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SARS May Be Just the Start

Crowded conditions, food production and world travel increase the odds for lethal viruses.

May 03, 2003|Rosie Mestel | Times Staff Writer

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 is still faceless because it has 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 Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota's School of Public Health.

For The Record
Los Angeles Times Tuesday May 06, 2003 Home Edition Main News Part A Page 2 National Desk 1 inches; 36 words Type of Material: Correction
Infections -- A list of infectious agents Saturday in Section A was incorrectly labeled as a grouping of viruses. In fact, the graphic was a list of emerging infections that included viruses, bacteria and other agents.
For The Record
Los Angeles Times Saturday May 31, 2003 Home Edition Main News Part A Page 2 National Desk 2 inches; 65 words Type of Material: Correction
"Mad cow" disease -- Recent articles in Section A and the Business section have stated that variant Creutzfeldt-Jakob disease in humans is caused by eating products contaminated with the agent that causes bovine spongiform encephalopathy, or "mad cow" disease. Although scientists believe that there is strong evidence that eating such products can cause a new variant of Creutzfeldt-Jakob disease, the link is not definitively established.
For The Record
Los Angeles Times Saturday May 31, 2003 Home Edition Main News Part A Page 2 National Desk 2 inches; 65 words Type of Material: Correction
"Mad cow" disease -- Recent articles in Section A and the Business section have stated that variant Creutzfeldt-Jakob disease in humans is caused by eating products contaminated with the agent that causes bovine spongiform encephalopathy, or "mad cow" disease. Although scientists believe that there is strong evidence that eating such products can cause a new variant of Creutzfeldt-Jakob disease, the link is not definitively established.

Today, there are more people than ever before packed onto the planet -- 6 billion compared with about 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.

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 may have only rarely encountered 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.

The Human Element

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 unprotected 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 quickly attacked. 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, Morse 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.

Plagues are by no means new to our species; they have long ravaged the world. In the 1300's, the bubonic plague, or so-called black death, that spread from China to Europe, killing 25 million Europeans, or about one third of the population there. Smallpox, the "speckled monster," crossed the Atlantic to the Americas in the 1500s, ravaging the Aztecs and Incas.

Records of deadly flu epidemics and pandemics date back as far as ancient Greece and Rome -- and one of these, in 1918, claimed at least 20 million lives.

It is also true that infectious disease experts are spotting more pathogens because they are looking more closely, aided by the tools of modern biomedicine.

Before 1993 nobody knew that a virus, now known as Sin Nombre, was endemic to this country, living its life for the most part in populations of deer mice, only occasionally hopping into people who were exposed to the rodents' urine, feces and saliva.

Then a spate of abnormally warm and wet winters caused a bumper crop of vegetation, leading to an explosion in the deer mice population. That was followed by a cluster of human deaths from a mystery respiratory disease in the Four Corners region of the southwestern U.S. -- and the discovery of a new virus that had been there all along. Since then, 25 viruses related to Sin Nombre have been discovered in the Americas.

Problems of Proximity

But other bacteria and viruses are truly emerging anew, or are spreading far beyond their traditional range, often because of the actions of human beings. Frequently, the diseases come from animals that we cultivate for food.

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