THE amount of young people being diagnosed with the sexually transmitted infection Chlamydia in Blackburn with Darwen has increased dramatically in a year, new figures show.

The borough had the highest Chlamydia detection rate in the North West in 2016, data released by Public Health England shows.

For those aged 15 to 24 the detection rate was 4,173 per 100,000 compared to 2,820 per 100,000 in 2015 while in Lancashire it was 2,101 per 100,000 compared to 2,247 in 2015.

Chlamydia is one of the most common STIs and although often symptomless it can cause long-term health problems including infertility if left untreated.

Health chiefs said the fact the detection rate was rising was good news as it means more people are getting tested and therefore treated.

Figures show in Blackburn with Darwen there was a new diagnosis rate of 957 per 100,000 residents in 2016 compared to 792 per 100,000 in 2015 for all STIs while in Lancashire it was 668 per 100,000 residents in 2016 and 702 in 2015.

The rate of Gonorrhoea diagnoses has also increased with a rate of 21 per 100,000 in 2016 compared to 12 in 2015 in Blackburn with Darwen and 28 per 100,000 in Lancashire in 2016 and 2015.

Prof Dominic Harrison, director of public health at Blackburn with Darwen Council, said: “We know there are undiagnosed infections in the population therefore the purpose of the screening programme is to identify as many as possible so they can be treated.

“A rise in detection is a good thing even though it looks like it is not. Because we have more diagnoses it is a sign of a good screening programme.

“One of the problems historically was an ever increasing number of infections that were not being diagnosed until they went on to get other diagnoses.”

He said a report due to be released early next week will show the borough is second out of 16 authorities in terms of its sexual and reproductive health services.

“That means in relation to STIs we have got lower rates than similar local authority areas which indicates the services are good and the broader prevention work must be good,” he said.

He said the message is to get regularly tested and practice safe sex.

He said: “Chlamydia testing is free and safe. Everyone who is sexually active should test themselves if they feel they may be at risk.

“People can have infections from a long time ago and not know about it because it is asymptomatic.”

A spokesman for Public Health England said they are now researching a health promotion campaign aimed at promoting condom use and positive sexual relationships among young people.

He said: “Health promotion and education remain vital for STI prevention, through improving risk awareness and encouraging safer sexual behaviour.”