates that one third of world’s population is infected with TB almost 9 million people develop TB disease every year and around 2 million deaths every year. It is the major cause of death from a single infectious agent among adults in the developing world. Generally, incidence is high in Africa, Asia and South America

The risk of infection differs between countries. In many countries of Africa and Asia, infection with HIV has further increased morbidity and mortality from TB. Drug-resistant TB is increasing in many areas of the world.

Risk for travellers is limited but travellers are advised to avoid exposure to known TB patients in crowded environments (e.g. hospitals, prisons, or homeless shelters).

Risk of tuberculosis transmission on airplane is similar to any other enclosed space.

Causative agent: Mycobacterium tuberculosis is a rod-shaped,nonmotile, acid-fast bacterium,. Humans can also become infected by bovine tuberculosis, caused by M. bovis

Transmission: Infection is usually by direct airborne transmission from person to person. Bovine TB (caused by the closely related Mycobacterium bovis) can be transmitted by ingestion of contaminated, unpasteurized dairy products from the infected cattle.

Exposure to M.tuberculosis may lead to infection, but most infections do not lead to disease. The risk of developing disease following infection is generally 5 to 10% during the lifetime, but may be increased by various factors notably immunosuppression (example, advanced HIV infection)

Incubation period: 2 – 10 weeks

Sign & Symptoms

  • The most common symptoms of TB include;
  • A cough that lasts for more than two (2) weeks
  • Cough with sputum which is occasionally bloodstained
  • Loss of appetite and loss of weight
  • Fever
  • Dyspnoea, night sweats, chest pain and hoarseness of voice.

Diagnosis

Laborating diagnosis of TB can be made when acid-fast bacilli (AFB) are seen on sputum smear or in other body tissues or fluids.

Diagnosis of TB disease is further confirmed by culturing M. tuberculosis from sputum or other respiratory specimens for pulmonary TB and from other affected body tissues or fluids for extrapulmonary TB. On average, it takes about 2 to 4 weeks to culture and identify M. tuberculosis, even with rapid culture techniques.

A diagnosis of TB disease can be made by using clinical criteria in the absence of microbiologic confirmation.

Complication

Haemoptysis, pneumothorax and empyema

Treatment

TB disease is treated with a multiple drug regimen for 6-8 months (usually isoniazid, rifampin, ethambutol and pyrazinamide for 2 months, followed by isoniazid and rifampin for 4 to 6 months) if the TB is not drug resistant.

Drug resistant TB is more difficult, requiring 4-6 drugs for 18-24 months; it should be managed by  a trained specialist.

Inpatient treatment (Patient who are hospitalised)

  • Gravely ill patients
  • Acute disseminated TB
  • TB involving Central Nervous System (CNS), pericardium, adrenal and spine
  • Multiple Drug Resistance -TB (MDR-TB)
  • Patients who default frequently or compliance is suspect
  • Complications such as haemoptysis, pneumothorax and empyema
  • Associated diseases such as uncontrolled diabetes and renal failure
  • Severe side effects such as severe skin reactions or jaundice
  • Patients who need desensitization to anti-tuberculosis drugs.

Directly Observed treatment (DOTS)

A standardized short course tuberculosis treatment regimen of six to eight months under direct observation by a trained supervisor (usually healthcare workers) to ensure that the patient takes every dose of medication.

Prevention & Precautions

Prophylaxis

Baille Calmette Guerin (BCG) should only be offered to those not previously immunised and who have a negative Tuberculin test. Protection from vaccine is only achieved after about 4 – 6 weeks. Boosters are not normally required. BCG immunisation has been shown to give 70% – 80% protection against TB meningitis.

In the first year of life it provides good protection against complications of TB. In countries with high TB prevalence like Malaysia, infants are generally immunized as soon after birth as possible with a single dose of BCG, which protects against severe forms of TB in infancy and early childhood.

BCG is one of the most difficult vaccines to administer and reconstituted vaccine must be given intradermally. Symptomatic HIV-infected individuals should not be vaccinated.

BCG vaccine is of limited use for travelers. BCG immunisation is advised for those who are at risk.

Type of vaccine: Live bacterial BCG

Number of doses: One

Contraindications: Symptomatic HIV infection

Adverse reactions: Local – abscess, regional lymphadenitis

Distant (rare) – Osteitis, disseminated disease

Consider for: Infants under 6 months of age traveling to high risk countries and health workers and the recommended to be given 4 weeks before departure

Precautions

Risk for travelers from non-endemic countries is limited but travelers are advised to avoid exposure to known TB patients in crowded environments (e.g. hospitals, prisons, or homeless shelters).

All healthcare workers should be advised on personal respiratory protective devices (e.g. N-95 respirators).

For travelers from low incidence countries who may be exposed to infection in relatively high incidence countries (e.g. health professionals, humanitarian relief workers, missionaries), a baseline tuberculine skin test is advisable in order to compare with retesting after return.

If the skin reaction to tuberculin suggests recent infection, the traveler should receive, or be referred for, treatment for latent infection.

Patients under treatment for tuberculosis

SHOULD NOT TRAVEL until the treating physician is satisfied that the patient is not infectious and therefore of no risk to others. The importance of COMPLETING THE PRESCRIBED COURSE OF TREATMENT SHOULD BE STRESSED.

References organisation/ support

International Travel & Health, WHO 2006

Control of Communicable Diseases Manual, 18th Edition by David L. Heymann, MD, Editor, 2004

Clinical Practice Guidelines, Management of Pulmonary Tuberculosis, Ministry of Health Malaysia, 2002.

WHO. Global tuberculosis control-surveillance, planning, financing: WHO Report 2007. Geneva: World

Health Organization; 2007.

http://travelhealth.co.uk/

Last Reviewed : 26 April 2012
Writer : Dr. Norhayati bt. Rusli
Accreditor : Dr. Zainal Che Me
Reviewer : Dr. Norhaya Mohd Razali

 

(Visited 178 times, 1 visits today)