Chlamydia rate sparks concern

By MARTIN JOHNSTON, health reporter

All pregnant women should be tested for chlamydia, say researchers who found "unacceptably high" rates in some groups.

Their study, published in yesterday's New Zealand Medical Journal, found that 12.2 per cent of pregnant women aged under 25 had the sexually transmitted infection.

For pregnant Maori women the rate was 15.2 per cent, and for all pregnant women it was 4.8 per cent.

The Wellington Medical School team, led by Dr Beverley Lawton, also found that only 37.5 per cent of the more than 6600 women in their study had been tested for the infection.

Chlamydia, which can be treated with antibiotics, is not a notifiable disease, but it is New Zealand's commonest sexual infection.

Over the past five years the infection rate has risen 65 per cent. Based on laboratory results, the upper North Island rate is six times higher than Australia's. Waikato and Bay of Plenty labs report a 7 per cent rate among females aged 15 to 19.

In 2002, 96 babies aged under 1 were diagnosed with chlamydia at Auckland, Waikato and Bay of Plenty labs, a 70 per cent increase on the previous year.

"It's being called an epidemic. People are worried," said Dr Lawton.

"There's no reason for any baby in New Zealand to acquire a sexually transmitted infection."

Swab tests for chlamydia cost $20-$30 each. "It is definitely cost-effective to screen pregnant women."

Auckland Sexual Health Service physician Dr Nicky Perkins writes in the journal that New Zealand has no organised chlamydia screening.

She says the most economical approach would be to screen high-risk groups, such as those aged 15-25, especially Maori and Pacific Islanders and those who have recently changed sexual partner.

"Screening pregnant women would be a useful place to start since they are generally all attending for healthcare during their pregnancies, they are young and, by definition, sexually active."

Routine antenatal screening is recommended in the United States, says Dr Perkins.

The Health Ministry said the evidence was insufficient on the cost-effectiveness of screening all pregnant women, but the Wellington findings reinforced the need for testing high-risk women during pregnancy - and for safer sexual behaviour.

The acting public health director, Dr Doug Lush, said the ministry recommended "opportunistic" testing during pregnancy, but not a mass screening programme such as the cervical cancer scheme.

Such a selective programme, for sexually active young adults, would be considered by the new National Screening Advisory Committee.

Professor Peter Stone, a maternal and foetal medicine expert at National Women's Hospital, said it screened only high-risk patients, in line with College of Obstetricians and Gynaecologists guidelines.

"A few years ago in the recurrent miscarriage clinic, when we did look in that population, we found almost nobody, so we just didn't do it [screen universally]."

Dr Lush said the ministry was preparing a safe-sex media campaign for next summer.

Chlamydia's effects

Babies: Premature birth, low birth weight, pneumonia, conjunctivitis.

Adults and teens: Pelvic pain in females, genital discharge in males, infertility if left untreated.