Scale-free sexual contact network of HCV carriers.

A) The cumulative frequency distribution P(k) versus the number of partners (k) shows that the low connectivity end of this network (individuals with 5 or less sexual partners) is associated with a higher prevalence of HIV-1b infected individuals compared to the high connectivity heavy tail-end of the network, which is in turn more frequently associated by HCV-1a and 3a carriers. B) Social, clinical and transmission risk factors are shown in increasing frequency in relation to the high-connectivity group that includes all HCV patients with 50 or more sexual contacts (dark grey) compared to the low-connectivity group that includes all HCV patients with 5 or less sexual contacts (light grey). The final two columns on the right show a preponderance of males with increased risk factors and behaviors. The high frequency of blood transfusions among the low-connectivity group shows its importance for HCV transmission among the general population at large up until the early 1990's.