Take what works and collaborate, WHO says
For too long the synergistic effect of the HIV/ AIDS epidemic and TB have created an unprecedented demand for effective and urgent action, and now the World Health Organization (WHO) in Geneva has a comprehensive plan that will focus on reducing TB morbidity and mortality among people in populations with high HIV prevalence.
"Irrespective of HIV status, people with TB need prompt diagnosis and effective treatment with anti-TB drugs from the individual perspective and from the public health perspective," says Dermot Maher, BM, BCh, medical officer of Stop TB Department of WHO. Efforts to slow the TB epidemic have been hampered by limited access and effectiveness of drugs, diagnostics, and vaccines in the areas most impacted by TB, and most of the tools available to treat TB are old technology, Maher says.
"Fortunately, there are now signs of increasing scientific efforts to improve the tools for TB control," Maher adds. "Under the overall auspices of the Global Partnership to Stop TB, there are now global scientific working groups on new TB drugs, new TB diagnostics, and new TB vaccines."
One success story worldwide is the use of direct observational therapy strategy (DOTS) for TB control, and evidence shows that this is increasingly being implemented: "The proportion of the world’s TB patients treated under the DOTS has increased from 7% in 1994 to 27% in 2000," Maher says. "Increased international commitment is necessary to achieve the target of 70% global DOTS coverage by 2005."
DOTS and current efforts to slow the TB epidemic appear to work, and with better HIV treatment, there could be an even greater impact, Maher says. "There is some evidence from countries badly affected by HIV that those countries with better TB control programs have been more successful in limiting the impact of HIV on TB," Maher says. "While it is the case today that a tiny proportion of people with HIV in the high HIV prevalence countries who need highly active antiretroviral therapy (HAART) have access to HAART, this proportion is certain to increase as the international community is galvanized into action."
Here are some of the strategies outlined in the WHO’s new plan, called "Strategic framework to decrease the burden of TB/HIV," which was prepared by Maher, Katherine Floyd, and Mario Raviglione, all of WHO, on behalf of the TB/HIV Working Group of the Global Partnership to Stop TB:
• Tackle both epidemics in joint efforts. "Tackling tuberculosis should include tackling HIV as the most potent force driving the tuberculosis epidemic," the plan states. "Tackling HIV should include tackling TB as a leading killer of people living with HIV/AIDS."
The plan focuses on stopping TB in countries with high HIV prevalence, which primarily are located in sub-Saharan Africa. Necessary measures include focusing on achieving high rates of detection and treatment, as well as measures to decrease morbidity and mortality in HIV-infected tuberculosis patients due to other common infections, the plan states. "The most efficient approach to detecting more cases and with shortened duration of infectivity involves intensified case-findings in settings where HIV-infected people are concentrated," the report says.
DOTS is one highly recommended measure, as are regimens that contain only rifampicin, and the use of innovative approaches to providing patients with the support needed to complete TB treatment.
• Use preventive tuberculosis treatment. Goals of preventive TB treatment should be aimed at decreasing the risk of a first episode of tuberculosis among those who have been exposed to TB or who have latent infection, and decreasing the risk of a recurrent episode, the strategic plan says. According to WHO statistics, countries that have high tuberculosis prevalence will have between 3.4% and 10% of people with TB and HIV developing active TB per year. Isoniazid preventive treatment can reduce the risk of active TB to around 40% of what it might have been without treatment, according to recent studies. WHO recommends providing six months of isoniazid preventive treatment to tuberculin-positive HIV-infected people who do not already have active TB.
• Use interventions to decrease HIV transmission. Interventions used to decrease HIV transmission should in turn result in a decrease in TB, so it’s important to increase and improve strategies for promoting condom use, treatment of sexually-transmitted infections (STIs), encouraging people to reduce the number of sexual partners, promoting safe injection behavior, and providing drugs to reduce mother-to-child transmission of HIV, the WHO report states.
"The most efficient way to constrain the spread of HIV in the whole population is to prevent transmission among those for whom the case reproduction number is very high, e.g., those with the most sexual partners," the report says. "Thailand has shown the effectiveness of this approach on a national scale."
However, the report notes, no government in sub-Saharan Africa has systematically attempted to reduce HIV transmission among those with the riskiest sexual behaviors. Also needed are greater efforts toward educating young people on HIV/AIDS and life skills development, the report says.
• Direct world resources to where they are most needed. In most of the 24 countries with the highest adult HIV seroprevalence, there is a lack of basic health care, HIV testing, and treatment. A recommended strategy for allocating resources most fairly and effectively would include to use a stepwise approach to implementing interventions, starting with the most cost-effective and aiming for the greatest impact within available resources, the report states. This strategy would include asking these questions of each intervention:
— Is the intervention a public good, i.e., is it both nonrival, which means that consumption by one individual does not affect the amount that can be consumed by others, and nonexcludable, meaning that once it’s provided, no one can be prevented from consuming it?
— Is the intervention associated with important externalities, such as the benefits and the costs of the intervention extend beyond the individual receiving the intervention?
— Is the intervention a catastrophic financial risk, but insurance is not available to cover costs when needed?
— Are market outcomes associated with the intervention unacceptable for reasons that include poor quality of care and treatment outcomes and equity concerns?
Although cost data are scarce, the WHO strategy plan estimates that TB treatment would cost approximately $100-$450 per health care unit provided per year in lower-income countries, whereas the cost of HAART would be more than $1,100 per person year of treatment.
In a hypothetical example, the report estimates that the cost of TB treatment in a nation with a population of 30 million and an adult HIV prevalence rate of 14% would cost about 3% of that nation’s health budget. Comparatively, the cost of HAART for the same hypothetical nation would cost absorb about 50.9% of the nation’s health budget. The report states that an estimated $7.5 billion is needed for a meaningful response to combating HIV/AIDS alone.
While the WHO’s strategic plan to stop TB and reduce HIV is ambitious and would be expensive to implement, it is possible to achieve, Maher says. "The current challenge is for everyone to have access technological tools and to develop better technology," Maher says. "If we don’t make any progress in developing tools then it will take much longer to achieve the goal of stopping TB."
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