Virus Hunters

The Centers for Disease Control and Prevention propose a plan for tracking airline passengers electronically to contain the spread of infectious diseases.

by / May 2, 2006
Somewhere high over the Pacific, a 747 cuts through the night sky on its way back to Los Angeles.

In the passenger cabin, hundreds of somnolent people in close quarters try to find a comfortable sleeping position. The return trip from Southeast Asia is long, and getting some shut-eye is the only way to bear it.

Drifting off proves difficult because somewhere aboard the mammoth airliner, a passenger is stricken with a terrible cough. After a while, a wave of relief washes over the rest of the cabin as the passenger falls asleep and the coughing ceases.

Hours later, the plane lands in Los Angeles and passengers begin exiting the plane. As travelers in the front clear the way, passengers in the rear begin to move forward -- except one. The languid passenger has not stirred from his seat.

Fear and confusion spread as the remaining passengers wonder if they too will contract whatever illness the now-deceased cougher brought on board.

Currently, should the Centers for Disease Control and Prevention (CDC) discover passengers were exposed to a deadly pathogen, tracking down each individual is a matter of collecting hand-scribbled customs declarations, discarded passenger manifests and seat assignment lists that the airline might maintain for only a day or two. As multiple viruses continue to make headlines, many fear this traditional strategy of contacting passengers is too slow to stop an outbreak.

In response, the CDC is proposing a new method of electronically tracking airline passengers.

Contact Tracing
Airlines have always kept records of their passengers. The most common data is the passenger manifests and customs declarations. Airlines tend to hold such information for a very limited time, however -- usually less than a week. In addition, this data is likely to be handwritten and often illegible, which can make analysis a long and painstaking process.

"We're aware that the old methods of trying to piece together records by hand may be too time consuming if you've got a large-scale outbreak like you had with SARS [severe acute respiratory syndrome]," said Katherine Andrus, assistant general counsel for the Air Transport Association (ATA). "So the prospect of some sort of electronic transfer of that data is something that has been discussed for the last three years."

With the looming threat of avian influenza, or bird flu, the CDC announced a proposal to change federal rules on passenger tracking and quarantine procedures in November 2005. The current rules have been unchanged for 25 years, and federal officials felt the time had come to update them. In the past, the CDC manually tracked airline passengers possibly exposed to a communicable disease while onboard an airplane to inform them of where to be treated and whether they would need to be quarantined.

Speaking in a press tele-briefing, Dr. Marty Cetron, director of the CDC's Division of Global Migration and Quarantine, outlined the proposed changes.

The modifications would require airlines to maintain passenger manifests in electronic form for 60 days after passengers land, said Cetron. As part of the plan, passenger information must be turned over in less than one day if requested by health officials -- preferably within 12 hours. In addition, the information must be provided electronically and must include specific fields, such as passenger manifests and seat assignments, for effective "contact tracing."

Contact tracing is the process by which public health officials track down passengers who may have been exposed to a communicable disease.

Elements such as passenger manifests, customs declarations and seat assignments are useful in finding and contacting a passenger only if the data is in good condition and can be gathered in time. Presently it can take days of work to identify, locate and contact passengers.

The SARS outbreak three years ago exposed the fact that present contact tracing methods were inadequate when confronted with the potential for a global pandemic.

Dr. Ram Koppaka, associate director for policy and preparedness in the CDC's Division of Global Migration and Quarantine, said the new proposal for electronic tracking of passengers is simply the CDC becoming more effective at what it already does.

"What we seek to do better is to perform that basic public health role for a traveling population," he said. "It's something the CDC has been responsible for for many years, and we do it on a relatively routine basis for diseases, for example, such as tuberculosis. If we become aware of an individual who had infectious tuberculosis while traveling ... then we do seek to contact the individuals who may have been exposed so they can be tested and provided with preventive care."

Privacy Concerns
There are, of course, some who are concerned about the implications of passenger privacy. The CDC is doing what it can to address privacy worries, Koppaka explained.

"First of all, we welcome the comments and would like to hear about the concerns," he said. "The second thing is that the CDC has established procedures for safeguarding confidential information, and this type of information would be handled according to these established privacy procedures that are intended to really safeguard the information so it is used only for the purpose for which it was collected."

Koppaka said the experiences of recent years have helped shape the CDC's strategy for getting passenger data from the airlines.

"The challenges we encountered during SARS were multifold; there were a number of things that arose," he said. "Number one, not all airlines collect the type of information we would need to contact individuals, and even if they collect the information, it's not in a form or a format that would be easily transmitted to CDC."

So far, no system or software has been chosen to help facilitate the exchange of airline data to public health officials. The ideal solution, according to the ATA's Andrus, would be some sort of software that considers the fact that each airline has its own unique system for managing data.

She said the ATA and the CDC are looking at available technology that will allow public health officials to quickly track down anyone who may have been exposed while flying.

"[Cross-platform software] is one of the things that has been looked at," she said. "The problem is each airline has a slightly different system and many of them are, frankly, not the most sophisticated or powerful systems, so you're putting a tremendous strain on them to try and do that sort of querying. We are trying to avoid creating a separate computer system, or at the very least a storage system, for each different situation because that becomes duplicative and costly."

For now, the CDC's proposal is under review by various federal and airline officials.

Most of the specific details have yet to be worked out, and the proposal calls for a two-year implementation.
Chad Vander Veen

Chad Vander Veen is the former editor of FutureStructure.