Despite its unsavory reputation as one of the legendary scourges of mankind, yellow fever is primarily a disease of animals-monkeys, in particular. In South America, the virus moves through the canopies of tropical rain forests in enormous waves. Carried by mosquitoes, its primary victims are howler monkeys, which are chimp-sized and notorious for being heard rather than seen. Researchers who study this jungle cycle of yellow fever say that they can tell when the waves of virus are rolling by because dead howlers start dropping out of trees. While the virus periodically finds its way into humans working in the rain forest, there hasn’t been an urban epidemic in this hemisphere since 1942, a situation that has epidemiologists and public health experts holding their breath.
In their worst-case nightmares, a traveler or tourist contracts yellow fever in the Amazon, gets on a plane before symptoms appear and gets off 3,000 miles away, where he or she can be bitten by the local mosquitoes before the disease has been discovered or diagnosed, and the victim effectively quarantined. That such nightmares are not solely the stuff of imagination was demonstrated on the night of June 28, 1996, when a Swiss physician posted a case report on a Web site known as ProMED-Mail. The report was short and pithy: the story of a single unfortunate, unvaccinated tourist, who contracted yellow fever on a boat trip through the Amazon on April 5, and died 10 days later in a hospital in Basel. The fact that such episodes have not yet sparked a new wave of urban epidemics of yellow fever, according to New York State Health Department epidemiologist Jack Woodall, founder of ProMED-Mail, can be attributed to a single factor: “pure luck.”
Welcome to the global village of emerging infectious pathogens, where the bubonic plague can erupt in India, ebola in Zaire, or avian flu in Hong Kong, and any or all could make it to Boston in 12 hours; where a traveler returning home can spread a disease to his family, friends and co-workers before making it to the hospital, perhaps infecting everyone he comes into contact with.
To fight the threat-popularized in such books as Richard Preston’s The Hot Zone and Laurie Garrett’s The Coming Plague-epidemiologists and public health experts have been trying to come up with methods of monitoring diseases that match the electronic rapidity of modern times. Yet because many repressive governments are loath to publicize their health problems, the job of disease reporting has fallen to non-governmental organizations, traditionally the World Health Organization (WHO). But the WHO will not release information on a potential epidemic until it has been reliably confirmed, which can take months. Public health experts who want their news now and not later have learned to rely on Woodall’s ProMED-Mail.
ProMED-Mail (the name represents Program for Monitoring Emerging Diseases) is an Internet, e-mail based system connected by satellite to ground stations and Internet nodes throughout the world. It can be found at www.healthnet.org and anyone can subscribe. Fill in your e-mail address and a dozen postings a day will appear in your in-box-cholera in Pakistan, Rift Valley fever in Kenya, tick-borne encephalitis in Russia, E. coli infections in Wyoming. In the four years since it went online, ProMED-Mail has grown from 40 subscribers in seven countries to 15,000 in 150 and is now considered by experts to be an indispensable, although not wholly reliable, medium for transmitting news of outbreaks and connecting health experts to the far corners of the globe. Meanwhile, the WHO has joined with Health Canada to produce what they call the “Cadillac of ProMEDs,” which was launched in early June.
The ultimate goal of these electronic efforts is what Woodall calls “global transparency” of disease reporting. Ideally, within days of an outbreak, public health officials worldwide will know where and what has happened and be able to mobilize immediately, sending teams to help contain the outbreak at its source or warning local hospitals and ports of entry to watch for travelers who might have to be quarantined. While the Internet is assuredly the way to do it, says Duane Gubler, director of the division of vector-borne infectious diseases at the Centers for Disease Control and Prevention, no one is quite sure yet what form the ultimate monitoring system will take, or who will run it. “This is the wave of the future as far as disease surveillance is concerned,” says Gubler. “Our challenge is how do we assure the quality of the reporting. If we can accomplish that and harness the thing properly, it’s going to be the best thing that ever happened to disease surveillance.”