Migration of sex workers - between and within countries - may limit the impact of projects that base their effectiveness on repeated contacts with the target group. It is necessary to maintain a continuous cycle of peer educator activities in order to train new workers. Mediators may attempt to maintain contacts with peer educators who have moved - this would contribute to further spread of health promotion messages to a broader audience.

It must also be recognized that the nature of sex work itself could make peer educator interventions difficult. Feelings of competitiveness and jealousy are not uncommon and some sex workers could find it hard to accept that their colleagues are gaining more knowledge and power as peer educators. Moreover, the peer educators must balance a new dual role: they may be considered "insiders" as sex workers and "outsiders" as educators.

TAMPEP has found that successful sex work peer educators are leading members of their target group (i.e., of the same ethnic/cultural background). They have some basic knowledge of health, educational talents and excellent communication skills. They further are characterized by high levels of ambition and motivation.

In the interventions carried out by TAMPEP, 2-3 months are spent to complete all activities related to selecting, training and following up peer educators. The educators are trained in courses with 10-12 persons; they receive a small attendance fee to cover possible loss of earnings during the course and to acknowledge the time and energy they invest in the training.

Trainees also participate in organizing the course itself, which usually has a neutral title such as "Prevention and hygiene". This is because many sex workers do not see sex work as an identity - they rather consider it a temporary occupation. Each session includes guest speakers such as physicians, staff of contraception counselling centres, social workers and already trained peer educators. A certificate is awarded upon completion of the course. This provides the peer educators with a symbol of recognition, both for their peers and members of public service agencies with whom they liaise.

Follow-up activities monitored by TAMPEP cultural mediators include: supporting the peer educators in their role of mobile health messengers; providing additional and updated knowledge as well as educational materials not included in the basic course; and facilitating contacts between the peer educators and public health personnel and official agencies.

Based on more than 5 years' work, TAMPEP notes that the following principles are important for sex work-oriented peer education projects:

• peer education programmes should be placed in a broader context of promoting self-esteem, health, safety and civil rights, including protection of the rights of migrant sex workers
• peer education programmes should be carried out using autonomous communitybased organizations as a base
• the sex work scene changes continuously (market "demand", sex workers' nationalities, governmental policies, etc.), so peer education models and programmes should be continuously adapted to these changes.

Continuous cycles of data collection, implementation and evaluation of work dynamics and the results of transnational peer education programmes are the basic conditions needed to gain positive results in achieving changes in sex workers' health behaviour.