What is the U.S. Role in Combating the Global HIV/AIDS Epidemic?

QUESTIONS FOR DR. TIMOTHY DONDERO

1. The current number of infected Africans is staggering, and continues to increase. This trend is occurring in other developing countries around the world as well. Does CDC have any projections as to how this epidemic compares to other past or present international health threats? Isn't this epidemic truly unique and deadly -- and resulting in unprecedented death and destruction from a world health perspective?

2. Is it likely that new strains of HIV/AIDS can and will develop among untreated populations, due to the vast numbers of carriers around the world? Would wider drug treatment in developing nations significantly increase the risks of new strains of HIV/AIDS? Does CDC support a policy of not making HIV/AIDS drug treatments more available in developing nations?

3. Are the recently publicized problems with CDC dedicating its limited resources to programs or purposes other than those intended by the Congress (i.e., funding other activities than chronic fatigue research), also problems in the HIV/AIDS research? Is there disagreement within CDC regarding the funding levels of HIV/AIDS vaccine and drug treatment research?

Responses to Supplemental Questions from the Subcommittee on Criminal Justice, Drug Policy, and Human Resources - from hearing on July 22, 1999

1. Question: The current number of infected Africans is staggering, and continues to increase. This trend is occurring in other developing countries around the world as well. Does CDC have any projections as to how this epidemic compares to other past or present international health threats? Isn't this epidemic truly unique and deadly-and resulting in unprecedented death and destruction from a world health perspective?

Answer: CDC does not make formal projections of the HIV/AIDS epidemic internationally, that being the work of the Joint United Nations Programme on HIV/AIDS (UNAIDS). However, a rough epidemiologic comparison with other great epidemics of history suggests that the HIV/AIDS pandemic truly is unique and deadly. The only other great epidemics that come to mind are the bubonic plagues (Yersinia pestis) that struck Europe in the late middle ages, where as many as a third of the urban population died of plague; and the influenza epidemic of 19181919 where as many as 6 million died through the world, over half a million in the U.S. But while the plague and the “flu” epidemics were terrible, they were relatively short lived (since the disease had a short duration the survivors were immune, and the infections died out for lack of susceptible hosts).

By contrast, the HIV/AIDS epidemic continues to kill. Virtually everyone infected in developing countries eventually dies of the infection, and in some parts of the world the epidemic continues to intensify years after its beginning. The HIV/AIDS epidemic also differs from these other epidemics in that HIV is preventable, and the biologic and epidemiologic aspects of this epidemic are well understood.

Answer: The virus, HIV, mutates easily, and a number of strains have already evolved within human populations. Indeed there are two different viral types (type 1 being the principal one around the world), each with multiple subtypes. Thus far, the subtype differences have been of public health importance principally in terms of requiring that antibody tests and other reagents be modified so as to detect all the infections, and the different subtypes may make vaccine development more difficult. Resistance to anti-retroviral drugs is currently the more important change occurring, and this appears to be a natural consequence of treatment with anti-retroviral drugs. Development of resistance occurs most quickly when only a single drug is used, somewhat less fast when two drugs are used simultaneously, and more slowly when triple drug therapy is used. Resistance also occurs more frequently if the treatment regimens are not strictly

followed and doses are missed. Wider drug use in developing countries will inevitably increase resistance (resistance has already been found in Uganda after only a few months of anti-retroviral use). The development of resistance is intensified if only single or two-drug therapy is practiced (the typical therapy available in developing countries) or where treatment is intermittent, as happens when the patient's financial resources are limited.

CDC does not have a policy on the practice of making HIV/AIDS drug treatment available in developing countries. CDC does, however, support the concept of adequate treatment and care for all AIDS infected individuals. Sadly, for reasons of cost and lack of infrastructure, this concept in not reality in most parts of the developing world. We do, however, have some very effective tools in our collective arsenal. CDC considers prevention a higher priority to combating the epidemic than anti-retroviral drug therapy. One area where the use of therapies has proved effective in developing countries is the use of short-course regimens in pregnant women to prevent mother-to-infant transmission. For HIV-infected people in developing countries, prevention and treatment of opportunistic infections, especially tuberculosis, is a more cost-effective and realistic means of treatment than is anti-retroviral therapy. It would also have the added benefit of combating the TB epidemic (which is worsening because of HIV.) Currently, in most places, screening HIV infected persons for TB and treatment is infrequent. In addition to the huge expense of triple-drug therapy, the medical infrastructure necessary for evaluating, maintaining, and monitoring patients on these drugs is frequently not available in the most heavily affected developing countries.

Answer: Each year Congress provides guidance and, often, very specific direction on the HIV/AIDS appropriation to CDC. This, together with the President's budget, provides the basis on which new and existing programs are implemented. CDC strives to assure these programs are consistent with the letter and intent of Congress and the President.

I am not aware of any major disagreement within CDC on the direction and scope of HIV/AIDS research. On an ongoing basis CDC conducts internal reviews of it's research portfolio and periodically supports an external review of its programs and directions. Although consensus is not always achieved on the recommendations, general agreement is the norm.

CDC does not have a major role in vaccine or drug development. Although some vaccine-related basic research activities are conducted at CDC, most of CDC's vaccine-related efforts are directed toward the latter stages of vaccine development, including phase III efficacy field evaluation of candidate vaccines, post-licensure evaluation (phase IV demonstration projects) and program implementation. Once a safe and effective vaccine is licensed and available, CDC's role includes: the development and evaluation of strategies for vaccine use; the surveillance of infection/disease and vaccine-related adverse events; epidemic investigations; and the provision of technical assistance to states, international agencies and developing countries.

QUESTIONS FOR DR. ALLEN HERMAN

1. In your testimony, you indicate numerous approaches to the HIV / AIDS epidemic. You include the needs for health professionals, infrastructures and resources. But isn't the availability of drug treatments the most essential resource, one that could lead to improvements in the others? Isn't the existing treatment of tuberculosis and other AIDS related ailments of those infected but not receiving HIV / AIDS treatment also resource intensive? Is it cost-effective to let millions die who are in the most productive phase of their lives?

2. How successful are the educational and counseling programs that are being financed by the United States? Are condom products and use instructions really working for most of the people in Africa? What educational efforts are working, and what evidence supports this success?

3. In your final recommended approach to combat the African HIV/AIDS epidemic, you indicate the following in discussing the cost of resources: "It will be critical for costeffective methods of treatment to be identified. We cannot simply import treatment regimes from other countries. It will become increasingly important for Southern Africa to identify effective and efficient mechanisms to cope with the epidemic." How is this approach and need inconsistent with South Africa's Medicines Act, which was passed to do that?

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What is the U.S. Role in Combating the Global HIV/AIDS Epidemic?: Hearing ...