Disease experts: Greater danger ahead
By Rosie Mestel
Los Angeles Times
In the few months since its emergence, the SARS virus has killed hundreds, sickened thousands and scared millions. But many infectious disease experts believe it is only a dress rehearsal for some other, more dangerous outbreak that could strike at any time.
Perhaps this future scourge will be an old, familiar foe, such as the influenza virus, ramped up to new lethality after borrowing genetic information from a related bird virus. Or maybe that foe still is faceless because it only recently evolved, or has been skulking in an isolated part of the world, unable until now to obtain a wider foothold.
The whens, wheres and whats are uncertain, but disease specialists believe that the emergence or spread of noxious bacteria and viruses has never been more likely.
"What we have today is the perfect storm — an entire puzzle that favors the microbes," said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota's School of Public Health.
Today, there are more people than ever packed onto the planet — 6 billion compared with 1.5 billion at the start of the 20th century. The human race has become a vast petri dish for the growth, evolution and spread of microbes.
More than ever, we are a species on the move, abandoning countryside for closely packed cities, and boarding planes, trains and buses that can swiftly transport a SARS virus, flu virus or mosquito infected with West Nile or dengue virus far afield.
Food, lifestyle
The need to feed a booming world population has altered how and where food is grown. It has pushed farmers into marginal lands — sometimes into closer contact with microbes they might have encountered only rarely before.
It has turned food production into a giant, industrial undertaking that crowds animals together in huge congregations where they can pick up bacterial or viral contaminants that in the past would have stayed localized. The resulting ground beef, cutlets and chops are shipped far and wide.
Many human actions — such as vaccine production and water treatment — tip the balance in favor of human beings. But countless other actions favor the bugs. Promiscuous sex, intravenous drug use and even blood transfusions have helped HIV spread.
Countering emerging diseases requires an effort as multi-pronged as the factors that make microbes a threat. It involves increased surveillance, diagnostics and public health responsiveness so that outbreaks can be attacked quickly. It requires the rapid development of vaccines against lethal new strains of flu, and the stockpiling of antiviral drugs that can be used until the vaccine is prepared.
Utterly annihilating a microbe from the world is usually impossible.
"There may well have been infectious diseases we accidentally eradicated in the process of killing off the dodo or the passenger pigeon, but the sad reality is smallpox is the only infectious disease we have intentionally eradicated," said Stephen Morse, director of the Center for Public Health Preparedness at Columbia University's Mailman School of Public Health.
Even in that remarkable case, he said, we neither finished the job, nor, as it turned out, removed the threat. Small samples of the virus are still maintained by the U.S. and Russian governments, and possibly others.
Weapons other than surveillance exist for fighting flu. There now exist antiviral drugs that target the influenza virus specifically. The virus, for all its mutability, appears unable easily to develop resistance to at least one class of these drugs.
Research, developments
In another development, Richard Webby, an influenza researcher at St. Jude Children's Research Hospital in Memphis, Tenn., and his colleagues have devised a way to grow a dangerous version of bird flu in fertile chicken eggs, which is the customary way that vaccines are prepared. Normally, this strain is so lethal that it kills the embryos so that vaccine cannot be grown. By slightly altering the genetic structure of the virus, the scientists have removed this chick embryo lethality while retaining features that would make it an effective vaccine.
Yet in spite of such developments we are hardly prepared for an influenza pandemic, experts say. Even in recent normal flu years there were insufficient stocks of vaccine to supply demand. The demand in those years was a fraction of what it would be if an especially lethal flu were to strike.
Moreover, there are no stockpiles of antiviral drugs — even though it takes six months or more to create a vaccine once a new strain of flu is identified.
It has been more than 30 years since a flu pandemic swept the globe — and if the past record is anything to go by, we are overdue for another one.
As they survey the invisible threat, infectious disease specialists say they walk a fine line between being unnecessarily alarming and leaving the country unprepared.
"There are a lot of lessons from SARS that go beyond the worry at the moment," Morse said. "Long after that worry has dissipated I hope we will have learned from it — about preparedness, about improving capacity, about asking questions such as how can we better understand the sources of these infections, and what can we do about them — particularly what we can do about them."
