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New Measures for Prompt Warning of Bioterrorism or Disease Outbreaks Depend on Rigorous Analysis
While health authorities have been taking steps to provide quicker warning of disease outbreaks or bioterrorism incidents, the information gathered can be ambiguous and must be rigorously analyzed, according to a leading Maryland state health official.
"You need an informed observer looking at the data and saying, 'What does this mean,'" Dr. Diane L. Matuszak of the Maryland Department of Health and Mental Hygiene, told a 3 April Capitol Hill seminar organized by AAAS's Center for Science, Technology and Security Policy and by a bipartisan study group called Security for a New Century.
Matuszak, director of the Maryland health department's Community and Public Health Administration, discussed her state's traditional surveillance for communicable diseases and some new measures undertaken to enhance the odds of quickly spotting an emerging health threat, whether natural or as a result of terrorism.
The seminar, the second in a series of four on public health preparedness, was attended by several dozen congressional staffers and others. The seminars are off-the-record to encourage frank exchanges, but speakers at the 3 April event agreed afterwards to put their remarks on the record.
Under the traditional surveillance system, physicians submit information on reportable diseases such as AIDS, encephalitis, and anthrax. The state also does laboratory analysis of suspect samples, keeps registries on influenza and hepatitis cases, and does sentinel surveillance for flu outbreaks by tracking pediatric hospitalizations and reports of healthcare workers hospitalized with pneumonia.
The traditional reporting system is well-accepted, Matuszak said, but its predictive value varies by disease and by the sensitivity of lab tests or the case definitions involved. Reporting by physicians continues to be spotty, she said.
Federal and state officials, looking to improve early warning in the wake of the 2001 anthrax attacks, which killed five people, and threats from terror groups, have embraced another approach called syndromic surveillance. It relies on careful monitoring of disease symptoms, such as breathing problems or diarrhea outbreaks, rather than waiting for confirmed diagnoses of disease. If over-the-counter medications for diarrhea are flying off the shelvesas they did during a 1993 outbreak in Milwaukee of a water-borne infection called cryptosporidiumit could be an early sign of mass illness.
The federal Centers for Disease Control and Prevention is funding a syndromic surveillance system called BioSense, which draws on symptom reports submitted to CDC and on similar data from Veterans'Affairs clinics and other federal health centers. In theory, such reports could give quicker hints of trouble than traditional disease surveillance methods, but Matuszak said the usefulness and cost-effectiveness of the system has not been established.
Maryland has started its own syndromic system, called ESSENCE, that draws information daily from emergency room visits in the state. It also receives information on over-the-counter purchases at three major pharmacy chains in the state and information on outpatient visits to clinics.
In the future, Matuszak said, the state hopes to tap additional data sources such as school absenteeism reports, private physician visits, calls to poison control centers and veterinary data, since many emerging diseases strike first in animal populations.
While syndrome surveillance has promise, it requires lots of effort to analyze the data and sort out false alarms, said Dr. Mark S. Smolinski, Vice President for Biological Programs at the nonprofit Nuclear Threat Initiative (NTI). Smolinski, who was study director for a 2003 Institute of Medicine report, Microbial Threats to Health, said that sifting through the data gathered "is very time intensive. … It takes a dedicated team to determine if there is a true problem."
The workforce issue is even more acute in some developing nations, some of which have only recently adopted lists of "reportable diseases" to be tracked. In India, Smolinski said, there are 600 health districts. They have been receiving technology, such as hand-held phones, that can be used to improve disease surveillance and response times. But he said there remains a serious shortage of trained health officers who can do the investigations and analyze the data.
Still, there are some promising developments abroad, including cooperative efforts in regions where political tensions remain high. Smolinski's organization has been a backer of the Middle East Consortium on Infectious Disease Surveillance, a joint effort by Egypt, Jordan, Israel and the Palestinian Authority to share information on the incidence of particular diseases in the region. Efforts are underway to establish a similar consortium among India, Pakistan and Bangladesh. Such health surveillance initiatives are "changing the lives of people around the world who are dealing with health threats that we can only imagine," Smolinski said.
Smolinski also described the Global Public Health Intelligence Network (GPHIN), a program established Health Canada, the Canadian government health department, and later expanded in language capacity by NTI. The electronic network monitors reports on news wires and web sites for information on any hint of disease outbreaks or threats. The information is gathered in seven languages. Since the network was established, Smolinski said, it has accurately identified about 40 per cent of all global disease outbreaks investigated by the World Health Organization. Had it been available for Chinese-language media, he said, it likely would have picked up reports of Severe Acute Respiratory Syndrome (SARS) early on.
Smolinski also mentioned ProMED Mail, a program sponsored by the International Society for Infectious Diseases that allows public health professionals to send e-mails on potential health threats to a central clearinghouse for sharing with others. The Nuclear Threat Initiative is helping to expand the program to Russia, he said.
The success of any surveillance system depends ultimately on human resources as much as technology, according to Smolinski. "We need to build the workforce to use the tools," he said. It also is imperative that governments and other partners provide the money to combat health threats when they do emerge, he said. "It's not fair to build systems that detect problems unless we offer the response as well," he said.
17 April 2006