Immunization is the greatest public health success story in history. Millions of lives have already been saved, thanks to massive worldwide vaccination campaigns.

A global immunization program has eliminated smallpox –the lethal disease that claimed more lives than all the wars of the 20th century combined –and a similar campaign has almost eradicated polio. Many children are now vaccinated to protect them against common life-threatening diseases.

Other diseases have been tamed by less-dramatic methods. Such waterborne infections as cholera rarely cause problems where there is adequate sanitation and a safe water supply.

In many lands increased access to doctors and hospital means that most diseases can be identified and treated before they become lethal. Better diet and living conditions, along with enforcement of laws regarding proper handling and storage of food, have also contributed to improving public health.

Once scientists tracked down the causes of infectious diseases, health authorities could take practical steps to halt an epidemic in its tracks. Consider just one example. An outbreak of bubonic plague in San Francisco in 1907 killed few people because the city immediately launched a campaign to exterminate the rats whose fleas transmitted the disease.

On the other hand, starting in 1896, the same disease had caused ten million deaths in India within 12 years because its underlying cause had not yet been identified.

                               FAILURES IN FIGHTING DISEASES

Clearly, significant battles have been won. But some public health victories have been confined to the richer countries of the world. Treatable diseases still kill millions of people, simply for lack of sufficient funds. In developing countries many people still lack adequate sanitation, health care, and access to safe water.
Fulfilling these basic needs has become more difficult on account of massive migrations of people from the countryside to the megacities of the developing world. As a result of such factors, the world’s poor suffer what the World Health Organization calls a disproportionate share of the burden of disease.

Shortsighted selfishness is the principal cause of this health imbalance. Some of the world’s worst infectious killers seem distant; some of these are limited entirely or mainly to poor tropical and subtropical regions. Since wealthy developed countries and pharmaceutical companies may not benefit directly, they begrudge allocating funds for treatment of these diseases.

Irresponsible human behavior is also a factor in spreading disease. In no way is this harsh reality better illustrated than in the case of AIDS virus, which spread from one person to another through body fluids. Within a few years, this pandemic has swept across the globe. Human beings have done it to themselves, asserts epidemiologist Joe McCormick. And that’s not moralistic, it’s just a fact.

How did humans unwittingly cooperate with the AIDS virus? The book The Coming Plague lists the following factors: Social changes –especially the practice of having multiple sex partners –led to a wave of sexually transmitted diseases, making it much easier for the virus to take hold and for one carrier to infect many other people.

The widespread use of contaminated secondhand syringes for medical injections in developing countries or for illicit drug use had a similar effect. The billion-dollar global blood industry also enables the AIDS virus to pass from one donor to dozens of recipients.

As mentioned earlier, the overuse or underuse of antibiotics has contributed to the appearance of resistant microbes. This problem is serious and is getting worse. Staphylococcus bacteria, which often causes wound infections, used to be eliminated easily by penicillin derivatives. But now these traditional antibiotics are often ineffective. So doctors must turn to newer, expensive antibiotics that hospitals in developing countries can rarely afford.

Even the newest antibiotics may prove unable to combat some microbes, making hospital infections more common and more deadly. Dr. Richard Krause, former director of the U.S. National Institute of Allergy and Infectious Diseases, bluntly describes the current situation as “an epidemic of microbial resistance.”

                               ARE WE BETTER OFF TODAY

Now, at the start of the 21st century, it is clear that the threat of disease has not disappeared. The relentless spread of AIDS, the appearance of drug-resistant pathogens, and the resurgence of age-old killers like tuberculosis and malaria show that the war on disease has not yet been won.

Are we better off today than we were a century ago? Asked Nobel Prize winner Joshua Lederberg. In most respects, we’re worse off, he said. We have been neglectful of the microbes, and that is a recurring theme that is coming back to haunt us. Can the present setbacks be overcome with determined effort by medical science and all nations of the world? Will the principal infectious diseases eventually be eradicated, as smallpox was?