Fig. 1.

Network diagram of PWID recruitment chain referral in Nairobi, 2011 (N = 275), by HIV serostatus and lifetime sharing of needle or syringe. Larger shapes depict seed participants (n = 6); smaller shapes are recruited respondents (n = 269). Gray HIV-seronegative respondents (n = 212; 1 seeds). Black HIV-seropositive respondents (n = 57; 5 seeds). Square Ever receptive syringe sharing (n = 151; 4 seeds). Circle Never receptive syringe sharing (n = 118; 2 seeds)