Gossip mongers push for national networks
Surveillance of disease rumours looks set to expand.
Public-health experts are poised to exploit an unlikely weapon in the war against bird flu and other fatal diseases. They want to expand a worldwide system for eavesdropping on rumours.
Listening to gossip may sound like a flimsy means of spotting potentially devastating microbes and viruses. But the World Health Organization (WHO) already uses 'rumour surveillance' to monitor online media for early signs of epidemics, including ebola, cholera and severe acute respiratory syndrome (SARS).
A study published this month is one of the first to show that this type of scrutiny actually works. Epidemiologist Gina Samaan of the WHO's Western Pacific Regional Office in Manila and her colleagues examined whether a 2004 effort to detect rumours of bird flu helped combat the disease as it whipped through poultry flocks in Asia.
Of 40 rumours from websites, newspapers, e-mails and experts, nine were found to be true, and several prompted action that may have helped to stem the disease's spread, the researchers report in Emerging Infectious Diseases1. For example, initial reports of duck deaths in China were later confirmed to be avian influenza, and prompted over 40 countries to ban imports of poultry from China.
Traditionally, the beginnings of a disease outbreak have been picked up by medical clinics and reported to government agencies, who in turn inform the WHO. But this can be slow, because many countries lack the resources to monitor and report diseases properly and the system can get bogged down in bureaucracy and politics.
The spread of electronic communication and the Internet opened up a comprehensive and speedy way of scanning the globe for disease. To take advantage of this, the WHO set up its rumour surveillance network in 1997.
The mainstay of the system is a sophisticated search engine called the Global Public Health Intelligence Network, based in Canada. It continuously scans and filters all news wires and online media reports for keywords such as 'outbreak' and 'epidemic' in six languages, ranging from English to Arabic.
A team of experts checks whether the hits are really outbreaks of international concern, based on the severity of the disease and the credibility of the source. This information is passed to WHO experts in regional offices around the world, who may ask the country involved for verification that the disease is real and then help them to tackle it.
The WHO compiles its own figures on the effectiveness of its rumour surveillance. From the tens of thousands of initial reports detected between January 2001 and October 2004, the system picked up around 1,300 disease outbreaks of potential global importance. Of these, 850 proved real, says Thomas Grein, who directs the operation at the WHO in Geneva, Switzerland.
Grein, Samaan and others now want individual countries to set up rumour surveillance systems that would run alongside the WHO's international one. These could filter reports according to different criteria that might be better at unearthing local incidents and diseases that are important to a particular country.
Samaan believes that the establishment of such national systems is increasingly urgent because of the possibility that avian flu might spread into humans and trigger a pandemic. "It's critical at this stage," she says.
Many countries may be pushed to introduce rumour surveillance if an updated set of rules, called the International Health Regulations, comes into effect later this year. The rules, which are likely to be adopted at the WHO's World Health Assembly in May, will require member countries to carry out real-time surveillance for a plethora of diseases and report potential emergencies to the rest of the world.
Prompted by the new regulations, Grein hopes that countries will create or strengthen both traditional means of surveillance and those relying on hearsay. "We want them to do it systematically," he adds.
- Samaan G., et al. Emerging Infectious Diseases, 11. 463 - 466 (2005).
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