Tuberculosis

Key considerations for people living with HIV

Tuberculosis (TB) is caused by Mycobacterium tuberculosis, a slow-growing bacterium that can only survive in humans.¹ TB is contagious. Each untreated person with active TB will infect on average 10–15 people per year.²

It is estimated that overall, one third of the world’s population is currently infected with M. tuberculosis,² although the proportion of infected individuals may be much higher in developing world settings.³ However, not all individuals infected with M. tuberculosis will necessarily progress to active disease; an infected individual may have asymptomatic latent TB for years without any awareness of their condition.

HIV is the strongest risk factor for developing active TB in people with latent or new TB infections.⁴

• 5–10% of people not infected with HIV who have latent TB will develop active TB at some point in their life²
• For people living with HIV (PLWHIV), the risk of developing TB is estimated to be between 20–37 times greater than that in people without HIV infection^4,5

TB is the leading cause of death in PLWHIV⁶; in 2008 and 2009, around 1 in 4 deaths among PLWHIV were attributed to TB.^5,7 However, TB is preventable and curable with inexpensive medication.

• most people infected with TB can be cured with a six-month course of medication costing approximately US $25⁸

Epidemiology of TB and HIV

• TB is closely associated with the HIV epidemic; in sub-Saharan Africa, TB is the most common serious opportunistic infection and the leading cause of death in PLWHIV before and whilst receiving highly active antiretroviral therapy (HAART)³
• In 2010, among the 34 million PLWHIV, there were:⁹

– 1.1 million new cases of TB (13% of all new cases of TB)
– 350,000 deaths attributed to TB (24% of all deaths from TB)

• Globally, 30% of PLWHIV are estimated to have concomitant TB infection.⁵

– in 2010, of an estimated 1.1 million new TB cases in PLWHIV, 82% were in sub-Saharan Africa⁶
– in countries of Southern and Eastern Africa, more than half of all TB patients are estimated to be infected with HIV⁷
– in Southeast Asia, 46% of PLWHIV are infected with TB⁵
– in Europe, 14% of PLWHIV are infected with TB⁵

• People living in congregate settings, such as prisons and centres for refugees, or internationally displaced people have an increased risk and incidence of TB, HIV infection and drug use⁵

Multidrug-Resistant (MDR) TB and Extensively Drug-Resistant (XDR) TB in PLWHIV

• MDR-TB refers to resistance to first-line anti-TB drugs (at least isoniazid and rifampicin), whereas XDR-TB refers to resistance to both first- and second-line anti-TB drugs (at least isoniazid, rifampicin and fluoroquinolones and one of three injectable drugs [capreomycin, kanamycin or amikacin])^6,10

MDR-TB can be treated with second-line anti-TB therapy, but XDR-TB is virtually untreatable.⁸

• Globally, there were 650,000 MDR-TB cases in 2010⁶
• Between 2007–2010, the WHO collected data on MDR TB from 80 countries and 8 territories¹¹

– the proportion of new TB cases reported as showing multidrug resistance ranged from 0–28.9%

• 12% of new TB patients in Belarus, Estonia, several oblasts of the Russian Federation and Tajikistan were reported to have MDR-TB

– the proportion of previously treated cases with MDR TB ranged from 0–65.1%

• proportions >50% were reported in Belarus, Lithuania, the Republic of Moldova, 5 oblasts of the Russian Federation and Tajikistan¹¹  
• Institutional outbreaks of MDR-TB have been shown to primarily affect HIV-infected people⁵
• MDR-TB in PLWHIV is often the result of exogenous transmission, although acquired rifampicin resistance has been established in HIV-infected individuals⁵

TB Prevention and Treatment for PLWHIV

• Key interventions of the World Health Organization core HIV and TB prevention, care and treatment services include:⁴

– provision of ART
– the Three I’s for HIV/TB¹²

• Intensified case-finding of TB
• Isoniazid preventive therapy
• Infection control for TB

The WHO 2012 policy on collaborative TB/HIV activities provides:¹³

– a summary of recommendations for TB/HIV management from current guidelines and policy documents
– guidelines for TB/HIV management for national programmes and other stakeholders
– strategic advice for decision-makers in the field of health and managers of TB-control programmes and HIV programmes

• Find out more about TB prevention
• Find out more about TB treatment

For more information on drug-resistant TB, view this presentation from Dr Christopher Dye of the World Health Organization: Drug resistant tuberculosis: biology, epidemiology and control.¹⁴

References

1. National Institute of Allergy and Infectious Diseases: Tuberculosis – Cause. Accessed 26 November 2011.
2. World Health Organization. Media Centre Tuberculosis Fact Sheet. 104 (2010). Accessed 27 November 2011.
3. Martinson NA, Hoffman CJ, Chaisson RE. Epidemiology of Tuberculosis and HIV: recent advances in understanding and responses. Proc Am Thorac Soc 2011;8:228–93.
4. World Health Organization. Guidelines for Intensified Tuberculosis Case-Finding and Isoniazid Preventive Therapy for People Living with HIV in Resource-Constrained Settings. Accessed 25 November 2011.
5. Getahun H, Gunneberg C, Granich R, Nunn P. HIV Infection-Associated Tuberculosis: The Epidemiology and the Response. Clin Infec Dis 2010;50:S201–207.
6. World Health Organization. HIV/TB Facts. 2011. Accessed 4 October 2012.
7. Stop TB Partnership. World Health Organization and Joint United Nations Programme on HIV/AIDS: The Global Plan to Stop TB 2011–2015. Accessed 27 November 2011.
8. Stop TB Partnership. World Health Organization and Joint United Nations Programme on HIV/AIDS: Time to act. Save a million lives by 2015. Accessed 27 November 2011.
9. World Health Organization. TB/HIV Facts 2011–2012. Accessed 4 October 2012.
10. British HIV Association. Guidelines for the Treatment of TB/HIV Coinfection 2011. Accessed 25 November 2011.
11. Zignol M, van Gemert W, Falzon D, et al. Surveillance of anti-tuberculosis drug resistance in the world: an updated analysis, 2007–2010. Bulletin of the World Health Organization 2012;90:111–119D. doi: 10.2471/BLT.11.092585. Accessed 15 February 2012.
12. World Health Organization. Three I’s Meeting (2008). Accessed 25 November 2011.
13. World Health Organization. Policy on collaborative TB/HIV activities. (2012). Accessed 13 April 2012.
14. Dye C. Drug resistant tuberculosis: biology, epidemiology and control (2009). In Gillespie, S. (ed.), Antibiotic Resistance: From genes to global prevalence. The Biomedical & Life Sciences Collection, Henry Stewart Talks Ltd, London. Accessed 5 December 2011.