MMWR report on HIV and TB highlights challenges, needs
[Editor's note: In this Q&A story, Kevin Cain, MD, epidemic intelligence service officer in the National Center for HIV, STD, and Tuberculosis Prevention, and Michael Iademarco, MD, MPH, associate director for science in the Division of TB Elimination, at the Centers for Disease Control and Prevention in Atlanta, GA, answer questions about the report on "Screening HIV-Infected Persons for Tuberculosis - Cambodia, January 2004 -- February 2005," published Nov. 25, 2005, in the Morbidity and Mortality Weekly Report.]
AIDS Alert: The program the MMWR describes for screening HIV patients in Cambodia for TB seems intuitive—especially with such high percentages of TB infection among this population. Why wasn't this screening routine prior to the pilot project?
Cain: TB and HIV programs historically evolved as public health programs directed from the top-down, and our report helps document why it is so difficult to improve collaboration between programs. For example, changing from a disease-centered approach to a patient-centered approach requires building human resources and dramatic changes in the public health programs.
CDC, USAID, and the Cambodia Ministry of Health are working to improve collaboration between programs and address the needs of patients with both diseases. In this report, we were able to identify barriers to screening and found that by addressing these barriers with simple and inexpensive interventions, rates of screening improved substantially.
AIDS Alert: Once an HIV patient has been diagnosed with TB, what treatments are available in Cambodia?
Cain: After being diagnosed with TB, patients are started on standard therapy for tuberculosis. For most patients, this is 6 month treatment regimen, including 2 months of 4-drug therapy and 4 months of 2-drug therapy. In addition, HIV-infected TB patients are offered co-trimoxazole, which is a medication which has been shown to improve outcomes for these patients. Antiretroviral therapy is now being expanded in Cambodia, and most HIV-infected TB patients who live in an area with access to antiretroviral drugs are eligible for therapy.
AIDS Alert: Is TB screening among HIV patients common in other developing nations, such as India or countries in sub-Saharan Africa? If so, are there cost-effective models readily available for doing this, and if not, why not?
Cain: CDC, USAID, and other USG agencies continue to work with countries around the world to implement and enhance collaboration between TB and HIV programs through the President's Emergency Plan for AIDS Relief. Many different models are being tried, based on local needs and resources. In our project, we showed how a detailed program evaluation can help substantially improve screening rates. Such evaluations should be performed on projects in other countries to identify effective ways to improve patient care.
AIDS Alert: The MMWR article states that new diagnostic methods for TB disease are needed. Would you please explain why the best diagnostic tests don't work in resource poor settings now and what kind of new test could be more effective and practical?
Cain: As of now, there is no single diagnostic test which is highly sensitive for diagnosing TB in patients with HIV. New diagnostic tests are being researched, but it will still be some time before such a test is available in areas with limited resources. Some of the best tests for tuberculosis include culture of the sputum, blood, or lymph nodes. These tests are not widely available yet in Cambodia and some other resource-limited countries because they are expensive and technically demanding; most countries do not have the human or financial resources to build and maintain the laboratory capacity for these tests.
Public health officials believe that it is essential to improve the diagnosis of TB in HIV-infected persons. The World Health Organization has recognized this as a tremendous problem and recommends that studies be performed to develop and validate clinical algorithms for diagnosing TB disease. Such an algorithm would be able to divide patients into three groups: 1) patients who have TB; 2) patients who do not have TB; and 3) patients who need more diagnostic tests. This type of evaluation would also help to determine which diagnostic tests are needed for those patients who need further testing. With this knowledge, we would know how best to scale-up diagnostic services to meet the needs of the HIV-infected patients in the country. With this type of an evaluation, we would be able to substantially improve the diagnosis of TB in HIV-infected persons within a short time—perhaps within a year. The results could be applied to all HIV-infected persons within the country, and the results could be used to make available the tests which are most important for the region—and do so in a way which is most effective and practical for the country.
AIDS Alert: Given the financial and health infrastructure realities of Cambodia and similar resource-poor countries, what do you think could be achieved with regard to TB screening and how could this best be achieved?
Cain: Clinical algorithms could be developed and implemented in a relatively short period of time. This would immediately help a large proportion of patients who could quickly be diagnosed with TB or have TB ruled out, even before more diagnostic testing can be made available. Algorithms can be simple and are inexpensive, so they are sustainable. By diagnosing TB earlier using an algorithm like this, it is our hope that outcomes for HIV-infected TB patients would improve.
AIDS Alert: Should more research and effort be put into developing an effective vaccine against TB that would work in adult HIV populations, and, if so, how close is the world's health community to having such a product?
Iademarco: Yes, more research and effort should be put into developing an effective vaccine. The Stop TB Partnership, hosted by the World Health Organization, places a strong emphasis on the development of new tools, i.e. new drugs, new diagnostics for TB and drug resistance, and new vaccines, to combat TB and TB/HIV. CDC is committed to helping WHO continue to research possible vaccines to combat TB worldwide.
AIDS Alert: The program the MMWR describes for screening HIV patients in Cambodia for TB seems intuitiveespecially with such high percentages of TB infection among this population. Why wasn't this screening routine prior to the pilot project?You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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