Assessment of sexual mixing patterns

The manner in which people with varying partner change rates choose their partners may have important implications for the future of the AIDS epidemic. A relatively rapid but small epidemic can be expected if sexual mixing patterns are highly assortative so that those with high partner change rates nearly always choose partners with similar rates. Direct estimation of sexual mixing is exceedingly difficult. On the other hand, information on the way people mix is implicitly contained in the epidemiology of other sexually transmitted diseases (STDs). If mixing is highly assortative, one might expect gonorrhea to be largely confined to a small subsection of the population who would frequently contract the disease repeatedly. In this paper a model of gonorrhea transmission in which partner change rates and preference are dealt with as continuous variables is used to extract information on mixing from data on an Australian heterosexual population. It was found that in this population mixing is not far from random with respect to partner change rates.