PHA-Exchange> TB and HIV links

[Claudio]

BACKGROUND ON TB/HIV 

1. TB/HIV Epidemiology

TB
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 SubSaharan 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 overthe past decade in many countries in sub­Saharan Africa are largely attributable to the HIV epidemic. In some countries in sub-Saharan Africa up to 70% of patients 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 progression 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 infection to active TB. The annual risk of developing TB in a PHA, who is co-infected with M. tuberculosis, 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 thatthe host immune responseto 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, susceptibility 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 immunosuppression.


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