FOR THE LATEST DISEASE, A FASTER RESPONSE
13 Apr 2003
Source: Washington Post, April 13, 2003
For the Latest Disease, a Faster Response
By Peter Hotez
In the weeks and months following the anthrax scare in the fall of 2001, the response of the nation's public health agencies could be summed up as "too little, too late." The Centers for Disease Control and Prevention (CDC) and other parts of the U.S. Public Health Service were slow to share scientific data and biological material with the other public health organizations and to provide up-to-date and useful information to the public and the media.
What a difference 18 months makes.
In February 2003, when CDC epidemiologists learned about the outbreak in China's Guangdong Province of a new, deadly disease known as severe acute respiratory syndrome (SARS), they sprang into action, collaborating intensively with the World Health Organization (WHO) to determine the cause.
Initially, they theorized that the disease might be caused by a strain of influenza virus similar to the one believed to be responsible for the pandemic that killed 20 million people worldwide and 500,000 people in this country in 1918. Flu was suspected because most new influenza strains originate in Guangdong as a result of the virus's ability to obtain new genetic material from other strains in China's domesticated pigs and birds. (This hypervigilence about a new strain of influenza helps explain the over-reaction to swine flu in the United States in 1976.)
But within two weeks of the WHO's first international alert about SARS on March 12, with the disease having spread to 11 countries, mostly in Asia, scientists at the CDC had determined that influenza was most likely not the cause. Using SARS patient samples flown in from Southeast Asia, Thomas Ksiazek and his colleagues at the CDC successfully isolated a new virus and determined by electron microscopy that it was a coronavirus -- the type of RNA virus that causes the common cold in humans but can cause much more serious disease in rodents and other animals.
The outbreak continues to grow -- at last count 2,890 cases of illness and 116 deaths in 21 countries and territories had been reported. But the response from the CDC and other components of the Department of Health and Human Services (HHS) has been unlike anything I have ever seen, and this bodes well for containing the outbreak. It also suggests that our public health infrastructure is back on track.
There is an unprecedented spirit of cooperation at the CDC today, and it stems directly from the anthrax episode, because criticisms of the CDC's response back then led to a shake-up at the agency's highest levels. From the start of the SARS crisis, CDC's new director, Julie Gerberding, showed a commitment to share the isolated coronavirus with scientists at the National Institutes of Health (NIH), the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) and several international virology laboratories.
NIH scientists will continue culturing the new coronavirus in vero cells, which are widely used in the production of antiviral vaccines. That's significant because being able to grow the virus in vero cells is a good indication of success in developing a vaccine. I wouldn't be at all surprised if we see an experimental SARS vaccine in a year.
Simultaneously, NIH scientists are also determining whether the virus is capable of inducing immunity in laboratory animals. All those involved seem to be working with the anticipation of successful vaccine development. HHS Secretary Tommy Thompson has become involved personally. He met last week with representatives of the nation's four major vaccine companies to enlist their help in producing a SARS vaccine.
At USAMRIID, the Army maintains a collection of thousands of drug compounds that are potential antiviral agents, and testing is underway to screen the new virus against those chemicals in an aggressive effort to identify potentially useful antiviral drugs.
Meanwhile, back at the CDC, scientists have developed two new diagnostic tests for the virus, which they are distributing to local and state health departments. And soon, the CDC will finish determining the entire nucleic acid sequence of the genome of the virus.
That's significant because then they can compare the genome sequence with that of other coronaviruses and perhaps find that the new one is similar to one of them but with genetic mutations. Or perhaps they will find whole pieces of genetic material that are new, which would represent a major shift and give us clues about the origin of the SARS virus and whether it jumped from animals to humans. The CDC has said it will publish the SARS genome sequence on its Web site to help other virologists.
Under the auspices of the WHO, the CDC is also communicating daily with a global network of epidemiologists to determine how the virus is transmitted, as well as its natural history -- meaning how it replicates and causes disease in infected individuals. And because of Thompson's involvement, each of the major scientific components of HHS is in close communication about SARS, with conference calls among them almost daily, which is quite unusual. As further evidence of the importance that Thompson has placed on controlling this outbreak, he requested and received on April 4 an executive order allowing him to add SARS to the short list of diseases for which the government can legally quarantine infected individuals. Rarely have diseases been added to this list, which includes smallpox and Ebola.
While the speed of the public health response to SARS in this country has been extraordinary, the illness itself is simply the latest in a series of infections known as emerging diseases. They are so named because they were either previously unidentified, not yet linked to a human disease or not previously shown to occur in a given region.
Among the better known emerging diseases are Ebola virus infection, West Nile virus infection, Lyme disease, Legionnaires' disease and AIDS. In each previous instance, it took months or even years before the infectious pathogen was isolated and characterized. For instance, AIDS was recognized as a new syndrome in 1981, but the human immunodeficiency virus wasn't identified until two years later. And although cases of Lyme disease were identified in 1975, the agent that caused them was not isolated until 1982.
The number of Americans infected with SARS continues to grow. So far, 166 cases have been identified. And there is still a danger that the disease could spread significantly. But we should be reassured by the stark difference between the American response and the initial response in China, where disease surveillance has been inadequate and the government allegedly tried to conceal the extent of the outbreak.
By doing business in a new way, HHS and its component agencies will have isolated the SARS virus and determined its entire genetic structure in just a few weeks, all while containing the outbreak and making headway toward a vaccine.
The extraordinary achievement of these government scientists is the peacetime equivalent of "shock and awe." They are to be congratulated.
Peter Hotez is a professor and chair of the Department of Microbiology and Tropical Medicine at George Washington University, and a senior fellow of the Sabin Vaccine Institute.