Tuberculosis (TB): exposure and preventative treatment
TUBERCULOSIS (TB) is a disease caused by mycobacteria tuberculosis (MTB) and infection is quite common.
We are exposed to this organism in various settings; in a crowded taxi or in large crowds where there is singing, speaking or coughing, resulting in a high risk of transmission.
However, infection with MTB does not mean you have TB disease.
Tuberculosis
The classic symptoms of TB are coughing, usually for over two weeks, night sweats, fever, weight loss and fatigue. However, TB can be completely asymptomatic or there could be an atypical presentation of the disease.
MTB can cause disease in various organs. The most common is the lung - which is the entry point of the organism - but it can affect the brain, abdomen, lymph nodes, or any organ that receives lymphatic or blood supply.
TB disease is diagnosed by looking for MTB in sputum, body secretions or tissue and, once diagnosed, treatment can be initiated.
Tuberculosis exposure
But what happens if one is exposed to MTB? Does this mean the individual should start TB treatment? This is a common dilemma. Let’s look at a few scenarios:
Scenario 1: A family lives in a two-bedroom home. One of the adult family members is diagnosed with TB. Should the whole family be treated for TB?
Scenario 2: A worker has been diagnosed with TB but the duties of the worker are confined to the outdoors. Do his colleagues need to start TB treatment?
The National Guidelines of the Treatment of Tuberculosis Infection published in 2023 gives us direction on what to do in these scenarios.
Firstly, it defines a significant exposure of MTB.
This is a known exposure to a person with pulmonary TB who shared the same enclosed space for one or more nights, or for frequent or extended daytime periods during the three months before the patient started their TB treatment. Significant TB exposure can occur in any setting such as the home, work or school. Secondly, it guides us on the next steps.
Each person with significant exposure should be tested for TB, which is conducted on a sputum sample and sent to the laboratory. Other tests like a chest X-ray may be required. Children may not be able to cough up sputum, so sampling swallowed sputum from the stomach may be required.
In cases where investigations are not possible, a thorough clinical examination should be done. If the tests do not show TB, the person is offered Tuberculosis Preventative Treatment.
Tuberculosis Preventative Treatment (TPT)
This is a course of medication for a person who has had significant exposure to MTB but has not been diagnosed with TB.
There are various regimens with different drug choices prescribed for various durations. TPT is offered by the Department of Health at all primary healthcare clinics and hospitals.
The medication used for TPT is a combination of some of the drugs used to treat TB, but the duration is usually less than that of TB treatment.
More facts on TPT
• TPT should be used even if an individual has been treated for TB in the past.
• If an individual completes TPT and has a second significant exposure, TPT should be recommenced.
• Pregnancy, HIV and chronic illness are not contraindications to starting TPT.
• If an individual declines TPT, he or she should be counselled on the symptoms of TB and be screened regularly. TPT should be offered again at every encounter.
Who should not receive TPT?
• Those diagnosed with TB as they will be started on TB treatment.
• Individuals with liver disease.
• Those who have had adverse reactions to the medication previously.
• Individuals who consume excessive amounts of alcohol and are unwilling to scale down. For men, this is five standard drinks a day or 15 drinks a week. For women, this is more than four standard drinks a day or eight drinks a week. Coming back to our scenarios… Scenario 1: The family members likely shared a common space for extended periods. Additionally, they probably had contact with the individual before the treatment was started. So in this scenario, all the family members should be screened for TB disease and then started on TPT if they are found to be TBnegative.
Scenario 2: The worker works outdoors which limits his contact and exposure to other workers, making it a non-significant exposure. His coworkers need not take TPT.
The above scenarios are real-life situations that you may find yourself in. In these cases, there is no need to panic but action is required. Visit your local clinic and the nurse will offer you TPT.
Tuberculosis remains a massive problem in South Africa and locally. Let us do our bit to avoid the spread of this infection and protect ourselves well.