Mapping Epidemics with Contact Tracing & Social Network Analysis [SNA]

Contagions that flow through human-based networks can be good(ideas and innovations) or bad(disease, infection).

A bad contagion such as SARS or TB, spreads through human networks based on how infectious and susceptible each party is in the network. Multiple contacts with infectious others play a role in the probability of infection for each person. 

Public health officials perform contact tracing to map the spread of infections and manage their diffusion. The network map above, created at the epidemiology unit of The Centers for Disease Control [CDC], shows the spread of an airborne infectious disease. The map was created using actual contact data from the community in which the outbreak was happening.

Black nodes are persons with clinical disease (and are potentially infectious), pink nodes represent exposed persons with incubating (or dormant) infection and are notinfectious, green represent exposed persons with no infection and are not infectious. The infection status is unknown for the grey nodes -- they are still to be tested. Unfortunately the 'social butterfly' in this community, the black node in the center of the graph above, is also the most infectious -- a super spreader.

Current procedures focus on inoculating the vulnerable -- often the very young and the very old. Network analysis tells us that it may be smarter, and more efficient, to focus on the spreaders -- those with many contacts to many groups, the bridges in the network.