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Piecing Together Clues to an Impending Disaster

Jeff Johnson, senior epidemiologist with the County of San Diego, provides insight into syndromic surveillance and how it’s used to prepare for and mitigate disasters, such as the recent wildfires.

What is syndromic surveillance?

Syndromic surveillance is, essentially, pre-diagnostic surveillance. It’s a type of enhanced surveillance that utilizes a variety of non-traditional data sources, looking for information or trends among data as early as possible. We use the data for early detection of outbreaks or large-scale public health situations. It’s like a smoke alarm in a data source looking for the earliest indication of a large outbreak.

How do you conduct surveillance?

As part of our enhanced health surveillance and syndromic surveillance activities, we’re monitoring a variety of data sources. These include emergency department encounters, 9-1-1 calls, paramedic transports, school surveillance and over-the-counter medication sales. We had it in place during the 2003 Cedar Fire — some of it was a fairly manual process. We still have those existing data sources in place, and since 2003, we’ve matured our surveillance with more automated and electronic processes. The process includes data collection, data processing, statistical analysis, reviewing and interpretation of results and, when necessary, epidemiological investigation of detected anomalies.

How is fire-related surveillance useful to the medical and public health communities?

We have the data coming in on a daily basis, which give us a background or a contextual understanding of what’s happening before a large-scale event. Once the event takes place — in this case the fires — we can understand the impact on the healthcare system in terms of volume and types of chief complaints being seen at emergency departments (EDs), or increases that are happening in terms of respiratory conditions, chest pain and other types of conditions that might be associated with the fires.

In a disaster situation, there is a great need for situational awareness — how much impact, how many people affected and where. Our surveillance data allows for us to have a better understanding of that, in addition to other sources of information. During a disaster, information management will take place utilizing a variety of information sources. Syndromic surveillance is a useful source of information during a natural or manmade disaster. For example, during this fire, there was a recommendation to close schools. School-age children were basically asked to stay indoors. Syndromic surveillance can help us determine what the pediatric population visiting the EDs might be in terms of trends in that age group before and after such recommendations were made. We’re able to track population age groups that are utilizing the health care emergency departments, and their chief complaint patterns.

The data helps provide situational awareness, either by population group, by syndrome categories, chief complaints that are being seen or geography. Based upon that, we can get a better understanding of the impact of those areas. For example, in some of our data we have information on the ZIP code of patients’ residences. We can use that to understand the impact in that geographic area, which might help in the decision process. The decision process during a disaster is handled at an emergency operations center. Our pieces of information go into that decision-making body, and they make recommendations to direct resources or to adequately recommend or provide appropriate public health measures.

How quickly does the information flow?

We do daily analysis, and we interpret the results on a daily basis. The county monitors all paramedic transports in their system, and the emergency department data we get from eight participating hospitals on a daily basis. Several of our systems are real-time — our prehospital transport system as well as our Firstwatch 9-1-1 call center surveillance tool. FirstWatch is a tool used by the County and the three major call centers in the County, which covers roughly 75 or 80 percent of the County’s 9-1-1 calls. For example, once the fire started, we could login to FirstWatch and visually see where the 9-1-1 calls were coming from and for what types of medical complaints. These types of smarter and quicker surveillance tools are important assets during a disaster.

How long has the County of San Diego performed syndromic surveillance?

We’ve performed syndromic surveillance in some shape or form since 1999. We improved and adapted our surveillance from a more manual data collection process to a mostly automated process. We have also conducted several special event surveillance efforts, such as during the 2003 Super Bowl, the BIO2001 Biotech Convention in 2001, following 9/11, and for the Cedar Fire in 2003 and right now.

Is syndromic surveillance fairly unique?

Since 9/11 it has definitely matured in the larger cities and states. I would say that San Diego County, from the input we’ve had from both the CDC and the Department of Homeland Security, is definitely one of the leaders in syndromic surveillance — ranked at least in the top five to 10 percent of jurisdictions.

For more on how San Diego fought the October wildfires, check out the complete December JEMS article, ˙San Diego Firestorm 2007.Ó