Cluster management and the role of concerned communities and the media.

Public health services often have to deal with reported clusters of adverse health events. An important characteristic of disease clusters is that the involved community often is concerned about environmental factors influencing health. To facilitate cluster investigations, a stepwise protocol was developed in the Netherlands, based on international literature. Essential is the two-way approach, consisting of a disease-track and an environment-track. Attention to potential environmental exposures is as important as attention to the reported diseases, not only because environmental pollution often is the reason of public concern and thus relevant for risk communication, but also for deciding about the boundaries of the population at risk. Moreover, environmental information is necessary for judgement of the plausibility of a causal relation and for advising measures to prevent exposure. Within this two-way approach, three stages are distinguished: orientation stage, verification stage and quantification stage. Only if an increased risk as well as an elevated exposure is verified, under certain conditions a case-control study may be useful to study causality between exposure and adverse health events. During all stages of the investigation, good risk communication strategies have to be taken into account. However, even then it might be difficult to prevent conflicts, because of the differing interests between experts and the community involved. One of the most important aspects that determine judgements about risks by threatened people, is controllability; that is why community participation is essential. Therefore it can be concluded that cluster management is a mutual endeavour for experts, public and media, where experts are judged on three characteristics: expertise, credibility and empathy.