EDITOR, - Peter Saunders rightly draws attention to the fact that an increasing proportion of newly diagnosed HIV infections in Britain is attributable to heterosexual intercourse; his statement that this is now the commonest mode of spread in Scotland merits comment.1 Since 1985 the Communicable Diseases (Scotland) Unit has maintained a register, based on laboratory reporting, of all people known to be infected with HIV in Scotland. As it is based on voluntary testing this register cannot be seen as an indication of incidence or prevalence, but it remains the most reliable source of data on HIV infection in Scotland and is used in resource allocation under the AIDS (Control) Act and in official predictions of the course of the HIV epidemic.

The table shows the distribution of newly diagnosed HIV infections by probable category of transmission and by year of specimen (since 1985) according to the Scottish HIV register.

Overall, the decreasing predominance of injecting drug use as a category of transmission and the increasing predominance of heterosexual transmission are clearly apparent, but in only one year (1992) has heterosexual intercourse been the commonest mode of spread. In 1993 sexual intercourse between men accounted for the highest proportion of cases, followed by injecting drug use.