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Revenge of the Killer Bugs: Emerging Infectious Diseases

From the WebMD Archives

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

Thanks to vaccines, smallpox has been wiped out, and other diseases such aspolio may soon be found only in medical history books. But other deadlyscourges such as tuberculosis are on the comeback trail, and reports offood-poisoning caused by bacteria and other microscopic organisms are on therise.

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 mostavailable antibiotics or other drugs and are therefore extremely difficult totreat. Cause for panic? Not exactly, but the growing number of emerginginfections is definitely cause for concern and action, say public healthexperts.

"The underlying cause of why these things happen is the changing foodsupply, growing world population, international travel, and overuse ofantibiotics," says Michael T. Osterholm, PhD, MPH, in an interview withWebMD. Osterholm, who wrote an editorial on the issue in the April 27 issue ofTheNew England Journal of Medicine, is chief executive officerof ican Inc., a medical information company. The issue contains several studiesreporting on outbreaks of new strains of disease caused by contact with animalsor contaminated food.

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

"We never had Ebola virus infections until people went out to cut treesand live in areas of the forest where they never used to live," says RobertW. 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 andbegin to encroach on certain environmental niches that we never used toencroach on, we're stumbling on them."

In other words, the spread of disease and the emergence of new infectiousorganisms 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 theNational Center for Infectious Diseases, part of the Centers for DiseaseControl and Prevention in Atlanta. Pinner tells WebMD that choices that we makeevery day can have profound effects upon the development and spread ofinfectious organisms.

For example, with the foods available in a typical supermarket, we can havea cantaloupe from Chile for breakfast, tuna from Thailand for lunch, andAustralian 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 bedistributed nationally and internationally and cause outbreaks around theworld," Pinner says.

Economic factors such as poverty and its handmaidens -- overcrowding, poorsanitation, 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 ofantibiotics to prevent disease and encourage growth in animals raised for foodalso 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 himantibiotics even though most colds are caused by viruses -- which aren'taffected by the drugs.

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

"Increasingly, food-borne disease is not [salmonella] on Cape Cod inJuly at a church picnic -- it's four or five cases in Nebraska, three more inOregon, and 12 in Connecticut. And because there is this national database, wecan increasingly link food-borne diseases across the country in a way that wenever could before," Ryder says.

"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 knifebefore you use it on any other type of food, that still holds true, and wedon't see increased resistance to that common-sense kind of food handling,"says Paul D. Fey, PhD, assistant professor of internal medicine at theUniversity of Nebraska Medical Center and associate director of the NebraskaPublic 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 ongoinghealth education, continual surveillance, acute observation, and even, onoccasion, serendipity or pure dumb luck, public health officials can marshalresources quickly and effectively.

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

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

On the legislative front, Sen. Edward Kennedy (D-Mass.) and Sen. WilliamFrist (R-Tenn.) are introducing a bill to amend Title III of the Public HealthService Act. This would establish a public health infrastructure to track andprevent infectious diseases and evaluate the public health consequences ofbioterrorism, 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 thestoplight on the corner fixed, but we don't often want to take on thebig-picture issues," Osterholm says.