Yesterday nursery worker Vanessa George was charged with abusing children in her care. The fact that she is a woman has caused widespread shock - but, reports Sandra Laville, it is an issue that society has long brushed under the carpet

Every so often, a criminal case jolts the national consciousness: James Bulger, the Soham murders, Beverley Allitt and the death of Baby P to name just a few. The mob who gathered outside Plymouth magistrates court yesterday for the arrival of Vanessa George signalled all too clearly that her story has already been added to that list.

Child sexual abuse is shocking and disturbing enough, but the added fact that this allegation is levelled against a woman who was in loco parentis for hundreds of very small children has created waves of outright confusion, anger and disbelief.

All our newspapers and broadcasters have pored over the details of the case of George, who is charged with four counts of sexually assaulting children, and three of making, possessing and distributing indecent images of children. The key talking points have been the rarity of women as sexual abusers, the easy access women have to children, and the nightmare question facing parents: if you cannot trust a nursery to look after your infant, then who can you trust?

If nothing else, the case raises awareness of a topic that society as a whole - from police officers to social workers, teachers and the general public - has historically failed to acknowledge fully. Women can and do sexually abuse children. What's more, according to recent research, the failure to recognise this can hinder child abuse investigations and the detection of female abusers. Research for the NSPCC from 2005 says there is "compelling" evidence of a wide variety of sexual offences known to have been committed by women, either alone or with a man - from voyeurism to inappropriate touching, rape, penetration and ritualistic, sadistic sexual abuse.

While the existence of paedophile websites has been acknowledged and investigated for years, it is not so widely known that there are several sites catering for female paedophiles. One of these sites has carried comments such as "I really look at little girls and want to see them naked", and "I am a 21-year-old and for as long as I can think I have been attracted to young girls around 5-12 years old ... I buy movies because there are little girls in them. Books about little girls in sexual situations ... I am not attracted to women, only young girls." This particular website is one of the most prolific. Agencies have tried to close it down, only for it to re-emerge under a new name.

Dr Sharon Lambert, a psychologist who has studied female sexual abusers, says: "We still don't really understand what effect the internet has on people, least of all on women. All of the research has been done on men interacting with these paedophile sites. But women are also interacting with them and, as yet, we don't know how likely it is that women who view these websites feel their behaviour is rationalised and validated enough to go on and commit further offences. One thing that is recognised is that women have far more unfettered access to children than men."

Everyone in the field agrees that the internet revolution has provided extraordinary opportunities for paedophiles. Images of children being abused in a home in the UK can be viewed around the world within minutes, making the investigation and prosecution an international concern. One of the most recent cases of a female sex abuser in the UK was uncovered by the FBI, who were viewing hundreds of images as part of a global operation.

From a single picture of a victim, they traced the abuse to a home in Northamptonshire and, within six hours of being contacted by the FBI, officers from the Child Exploitation and Online Protection Unit were on the doorstep. They arrested Katie Scott, 26, and her partner Christopher Oxtoby, 27. Scott was jailed last year for four-and-a-half years for sexually abusing a four-month-old child, an act that was filmed and distributed on the web by Oxtoby, who received an indeterminate sentence.

Two years ago, police in Kent broke up a paedophile ring in which a middle-class woman, a pharmeceutical rep, was convicted of four offences of sexual activity with a child and one of engaging in sexual activity in the presence of a child. Monica McCanch, 55, and two male companions had subjected two children to what the police described as "horrific abuse". She was jailed for six years.

Research suggests that between 5 and 10% of sexual offences against children are carried out by women, either acting alone or with a male accomplice, but the true extent of female sexual abuse is simply not known.

A senior paedophile investigator says lack of acknowledgement that women can and do sexually abuse children could delay detection of sexual assaults. "It's almost certainly the case that people tend to make assumptions it is the male doing the abuse. There have been a few cases where teams have had medical evidence that sexual assaults are taking place, but the officers have looked at the man again and again and found nothing - and then later thought; 'Ah, perhaps we should have a look at mum here.'"

"We have to get away from believing in the typical image of a paedophile - a middle-aged, balding man wearing a dirty raincoat," says Zoe Hilton, policy adviser for child protection with the NSPCC. "It's important that we don't become fixated with this image. It blurs the real extent of sexual abuse and can make it difficult for children to speak out. Child abuse is very prevalent in society, and it comes from a range of sources, including those people whom society views as maternal and nurturing: women".

• Are women who abuse children more demonised than their male counterparts? Are teenage victims of sexual abuse treated differently? Email us at women@theguardian.com with your thoughts, and we will use the best in our new response column in next Friday's women's pages.