Global diseases outpace U.S. quarantine system

March 31, 2003, 9:39AM By EDWARD HEGSTROM Houston Chronicle

RESOURCES • Q&A on SARS • Facts about virus • CDC information page • World Health Organization information

The sudden global spread of a lethal new disease out of Asia illustrates how little power modern medicine has to prevent deadly germs from moving around the world as fast as an airplane can carry them, experts say.

The disease, known as severe acute respiratory syndrome, or SARS, appears to have spread from China to Hanoi, Hong Kong, Singapore, Taipei, Frankfurt, Toronto and now Houston.

Because health officials in Hong Kong say they believe it has been spread among passengers during a flight, SARS raises particularly serious questions about air travel. And the reports resonate with some in the United States, which has been on heightened alert for bioterrorism the past year and a half.

The United States used to maintain a robust quarantine system to prevent the arrival of dangerous diseases on ships and airplanes, but that system has been severely slashed in recent years. More than 15,000 international travelers arrive at Houston's Intercontinental Airport every day, including some on a direct flight from Tokyo. But the quarantine inspector who ostensibly polices the Houston airport works out of an office in Los Angeles.

SARS is not the first disease to arrive in America from overseas. In an era of globalization, with millions of people crossing borders daily, diseases regularly jump continents, and experts say they have no way to prevent that.

"This is the sort of disease that will spread everywhere because it is carried by people, and people travel," said Dr. Mary E. Wilson, an international health expert at the Harvard School of Medicine. " I think we have to expect that this sort of thing will continue to happen. Borders are porous."

Though none of the 62 suspected SARS cases in United States has proven fatal as of yet, other internationally imported diseases have been more lethal. World Health Organization Director General Gro Harlem Brundtland estimates that in the latter half of the 20th century, five times as many Americans were killed by internationally imported infectious diseases than by war.

Many studies -- including one released earlier this month by the Institute of Medicine -- find that the best way to stop the global spread of infectious disease is by improving surveillance. If countries can cooperate to identify diseases as soon as they emerge, international health authorities can step in and stop them from spreading, the studies conclude.

Good surveillance and early international intervention prevented the spread of a dangerous avian influenza virus that emerged in Hong Kong a few years ago, Wilson noted. And good surveillance may be preventing the secondary spread of the SARS in the United States, she added.

But surveillance only works if officials are willing to disclose outbreaks. Many countries cover up epidemics in an attempt to prevent the damage that may result to their trade and tourism industries, said David Fidler, a University of Indiana law professor who writes extensively on the links between international law and infectious disease.

"History shows that if there is an outbreak in a country, that country does not want to share that information because of the effect it could have on their economy," Fidler said.

WHO officials issued their first warnings about SARS in mid-March. But the organization now reports the disease first emerged in south China in early November. Officials still do not know if that four-month delay in diagnosing the new disease proved crucial in allowing its spread.

Wilson acknowledged that the Chinese government's reluctance to alert the world about the disease may have been related to "economics." Reports of an unknown disease in southern China began circulating as early as mid-February, but Chinese officials initially refused international help in identifying the disease, she said.

The globalization of infectious disease is not new. European explorers brought smallpox to the New World nearly five centuries ago; an influenza pandemic spread around the world in a matter of months in 1918.

But the pace of international trade and travel has accelerated the movement of diseases. After essentially disappearing from Latin America in the 1970s, dengue fever has returned with a vengeance, reaching from Venezuela to northern Mexico, and creeping across into South Texas. As many as 100 million people catch the disease, and jet passengers continue to take it to new areas, including Hawaii.

After first appearing in New York in 1999, West Nile Fever spread south and west, reaching Houston last summer. Despite years of study, officials say they still do not know how the disease reached the Americas.

Quarantine used to be the preferred way of stopping diseases at a country's border, but that approach has lost favor with world health experts. Modern jet travel is so fast and so frequent that quarantine officials cannot possibly stop diseases at an airport, Wilson said.

The emergence of SARS may change that thinking. Health officials in Asia are now using quarantine, and the U.S. Centers for Disease Control and Prevention has set up a screening process in which quarantine officers are being asked to identify sick passengers at some airports.

At Los Angeles and other airports where the CDC has staff, quarantine officers now monitor incoming flights and hold ill passengers to make sure they go straight to a doctor.

But years of neglect and underfunding have left the U.S. quarantine system short-staffed. In the 1960s, the United States had more than 50 quarantine stations; now it has eight. Officers at those quarantine stations are expected to patrol numerous air and land ports of entry.

If a sick passenger shows up on a flight in Houston, airline officials are asked to call the quarantine inspector in Los Angeles.

There are U.S. Customs Service agents at the Houston airport who screen for incoming drugs and contraband. The Department of Agriculture keeps agents there every day to screen for possible disease-carrying fruits, vegetables or pets. But no one at the airport screens for dangerous human diseases such as SARS.

"The CDC doesn't have a presence out here," said Ernest DeSoto, spokesman for the Houston Airport System.

With the CDC so short-staffed, quarantine in this country works essentially on the honor system. Airline crews who identify a sick passenger on an international flight arriving in the United States are expected to call ahead and notify quarantine officials. If the flight attendants fail to notice the disease, customs and immigration agents are supposed to stop it. But the honor system doesn't work.

Interviews and CDC quarantine records obtained by the Chronicle show that airlines have routinely allowed obviously sick passengers to board international flights bound for the United States, and customs officials sometimes let them enter the country.

The CDC quarantine reports tell of passengers flying to the United States while noticeably sick with AIDS, chickenpox, dengue fever, hepatitis, malaria, measles, meningitis, mumps, pneumonia, rabies, rotavirus, rubella, syphilis and typhoid fever, among others. Many were allowed to board planes while showing unmistakable symptoms of disease.

Allowing obviously sick passengers to board jets could open the country to the threat of bioterrorism. Under one frequently postulated scenario, a terrorist could spread smallpox by infecting himself with the disease and then boarding a jet to spread it to the other passengers.

Some experts dismiss the "smallpox martyr" theory. They say that people with infectious smallpox would have a rash and fever and that no airline's ticketing agent would allow them to board a plane.

But the CDC quarantine reports obtained by the Chronicle indicate that -- at least before Sept. 11, 2001 -- passengers were sometimes allowed to board U.S.-bound international jets while seriously ill with fevers and rashes.

In 1999 alone, at least six passengers with chickenpox were pulled aside by quarantine authorities after arriving in the United States on an international flight. To someone who is not an expert, chickenpox is hard to differentiate from smallpox.

Bioterrorism expert Jonathan Tucker, author of Scourge: The Once and Future Threat of Smallpox, said he believes a passenger with chickenpox would have a harder time travelling after 9/11. "I just think people are more alert and more sensitive to passengers getting on planes with rashes now," he said.

Beside the threat of bringing disease into the country, sick passengers also risk infecting others on the plane. Airline passengers have contracted flu, measles and even deadly strains of drug-resistant tuberculosis from breathing the air in a jet cabin, studies have shown.

Hong Kong officials now say they believe SARS has also spread among passengers on a flight. In response, WHO issued guidelines late last week asking airlines to step up their efforts to screen passengers.

CDC officials did not return phone calls seeking comment on the connection between SARS and quarantine. But in an interview last year, James Barrow, chief of field operations for the CDC's Division of Global Migration and Quarantine, acknowledged that globalization has caused the government to question whether quarantine is even feasible anymore.

"If you look at the sheer volume of travelers," he said, "I don't think you could have enough quarantine inspectors to look each of them in the eye and determine if they're carrying an infectious disease."