ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Thursday, February 20, 1997 TAG: 9702200002
SECTION: EDITORIAL PAGE: A-13 EDITION: METRO
SOURCE: JOHN G. BARTLETT
WHEN PENICILLIN was introduced to the public in the 1940s, many people assumed that infectious diseases soon would be conquered. But reality has a way of shattering expectations. In the developing world, infections still cause about one-third of all deaths - and most of them are preventable. Here in the United States, deaths due to infectious diseases actually increased by 58 percent during the past decade.
Far from being a discipline in decline, the study of infectious diseases has been booming. Since 1980, researchers have discovered more than 20 microbes that cause major diseases. We are beginning to think that infectious organisms play a key role in major illnesses like cancer, stomach ulcers, arthritis and possibly heart disease. Research is opening up new areas that need to be explored to counter the continuing threat from infectious diseases.
The AIDS epidemic certainly has been responsible for part of the increased visibility of the field. An estimated one in 200 young adults in the United States is infected with HIV, the virus that causes AIDS. In the city where I live, Baltimore, about 7 percent of young men are infected.
The epidemic is even worse in other parts of the world. Approximately 21 million people worldwide are infected, with the great majority of cases in sub-Saharan Africa and Southeast Asia. For perspective, the bubonic plague that decimated Europe in the 14th century killed about 25 million people. The death toll from HIV clearly will be greater.
Meanwhile, old microbes have retained their punch. Tuberculosis remains the single most common cause of death, infecting about one-third of the world's population. And old microbes are evolving into new strains that are resistant to antibiotics. A quarter of the strains of the bacterium responsible for most cases of pneumonia, ear infections in children and meningitis in adults are now resistant to penicillin and other antibiotics.
There continue to be large epidemics - some caused by long-recognized microbes, others by newly discovered ones. The 1990s have seen a cholera epidemic in South America, plague in India, an outbreak of Ebola virus in Zaire, diphtheria in Russia, dengue in Central America, and a new, potentially fatal form of diarrhea in Japan.
At the same time, researchers have been discovering that microbes may be involved in diseases that never before have been linked to infectious organisms. For example, a bacterium has been identified as the major cause of stomach ulcers, stomach cancer and other diseases. Hepatitis C virus now is recognized as the most common cause of cirrhosis of the liver in the United States - even more common than alcoholism.
There also is much good news to report about infectious diseases. Over the past decade, new vaccines have been developed or promoted against chicken pox, hepatitis A and B, pneumonia and Haemophilus influenzae. As these vaccines are more widely distributed, the corresponding diseases will decline.
Even more remarkable, the nations of the world are on the verge of eliminating polio from the planet. The precedent was set with the global elimination of smallpox - arguably the greatest achievement in the history of public health. Polio already has been eliminated in the Western hemisphere, and its elimination from a few remaining regions is only a matter of time. With 85 percent of the world's population now vaccinated, the virus has difficulty finding enough vulnerable hosts to survive. For those of us who lived through the polio epidemics of the 1950s, this represents a stunning victory.
Probably the most profound message from the recent history of infectious disease research is the unpredictability of the field. In 1980, no one guessed that anything like the AIDS epidemic was about to strike the United States. No one expected that polio would be largely eradicated. No one predicted that a bacterium would cause stomach ulcers, that a virus would prove to be the major cause of liver disease, or that a vaccine (against hepatitis B) could prevent one of the most common causes of cancer.
The best way to prepare for an uncertain future is with a robust system of research, development and health-care delivery. Experts from multiple disciplines need to be ready to perform the cascade of activities needed to control disease: first, detecting the microbes, then developing diagnostic techniques, describing the clinical symptoms of the disease, conducting epidemiologic studies, and developing methods to treat and prevent the disease.
Without strong capabilities in these areas, the microbes ultimately may win.
John G. Bartlett is chief of the division of infectious diseases at the Johns Hopkins University School of Medicine in Baltimore.
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