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Do We Need New Drugs and/or New Vaccines?

Dr Donald A ENARSON

Head, Division of Clinical Trials, France

I would like to welcome to you all and express my pleasure at seeing you all here today. The aim is not simply to make presentations but rather that you should participate and provide your ideas and views. To this end, I will begin by making a short presentation to stimulate the discussion. I have been asked to discuss the question of whether we need new drugs or vaccines. This would appear to be a silly question given that the workshop is concerned with the very issue of new drugs and vaccines.

Tuberculosis in Europe

We all know that tuberculosis entered Europe in the late Middle Ages, reaching a peak in about the early 1800s. It then began to decline and, by 1950, it was virtually no longer present. My decision to work in the area of tuberculosis in the 1970s may thus seem to be quite incongruous. I was advised that I would never make a living in this area. However, let us now look at specific areas of Europe. This chart refers to various provinces in Norway. It would appear that tuberculosis probably entered Europe from the South and moved toward the North. Norway was thus the last European country to be touched by tuberculosis, and was the latest part of the tuberculosis wave. As we go further north in Norway, we can see that each of the counties was affected in a different way by the different waves of the disease. We thus know that tuberculosis will eventually go away, regardless of the actions we take. In the early 1920s in Norway, tuberculosis was a disease that affected young people, which is the case in many developing countries today. As tuberculosis began to disappear, it began to affect an older generation of people. This chart demonstrates the experience of tuberculosis in the Inuit community, living in the most northern part of the world in Greenland, Canada and Alaska. Prior to the AIDS epidemic, this group was the most heavily touched by tuberculosis in the world. At the same time, it also saw the most rapid decline in tuberculosis ever observed in a human population. During the 1950s and early 1960s, we saw a decline in tuberculosis of up to 20% per year. We do not exactly understand why this occurred. Tuberculosis is thus an interesting disease. We have been studying it for more than 100 years and we still do not understand much about it.

What Do We Know about Tuberculosis

It would appear that tuberculosis seems to disappear by itself. This may be hastened by drugs, vaccines and other interventions. With massive interventions, for example in the Inuit communities, its disappearance can be speeded up even further. Therefore, why do we need more interventions? What is the point of holding this workshop today? Do we really need new drugs and vaccines given that the disease will go away by itself? While tuberculosis will go away by itself, it will then come back again. In the Harlem district of New York City, for example, we can see that tuberculosis began to decline steadily but then came back again. Why did this happen? It began rising again in 1979. This was thought to be due to HIV and AIDS. However, 1979 was the year of Ronald Reagan's election. Under his Presidency, funds were cut to the most disadvantaged groups in society, and tuberculosis began to rise again. Addressing the resulting problems was a very expensive experience. Unfortunately, politicians continue to make these kinds of mistakes today. The experience in Tanzania shows the impact of HIV/AIDS on tuberculosis. HIV/AIDS entered Tanzania in 1982, leading to a tremendous five-fold rise in tuberculosis. If we continue to do business as usual, we will not solve this problem and tuberculosis will not continue to go away. We also know that political commitment to fighting a disease such as tuberculosis cannot be sustained indefinitely. For example, the current strategies would need to be sustained for a number of generations in order to successfully eliminate tuberculosis. I do not believe that this will be possible. In addition, HIV/AIDS has completely changed the situation. We cannot commit to the control of tuberculosis without committing to the control of HIV/AIDS. We have to consider tuberculosis as a multi-faceted entity. For example, the huge problem in the Inuit population went away very quickly. No particular subsets of the population contributed to the epidemic. However, in large populations, we can quickly control infection of the main parts of the population. Certain subsets of the population in Canada, for example, have disease rates that are very high: alcoholics, drug addicts etc. This differential behaviour of the epidemic must be addressed. In the past, strategies were based on very strong interventions, which led to the stopping of new infection. However, old infection remained. In the past, this was felt to be enough. As our populations are ageing, this issue is becoming more crucial, and argues against our current strategies. Even when we do intervene, we have to treat patients for six to eight months. We know that the longer someone has to take to medication, the less they will take it. In Sudan, for example, a study has shown that both women and men will stop taking their medication after a certain amount of time, even when they are ill and know they need to continue to take medication. This is the case in both the developing and the developed world. It is thus normal not to adhere to the regular taking of medication. We have drugs at our disposal. However, they have to be taken for too long a period of time. We have vaccines. This chart provides information on Aboriginal people in Alberta, Canada, who were given BCG vaccinations when they were young. This population of 35 000 was monitored for up to 20 years. Over this period, there was not much difference between the vaccinated and unvaccinated patients in terms of appearance of new episodes of disease.

What Do We Need?

I began by saying that we no longer need anything. Many people involved in the global fight against tuberculosis stated that we only need to pursue our current knowledge and strategies. I do not believe that this is true. I believe we need vaccines. The need for new drugs is a lower priority, as they generally must be prescribed for too long a time. While waiting for new vaccines, we need certain drugs, especially to deal with the increasing number of drug resistant cases emerging and those drugs that will drastically reduce the duration of treatment. We also need to improve our ability to diagnose and detect cases.

Brigitte GICQUEL

When you stated that women have the same rate in fall off for taking medication, does this mean that women do not want to follow treatment or that they have no access to treatment?

Dr Don ENARSON

I suspect that this is an unusual example, and women are generally better than men when it comes to taking medication.