Infections make deadly comeback.

Infectious diseases, once thought to have been vanquished by vaccines and antibiotics, are reemerging as a serious health threat both in the United States and worldwide, researchers reported at an American Medical Association press conference in Washington, D.C, this week.

Ebola, HIV, hantavirus, and antibiotic-resistant bacteria serve as reminders that microbes remain a menacing force. A new study of death certificates shows that from 1980 to 1992, death from infectious disease increased by 58 percent; another study indicates that infections caused by a strain of streptococcus bacteria resistant to penicillin-the first line of pharmaceutical defense-increased by 14 percent from 1991 to 1994.

"We aren't facing impending calamity," says Nobel laureate Joshua Lederberg of Rockefeller University in New York City. "The war is winnable, but nobody was on watch, and we have become complacent."

Scientists are urging governments to enhance global monitoring of disease outbreaks and are imploring physicians to use antibiotics properly.

Robert W. Pinner and his colleagues at the Centers for Disease Control and Prevention in Atlanta surveyed 12 years of U.S. death certificates. As they report in the Jan. 17 Journal of the American Medical Association (JAMA), the annual death rate from all infectious diseases increased over that period from 41 to 65 deaths per 100,000 people. Even after subtracting deaths due to HIV, which became epidemic during the last decade, those from other infectious diseases increased by 22 percent. This jump largely reflects fatal respiratory and blood infections.

"Despite historical predictions that infectious diseases would wane, that hasn't been the case," says Pinner. "The things that make infectious diseases serious threats are constantly changing, and we need to be vigilant."

Joseph F. Plouffe and his colleagues at the Ohio State University Medical Center in Columbus studied severe Streptococcus pneumonia infections that progressed from the lungs to a patient's bloodstream. The bacteria cause 500,000 cases of pneumonia in the United States each year. Between January 1991 and April 1994, the bacteria became increasingly resistant to penicillin and other common antibiotics; 24 percent had acquired resistance to Bactrim and 12 percent to ceftazidime. The researchers report these results in the Jan. 17 JAMA.

Because bacteria tend to develop resistance after they are exposed to an antibiotic, Plouffe urges physicians to prescribe prudently. He also recommends that they rely more on the Streptococcus pneumonia vaccine.

Patients can also play a role in preventing antibiotic resistance, says George D. Lundberg, editor of the JAMA. They shouldn't demand these drugs whenever they have a case of the sniffles, because antibiotics can't cure the common cold or other viral infections.