Being an aid worker can be a risky business. Those who do it know what they're getting into: they sign up to be exposed to extreme human need, with its attendant psychological stresses. They work in areas where security is fragile, on the fringes of war zones or sometimes within them. Normality is different.

Reputable agencies do their best to train and prepare them for this, but they are inevitably at more risk of violence than if they'd stayed safely at home.

Now a new campaign has focused attention specifically on sexual violence directed against women. It says that this is significantly under-reported and that women are at far greater risk than anyone realised.

The campaign, Report the Abuse, notes that "Sexual violence in humanitarian settings is not an emerging issue. On the contrary, it is a problem that has been quietly discussed amongst the humanitarian community for years."

The campaign stresses that the project is "not just about rape, though it was born out an experience with rape". It's also concerned with harassment, assault and other forms of gender-based violence and aims to "break the silence" about these things.

It was started by Megan Nobert, who was drugged and raped by an employee of a UNICEF contractor while working as a humanitarian in Bentiu, South Sudan. She writes: "I am far from the only humanitarian to have experienced sexual violence, in the wide sphere of what the crime encompasses. I am not alone, and I needed to tell the people that I was working alongside that they were not alone either."

The project invites participants to report abuse they have experienced or witnessed using an online form. It includes anonymous testimonies from people who have experienced a range of abuse. Some of them had good support from their organisations, though others did not.

One victim says: "The majority of my colleagues were incredibly supportive. However, one or two colleagues complained to my supervisor about the fact I was talking about what had happened and felt that it was inappropriate. My supervisor used this as an example of how I was not handling things appropriately. If I was to go back and do it again, I wish I had not spoken out."

Another says: "Talked with a few other female co-workers about [my sexual assault], but they just laughed it off. One said 'sorry it happened'."

But anecdote aside, how widespread is the problem? According to IRIN, the Aid Worker Security Database, which bills itself as a comprehensive source for acts of violence against aid workers, says there have been just 15 incidents of sexual assault reported since 2005, involving 26 individuals. Of these, the majority were international aid workers.

However, IRIN also cites the Headington Institute, which estimates that two per cent or more of humanitarian workers have experienced sexual violence. There are more than 400,000 aid workers worldwide, meaning that sexual violence has directly affected between 4,000 and 8,000 aid workers in the last five to eight years.

"We believe that humanitarians are experiencing sexual violence to a far greater extent than we know," Chief Operating Officer Alicia Jones told IRIN. "We think it is a much bigger problem than currently recognised."

Christian Today spoke to Christian Aid, one of Britain's largest humanitarian charities. Spokeswoman Amy Sheppey said that the threat to aid workers had gone up in the last decade. "Sexual violence happens in the work place and in the wider field setting. Both international and national staff are targeted yet face differing risks," she said.

"With aid/development work, risk is always an accepted part of the job. But what is important is that it's managed effectively and we take into account gender specific risks."

Christian Aid runs a gender and security programme for its workers. As a rule, Sheppey says, women tend to experience more specific cases of sexual harassment and assault, although it's certainly something that also affects men.

She also points to the need to spread training and good practice more widely. Female staff are trained in gender and security issues and then go on to train others. Actors are used to conduct role plays. PEP (Post-exposure prophylactic) kits to help prevent someone contracting the HIV virus after they have been attacked are made available.

Another aid organisation that's deeply conscious of the issue is Tearfund. Its head of humanitarian support, Oenone Chadburn, told Christian Today that she believed the problem was under-reported, but that documenting it would difficult because different agencies didn't necessarily share information. Tearfund offers training to its staff and regularly reflects on its security management policies – aid work, she admits, is inherently risky.

"In humanitarian situations, social norms go out of the window. There is sigificantly more abuse in these settings," she says.

So Tearfund trains staff in managing their safety, which might be small things like carrying a wedge with them to keep a hotel door shut. There might be safety protocols for particular situations, like a curfew or not going out unaccompanied. 

She welcomes the campaign to raise awareness of the issue. "Aid workers are generally unsung – we haven't really given them due recognition," Chadburn says, noting that Britain provides more than its fair share to the sector. And she stresses the particular dangers faced by national workers, who sometimes choose to stay in dangerous situations when international staff are evacuated.

Christian Aid and Tearfund are aid organisations which seem to have a good grip on the problem. Not all do – and it's not just charities. A report on sexual abuse by UN peacekeepers found that among some countries' troops it was widespread, leading UN secretary general Ban Ki-Moon to describe it as "a cancer in our system". In April, a senior United Nations aid worker, Anders Kompass, was suspended for disclosing to prosecutors an internal report on the sexual abuse of children by French peacekeeping troops in the Central African Republic.He said he had pass the case on to French authorities because the UN had failed to deal with it. 

For Report the Abuse, Megan Nobert says at the end of her own testimony that speaking out is just a first step: "I do not expect anything to happen overnight. It will happen though, and we cannot give up until the organisations that we work for take our experiences and voices seriously.

"Change will occur, work environments will adapt, perpetrators will be punished. We will no longer need to be afraid."

Given what many aid workers give up in order to support the most vulnerable people in the world, it doesn't seem much to ask.  

Follow @RevMarkWoods on Twitter.