Infectious disease outbreaks signal need to think globally

Increased travel, growing antibiotic resistance and resurgence of diseases long thought to be controlled have public health experts warning against complacency.

By Victoria Stagg Elliott, AMNews staff. April 7, 2003.

Ed Septimus, MD, medical director of infectious diseases and occupational health at Memorial Hermann Healthcare System in Houston, is keeping his physicians on high alert.

Most recently, their vigilance has been focused on detecting symptoms that might indicate a case of severe acute respiratory syndrome. SARS is characterized by rapid onset of high fever, myalgia, chills, rigor and sore throat followed by shortness of breath, a cough and radiographic evidence of pneumonia. At press time, Centers for Disease Control and Prevention officials were attributing its cause to a strain of coronavirus.

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Dr. Septimus' hospital has already seen two possible cases. Each time, the patient had to be immediately isolated. In both instances, the illness turned out to be something more benign.

Still, SARS is an assailant with which public health officials around the world are now struggling.

Overall, as of March 25, 39 suspected cases in 18 states were being investigated by U.S. health officials. Worldwide, according to reports to the World Health Organization, the count totaled 487 suspected cases and 17 deaths.

But SARS is only one threat.

Dr. Septimus juggles a variety of constant infectious disease concerns -- from an awareness of bioterrorism agents to the reality that he can no longer assume that the usual antibiotics will work against what once would have been viewed as a simple staph infection.

Sometimes it seems these bugs have developed incredible superpowers and the challenge of battling them has become an intense tug-of-war.

"It's either an exciting or scary time to be in infectious disease," he said.

Primed to infect

The modern world is a prime environment for infectious agents to present a serious threat to human health and international security, according to conclusions drawn by the Institute of Medicine report, "Microbial Threats to Health: Emergence, Detection, and Response," released last month.

New infectious diseases such as the atypical pneumonia, SARS, can emerge and then easily travel around the globe, infecting less-resilient hosts and mutating because of the influence of viruses and bacteria in their new environment. It's what the IOM termed "a perfect storm."

"People are traveling a lot, and that brings the virus to many areas," said Peter W.S. Chang, MD, MPH, ScD, health attaché to the Taiwanese mission to Europe in Geneva. "Everywhere should be alarmed." Taiwan had several cases of SARS linked to travel to China.

And how did the transmission happen? The virus, which initially was identified as a probable member of the paramyxovirus family, first appeared a few months ago, in just one province in China.

But February brought Chinese New Year, when many Asians travel to visit their families, and the virus gained an opportunity to infect new hosts and then travel worldwide when these hosts returned home.

A new level of resistance

Clearly, bugs are getting around. But they are also more resistant to the tools usually used to fight them off. Drug-resistant organisms have been a long-standing problem in health care settings, but these strains now appear to be spreading in the community at large.

Within the past year, public health officials have noted outbreaks of methicillin-resistant Staphylococcus aureus acquired in settings that included sports teams, the prison population and communities of men who have sex with men.

"This has been bubbling under the surface for a long time," said Kenneth Haller, MD, president of the Gay and Lesbian Medical Assn. and assistant professor of pediatrics at St. Louis University School of Medicine. "But it's now reached critical mass."

Researchers have also noted a few cases where this S. aureus strain is resistant to vancomycin, traditionally regarded as the antibiotic of last resort. This development, combined with the fact that few new antibiotics are in process, has experts worried that the medicine chest may soon offer no more options.

"Clearly, the organism that was created in a health care setting has now gotten into the community," said Sandra Kemmerly, MD, medical director of infection control at the Ochsner Clinic Foundation in New Orleans. "But the part that's really troubling is that there are very, very few new antibacterial drugs that have been released in the last year or two. And there are not a whole lot of new antibacterial agents in the pipeline."

Other warning signs

Drug resistance and travel are, however, not the only factors that have public health officials and infectious disease experts nervous. Also noted by the report is that known diseases long considered to be defeated, such as pertussis, appear to be making a comeback.

Mosquito-borne diseases are again a problem. Sexually transmitted diseases are no longer declining as they once were, and some are on the increase. And there is a very real threat that an infectious agent could be used deliberately as a weapon.

"We're having many factors converge to create an environment in which many new diseases can emerge. Old diseases can spread. Microbes can adapt," said Ruth L. Berkelman, MD, co-author of the report and director of the Center for Public Health Preparedness and Research at Emory University, Atlanta.

Although public health experts find themselves faced with new challenges, the IOM report does state that the U.S. response to infectious disease outbreaks has improved. Surveillance systems are better, and most experts regard the response to SARS as astonishingly rapid.

Authors did note, however, that a lot of work needs to be done if the United States is to be prepared for infectious disease outbreaks, whether related to bioterrorism or naturally occurring. The SARS situation, in particular, underscores the message that the United States must think and act globally because infectious diseases do not respect borders.

"There have been substantial improvements and attention to the U.S. domestic situation, although there's a long way to go on that," said Donald Burke, MD, professor of international health and epidemiology at Johns Hopkins University's Bloomberg School of Public Health and co-author of the report. "But there hasn't been much attention to the overall international surveillance and response preparation. The world is a shrinking place. Diseases end up everywhere."

Where do we go from here?

The IOM report recommends that the public health infrastructure be rebuilt and staffed with a properly trained work force in order to respond to this growing threat posed by infectious diseases. Better lines of communication between medicine and public health are a necessity, and there is an urgent need for new antimicrobial drugs. Developing new vaccines and diagnostics should be a government priority as should reining in antibiotic use in humans and animals.

A majority of the IOM recommendations were directed at the Centers for Disease Control and Prevention.

The agency announced that it would be working toward an updated infectious disease strategy based on these suggestions.

"This is not the time to become complacent," said CDC Director Julie L. Gerberding, MD, MPH.

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