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General interest items edited by Janice Flahiff

Human networking theory gives picture of infectious disease spread

Human networking theory gives picture of infectious disease spread

High school students’ interactions provide new look at disease transmission

From a December 13, 2010 Eureka news alert

It’s colds and flu season, and as any parent knows, colds and flu spread like wildfire, especially through schools.

New research using human-networking theory may give a clearer picture of just how, exactly, infectious diseases such as the common cold, influenza, whooping cough and SARS can spread through a closed group of people, and even through populations at large.

With the help of 788 volunteers at a high school, Marcel Salathé, a biologist at Penn State University, developed a new technique to count the number of possible disease-spreading events that occur in a typical day.

This results is published in this week’s issue of the journal Proceedings of the National Academy of Sciences.

The research was funded by the National Science Foundation (NSF) and the National Institutes of Health (NIH)…

Using a population of high-school students, teachers and staff members as a model for a closed group of people, Salathé and his team designed a method to count how many times possible disease-spreading interactions occurred during a typical day.

Volunteers were asked to spend one school day wearing matchbox-sized sensor devices–called motes–on lanyards around their necks.

Like a cell phone, each mote was equipped with its own unique tracking number, and each mote was programmed to send and receive radio signals at 20-second intervals to record the presence of other nearby motes….

Salathé and his team found that, at the end of the day, most people had experienced a fairly high number of person-to-person interactions, but they also found very little variation among individuals.

Strikingly, they did not find any individuals who had an extraordinarily high number of contacts when compared with the rest of the group. Such individuals–called super-spreaders–are known to be very important in the dynamics of disease spread.

“For example, in sexual-contact networks, one often finds a group of people with a much higher potential to contract and spread a virus such as HIV,” Salathé said.

“This potential is due to these individuals’ extremely high number of interactions. But in our experiment, while there may have been kids with a few more interaction events, for the most part, everyone had about the same high level of interaction.”

Salathé explained that while schools may indeed be “hot beds” for colds and the flu, individual students do not seem to vary with regard to exposure risk due to their contact patterns.

Data from the motes also confirmed an important social-networking theory–that contact events are not random because many “closed triangles” exist within a community.

“If person A has contact with person B, and person B has contact with person C, chances are that persons A and C also have contact with each other,” Salathé said.

“Real data illustrating these triangles provide just one more piece of information to help us track how a disease actually spreads.”

Salathé also said that networking data such as his may help guide public-health initiatives such as vaccination strategies and prevention education.

 

 

December 14, 2010 - Posted by | Uncategorized | , ,

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