Revenge of the Killer Bugs: Emerging Infectious Diseases

From the WebMD Archives

April 26, 2000 -- In the movie Outbreak, Dustin Hoffman and Rene Russo race against the clock to stop the spread of a deadly Ebola-like virus that emerged from the African jungle. Life isn't usually as dramatic as Hollywood would have us believe, but public health experts caution that the source of a serious infectious illness could be as close as our kitchen tables or backyards.

Thanks to vaccines, smallpox has been wiped out, and other diseases such as polio may soon be found only in medical history books. But other deadly scourges such as tuberculosis are on the comeback trail, and reports of food-poisoning caused by bacteria and other microscopic organisms are on the rise.

Most troubling of all is that many of the new disease-causing agents are "super-bugs," so called because they can't easily be killed by most available antibiotics or other drugs and are therefore extremely difficult to treat. Cause for panic? Not exactly, but the growing number of emerging infections is definitely cause for concern and action, say public health experts.

"The underlying cause of why these things happen is the changing food supply, growing world population, international travel, and overuse of antibiotics," says Michael T. Osterholm, PhD, MPH, in an interview with WebMD. Osterholm, who wrote an editorial on the issue in the April 27 issue of TheNew England Journal of Medicine, is chief executive officer of ican Inc., a medical information company. The issue contains several studies reporting on outbreaks of new strains of disease caused by contact with animals or contaminated food.

Never underestimate the ability of contagious bacteria, viruses, and parasites to survive, grow, and cause disease, public health experts caution. In many cases, modern medicine is fighting back against bugs that have exploited modern technology and the habits of modern man to find a new ecological foothold.

"We never had Ebola virus infections until people went out to cut trees and live in areas of the forest where they never used to live," says Robert W. Ryder, professor of epidemiology of microbial diseases at Yale University, in an interview with WebMD. "Emerging infections are not really new ? strains, just newly encountered strains, but as we live in different ways and begin to encroach on certain environmental niches that we never used to encroach on, we're stumbling on them."

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In other words, the spread of disease and the emergence of new infectious organisms are the unintended consequences of human actions.

"The things that make infectious diseases come and go are dynamic," says Robert W. Pinner, MD, director of the office of surveillance at the National Center for Infectious Diseases, part of the Centers for Disease Control and Prevention in Atlanta. Pinner tells WebMD that choices that we make every day can have profound effects upon the development and spread of infectious organisms.

For example, with the foods available in a typical supermarket, we can have a cantaloupe from Chile for breakfast, tuna from Thailand for lunch, and Australian lamb with Mexican asparagus for dinner.

"A contaminated product in a locale which might, a hundred years ago, have affected a few people around the place where it grew now can be distributed nationally and internationally and cause outbreaks around the world," Pinner says.

Economic factors such as poverty and its handmaidens -- overcrowding, poor sanitation, and lack of access to clean drinking water or adequate health care -- play a key role in the spread of contagious diseases. Overuse or misuse of antibiotics to prevent disease and encourage growth in animals raised for food also fosters the growth of drug-resistant strains of bacteria.

But livestock producers aren't the only responsible parties. For example: when a boy has a cold, his parents may pressure their family doctor to give him antibiotics even though most colds are caused by viruses -- which aren't affected by the drugs.

So what's to be done? To fight infectious disease, the CDC has established a national surveillance network that is designed to spot the earliest signs of an outbreak -- whatever the source -- before it becomes an epidemic.

"Increasingly, food-borne disease is not [salmonella] on Cape Cod in July at a church picnic -- it's four or five cases in Nebraska, three more in Oregon, and 12 in Connecticut. And because there is this national database, we can increasingly link food-borne diseases across the country in a way that we never could before," Ryder says.

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"I still think that if you use common-sense measures that we all know, such as cooking meat to the appropriate temperature and cleaning your knife before you use it on any other type of food, that still holds true, and we don't see increased resistance to that common-sense kind of food handling," says Paul D. Fey, PhD, assistant professor of internal medicine at the University of Nebraska Medical Center and associate director of the Nebraska Public Health Laboratory.

It may never be possible to predict with certainty where the next epidemic "hot zone" will be, the experts say. But with a combination of ongoing health education, continual surveillance, acute observation, and even, on occasion, serendipity or pure dumb luck, public health officials can marshal resources quickly and effectively.

Still, we're not there yet, Ryder tells WebMD. For example, the outbreak of West Nile fever, a mosquito-borne infection that showed up for the first time in New York City last year, "is a classic example of how we were doing what was considered to be state of the art and were looking for unexplained deaths and serious illness, but that project wasn't sensitive enough," he says. "It really took something pedestrian: someone walking out on the street and seeing that there were a lot of dead crows and then some exotic birds in a New York zoo dying, and that triggered alarm bells."

This year, however, the CDC has been on the lookout specifically for the virus. As reported by WebMD on April 25, health agents have detected the virus in hibernating mosquitoes in the New York area, and the CDC has issued public health warnings and distributed nearly $3 million in funds to local health departments along the eastern seaboard and the Gulf of Mexico to assist in planning and implementing prevention and control programs.

On the legislative front, Sen. Edward Kennedy (D-Mass.) and Sen. William Frist (R-Tenn.) are introducing a bill to amend Title III of the Public Health Service Act. This would establish a public health infrastructure to track and prevent infectious diseases and evaluate the public health consequences of bioterrorism, according to information supplied by Frist's office.

"What people need to do is ask their representatives and policy makers: 'What are we going to do to address this?' We're very good at getting the stoplight on the corner fixed, but we don't often want to take on the big-picture issues," Osterholm says.

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