Issue 16 - October 2003 : WITH WINTER COMING, WILL SARS RETURN? WILL WE CATCH IT IN TIME?

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WITH WINTER COMING, WILL SARS RETURN? WILL WE CATCH IT IN TIME?
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It’s late October 2003 and all is quiet on the U.S. emerging disease front, so far. West Nile virus illnesses are fading along with the mosquito population. A few scattered reports of Influenza have appeared, but nothing unusual. Flu Fight 2003 is rolling, and the introduction of the new Flu Mist® will entice even more patients to consider vaccination.

And so far there is no evidence of the return of SARS. But when it does return, will it be recognized in time to prevent the epidemics that swamped the healthcare systems of Hong Kong and Toronto? Only time will tell. The good news is that syndromic surveillance systems (some simple and some elaborate) are in various stages of implementation throughout the world, specifically looking for SARS and or other infection clusters.

In September, the World Health Organization launched a surveillance system in China, focusing on regions that were the hardest hit by SARS last winter. The trial will involve 10 to 14 hospitals, and has been designed with the help of Chinese health officials. Medical workers will question people with SARS-like symptoms. Facilities with two or more SARS-like cases will be visited by a team from China’s equivalent to the Centers for Disease Control. Isolation wards will be setup and contact tracing performed. (1)

In the United States, Milwaukee also learned the importance of syndromic surveillance the hard way, after a massive outbreak of Cryptosporidium due to contaminated municipal water in 1993. The outbreak continued undetected for weeks, with a final toll of over 400,000 symptomatic cases. (2)(3) To avoid a similar experience with SARS, they are using a web-based syndromic surveillance system to track potential cases. Emergency department personnel will identify patients with SARS-type symptoms and record their foreign travel histories. (4)

What system is your community using? A good syndromic surveillance system will identify multiple symptoms, and then group those symptoms into one or more possible syndromes. This is critical for a disease such as SARS, where only 30% of the patients have respiratory symptoms for the first few days (common early symptoms were fever, aches, chills, headache and diarrhea). (5) Thus, a surveillance system that only focuses on respiratory symptoms or “flu-like” illness could miss many early cases.

Likewise, programs that perform “diagnosis” surveillance (rather than syndromic surveillance) using ICD-9 codes may miss SARS cases. Of course, recognizing early cases and isolating them is key to containing a potential outbreak. In the 2002-2003 SARS season, one of the biggest factors allowing rapid spread around the world was failure to recognize contagious cases. Some of these patients did not have respiratory symptoms, and therefore were sent home with diagnoses such as ‘viral syndrome.’ (6)

We believe that recognizing and containing SARS this year will take a combination of both clinical and epidemiologic tools, and “an astute observance of patterns”. (6) The Centers for Disease Control has done an excellent job mobilizing the US public health community with detailed plans for dealing with most every aspect of a potential SARS outbreak, including education, communication, laboratory issues, quarantine, overcapacity problems, legal and policy issues and more. (7) But the most important question remains unanswered: “Will we catch it in time”?

(1) http://www.ledger-enquirer.com/mld/ledgerenquirer/news/6681204.htm

(2)http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9583416&dopt=Abstract

(3) http://www.doh.wa.gov/ehp/dw/Contaminants/crypto.pdf

(4) www.cio.co.nz/cio.nsf/0/C7CD6A219E49FC1CCC256D600019192C?OPENDOCUMENT

(5) The Centers for Disease Control and Prevention. Update: Severe Acute Respiratory Syndrome – United States, 2003. MMWR 2003;52:357-360

(6) American Health Consultants. Health Care Worker Illness May be the clue to next SARS outbreak. Hospital Employee Health. 2003;22:133-136

(7) http://www.cdc.gov/ncidod/sars/sarsprepplan.htm

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