Rare diseases are the sentinels that protect us from common diseases. A few new cases of a rare disease will raise the suspicions of astute public health workers and can warn us that the general population has been exposed to a new or growing environmental hazard. A few new cases of a common diseases will go unnoticed by epidemiologists.
In most instances, a sudden increase in a rare disease has revealed totally unexpected threats to the general population, necessitating enduring improvements in industrial methods and resetting the normal mode of societal behavior. We can trace the origins of chemical carcinogenesis (the study of cancer causes) and of teratogenesis (the study of the causes of congenital malformations) to epidemiologic observations on rare diseases.
There are numerous rare diseases that have served as sentinels for environmental hazards. We listed a few of them in Section 8.4 when we were discussing cancer. Here, we extend the concept to cover all common diseases and we provide the back-stories that clarify the important role of rare diseases in disease prevention and public health.
Here is one example (of many described in the book): Rare mesothelioma caused by asbestos exposure
Asbestos is an insulating material that was used extensively in the mid-twentieth century. Asbestos inhalation is associated with an increased risk of bronchogenic lung cancer, the number one cause of cancer deaths in the U.S. [10]. In most cases of asbestos-related lung cancer, patients have a history of smoking. If asbestos caused bronchogenic lung cancer exclusively, we probably would have no idea of its carcinogenicity, because its effect among the many smoking related lung cancers would be negligible.
In 1960, a link was established between occupational asbestos exposure in miners and rare mesotheliomas of the pleura and peritoneum, the tissues lining the lung cavity and the abdominal cavity, respectively [11]. The news came too late to help individuals who were exposed to asbestos in its heyday, during the booming construction years of World War II. In those days, naval ship-workers, eager to protect vessels from fire, lavished pipes and ceilings with asbestos insulation. In so doing, they exposed themselves to asbestos dust. Their family members, who washed their dusty uniforms, were also exposed. Single exposures to the dust could cause mesotheliomas, and these mesotheliomas tended to occur 20 to 40 years following exposure.
Today, we treat asbestos as a serious occupational and environmental hazard. At enormous cost, we have abated our exposures to asbestos found in attic and pipe insulation, brake liners, and cigarette filters. Once again, occurrences of a rare cancer warned us to take measures to reduce exposure to a hazardous substance. Asbestos carcinogenicity also taught us a new lesson; solid and nonreactive agents could cause cancer.
I urge you to read more about this book. There's a good preview of the book at the Google Books site. If you like the book, please request your librarian to purchase a copy of this book for your library or reading room.
- Jules J. Berman, Ph.D., M.D. tags: endemic, epidemic, epidemiology, genetic disease, health threat, orphan diseases, orphan drugs, public health, rare diseases, sentinel, prevention, rare diseases, genetic diseases
