May 4 (HealthDay News) -- Seemingly out of nowhere, a new strain of flu linked to one usually seen in pigs emerges, spreads and sets off alarms among officials and the U.S. public.
Sound familiar? Just such a swine flu outbreak occurred decades ago, in 1976, and the course of that event shows that such an outbreak doesn't necessarily lead to mass mortality or even widespread infection, experts say.
It may also show how far the country has come in dealing with epidemic disease.
"Isn't it impressive we have detection and connectivity and surveillance worldwide on influenza that is changing on an hour-by-hour basis?" said Dr. Scott R. Lillibridge, a professor at the Texas A&M Health Science Center School of Rural Public Health in Houston and executive director of the National Center for Emergency Medical Preparedness and Responses. "What a change in the way we do business."
The 1976 outbreak occurred in wintertime among troops stationed at Fort Dix, N.J. In the end, about 240 people fell ill, and the original infected soldier died. But the illness never spread beyond the base.
While the way the outbreak was handled has some lessons for today's scare, "the parallels we can draw from the 1976 outbreak are very limited because it was a limited outbreak," said Chiehwen Ed Hsu, an associate professor of public health informatics at the University of Texas School of Health Information Sciences at Houston and associate director of health informatics at the Center for Biosecurity and Public Health Preparedness at the University of Texas School of Public Health.
"It was pretty straightforward," recalled Robert A. Lamb, a professor of immunology at Northwestern University's Feinberg School of Medicine in Chicago and an investigator with the Howard Hughes Medical Institute. "There was an outbreak at Fort Dix. One recruit died who had been on a route march, which is fairly strenuous to anybody, especially with a fever."
The fear at the time was that the swine flu was related to the 1918 pandemic that had killed millions worldwide. That turned out not to be the case. In fact, the virus implicated in 1918 was probably derived from an avian species of the flu virus, Lamb said. But that simply was not known at the time.
The main difference between the last outbreak of swine flu and the current one is that this one spread beyond national borders, affecting countries worldwide.
"The 1976 outbreak was contained within that army base. They basically shut the door, and threw the key away for a while," Lamb said.
Another major difference between the 1976 and 2009 viruses was that the current "swine" flu is actually part swine flu, part human flu and part avian flu. "This is a hybrid," said Dr. George T. DiFerdinando Jr., director of the Center for Public Health Preparedness at the University of Medicine and Dentistry of New Jersey's School of Public Health. "That's unusual. The 1976 virus did not have avian in it."
According to the U.S. Centers for Disease Control and Prevention, it's still not clear why the 1976 swine flu didn't spread beyond the Fort Dix base. Nor is it known exactly how the virus was introduced.
And while the current version of swine flu is passing from person to person, it's unclear how easily that happened in 1976.
Isolated cases of swine flu in humans are not uncommon, Lamb noted. "Every year, you will find some pig farmer somewhere who gets swine flu," he said. "But it usually doesn't transmit to his family."
In fact, John Quarles, head of microbial and molecular pathogenesis at the Texas A&M Health Science Center in College Station, isolated a swine flu virus on campus a few years ago in a student who had just judged a big swine show in San Antonio.
Quarles took samples from him and from about 100 people close to him. Not a single one of those other individuals was infected. "That's pretty classic for swine flu," he said.
Perhaps the main lesson to be learned from the 1976 outbreak is one for health authorities, said Hsu and other experts.
Back in 1976, the administration of then-president Gerald Ford, on the advice of the CDC, initiated a mass vaccination program, inoculating more than 43 million people (25 percent of the population). But that undertaking resulted in serious side effects, most notably an estimated 500 cases of a rare condition called Guillain-Barre syndrome, including 25 related deaths.
The debacle -- where vaccination actually caused more trouble than the flu itself -- forced the resignation of the director of the CDC.
This time around, "it looks like the CDC is evaluating that lesson very carefully," Hsu remarked. "They've been watching very carefully and evaluating the investment of a vaccine."
Given the time in which they lived and the resources available, health officials responded relatively quickly to the 1976 version of swine flu, said DiFerdinando, who was acting commissioner of health for New Jersey during another public health emergency, the 2001 anthrax attacks.
Still, the current outbreak also illustrates how far public health responses have progressed since 1976, Lillibridge said.
The CDC's rapid and constantly updated response to the outbreak was first in evidence during the 2003 SARS outbreak, and "it's happening again here in 2009," he said.
There's more on the current swine flu outbreak at the CDC.
SOURCES: Chiehwen Ed Hsu, Ph.D., associate professor, public health informatics, University of Texas School of Health Information Sciences at Houston, and associate director, health informatics, Center for Biosecurity and Public Health Preparedness, University of Texas School of Public Health; John Quarles, Ph.D., professor and head, microbial and molecular pathogenesis, Texas A&M Health Science Center, College Station; Robert A. Lamb, Ph.D., D.Sc., professor, immunology, Feinberg School of Medicine, Northwestern University, Chicago, and investigator, Howard Hughes Medical Institute; Scott R. Lillibridge, M.D., professor, Texas A&M Health Science Center School of Rural Public Health, Houston, and executive director, National Center for Emergency Medical Preparedness and Response; George T. DiFerdinando Jr., M.D., director, Center for Public Health Preparedness, School of Public Health; University of Medicine and Dentistry of New Jersey