Diseases: The winners are... A Johns Hopkins expert looks at achievements and challenges

November 10, 1996|By John G. Bartlett

INFECTIOUS DISEASES, caused by microbes such as bacteria, viruses, parasites and fungi, result in illnesses such as pneumonia, influenza, tuberculosis and AIDS. The field has witnessed remarkable accomplishments in both the recent and remote past.

From a historical perspective, the most substantial progress has come in the categories of antibiotics, vaccines and public health. Of these, the most important is probably antibiotics, introduced during the 1940s with penicillin, which revolutionized medicine and is sometimes viewed as the greatest curative revolution in medical history. To paraphrase the late physician and educator Walsh McDermott, penicillin gave more curative power to a barefoot, itinerant care provider in the farthest reaches of Africa than all the collective talent of physicians in New York City.

With vaccines, the record is equally impressive: Diphtheria, mumps, whooping cough, measles, polio and tetanus have been reduced by 98 percent or more. Perhaps the most spectacular achievement was the elimination of smallpox in 1977. (Despite the magnitude of their effort, the architects of the smallpox eradication program have never been awarded a Nobel Prize).

In public health - food inspection, water purification, rodent control - progress is best illustrated by the remarkable difference between developed countries, where infectious diseases are the major cause of death in 5 percent, and underdeveloped countries, where they are the major cause of death in 35 percent.

With this rich heritage, I submit the following as the most substantial accomplishments and challenges in this field during the past ten years, a sort of Academy Awards of Infectious Diseases.

Diseases facing elimination

The nominees, identified by the Centers for Disease Control and Prevention and the World Health Organization, are mumps, rubella, cysticercosis, filariasis, guinea worm and polio. All are considered ""potentially eradicable," but polio is the most likely winner for the near future. Because about 88 percent of the population has been vaccinated, not enough vulnerable patients remain to sustain the virus. The last isolation of poliovirus occurred in 1990, and its eradication in the Western Hemisphere became ""official" about a year ago. A few focal points of polio cases remain in other parts of the world, but most authorities consider elimination to be simply a matter of time. For those who lived through the 1950s, polio eradication is a stunning victory.

Vaccine

Nominees, developed or newly promoted during the last decade, are vaccines against chicken pox, hepatitis B, pneumonia (Pneumovax), hepatitis A and Haemophilus influenzae.

The winner is hepatitis B vaccine, for several reasons. A devastating disease, hepatitis B is responsible for about 5,000 deaths a year in the United States because of cirrhosis or liver cancer. Its toll is much heavier in other parts of the world, where it is the most common cause of cancer. Another reason hepatitis B vaccine wins is that the virus, never having been grown successfully in the test tube, is a special pharmacologic challenge. The original vaccine was made by taking parts of the virus from blood donations, but in 1986, ""recombinant" techniques allowed the vaccine to be produced by microbes, making it a pure product. The U.S. Public Health Service introduced it as a component of routine vaccinations in children in 1991. Although hepatitis B is on the way out, it will take a vigorous vaccination campaign and a few generations to achieve eradication.

My second-place winner, the vaccine for Haemophilus influenzae, is worth noting. Severe infections with this bacterium, formerly a devastating problem in children and the most common cause of pediatric meningitis, now virtually have disappeared in the United States.

New virus

Nominees that have dominated medicine in the last decade include hepatitis C virus (now recognized as the most common cause of cirrhosis, even more common than alcoholism), herpes virus 6 (a common pediatric virus and the most common cause of seizures in children), Sin Nombre virus (the cause of the lethal infections originally discovered in the four corner states in 1993), and HIV (the cause of AIDS). This is a no-brainer: The award must go to HIV.

It is estimated that about one in 200 young adults in the United States is infected; for Baltimore residents, the estimate is about 7 percent of young adult men. About 90 percent of new cases are in the developing world, and the estimated total number currently infected is 21 million - the great majority in sub-Saharan Africa and Southeast Asia. For perspective, the largest temporally defined epidemic in the history of medicine - bubonic plague in the 14th century - caused 25 million deaths. HIV clearly will exceed that record.

New bacterium

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