Death of TB

To the Editors:

In his zeal to propagate the claims of modern scientific medicine, Lewis Thomas (NYR, November 9) has badly distorted the history of tuberculosis and, by implication, of the other major killing diseases of the past. The impression given by Dr. Thomas is that tuberculosis was a great scourge of the 1930s (“Everyone lived in fear of tuberculosis, but it was not much talked about”) and that its final conquest as a serious killer was the result of scientific medicine beginning with Koch’s discovery of the tubercle bacillus in 1882 and ending with the discovery, a few years ago, of isoniazid. “The conquest of tuberculosis became, at last,” he writes, “a stunning success.”

But the historical truth is rather different.^* In 1828, when causes of death were first systematically recorded in Britain, the death rate from tuberculosis was nearly 4,000 per million. The rate can only be appreciated in contrast to the present death rate in the US and Britain from all causes of only 9,000 per million. By 1855 the death rate from tuberculosis had fallen to about 2,700 and continued to fall steadily so that by the turn of the century it had reached about 1,200 per million. Koch’s discovery of the causal bacillus in the 1880s had no effect whatsoever on the rate of decline, and by 1925, after the Flexner revolution in medical schools, the rate was about 800, only 20 percent of its value in 1838. Totally unaffected by the arrival of modern medicine, the death rate continued its steady drop to 400 per million until 1948 when the introduction of chemotherapy on a broad scale did indeed accelerate the decline to its present negligible level. It is important to note that 57 percent of the decline had occurred by 1900 and 90 percent of the decline had occurred by the time of the introduction of chemotherapy. Extrapolation of the trend predicts that by 1970 death from tuberculosis would have reached its present low value even in the absence of chemotherapy.

The history of tuberculosis is the history of nearly all the major killers of the nineteenth century. Whooping cough, scarlet fever, and measles, all with death rates in excess of 1,000 per million children, and bronchitis, all declined steadily with no observable effect of the discovery of causative agents, of immunization or of chemotherapy. The sole exception was diphtheria which began its precipitous decline in 1900 with the introduction of anti-toxin and which was wiped out in five years after the national immunization campaign. The most revealing case is that of measles which killed about 1,200 in every million children in the nineteenth century. By 1960, despite the complete absence of any known medical treatment, it had disappeared as a cause of death in Britain and the US while in much of Africa it remains the chief cause of death of children.

The causes of the tremendous decline of mortality from infectious diseases in the last 100 years are not certain. All that is certain is that “scientific medicine” played no significant part. Water supply and sanitation are not involved, since water-borne diseases have not been the major killers. The suggestion that a reduction in crowding may have reduced the rate of transmission of respiratory diseases is not altogether convincing, since measles remains pandemic although it kills virtually no one in advanced countries. The most likely explanation, both for the historical trend and for the differences between regions of the world today, is in nutrition, although hard evidence is not easy to come by. It is at least suggestive that in the State of Sao Paulo during the last twenty years, fluctuations in the infant mortality rate are paralleled exactly by inverse fluctuations in the minimum real wage.

It is perhaps not surprising that the president and chief executive officer of the Memorial Sloan-Kettering Cancer Center would like us to believe that scientific medicine and medical research are responsible for our present longevity. But he and his colleagues will have a difficult time explaining why, despite the exponential growth in funds for medical research, the death rate in the United States has remained unchanged for the last twenty-five years. Medical scientists sometimes speak as if they could prevent death rather than simply postpone it. Yet they have done precious little even in this respect since the expectation of life at age forty has increased by a paltry two months since 1955.

Modern medicine has had successes in cases like polio, leukemia, and diabetes, but these have never been major causes of death. To suggest that most of us owe our present longevity to medical research is a total distortion of history.

Richard C. Lewontin

Professor of Population Sciences

Harvard University

School of Public Health

Boston, Massachusetts

Lewis Thomas replies:

It is probably not fair for me to begin by saying that I was around in the wards of the Boston City Hospital in the mid-1930s and Professor Lewontin was not, and therefore I have memories that he could not have, but there it is; it is partly the basis for our disagreement. I was greatly impressed by tuberculosis as a threat to survival, and so was everyone else on those wards. The fact, well known to the epidemiologists of that time, that this disease was considerably less a threat than it had been 100 years earlier, and that the death rate had been halving every twenty years or so in the century, was small comfort when there were still so many cases around, and so many deaths (about 500 per million in the total population, and about 2,000 per million among blacks). The introduction of effective chemotherapy, in the late 1940s, accomplished two spectacularly visible results: 1) the death rate in this country dropped over the next few years to less than forty per million for both whites and blacks, and 2) the incidence of the disease dropped correspondingly, due presumably to the reduction in the spread of tubercle bacilli from infected cases. I was enormously impressed by these events, and I do not believe they would have happened without chemotherapy.

Professor Lewontin’s prediction that we would have reached today’s “negligible” mortality by 1970 without chemotherapy puzzles me, and I doubt it. It depends on whose extrapolation of those mortality curves you elect to use. According to Dr. Walsh McDermott, professor emeritus of public health at Cornell, we might have reached today’s level by the year 2020, leaving society with a very substantial number of deaths from tuberculosis in the meanwhile (Perspectives in Biology and Medicine, University of Chicago, Volume 21, 1978).

Lewontin wants to make the point that the health of the people has been, and can continue to be, greatly improved by progressive improvements in the way society organizes’ itself, and I am in full agreement with this. There is no doubt that major changes in our mortality from infectious disease in general have occurred over the past two centuries, long before the sulfonamides and penicillin, and it is quite likely that these benefits came along with improvements in the standard of living in the western world, perhaps by improved nutrition as he suggests, perhaps also because of better housing and sanitation and less crowding. We are rid of typhoid and cholera in this country largely because of modern plumbing.

But we are rid of some other important infections thanks to immunization, with lobar pneumonia and epidemic meningitis soon to be added to this list, and we possess antibiotics for turning off a considerable number of bacterial diseases, making relatively trivial inconveniences out of what used to be prolonged and incapacitating illnesses. The technology of medicine surely has a long way still to go, but even in its present form it represents a useful endeavor. I do not understand why Lewontin wants so much to dismiss it, especially in the case of tuberculosis.

We may be nearing the maximum achievable span of longevity for human beings for all I know, and much of that achievement may, as Lewontin suggests, be due to changes in the way we live. Some of it, however, is due to modern medicine. I commend a close reading of Walsh McDermott’s temperate and non-ideological essay on this matter to anyone interested in the details.