A report published by Public Health England has revealed that around 25% people infected with HIV remain unaware of their status.

"We can’t overstate the importance of testing for HIV to ensure an early diagnosis," said Dr Valerie Delpech, head of PHE ‘s national HIV surveillance. “In 2013, people diagnosed with HIV late were 10 times more likely to die in the first year of diagnosis, compared to those diagnosed promptly. People who remain unaware of their infection are also at risk of transmitting HIV to others."
While painting a grim picture over the diagnostic angle, the report did state that the number of people diagnosed with a late stage of HIV infection dropped from 57% in 2004 to 42% in 2013.
Source-Medindia