TB can become resistant to the two most powerful medicines that we have to treat it - isoniazid and rifampicin. If a TB infection is no longer able to be treated with either of these drugs, it is classed as multi-drug resistant TB.

Multi-drug resistant TB is a big problem. Normally treatment for TB is 90% effective, but with drug resistance, this effectiveness drops to as low as 50%. Extensively drug-resistant TB can occur if a person's TB is resistant to other second-line treatments as well as isoniazid and rifampicin. Only a third of people with extensively drug-resistant TB will be successfully cured.

Multi-drug resistant TB is more likely to develop when a person does not adhere to treatment. This can sometimes be a result of clinics not handling their care properly, for example, if they do not give the patient the medicines they need at the right time. It can also happen if an individual finds it hard to take the treatment.

Where drug-resistant TB is common in a community, it's possible to be infected with a strain of TB that's already got some resistance before you've started treatment.

Policymakers and healthcare professionals around the world are looking for ways to respond to the rise of multi-drug resistant TB. For now, the most important thing is that people take their treatment properly and receive proper support around adherence.    

Yes, the BCG vaccine can protect against TB. The vaccine is very effective against the most severe types of TB, offering up to 80% protection, however, protection against TB of the lungs is slightly lower.

Guidelines on who should be vaccinated will vary depending on where you are in the world. For countries with higher rates of TB, the World Health Organization recommends giving infants the BCG vaccine at birth. However, it's not recommended for babies who may be HIV-positive, as HIV-positive babies can develop a TB-like illness from the vaccine.

TB bacteria die slowly. To make sure that all the bacteria have gone you need to keep taking your medication as prescribed for the full length of time. You might start to feel better quite quickly, but you must keep taking your treatment until the end of the course.

If you don't finish all your medication or you take it irregularly, it can stop working. This is because if you haven't got enough of the medicine in your body, the bacteria will still be able to grow and will learn how to get past the medicine. This means that in the future your TB will be harder to treat. If your TB becomes resistant the chances of being cured will be smaller and you will have to take treatment for longer.
 

One way of helping people take their treatment regularly is 'directly observed therapy' (DOT). DOT is a way of taking treatment. It involves meeting with a health worker at a clinic, in the community or at home, for them to watch and make sure that you take your medicine correctly. It's a widely used approach to TB treatment and can be particularly helpful in cases where a person has difficulty in adhering to treatment.

DOT works best when healthcare workers use these meetings to provide patients with additional support. This could include helping them watch for side effects or providing counselling. The World Health Organization is currently exploring whether video calls could be used as a way of providing DOT in a more cost- and time-efficient way.

Certain factors increase people’s risk of getting ill from TB. These are:

. having diabetes (high blood sugar)

. having a weakened immune system (for example, having HIV, particularly if it is unsuppressed, or AIDS)

. being malnourished

. smoking tobacco

. having alcohol use disorder

. coming into regular contact with people with active TB. 

The people who should be prioritised for TB screening include:

. the close contacts of people with TB

. people with HIV

. children and adolescents

. older people

. health workers.  

It also includes people who are likely to live in cramped conditions, be food insecure and have poor access to healthcare, such as:

. people living in poverty, particularly in urban encampments  

. people who are refugees or displaced  

. people most at risk of HIV (key populations), particularly people in prison and people who use drugs. 

Data from the World Health Organization (WHO) suggests people with HIV are 13 times more likely to fall ill from TB than people without HIV.  

TB is the leading cause of death among people with HIV. HIV and TB can form a lethal combination, each speeding the other's progress.  

To reduce the risk that TB poses, people with HIV need to be able to access and stay on antiretroviral treatment (ART). ART strengthens the immune system, which is vital for fighting TB infection. But although ART (if taken correctly) will reduce people with HIV’s risk of developing active TB, their risk is still higher than people without HIV, especially if they live in areas with high TB prevalence.  

This makes it essential for people with HIV to be able to access TB preventative treatment. WHO guidance is that all adults and adolescents with HIV should take TB preventative treatment as part of their HIV care in addition to ART, regardless of their CD4 cell count.  

People with HIV also need access to rapid TB testing and treatment if they develop TB symptoms. And people newly diagnosed with TB should be offered an HIV test.  

Most people who get TB will not develop active TB, but between 5-10% will. The risk for getting ill from TB depends on several risk factors, including HIV (see ‘Who is most at risk of TB?’).

It is essential that TB preventative treatment is given to people at highest risk of progressing from TB infection to disease. If someone is at risk, a healthcare provider will first check they do not have active TB before assessing if they need TB preventative treatment.

TB preventative treatment works by killing TB bacteria before it causes illness or organ damage. If taken correctly, it can provide protection from active TB for years.

New, shorter preventative treatment options are now available that last only 1 or 3 months. But in some circumstances, 6 to 9-month treatment may still be offered. Preventative treatment is also available if someone has been exposed to multidrug-resistant TB, which is a 6-month course. Whatever course of medication is offered, if a person is at risk of getting ill from TB it is important that they take up the offer or their health will be at risk. 

The World Health Organization (WHO) estimates that around half of all children with TB go undiagnosed due to a lack of TB testing within paediatric care. Around one-third of children in households where others have active TB are not given TB preventive treatment.  

Combining health facility and community-based approaches can help to change this. This includes:

. community outreach to raise awareness about TB among children, adolescents and their families  

.community-based TB screening for children and adolescents (including symptom checking)  

. community-based distribution of TB preventative treatment for children and adolescents most at risk of TB. 

The WHO also recommends that health clinics provide ‘child-friendly’ TB treatment for children and adolescents with non-severe TB. This is treatment that lasts for 4 months instead of 6. This is recommended regardless of HIV status.  

For both preventative treatment and treatment for active TB, one of the key challenges is ensuring children and adolescents take their medication course until the end. Providing regular peer group or 1:1 support, plus support for caregivers and treatment monitoring (e.g. DOT), can help with this.