1The present expert group review survey is timely: existing dengue fever control methods have not succeeded in halting the spread of the disease in either its classic form or its haemorrhagic form, in any of the three French départements of America (the FDAs: Guadeloupe, French Guiana and Martinique)1.

2The world picture is no more reassuring: dengue has been on the increase throughout the tropics and subtropics over the past forty years. An estimated two and a half billion people are at risk; the World Health Organisation (WHO) estimate is 50 million cases of dengue, and the annual mortality figure is over 30,000. Severe forms (haemorrhagic dengue, dengue with complications or shock syndrome) are increasingly common in Southeast Asia and South America.

3The Caribbean region is no exception and, following some other Caribbean countries, the FDAs have suffered outbreaks of dengue, including haemorrhagic dengue, for several years now.

4The health authorities were already alert to the problem in the 1990s. Significant steps taken before the IRD was commissioned to conduct the present survey included publication of the Guide de surveillance de la lutte contre la dengue dans les départements français d'Amérique (Blateau et al., 1999, Institut de veille sanitaire, Paris).

5The decision to commission a collegial expertise survey on optimising dengue control in the FDAs was taken at the international meeting on “Mosquito control methods at the dawn of the third millennium” held in Fort-de-France, Martinique, in March 2000. That meeting was initiated by the Martinique département Council, organised by ADEGE (Agence nationale pour la démoustication et la gestion des espaces démoustiqués), EDEN (European Association of Public Operators for Mosquito Control) and the IRD, and attended by some 150 participants from all over the world, but especially the Caribbean. Dengue prevention was a focus of much debate. All in all, the papers and discussions highlighted two causes of uncertainty, anxiety and operational difficulty:

• Building predictive models of the way dengue epidemics break out and spread seems to be particularly difficult because of the recent extension of its range, the variability of the virus and the behavioural particularities of the mosquito vector. To design adequate dengue prevention policy instruments, we must therefore start by establishing the state of the local knowledge in such regions as the Caribbean and the Guyanas.
• Existing control methods require rigorous, precise, decentralised technical and scientific monitoring, but also active participation by at-risk populations, because the vector can breed in small volumes of water such as are commonplace in everyday life.

6The purpose of the survey is to elucidate these points for the public authorities and the population of the FDAs. It was the Département Council of Martinique that first asked the IRD to make a survey. Significantly, all the authorities responsible for health and vector control in the FDAs (the three Département Councils and the national Health Ministry, directly or through its three département-level branches) joined forces to formulate the assignment, despite wide differences in the way tasks and responsibilities are divided in the three départements. This certainly reflects the shared anxieties of a population increasingly affected by a disease whose nature and evolution is poorly understood.

7It was therefore particularly important that the experts working on the survey comply with the IRD's principle for collegial expertise surveys by taking these very practical concerns into account. This they have done, throughout their work and in drawing up their report.

8The topics addressed by the survey were defined in the course of in-depth discussions at an initial workshop held in Fort-de-France in February 2001. The viewpoints expressed and questions raised by some thirty participants representing all the health organisations and institutions of the FDAs were set out and discussed at that meeting. By the end of the meeting's discussions, the 88 questions initially raised by participants had been distilled into eleven specific questions, under five headings (as set out in Appendix 1). These eleven questions, validated by the IRD and the commissioning authorities, constituted in effect the "specifications" for the survey.

9To address these questions, the group held several meetings in Guadeloupe, French Guiana and Martinique. The meetings served to establish the contacts with the authorities and actors in the field that were essential for the experts to assess the environmental, social and health conditions for the spread of the disease or its control – especially as the three départements' . situations differ, in some respects quite sharply.

10It was during these meetings that the experts organised themselves to review all the available scientific literature, to produce the specialist analyses grouped by topic in the second part of this report (on CD-ROM) and to draw the collective conclusions presented in this first part of the report, the printed synopsis.

11The panel consisted of four entomologists, two clinicians, three epidemiologists, a virologist and a sociologist. During the discussions, they were able to appreciate how closely their particular disciplinary approaches complemented each other. Most of the topics addressed involve several fields of knowledge, and this combination of scientific approaches was an original and valuable feature of the exercise.

12The experts focused on the need to explore every facet of a situation -biomedical, environmental, spatial, social etc. – to draw general, operational conclusions. Often stimulated in their own fields by input from the other disciplines, and having themselves tested the importance of full, wide-reaching information, they argue that the public – professionals, social mediators and the populations concerned – should also be provided with full information, issued in appropriate forms but not reduced to prescriptive advice. Because advice will not be followed if it is not backed by explanations that include all the aspects that will enable people to understand the phenomena concerned.

13In writing the report, the experts have made every effort to ensure that it is readable for the layman, without compromising on scientific quality.

14The synopsis is intended for a broad readership. The context – an IRD collegial expertise survey – called for a synopsis intelligible to non-specialists. Furthermore the experts considered that widely-disseminated information and a widely-shared understanding of the process by which dengue is transmitted are to be counted among the tools available for controlling the disease. The panel wished its report to be used not only as a reference base for professionals but also as a useful conceptual instrument for raising public awareness. Public awareness is essential for curbing the spread of the vector, since this will largely depend on changing individual behaviours in everyday activities.

15While not all accessible to the general reader, the chapters in the second part of the report, on CD-ROM, are detailed, rigorous scientific reports on the data and analyses of each of the topics addressed. They present and discuss the currently available knowledge on which the panel's common conclusions are based, providing as exhaustively as possible for further debate. Each chapter closes with a complete bibliography to enable specialist readers to pursue the issues from original sources.

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16One key feature that emerges is the information gaps, sometimes major gaps, in many of the fields concerned. This makes it difficult to design effective prevention measures. The experts emphasize this point and recommend that the necessary steps be taken to fill these knowledge gaps.

17At the end of the synopsis the experts make a series of recommendations based on their conclusions. However, it was not their role to encroach on the decision process that is the preserve of the authorities to whom the report is addressed. It remains, therefore, to make an operational interpretation of the experts' recommendations.

18Nonetheless, the experts considered it their duty to propose applied research to enable actors in the field to fill the information gaps and so improve dengue control in the FDAs. If investigation protocols are drawn up on the basis of these research suggestions, the survey will as it were continue after the delivery of its conclusions.

19On a less technical level, the experts note that any operational use of their report will have to be made in a particularly fragmented institutional setting. Most département-level actions will have to involve several local authorities or decentralised State bodies. Some actions would be most effective if carried out on an inter-département level or by all countries in the sub-region together. The panel of experts is aware that it is difficult to organise coordinated actions under these conditions, but emphasizes that it is desirable in the interests of public health in the FDAs.

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20In this synopsis (first part of the report), we summarize the chapters in the second part (on CD-ROM). The synopsis is divided into five sections covering the topics selected at the end of the initial workshop, and which formed the backbone of the survey specifications. Each topic starts with the questions asked, and the references of the corresponding chapters on the CD-ROM, of which a summary is then given.

21At the end of the synopsis we summarize the experts' conclusions, and list their recommendations.

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22The coordination team would like to thank all the scientists who took part in this survey for the rigour, open-mindedness and fellowship they brought to the work. Without that, and without their helpfulness and willingness to share and compare their knowledge with specialists from other scientific cultures, this multidisciplinary reading of such a large and diverse mass of information would not have been possible.

23We would also like to thank the officials of the Département Councils and the Health Ministry in the three FDAs, the IRD representatives in French Guiana and the Caribbean, and all their staff. They not only made the necessary information and material resources available to the experts, they were also very welcoming, helpful and friendly.

24We are grateful to the IRD's Expertise and Consulting Department and administrative departments for their assistance throughout the survey work.

25We are also grateful to all the readers who reviewed all or part of the papers at various stages of completion and gave the authors the benefit of their valuable advice, comments and corrections. Our warmest thanks in this regard to J.-P. Boutin of the IMTSSA, Marseille; M. Giraud, CNRS, Paris; M.-E. Gruénais, IRD, Marseille; M.-L. Hazebroucq, IRD, Paris; A.-M. Moulin, CNRS, Cairo; B. Murgue, IRD, Paris; and F. Rodhain, Pasteur Institute, Paris.