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Tuberculosis and HIV

A man is successfully treated for Tuberculosis

 

What is tuberculosis?

Tuberculosis, usually shortened 'TB', is a disease caused by an organism called mycobacterium tuberculosis. The mycobacterium tuberculosis bacteria can attack any part of the body, but most commonly attacks the lungs.

2013 global TB facts

  • 9 million TB cases
  • 1.5 million people died from TB - 360,000 of this number were co-infected with HIV
  • 13 percent of new TB cases were in HIV-positive people
  • 510,000 women and 80,000 children died from TB
  • Asia (56 percent) and Sub-Saharan Africa (29 percent) accounted for the vast majority of TB cases 1

How is tuberculosis transmitted?

A person can have active or inactive (sometimes called latent) tuberculosis.

Active tuberculosis

Active tuberculosis or TB disease means the bacteria are active in the body and the immune system is unable to stop them from causing illness. People with active tuberculosis in their lungs (pulmonary TB) can pass the bacteria on to anyone they come into close contact with. When a person with active tuberculosis coughs, sneezes or spits, people nearby may breathe in the tuberculosis bacteria and become infected. 2 Some people have active tuberculosis in other parts of their body, besides the lungs; for example, the lymph nodes, spine or brain.

Symptoms of Active Pulmonary TB

  • Current cough
  • Fever
  • Weight loss
  • Night sweats

Inactive (or latent) tuberculosis

People can also be infected with tuberculosis bacteria that are not active in their body. If a person has inactive (or latent) tuberculosis, it means their body has been able to successfully fight the TB bacteria and stop them from causing illness. People who have latent tuberculosis do not feel sick, do not have symptoms and cannot pass tuberculosis on to other people. In some people tuberculosis bacteria remain inactive for a lifetime without becoming active. But in some other people the inactive tuberculosis may become active tuberculosis if the person's immune system becomes weakened - for example by HIV.

Getting tested for TB

Xpert MTB/RIF Rapid Test

This test detects active TB and rifampicin drug-resistance in sputum samples. A modern test that gives results within 2 hours – including among people with HIV, who may otherwise receive a negative sputum smear microscopy result. The WHO recommend using this test as the initial diagnostic test for people suspected of having multi-drug resistant TB or HIV-related TB. A positive rapid TB test result should be confirmed with a TB culture test. 3 4

Sputum smear microscopy

This test requires a sputum sample being taken and it being analysed under a microscope. It can take a day for a sputum smear microscopy result. TB present in people with HIV may not be detected via a sputum sample.

Chest x-ray

People with symptoms of active TB, who have received a negative sputum smear test should have a chest x-ray. Active TB can cause scarring to the lungs, which shows up on a chest X-ray. Diagnosing TB in HIV-positive people in this way can be difficult due to scarring from previous TB episodes or due to other HIV-related causes.

TB culture test

This test involves growing a sputum sample in a laboratory – this can take a few weeks. People who have the symptoms of TB, but a negative sputum smear microscopy should have a TB culture test. This can also be used to test for suspected drug-resistant TB.

Tuberculin skin test

This test finds out if a person has been exposed to TB bacteria by detecting antibodies to TB. This will be present in anyone who has TB (latent and active), had TB in the past.

Active tuberculosis: Treatment and cure

Tuberculosis (Mycobacterium tuberculosis bacillus) Active tuberculosis disease can almost always be cured with a combination of antibiotics. The variety of treatments and drug options depend on the country you are in. A proper combination of anti-tuberculosis drugs provides both prevention and cure. Effective treatment quickly makes the person with tuberculosis non-contagious and therefore prevents further spread of tuberculosis. Even in settings where antiretroviral drugs are unavailable or inaccessible, it is crucial that the health system is able to offer HIV positive people the simple drugs needed for DOTS. Achieving a cure for TB takes about six to eight months of daily treatment.

Several drugs are needed to treat active tuberculosis

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 four first-line drugs - typically a six month regimen, consists of:

  • Isoniazid
  • Rifampin/Rifampicin (Rifabutin, Rifapentine)
  • Ethambutol (Myambutol)
  • Pyrazinamide 5

Multi-drug resistant TB (MDR-TB) and extreme drug resistant TB (XDR-TB)

When a strain of tuberculosis bacteria is resistant to two or more 'first-line' antibiotic drugs it is called multi-drug resistant TB or MDR-TB. When it is resistant to three or more 'second-line' antibiotics as well, it is classed as extreme drug resistant tuberculosis, or XDR-TB.

Drug resistance usually arises when tuberculosis patients do not or cannot take their medicine as prescribed, and drug-resistant mutations of the bacteria are allowed to replicate.

People can also get MDR-TB and XDR-TB from others.

MDR-TB

MDR-TB is a serious problem and is very difficult to treat. In normal treatment (sometimes referred to as 'first-line' treatment) for tuberculosis, patients take the drugs isoniazid and rifampicin (the most effective tuberculosis drug available) plus other drugs for around six to eight months.

If a person is resistant to isoniazid and rifampicin however, they are said to have MDR-TB, and will need to change to a regime containing newer and often less widely-available 'second-line' drugs. Treatment with second-line drugs can take a very long time, and is usually far more expensive than standard DOTS therapy because most of the drugs are still under patent.

XDR-TB

XDR-TB is even more serious. If someone has XDR-TB, it means they are not only resistant to isoniazid and rifampicin, but to three or more of the six available second-line drugs too. This can make it virtually impossible to formulate an effective treatment regime for them. Many people with XDR-TB will die before it is even realised that they have the extreme resistant strain.

In 2006, 53 people in the province of KwaZulu Natal in South Africa were identified as having XDR-TB. Of these people, 52 died within 25 days of tuberculosis being diagnosed. The majority were HIV positive. However, progress is being made to better understand XDR-TB globally. In South Africa, by late 2006 an estimated 2000 - 3000 people with XDR-TB, and a similar or higher number of people with MDR-TB were on treatment with second-line drugs. 6 This report highlights that a robust national treatment programme that includes facilities for infection control, improved laboratory and clinical capacity and more efficient diagnostic technologies can be effective, not only for treatment but also to prevent untreatable patients from transmitting XDR-TB within hospitals and their communities.

TB drug resistance and HIV

Although HIV infection does not of itself increase the chance of drug resistance occurring, both MDR-TB and XDR-TB are very serious threats to HIV positive people, whose weakened immune systems render them unlikely to fight off tuberculosis naturally (often the only hope for those with a resistant strain).

The global response to tuberculosis (TB)

The discovery of antibiotic drugs that kill bacteria was a turning point in tuberculosis control. In well resourced countries, tuberculosis was previously treated with a special diet and bed rest, usually in a sanatorium. In the late 1950s it was found that this was unnecessary and that tuberculosis could be cured with well-supervised antibiotic treatment at home. 7

The World Health Organisation (WHO) first implemented the DOTS strategy in 1995; a strategy nearly all countries have adopted. Between 1995 and 2011, more than 51 million patients have been treated using the DOTS approach and up to 20 million lives have been saved. 8 Nevertheless, improved diagnostic methods for detecting tuberculosis are desperately required, as is a more effective vaccine against the disease.

New and more potent drugs are also needed to help simplify and shorten treatment, and fight multi-drug resistant TB (MDR-TB). The emergence of MDR-, and especially XDR-TB, threatens tuberculosis control efforts across the globe, including those in well resourced countries. In 2011 there were an estimated 310,000 cases of MDR-TB among notified TB patients with pulmonary TB. 9 Almost 60 percent of MDR-TB cases worldwide are estimated to occur in India, China and Russia.

For many years, tuberculosis remained relatively overlooked on the global scale, but the importance of addressing MDR and XDR-TB, and other issues, is now being recognised internationally. In 2006, the Stop TB Partnership launched "The Global Plan to Stop TB", an initiative that aims to achieve the Millenium Development Goal (MDG) of halving the death rates and prevalence of tuberculosis worldwide by 2015. If successful, the plan will save over 14 million lives, and will pave the way for the ultimate goal of eradicating tuberculosis by 2050. 10

On 21 March, 2013, one thousand days before the MDG's expire, African health leaders and international organisations launched a new initiative aimed at accelerating progress towards the target. Termed the 'Swaziland Statement', U.S.$120 million worth of investments are part of the package to eradicate deaths to tuberculosis. 11

Tuberculosis (TB) and people living with HIV

A person being treated for TB takes medication

HIV weakens a person's immune system, at which point people who have latent tuberculosis (TB) develop active TB and become unwell. People who are co-infected with both HIV and latent TB have an up to 50 times greater risk of developing active TB disease and becoming infectious compared to people not infected with HIV. As such, there is an urgent need to prevent people living with HIV from getting infected with TB as well as provide proper and proven treatment to those who get TB.

People with advanced HIV infection are vulnerable to a wide range of infections and malignancies that are called ' opportunistic infections'. These infections are called 'opportunistic' because they take advantage offered by a weakened immune system. TB is one such HIV-related opportunistic infection. A person that has both HIV and active TB is said to have an AIDS defining illness.

Why is TB and HIV co-infection dangerous for people living with HIV?

There are several important associations between the epidemics of HIV and tuberculosis:

  • Tuberculosis is harder to diagnose in HIV-positive people
  • Tuberculosis progresses faster in HIV-infected people
  • Tuberculosis in HIV-positive people is more likely to be fatal if undiagnosed or left untreated
  • Tuberculosis occurs earlier in the course of HIV-infection than other opportunistic infections

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. Some anti-HIV drugs can also interact with some tuberculosis drugs making the treatment more difficult. It is important that the tuberculosis treatment is taken regularly and exactly as the health care provider has advised. If the drugs are not taken regularly, the bacteria can become resistant to the drugs and this can be dangerous. Multi-drug resistant TB (MDR-TB) is when the bacteria has become resistant to Isoniazid and Rifampin, the two most powerful anti-TB drugs. It is more difficult to treat MDR-TB as well as being considerably more expensive. 12

To ensure thorough treatment, it is often recommended that the patient takes his or her pills in the presence of someone who can supervise the therapy. This approach is called DOTS (directly observed treatment, short course). DOTS cures tuberculosis in 95 percent of cases, and a six-month supply of DOTS costs as little as $10 per person in some parts of the world.

TB Preventative therapy

To prevent TB infection in people living with HIV, the World Health Organisation (WHO) recommends using the antibiotic, Isoniazid which can eliminate latent TB present inside the body, preventing active TB from developing. Before taking preventative Isoniazid therapy, it is important that people are tested for active TB . This is because taking Isoniazid when you have active TB can lead to resistance to this drug in the future.

Isoniazid use specifics:

  • All children and adults living with HIV should receive Isoniazid preventive therapy. This includes pregnant women and people taking antiretroviral therapy.
  • This should be taken for between 6 and 36 months.
  • In places where HIV and TB prevalence is high, life-long preventative therapy should be provided.

Regular screening

People with HIV should be screened for TB regularly, ideally at every health clinic visit.

  • Screening of pregnant women with HIV, for active TB should be part of maternal HIV services.
  • People living with HIV in crowded settings, such as, prisons, centres for refugees or internally displaced persons, should receive screening and Isoniazid preventative therapy.

TB Vaccine

There is a vaccine against tuberculosis called BCG, but the vaccine is now very old (it was first used in the 1920s), and tests have found it to be very variable in its ability to protect people from infection in modern settings. When it does provide protection form tuberuclosis, this generally only lasts for around 15 years. The BCG can also cause false-positive readings on the tuberculin skin test. If given to HIV positive adults or children with very weak immune systems, the BCG can occasionally cause disseminated BCG disease, which is often fatal.

References

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