December 03, 2008
Wednesday

The city is crammed with people -- citizens, visitors, and soldiers -- many from distant places. In the overcrowding, sanitation, food and water supplies are all disrupted. And people begin to get sick and die. The streets and houses fill with bodies, and social order breaks down.

It's a scenario played out through history -- Athens in 430 B.C., London in 1665, Philadelphia in 1793, Paris in 1832, flu in cities throughout the world in 1918-19.

More recently, human immunodeficiency virus spread across much of southern Africa largely along trucking routes. West Nile virus rode a combination of birds and mosquitoes from a few boroughs of New York City to become established coast to coast in less than a decade.

Just how susceptible modern societies really are to a new plague or pandemic is a matter of some debate and concern, with billions being spent to detect outbreaks, whether delivered naturally or from a terrorist act.

A team of specialists at the National Institute of Allergy and Infectious Diseases recently analyzed 10 historically notable outbreaks of disease, from the Plague of Athens to the march of AIDS, and found there were common factors, like international trade or troop movements, political weakness or drastic changes in climate or land use, behind all of them.

Yet knowing just what indicators and diseases to monitor to predict the emergence or re-emergence of some scourge remains an art that is "not well developed,'' said Dr. David Morens, one of the authors of the report, published in the November issue of The Lancet Infectious Diseases.

"We know, however, that the mixture of determinants is becoming ever more complex, and out of this increased complexity comes increased opportunity for diseases to spread rapidly,'' Morens continued.

"Airport malaria" is just one example of an intersection between global air travel and changing climate.

Researchers coined the term after documenting a small but growing number of cases of the tropical infection among people in the U.S. and Europe who had been nowhere near the tropics. But they had spent time at airports in major cities with a large number of international flights on which infected female mosquitoes had hitchhiked and went on to bite the otherwise unexposed travelers.

"As international travel increases and climate patterns change -- particularly warming nighttime temperatures and increased precipitation -- the U.S. becomes a more stable ecosystem for these disease carrying insects to survive and flourish for longer periods of time,'' said Dr. James Diaz, an environmental health researcher at Louisiana State University who will report on the outbreaks at a meeting of the American Society of Tropical Medicine and Hygiene in New Orleans Dec. 7-11.

Modern epidemiology detected the malaria cases around airports. But citizens of ancient Athens had no such scientific tools to discover what it was that felled a third of the city-state's population over a 3-year period, and ended the Golden Age of Greece.

By 1832, with an epidemic of cholera spreading from Asia across Europe, French health authorities sent monitors to Russia and Poland to study outbreaks there, and set up quarantine stations and teams of well and cesspool inspectors.

Still, the disease erupted in Paris that spring, claiming hundreds of lives. The newspapers published lists of the newly ill and dead. Pioneering epidemiologists checked the names against census rolls to track where the disease was worst, and the age, sex, and occupation of the victims. Morens and his colleagues say it was the first time such a scientific investigation of disease was done virtually "real time."

Today, health departments in the U.S. and most developed nations track a long list of "reportable" diseases that are collected and analyzed constantly by agencies such as the federal Centers for Disease Control and Prevention. But the system still relies on diagnoses being made and reported from doctors and hospitals.

Some disease detectives think computer programs that monitor, say, purchases of cold and flu remedies or calls from school nurses can be used to spot trends for illness even more quickly and accurately. Authorities in New York City already monitor pharmacy traffic as sentinels for disease.

And researchers at the search engine giant Google found last winter that by tracking where people were querying flu-related topics, they could estimate how much flu was circulating in various regions and states at least 1 or 2 weeks faster than the CDC could using a network of health departments and physicians.

Presumably, a lot of people Googling for flu-like symptoms at a time of the year when flu should be dormant would set off alarms across the public health system.

On the Web:

http://www.niaid.nih.gov
www.cdc.gov
www.astmh.org
www.google.org/flutrends/

SitNews ©2008
Stories In The News
Ketchikan, Alaska

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