From 18 months until he was eight years old David Passell, now 57, was sexually tortured. A woman trusted by his mother, who was busy with five children, exploited her access to David.

She forced David to perform oral sex on her and attacked his genitals with a safety pin.

“The last of this stuff happened when I was eight and I first spoke about it when I was 36,” Passell told the Sunday Star-Times.

He is a part of a hidden group of New Zealand men who were sexually abused in adolescence. Silenced and isolated by shame, stigma and guilt, they were unable to come forward at the time of their abuse.

“I couldn't talk about what had been done to me as a boy because I would be perceived as weak,” he said. “If I had spoken about this when I was playing competitive rugby in my 20s I would have been laughed off the team.”

Research shows that an estimated one in eight New Zealand men experiences sexual abuse before the age of 18 but because so few males are willing to come forward, others put the number much higher.

Ken Clearwater, manager of the Male Survivors of Sexual Abuse Trust (MSSAT), believes as many as one in five men is sexually assaulted in adolescence.

“This is something people don't know about and don't want to know about,” Clearwater said.

Of the victims who reach out to MSSAT, 87 per cent have kept their abuse secret.

“Society has to accept that this is not an isolated case. Young boys are not able to come forward and disclose.”

Detective Inspector Tusha Penny, manager of the national Child Protection and Sexual Violence team, said hiding sexual abuse meant offenders can continue to get away with crimes against other boys.

Last week James Parker, the former deputy principal of Pamapuria primary school, outside of Kaitaia, pleaded guilty to 49 charges of sexual assault against boys under the age of 16. Just one boy initially complained to police.

The subsequent investigation revealed 12 victims since 2006. And since Parker's appearance in court more boys have come forward.

“Having the confidence to come forward is a huge thing to prevent further victimisation,” Penny said.

Andrew Thomson* was abused by his art teacher, William Baine, at Hutt Valley High School in 1959. It took him 40 years to seek help.

“I had a great counsellor. She built up my confidence, worked on the shame issues,” he said.

Once he was confident enough to go to the police about Baine's offending, other victims came forward. In total seven complainants were heard in court in 2003.

“The seven of us covered 50 years. That's the huge problem of the difficulty of disclosure, the opportunity to keep offending,” Thomson said.

Penny said encouraging men to feel enough confidence in the police to come forward and lodge a complaint was challenging for investigators.

She recognises the important work being done for women who have suffered sexual abuse but says similar systems are not in place for men.

“A lot of emphasis goes on the female survivors, which is fantastic because that needs to happen, but we have to be very careful we don't neglect men in the process.”

About 70 per cent of New Zealand is covered by specialist crisis agencies that can respond to, and have long-term involvement with, female survivors of sexual abuse. “For men we don't have that kind of coverage,” Penny says.

Dr Clare Healy, the executive chairperson for Doctors for Sexual Abuse Care, says there is much more sex-abuse awareness education for girls.

“For teenage boys and primary school boys, they feel isolated, guilty and angry and don't know who to turn to. They don't really know who to tell about it.”

Victims respond with a number of coping mechanisms. Boys can become isolated and withdrawn. Or the victim will respond by turning to drinking and drugs.

Passell said his emotional and physical intimacy was affected “big time”. He would suffer from panic attacks triggered by sexual contact. He turned to alcohol and physical training as coping mechanisms.

But the effects can be even more serious.

Research indicates about 40 per cent of male perpetrators have themselves been sexually abused.

“We know with child abuse that is a risk, so that it is why it is even more critical that we are working really hard across communities to identify victims,” Penny said.

MSSAT is the only agency that advocates and supports male victims of abuse. The lack of resources for men makes Clearwater start to shout.

“Not a day goes by when we don't get a phone call. This year we have 74 new clients already.”

Last week, the opening of a new MSSAT premise in Hamilton was “bittersweet”. The growth in resources has come with a growing number of male victims seeking support.

Passell was able to open up to a counsellor. He attended group meetings and was strengthened by seeing others who could talk about the pain in their lives. He was finally able to grieve.

“In the past 20 years my life has turned around. I have another daughter with my second wife of 18 years. And I have four adult children and three grandchildren.”

He now runs the Auckland support group of MSSAT.

Meeting once a week, the group gives men the courage to disclose the abuse they have suffered. It has changed life for Passell and many of the victims he has worked with.

“I still have difficult days, but I don't have difficult months.”

*Name has been changed