Web Extras: Article

Following Flu
By Alison Davis
Posted June 11, 2008

You might be off for the summer, but the flu isn't. The influenza viruses that cause seasonal flu work year-round to attack our immune systems in the late fall.

Accurate flu surveillance is crucial for predicting how flu viruses evolve to outwit our immune system. Determining where the viruses travel and how infectious they might be is the main job of the World Health Organization's Global Influenza Surveillance Network. This group of public health officials also chooses which types of flu viruses should be included in the coming year's vaccine.

A common flu strain migrates from East and Southeast Asia into the rest of the world annually from 2002-2007. Credit: NASA Visible Earth/Kristin Wuichet Click for larger image

One of the network's scientists, Derek Smith of the University of Cambridge in England, looked for a better way to track the flu's travels. Mixing virology, immunology, computer science, and math, Smith developed a unique approach called antigenic cartography.

Antigenic cartography is a type of computer modeling. It takes into account how strongly some 13,000 strains of flu might grip onto human antibodies, a strong predictor of the effectiveness of a given vaccine. The information is then overlaid onto a world map to trace the flu's spread throughout the year.

Smith and his team discovered that the most common type of flu starts a predictable, yearly journey in East and Southeast Asia, then travels around the world before puttering out in South America.

Using the new method and expanding surveillance should help public health officials detect emerging strains of flu, enabling them to make vaccines that offer better protection from the aches and pains of seasonal flu.

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