That HIV and AIDS are still increasing despite continuing publicity and educational effort is almost certainly partly due to the combination of a number of factors.

The first is the long incubation of HIV before it produces any symptoms at all. As a result, it has been estimated that over a quarter of those in the UK who are infected with HIV are unaware of it.1

Undiagnosed HIV in people co-infected with another acute STI poses a particular risk since the STI appears to increase the chance of transmission of the HIV.1

The second is that their knowledge of HIV/AIDS and other STIs has not influenced the sexual behaviour of 38% of men and 35% of women.2 This again is more of a problem in the heterosexual community, since despite the facts, HIV/AIDS is still largely perceived as a problem of gay men and injecting drug users.

The role of international travel and population movement is also important, with a high proportion of heterosexually acquired cases having been contracted in sub-Saharan Africa, either by British born people travelling there, or by African born people migrating to Britain. Within the latter group, women are particularly affected.1