[1] Univ Calif San Francisco, Dept Anthropol Hist & Social Med, 3333 Calif St, San Francisco, CA 94118 USA
[2] Univ Witwatersrand, Fac Hlth Sci, Sch Publ Hlth, Johannesburg, South Africa
[3] Univ Calif San Francisco, San Francisco Gen Hosp, Div Gen Internal Med, San Francisco, CA USA
[4] Univ Calif San Francisco, Sch Nursing, San Francisco, CA 94143 USA