A fifth of people living with HIV are unaware of their infection, according to figures published by health authorities in Northamptonshire.
The figures show that nationally 103,700 people have HIV in the UK and about 20,000 are unaware and at risk of passing the virus to others through unprotected sex.
Northamptonshire County Council and Northamptonshire Healthcare NHS Foundation Trust are backing calls for more people to get tested.
A spokesman said: “People diagnosed promptly with HIV infection can expect to live long and healthy lives.
“But a late diagnosis means greater costs to the health economy with increased hospital admissions and demands on social care services, and most significantly, those individuals receiving a late diagnosis are ten times more likely to die within a year of being diagnosed,” he said.
People at higher risk of HIV are being encouraged to register online for a free HIV home sampling kit. Kits can be ordered from www.freetesting.hiv.
Councillor Robin Brown, county council cabinet member for public health and wellbeing, said: “Testing for HIV to ensure an early diagnosis is absolutely vital. Early diagnosis means timely treatment, which radically improves prognosis and can mean a near-normal lifespan.
“Plus if people do not know that they have HIV, they are also risking transmitting the infection to others.”
Dr Ghanem, genitourinary and HIV medicine consultant at Northamptonshire Healthcare NHS Foundation Trust, said: “Evidence shows that early diagnosis of HIV and the immediate start of treatment provides the best outcome for a normal healthy life. The current HIV medications are easy to take and some are in the form of only one tablet per day.
“The local HIV service provides excellent care for people living with HIV in Northamptonshire and the majority are virally suppressed.”
In Northamptonshire, HIV testing is available at all sexual health clinics throughout National HIV Testing Week with results available within 24 hours. Further information, including opening times, is available at www.nhft.nhs.uk in the sexual health section of the website.
Alternatively people can request a free sampling kit online www.freetesting.hiv.