TB and HIV links
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BACKGROUND ON TB/HIV
1. TB/HIV Epidemiology
TB is still a major health problem worldwide.
HIV/AIDS
An overwhelming share of the global HIV burden is borne by low-
and middle-income countries, where 95% of HIV-infected people
live. Of the global total of 40 million people living with
HIV/AIDS at the end of 2001, 28.1 million (70%) were in sub-
Saharan Africa followed by 7.1 million (18%) in Asia. In 2001
alone, an estimated 1.07 million adults and children were newly
infected in Asia. WHO estimates that nearly 1 million adults and
children are living with HIV/AIDS in the Region.
TB/HIV
Escalating TB case rates over the past decade in many countries
in sub-Saharan Africa are largely attributable to the HIV epi-
demic. In some countries in sub-Saharan Africa up to 70% of pa-
tients with sputum smearpositive pulmonary TB are HIV-positive.
Since the mid-1980s, in many African countries, including those
with well-organized programmes, annual TB case notification
rates have risen up to fourfold, reaching peaks of more than 400
cases per 100 000 population.
2. Links Between TB and HIV
Clinical Interaction between TB and HIV
HIV fuels the TB epidemic in several ways. HIV promotes progres-
sion to active TB both in people with recently acquired and with
latent Mycobacterium tuberculosis infections. HIV is the most
powerful known risk factor for reactivation of latent TB infec-
tion to active TB. The annual risk of developing TB in a person
infected with HIV/AIDS (PHA), who is co-infected with M. tuber-
culosis, ranges from 5%-15%. Up to 50% of PHA develop TB during
their lifetime, compared to 5%-10% of HIV negative persons. HIV
increases the rate of recurrent TB, which may be due to either
endogenous reactivation (true relapse) or exogenous re-
infection.
TB may have an adverse effect on HIV progression (some studies
show that the host immune response to M. tuberculosis enhances
HIV replication and may accelerate the natural progression of
HIV infection). Increasing TB cases in PHA pose an increased
risk of TB transmission to the general community, whether or not
HIV infected.
At the level of immunodeficiency at which PHA develop TB, sus-
ceptibility to a range of diseases is associated with high case
fatality rates by the end of TB treatment, typically about 20%
for new sputum smear-positive and up to 50% for new sputum
smear-negative cases. Yet many of the illnesses and causes of
death in HIV-infected TB patients are potentially treatable or
preventable.
TB/HIV and National TB and AIDS Programmes
The TB/HIV epidemic not only affects individual patients, but
also has an impact on the National TB Programme (NTP) and the
National AIDS Programme (NAP).
Impact of HIV on NTP
* Higher incidence of TB: increasingly stretched services for
diagnosis and case-holding
* Higher death rates: lower treatment success rates
* Increasingly stretched human resources in the health sector
* Increased risk of nosocomial TB infection
* Increased HIV-related mortality and morbidity in TB patients
* The stigma of HIV causes TB suspects to delay accessing health
services.
Impact of TB on NAP
* TB is the most common treatable infectious HIV-related disease
of PHA in countries with a high burden of TB.
* TB is the most common cause of death among PHA.
* Late TB diagnosis contributes to increased death rates in PHA.
* TB may accelerate the progression of HIV-related immunosup-
pression.