M. Giovanna Merli and James Moody used network simulation models and egocentric sexual network data to study the spread of HIV and other sexually transmitted infections (STIs) in China. The profound sexual revolution ongoing in China is accompanied by an active resurgence of STIs, especially syphilis, but the prevailing concern is centered around HIV. Given that half of HIV infections in China are thought to happen through heterosexual sex with a large majority of those through paid sexual encounters, the study team (in collaboration with Chinese colleagues in Shanghai) use information collected on the sexual partnerships of 1,200 respondents, who are representative of the Shanghai general population and 550 female sex workers between 2007-2009, to simulate the heterosexual network of Shanghai residents and the HIV transmission over this network.
Data show that the sexual network of sex workers, their customers and partners of these customers are still far too constricted to sustain transmission of a virus such as HIV, which is not highly infectious. But the research team argues that this network may be more compatible with the transmission of bacterial sexually transmitted infections, such as syphilis, which are more infectious and less susceptible to structural breaks in transmission of infection. These results suggest that policies that force commercial sex underground could have an adverse effect on the spread of HIV and other STIs, because the higher rate of partner change of a smaller number of FSWs required to meet demand will create shortcuts in transmission and more robust transmission routes.