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Tuberculosis and HIV Co-infection

A man is successfully treated for Tuberculosis

What is tuberculosis?

Tuberculosis, or 'TB', is a bacterial infection caused by an organism called Mycobacterium tuberculosis.

TB most commonly attacks the lungs or throat (pulmonary TB) but can attack any part of the body (extra-pulmonary TB), such as the lymph nodes, spine or brain. 1 2

Tuberculosis (TB) and HIV co-infection

During 2013, over 9 million people were diagnosed with TB, and 1.1 million of these people were also living with HIV. 3

People living with HIV have weakened immune systems and are around 30 times more likely to develop opportunistic infections such as TB. 4

It is important that people who receive a positive HIV diagnosis are tested for TB and vice versa. 5 Screening for TB should take place regularly, at every health clinic visit.

How is TB passed on?

Pulmonary TB is the only type of TB that can be passed on to others. If someone with TB coughs or sneezes, the bacteria in these tiny droplets can be inhaled into the lungs of another person, causing infection. 6

Girl sneezingHowever, not everyone infected with TB will become ill because there are two types of infection: active and inactive.

Active TB

Active tuberculosis means the TB bacteria are replicating in the body, causing tissue damage. The immune system is therefore unable to prevent illness and symptoms of TB.

People living with HIV are likely to experience latent TB becoming active TB due to their weakened immune system.

Active TB symptoms

  • Cough for more than 3 weeks
  • Extreme tiredness
  • Fever
  • Night sweats
  • Loss of appetite
  • Weight loss. 7

Symptoms of active extra-pulmonary TB often include these symptoms alongside extra symptoms related to the area of the body that is infected, such as swollen glands or pain in the affected area. 8

Inactive TB

If a person has inactive (or latent) tuberculosis, it means their body has been able to successfully fight the TB bacteria and stop it from causing illness.

People who have latent tuberculosis do not have symptoms and cannot pass tuberculosis to other people.

In some people, tuberculosis bacteria remain inactive for a lifetime. In other people, the inactive tuberculosis may become active if the person's immune system weakens - for example by HIV. 9

The risks of HIV and TB co-infection

Among people living with HIV, tuberculosis:

  • is harder to diagnose
  • progresses faster
  • is more likely to be fatal if undiagnosed or left untreated
  • can spread to other areas of the body (extra-pulmonary TB)
  • is more likely to return after being successfully treated
  • strains that are drug-resistant are even harder to treat. 10

Preventing TB

It is difficult to prevent TB because it can be passed on via the air. Covering the mouth with the hand or a tissue when coughing or sneezing can help to stop the spread of TB.

The most effective way to prevent TB is to get tested and treated in order to prevent transmission to others.

BCG vaccine

There is a vaccine against tuberculosis called the BCG, but the vaccine is now very old (it was first used in the 1920s). It is around 80 percent effective but only for 15 years, and is being phased out in some countries where TB is not a major threat. 11

Testing for TB

Blood test

A blood test is a reliable way of detecting TB infection, but it cannot determine if the infection is active or inactive. Other tests are needed to confirm this. 12

Sputum smear microscopy

A sample of sputum (mucous that is coughed up from the airways) is analysed under a microscope. If TB bacteria are visible, the result will be confirmed with a culture test. Detecting TB in people living with HIV via a sputum sample is not considered very accurate, and less infectious forms of TB are often missed. 13

TB culture test

A sample of body fluid or tissue is collected and grown in a culture. Any bacteria present in the sample can be grown and analysed for drug resistance and be used to determine which treatment will be most effective. 14

GeneXpert

This test detects active TB in sputum samples, and whether the strain of TB is resistant to rifampicin (RIF) - a type of TB treatment. It gives results within 2 hours – including among people with HIV who may otherwise receive a false sputum smear microscopy result. 15

The GeneXpert test is recommended for people suspected of having multi-drug resistant TB or are living with HIV. 16

Chest x-ray

A chest x-ray will show any scarring on the lungs caused by active TB. Further tests will be needed to prove that TB caused the damage.

Diagnosing TB in people living with HIV in this way can be difficult due to scarring from previous TB episodes or due to other HIV-related causes. 17

Tuberculin skin test (TST)

This test finds out if a person has been exposed to TB bacteria by detecting antibodies to TB. A small amount of tuberculin (tuberculosis protein) is injected under the skin. If the skin becomes red and raised it means TB antibodies are present.

However, this test can provide false results, for example among people who have received the BCG vaccine and those who had TB in the past but were since successfully treated. 18

Treating TB

Treating active TB

Tuberculosis treatmentActive TB can almost always be cured with a combination of antibiotics. The drug options depend on the country you are in.

Treatment for pulmonary TB is usually taken daily for 6 months, to cure the infection and prevent onwards transmission to others. For people with TB in other parts of their body, a similar course of drugs will be prescribed but for a longer period of time. 19

It is important to adhere to the treatment for the whole length of the course to prevent TB becoming resistant to the antibiotics. 20

Taking several drugs does a better job of killing all of the bacteria and is more likely to prevent them from becoming resistant to the drugs. The most common first-line (first option) drugs are:

  • Isoniazid
  • Rifampin/Rifampicin (Rifabutin, Rifapentine)
  • Ethambutol (Myambutol)
  • Pyrazinamide 21

Treating inactive TB

Treatment is not required for most people with latent TB. However, for people with weakened immune systems, such as those living with HIV, treatment is necessary to prevent the infection causing illness. A similar course of treatment to that for active TB will be recommended. 22

Treating TB and HIV at the same time

For some people it can be difficult to take drugs for both tuberculosis and HIV at the same time because of the amount of drugs, how often they need to be taken, and because of drug interactions.

To ensure adherence to treatment, it is often recommended that the patient takes their treatment in the presence of someone who can supervise the therapy. This approach is called DOTS (directly observed treatment, short course). 23

Drug-resistant TB

Drug-resistant TB is when the bacteria cannot be killed with certain drugs and the bacteria begin to replicate in the body. These strains can also be transmitted to others.

Drug resistance usually arises when people infected with TB do not, or cannot, take their treatment as prescribed, or stop taking it before the end of their prescribed course. 24

Multi drug-resistant TB (MDR-TB)

When a strain of TB is resistant to two or more first-line antibiotic drugs (at least Isoniazid and Rifampin) it is called multi-drug resistant TB or MDR-TB.

A person with MDR-TB will need to change to a regime containing different first- or second-line drugs which can be less widely available and more expensive. 25

Extensively drug resistant TB (XDR-TB)

When a TB strain is resistant to three or more second-line antibiotics as well, it is classed as extensive drug resistant tuberculosis, or XDR-TB.

The treatment options for someone with XDR-TB are limited as the remaining available drugs are less potent, and the regime will have to be very closely monitored throughout treatment to ensure it is effective. 26

Further information

References

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Page last reviewed: 
19/03/2015
Next review date: 
19/09/2016

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