Tuberculosis
Overview
Tuberculosis (TB) is a communicable disease caused by a type of bacterium known as Mycobacterium tuberculosis complex. The organism usually affects the lungs, causing pulmonary TB (PTB). TB bacteria can also affect other parts of the body such as the spine, lymph nodes, brain, skin, bones, fallopian tubes, kidneys etc; this is known as extra-pulmonary TB (EPTB). Other forms of Mycobacteria include Mycobacterium bovis, Mycobacterium africanum, Mycobacterium microti and Mycobacterium canetti.
TB is mostly an airborne disease transmitted when individuals inhale the droplets that contain the organisms expelled into the air by infected TB patients. TB organisms can be expelled when individuals sneeze, talk or spit. Mycobacterium bovis is transmitted through animals especially cows by ingesting unpasteurized milk and diseased cow.
If not treated, a person with active pulmonary TB disease will infect, on average, between 10 and 15 persons every year. After infection, TB bacilli can lie dormant in the body for many years. If the immune system is compromised in situations such as HIV infection, malnutrition, old age, diabetes, cancer etc. the TB infection progresses to active TB disease.
Signs & Symptoms
A person who presents with symptoms or signs suggestive of TB is called a Presumptive TB case. The commonest symptom of pulmonary TB is a productive cough for 2 weeks or more, which may be accompanied by other respiratory symptoms. The absence of fever or cough does not exclude a diagnosis of tuberculosis, particularly in immuno-compromised patients eg. PLHIV, cancer patients or malnourished individuals.
Other respiratory symptoms of TB may include:
- Shortness of breath
- Chest pain
- Coughing up blood (haemoptysis)
There may also be constitutional symptoms such as;
- Loss of appetite
- Fever
- Weight loss
- Night sweats
- Tiredness
TB cases are frequently found among the following high-risk/key population groups:
- Household contacts of Bacteriologically-confirmed TB patients
- PLHIVs
- Co-morbid conditions such as diabetes mellitus, cancer etc
- People on immunosuppressive therapy eg steroids, chemotherapy etc
- Persons who smoke tobacco (Passive and active tobacco smokers)
- Alcoholics (high alcohol consumption)
- Persons who live in crowded conditions, such as prisons, urban slums or Internally displaced persons (IDP)/refugee camps
- Those working in the mines include quarries, cement, asbestos, etc.
- Migrants population includes Nomads, IDPs and refugees.
Prevention & Treatment
Latent TB infection is defined as a state of persistent immune response to stimulation by Mycobacterium Tuberculosis antigens with no evidence of active TB. Most infected people have no signs or symptoms of TB but are at risk for active TB disease.
The following groups are prioritized as having a higher chance of developing active TB
- Children aged less than 5 years (<5 years) who are contacts of an infectious index TB case
- Children aged 5 years and above, adolescents and adults who are contacts of an infectious index TB case
- All HIV-infected persons
All persons categorized as being at high risk for TB after careful evaluation by a medical officer or a Trained GHCW, who do not have active TB, should receive TB Preventive Therapy (TPT). The following medicines regimens are used for TPT;
- INH (daily dosage for 6months)
- Rifapentine and INH (3HP) – weekly dosage for 3 months
- Rifampicin and INH (3HR) daily dosage for 3 months
- Rifapentine and INH (1HP) daily dosage for 1 month
To ensure quality TB treatment and reduce drug resistance, the following principles should guide treatment of TB:
- Directly observed therapy (DOT) by health workers or treatment supporters to ensure that TB patients take the right medicines, in the right doses at the right times under supervision.
- Adjust the dose based on the weight of the patient during treatment.
- All previously treated TB patients should immediately have access to Xpert MTB/RIF assay to determine the correct treatment regimen to offer to the patient.
- All patients diagnosed as DS-TB should be managed with regimen 1 or regimen 2
- For patients that are declared failed and loss to follow up (LTFU), the repeat of the Rifampicin-based regimen (regimens 1 and 2) should not be more than once except it is recommended based on culture and DST results.
- DOT must be ensured for all TB regimens through a patient-centred approach
The first line anti TB medicines used in the country include:
- Rifampicin (R)
- Isoniazid (H)
- Pyrazinamide (Z)
- Ethambutol (E)
Two standardized treatment Regimens have been adopted for the treatment of all susceptible TB cases. These regimens are as follows:
- Regimen 1 – six-month treatment (2(RHZE)/4(RH): for all forms of TB (PTB and EPTB cases – both new and previously treated) with the exception of TB meningitis Osteo-articular and miliary TB cases.
- Regimen 2 – twelve-month treatment (2(RHZE)/10(RH): for all cases of TB Meningitis (TBM), Osteo-articular and miliary TB cases.
The medicines come in fixed dose combinations (FDCs) and each regimen is divided into two phases (intensive and continuation).
