Transmission of HIV in sexual networks in sub-Saharan Africa and Europe David A.M.C. van de Vijver, Mattia C.F. Prosperi and José J. Ramasco Eur. Phys. J. Special Topics, 222 6 (2013) 1403-1411 Published online: 13 September 2013 DOI: 10.1140/epjst/e2013-01934-8