to determine exactly what they are dealing with.

The DHMH uses a health alert network (HAN) in conjunction with the syndromic surveillance system when a possible outbreak is detected. The HAN provides rapid notification, specific instructions and additional information to the health provider community via e-mail and fax. The only downfall is, because HAN is a subscriber-based system, it's up to the DHMH to get health providers to subscribe to make the best use of the system.

"We currently have 1,000 medical providers that are part of the HAN community," said Dale Rosenberg, HAN coordinator. "Our goal is to eventually get all medical providers in New York City to subscribe -- potentially 40,000 to 100,000 individuals."

The DHMH paid for both systems with federal funding designated for public health preparedness. The department recently received a grant to continue developing the application into an open source Web service, which could be used nationwide.

The syndromic surveillance system came together quickly, according to Carubis. "We basically put something in place between October 2001 and January 2002, but there was a lot of background work before that, and there's been continuous work since."

Critical Clues

The DHMH continuously looks to improve and expand its syndromic surveillance system. "There's really no end to a data-mining system -- you're always looking for new ways to refine the model and take advantage of new data sets," said Carubis.

The department is building a contact-tracing component into the system, so it can manage not only individuals who have contracted an illness, but also people with whom they came into contact.

"When you try to do that on paper, it can become unmanageable very rapidly," said Carubis. "Speed is of the essence in managing an outbreak. Once there's repeated exposure, it's very difficult to contain, so information systems are critical."

The DHMH also is evaluating school absenteeism and ambulance transport data as possible sources of additional information. "We're not sure the school absenteeism will be worth adding to the system," Carubis said. "The problem is you know someone is absent but you don't know why, so that really reduces the value of the information."

Whether or not the DHMH expands its data sources, the system already provides them with critical clues to public health concerns. Shortly after the blackout in New York City in fall 2003, the system detected an increase in diarrheal illnesses. The agency immediately deployed public health messages encouraging people to dispose of food that might have spoiled during the blackout.

The system also detected Norovirus-like symptoms before the first cruise ship outbreak occurred, allowing the DHMH to notify medical providers in the city to look for more cases of the fast-spreading virus.

When individuals come to health-care providers with common symptoms, such as fever or cough, it can mean a lot of different things, Carubis said. "It really helps to know what we're seeing outside of the physician's office. Getting a head start by even a day or two in a communicable disease outbreak can significantly curtail the spread of disease."

Justine Brown  |  Contributing Writer