TB & HIV - Co-infection, statistics, diagnosis, treatment

TB & HIV co-infection

TB and HIV co-infection is when people have both HIV infection, and also either latent or active tuberculosis. When someone has both each disease speeds up the progress of the other. In addition to HIV infection speeding up the progression from latent to active TB, TB bacteria also accelerate the progress of HIV infection.[efn_note]Mayer, K & Hamilton, C. “Synergistic Pandemics: Confronting the Global HIV and Tuberculosis Epidemics" Clinical infectious diseases, 2010, 50 Suppl 3. S67-70. 10.1086/651475[/efn_note]

HIV infection and infection with TB bacteria are though completely different infections. If you have HIV infection you will not get infected with TB bacteria unless you are in contact with someone who also is infected with TB bacteria. Although if you live in a country with a high prevalence of TB (such as India or South Africa) this may have happened without you realizing it. Similarly if you have TB you will not get infected with HIV unless you carry out an activity, such as unsafe sex, with someone who already has HIV infection.

TB occurs earlier in the course of HIV infection than many other opportunistic infections. The risk of death in co-infected individuals is also twice that of HIV infected individuals without TB. This is even when antiretroviral (ARV) therapy is taken into account.[efn_note]Suchindran, S. “Is HIV infection a Risk Factor for Multi-Drug Resistant Tuberculosis? A Systematic Review” PLoS one, May 2009, 4(5): e5561
http://www.plosone.org/article/[/efn_note]

The natural history of TB in people with HIV

A patient with HIV and TB in hospital in Nigeria © DAHW

When people have a damaged immune system, such as people with HIV who are not receiving antiretrovirals (ARVs), the natural history of TB is altered. Instead of there being a long latency phase between infection and development of disease, people with HIV can become ill with active TB disease within weeks to months, rather than the normal years to decades.

The risk of progressing from latent to active TB is estimated to be between 12 and 20 times greater in people living with HIV than among those without HIV infection.[efn_note]Luetkemeyer, A. “Tuberculosis and HIV”, HIVInSite,
http://hivinsite.ucsf.edu/[/efn_note] This also means that they may become infectious and pass TB on to someone else, more quickly than would otherwise happen. Overall it is considered that the lifetime risk for HIV negative people of progressing from latent to active TB is about 5-10%. For HIV positive people this same figure is the annual risk.[efn_note]“Implementing the WHO Stop TB Strategy: a handbook for national tuberculosis control programmes” Geneva, World Health Organization, 2008, p67 www.who.int/tb/publications/2008/[/efn_note]

HIV positive people with pulmonary TB may have the classic symptoms of TB. But many people have few symptoms of TB or even less specific ones. In addition, up to a fifth of people may have normal chest X-rays. HIV positive people with TB may indeed frequently have so called “sub clinical” TB. This is often not recognized as TB and subsequently there can be delays in both TB diagnosis and TB treatment.

People living with HIV are more likely to have extrapulmonary TB. Therefore it is much more common in countries with a high HIV prevalence, such as South Africa.[efn_note]"Extrapulmonary TB", TBCAB, http://www.tbonline.info/posts/2016/3/31/extrapulmonary-tb/[/efn_note]

Global co-infection mortality

In 2019 208,000 people who had both TB and HIV are estimated to have died. This is in addition to the 1.2 million people who died from TB alone.[efn_note]“Global Tuberculosis Control 2020”, WHO, Geneva, 2020,
www.who.int/tb/publications/global_report/en/[/efn_note] Those people who have co-infection when they die, are internationally reported as having died of HIV infection. An estimated 690,000 people died of HIV infection in 2019. So:

Since 2007 TB has been the leading cause of death from a single infectious agent, ranking above HIV/AIDS.

Deaths in people with TB & HIV co-infection

Diagnosing TB and HIV when there is co-infection

Because of the limitations of current TB tests, it is even more difficult to diagnose TB in HIV positive individuals, than to diagnose TB in people without HIV infection. Many people with HIV will have a false negative result from a TB sputum smear test. This can result in a large number of cases of active TB disease going undiagnosed.

By contrast the diagnosis of HIV in people with TB should always be straightforward because of the availability of quick and cheap point of care diagnostics for HIV infection.

Globally in 2018, 64% of notified TB patients had a documented HIV test. This was an increase from 60% in 2017. In the WHO African region, where the burden of HIV associated TB is highest, 87% of TB patients had a documented HIV test result.

A total of 477,461 TB cases among HIV positive people were reported (56% of the estimated incidence of 862,000 cases). Of these 86% were on antiretroviral therapy.

According to the World Health Organisation (WHO) improvements are still needed globally in the detection of active TB disease among PLHIV, the coverage of HIV testing among TB patients, and the enrolment of HIV positive TB patients in ART.

Treating co-infection

Treatment outcome data gives a success rate of 85% for TB and 75% for HIV associated TB.

Starting treatment for either HIV or TB

Providing HIV ARV therapy and anti TB drug treatment together

Starting both HIV ARV and anti TB drug therapy

For adults with co-infection, who need to receive both antiretrovirals and TB drugs, the WHO guidelines recommend starting ARVs within the first 8 weeks of starting TB treatment. This should be two weeks in individuals who have a CD4 count of less than 50. It is not now considered necessary to delay the initiation of ARV therapy until TB treatment has been completed.[efn_note]“Antiretroviral Therapy for HIV Infection in Adults and Adolescents: Recommendations for a public health approach 2010 revision”, WHO, Geneva, 2010, 45 www.who.int/hiv/topics/treatment/en/index.html[/efn_note]

The stigmas of TB and HIV/AIDS

The stigmas of HIV and TB have come full circle.

Now in the townships of South Africa, people will enter the shack (township home) of someone with HIV, but they will stop at the door if the person has XDR TB.[efn_note]Personal communication[/efn_note] There is more about TB in South Africa.

Footnotes