'Aid workers are motivated by a wish to help others and they often bring with them a lot of Western notions about how things should be organised and how technology should be used. They leave the airport with high expectations.
'When they arrive, instead of seeing starving children, they meet rapacious landlords, black marketeers, swindlers and cheats, and consequently they suffer disillusionment.
'When they enter the theatre of the disaster itself, they get secondary traumatisation. They are not the primary victims of the disaster, but experience the suffering at second-hand.
'What they see looks like 'real life' because what they are seeing is life in its rawest form. The result is that when they come back to clean streets and Sunday colour supplements, they often feel that life here is unreal.
'Emotionally speaking, these people remain out in the disaster zone until the situation is resolved, which can take years, or might never happen.'
Charities can take steps to reduce the trauma of their staff. 'A good organisation will tell people straight: 'You are not Florence Nightingale. You may find that, instead of heroic saving, you are involved in the politics of food distribution.
'In an earthquake situation, for example, local people may not care about using a heat-seeking device to find a body in the rubble, but they might care about the way food is distributed so that the local villagers get more of it than people who have arrived as refugees.
'When people finish a tour of duty, they need to recount their experiences, possibly even write them down. Some charities take people away for debriefing sessions. Aid workers also need to be encouraged to understand that life at home is just as real as out on the front line.'
Workers need to keep a distance between themselves and the events with which they are dealing, says Dr Thompson; and at the end of a tour of duty, they need to sit down with colleagues and look at what good has come out of the project, however terrible it was.
Aid agencies have changed, says Marcus Thompson, emergencies director for Oxfam (see above left). 'Some of the old attitudes have disappeared,' he says. 'It's no longer 'I was out there, in the front line, among the muck and bullets, sorting it all out', and 'Counselling is only for poofters'. For Oxfam, the top priority is the safety of our staff.'
However, it can be difficult for agencies to find suitable counsellors. Those experienced in helping people to deal with stress at work, marriage problems or wayward teenagers are not always best able to help those traumatised by seeing people slaughtered. 'We sometimes use counsellors who have helped people in the armed services, who have seen their friends shot, for example. But there is a shortage,' Mr Thompson says.
He has to advise his own workers in Goma on some of their difficult decisions. 'They are organ
ising the water supplies, but people are dropping dead from thirst all round them. They know that if they stopped and picked up some of these individuals and took them back to their headquarters they could revive them, but if they kept stopping to do that they would never get their job done. And their job is to deliver supplies to hundreds of thousands.
'I say to them: 'Don't blame yourself for not doing what you can't do.' '
Save the Children Fund has an elaborate system of preparation and debriefing for its staff. Helen Daly, the charity's staff health officer, talks to staff both before and after their trips abroad.
'Before they go, we address physical and psychological health issues. The psychological briefing includes the impact of their whole environment - the job, culture, isolation, stress, relationships and the appalling events that may be happening around them. Staff are encouraged to think about their motives for wanting to work overseas, and how this may affect their lives and the lives of the people in the country.
'On their return, they have a technical debriefing about the programme, and a personal one, where they can unload any concerns that they may feel. It is important for staff to air their feelings and concerns and for the organisation to support them in whatever way possible. For those who have suffered trauma, Save the Children Fund offers further support through counselling.
'I feel we must reinforce the positive for them - if the agency had not got involved, how much worse it would have been.'
She advises people going abroad to identify someone in the field whom they can trust to tell them when they are overworking; she emphasises the need to take annual and local leave; and she tells team members to meet and discuss traumatic events when they occur, so that staff have an opportunity to express their feelings and not suppress them.
Ms Daly recognises the same difficulties of readjustment that Dr Thompson describes. 'Field workers returning home feel that people here have so much more than those people in the countries where they work. They see life differently and feel isolated.'