In Australia, HIV infections are mainly diagnosed in people who have engaged in an identifiable risk behaviour (such as men who have sex with men). However significant rates of infection are being diagnosed in women, people from culturally and linguistically diverse (CALD) backgrounds and people in older age groups.  Personal and health-care provider ignorance about risk, social isolation, poor access to health care, language and cultural barriers, HIV-related stigma and fear of discrimination are some factors which prevent people from having timely HIV testing. Regular HIV testing is often not the norm among groups who do not perceive themselves as at risk for HIV and it has been reported that testing in some cases is motivated only by a serious health crisis.
While late presenters have often had limited contact with health services before their HIV diagnosis, in some cases a person may have presented to primary health services with potential HIV-related signs and symptoms e.g. seborrhoeic dermatitis, oral candidiasis or unexplained weight loss, but the diagnosis has been missed. This can be because the attending health-care worker does not have the knowledge to consider HIV as a possible cause and does not identify risk factors for HIV infection.