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Tuberculosis and HIV Co-infection
What is tuberculosis?
Tuberculosis, or 'TB', is a bacterial infection caused by an organism called Mycobacterium tuberculosis.
Tuberculosis (TB) and HIV co-infection
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
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
- 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
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.
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
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.
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
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
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
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 active TB
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:
- 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 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
- 1. NHS Choices (2014, December) ' Tuberculosis (TB)'
- 2. CDC (2012) ' Basic TB Facts'
- 3. WHO (2015) ' Tuberculosis and HIV'
- 4. TB Alert (2015) ' TB and HIV'
- 5. CDC (2013, March) ' HIV and Tuberculosis Fact Sheet'
- 6. TB Alert (2015) ' What is TB?'
- 7. TB Alert (2015) ' Symptoms'
- 8. NHS Choices (2014, December) ' Symptoms of tuberculosis'
- 9. CDC (2012) ' Basic TB Facts'
- 10. TB Alert (2015) ' TB and HIV'
- 11. TB Alert (2015) ' Prevention'
- 12. TB Alert (2015) ' Diagnosis'
- 13. TB Alert (2015) ' Diagnosis'
- 14. TB Alert (2015) ' Diagnosis'
- 15. WHO (2013, September) ' TBXpert Project'
- 16. WHO (2013) TUBERCULOSIS DIAGNOSTICS: Xpert MTB/RIF Test
- 17. TB Alert (2015) ' Diagnosis'
- 18. TB Alert (2015) ' Diagnosis'
- 19. NHS Choices (2014, December) ' Tuberculosis (TB) - Treating tuberculosis'
- 20. TB Alert (2015) ' Treatment'
- 21. TAG (2014, May) 'An Activist's Guide to Tuberculosis Drugs'
- 22. TB Alert (2015) ' Treatment'
- 23. CDC (2013, March) ' HIV and Tuberculosis Fact Sheet'
- 24. Target TB (2015) ' Drug Resistance and TB'
- 25. CDC (2014, April) ' Drug-Resistant TB'
- 26. CDC (2014, April) ' Drug-Resistant TB'
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