As many as one in four young people in some Northland communities have been diagnosed with the sexually transmitted disease chlamydia and health officials have become increasingly alarmed at its spread.
Exceedingly high rates of the disease had been revealed through a laboratory surveillance programme launched in November last year, Northland medical officer of health Dr Jarman said.
The programme is the first time health officials have got a true picture of the spread of chlamydia - commonly known as the "love bug" - in the region, confirming concerns over the years that it was getting out of control.
Dr Jarman would not name the communities in question on the grounds that the high diagnosis rates were due to greater awareness rather than a higher prevalence in those areas.
Dr Jarman, who had repeatedly stated the disease was out of control, said it was an issue that affected the whole region.
However, statistics show that Kawakawa with 2213 cases per 100,000 people had the highest chlamydia rate in the region followed by Kaeo with 2070 and Kaikohe with 1491.
Eighteen cases of the disease are diagnosed in Northland each week and 820 new cases were recorded last year.
Eighty-three percent of cases were aged between 15 and 30 years old. However, there were also some young children with the disease.
Seven babies had caught the disease from their mothers and 17 children under the age of 15 had caught it as a sexually transmitted infection.
The overall Northland figure of 584 cases per 100,000 people was three times higher than rates reported in Australia and almost twice that of the USA, but lower than the the 613 cases per 100,000 people reported in Auckland.
Rates of the disease in Northland were similar to those reported in Auckland and the Waikato where other surveillance programmes had been established. Dr Jarman said it could be assumed that other areas in New Zealand had similar case numbers.
"I'm not sure that Northland is any worse than any other area although certainly there are some areas that have very high rates and the reasons for this are not clear," he said.
"The figures show that there are a high number of sexually-active young people who are not using condoms and not practising safe sex."
Chlamydia was the most common sexually transmitted infection in New Zealand and was largely without symptoms.
Without treatment, men risk infertility and infection of the testicles. Women risk infertility, ectopic pregnancy and long-term pelvic pain.
Dr Jarman urged people under the age of 30 who were sexually active to have regular check-ups with their doctor, family planning or sexual health clinic.
"There are three options if people want to avoid the disease. Of course there is abstinence or being faithful. Using a condom with a new partner until you both have been checked out for sexually transmitted infections is a very good idea."
Chlamydia was sending a ``powerful message'' that other STIs could spread just as easily in the region, he said. ``It's a warning,'' Dr Jarman said.
Meanwhile, a number of cases of antibiotic-resistant gonorrhea had been reported in the Far North this year and two cases of HIV/Aids were reported in Northland last year.