Large number of imported chikungunya cases in mainland France, 2014: a challenge for surveillance and response.

During the summer of 2014, all the pre-requisites for autochthonous transmission of chikungunya virus are present in southern France: a competent vector, Aedes albopictus, and a large number of travellers returning from the French Caribbean islands where an outbreak is occurring. We describe the system implemented for the surveillance of chikungunya and dengue in mainland France. From 2 May to 4 July 2014, there were 126 laboratory-confirmed imported chikungunya cases in mainland France.

Lessons raised by the major 2010 dengue epidemics in the French West Indies.

Dengue fever has been endemo-epidemic in the whole Region of America. In 2010, Guadeloupe and Martinique experienced historical epidemics, with an estimated attack rate of 10% in two islands. When considering the temporal evolution of epidemiological indicators, an unusual increase in the number of dengue cases could be detected very early. Two main factors might have facilitated the settlement of a viral transmission despite the dry season: a low immunity of the population against the circulating serotype and particular climatic conditions, notably very high temperatures which could have improved both virus and vector efficiency. This unusual situation was considered as a warning sign, and indeed led to major outbreaks in both islands a few weeks later. This event underlines that follow-up of epidemiological indicators is necessary to detect the unusual situations as soon as possible. Furthermore, development of biological and modelling tools should be promoted, as well as integrated management strategies for dengue prevention and control.

[Comparison of sentinel surveillance of influenza like infections in Martinique and in Guadeloupe during influenza A(H1N) 2009 pandemic: use of a phone survey and hospital surveillance]. / Comparaison de la surveillance des syndromes grippaux par les réseaux sentinelles en Martinique et en Guadeloupe au cours de la pandémie grippale A(H1N1) 2009 : apports d'une enquête téléphonique en population générale et de la surveillance hospitalière.

BACKGROUND: Sentinel general practitioner networks monitor influenza-like infections (ILI) in Martinique and in Guadeloupe (French West Indies). During the A(H1N1)2009 pandemic, they gave an ILI incidence estimation higher in Martinique than in Guadeloupe. In October 2009, a telephonic survey was launched in both islands to assess the number of ILI diagnoses performed by general practitioners since the beginning of the pandemic. This paper compares the results of sentinel surveillance, of telephonic survey and of hospital surveillance in Guadeloupe and in Martinique. METHODS: On each island, the sentinel network gathers a representative sample of voluntary general practitioners. Each week, they report the number of ILI they diagnosed the past week. Times series of these weekly numbers were modelized using the Serfling method with the upper limit of the confidence interval of the expected value representing the epidemic threshold. The telephone survey was conducted from October 2, 2009 to October 12, 2009 in Martinique and from October 13, 2009 to October 21, 2009 in Guadeloupe. The quota method was used for sampling individuals older than 14 years, leading to 507 interviews in Guadeloupe and 508 in Martinique. RESULTS: The epidemic lasted 12 weeks in both islands, from August 3 to October 25 in Martinique and from August 17 to November 8 in Guadeloupe. During August and September, estimated attack rate in Martinique was 5.52% (CI95: 5.23-5.83) from the sentinel network versus 8.3% (CI95: 6.0-11.0) from the telephone survey. In Guadeloupe, it was 2.13% (CI95: 1.97-2.24) from the sentinel network versus 6.9% (CI95: 4.8-9.5) from the telephone survey. An equivalent number of confirmed hospitalized cases was observed in the two islands. CONCLUSION: These results suggest that the sentinel network underestimates ILI incidence in Guadeloupe. According to Emergency Room activity for ILI, it seems possible that ILI incidence was actually higher in Martinique. A lower proportion of swab sampling among ILI hospitalized people could partly explain the observed differences in hospitalization ratio, in severity and in lethality between the two islands.

[Epidemic of influenza A(H1N1) 2009 in the French overseas territories of the Americas: epidemiological surveillance set up and main results, April 2009-January 2010]. / L'épidémie de grippe A(H1N1) 2009 dans les territoires français des Amériques: dispositif de surveillance mis en place et principaux résultats, avril 2009-janvier 2010.

Guadeloupe, French Guiana, Martinique, St. Martin and St. Barthelemy were the French territories most exposed to the new influenza A(H1N1)v, and adequate epidemiological surveillance tools were promptly developed in order to detect its emergence. The first stage, "containment phase", consisted in detection and management of individual cases. Then, when an autochthonous A(H1N1)v circulation was confirmed, its evolution has been monitored within the whole population, mainly through data collected from sentinel doctors' networks and virological surveillance. This allowed to detect very early the occurrence of epidemics, and to follow their evolution until they were over. Like all the other Caribbean countries, the five French overseas territories were hit by an outbreak of influenza A(H1N1)v. Although they had globally similar characteristics, each epidemic had its specificity in terms of scale and severity. They started between August and September 2009 in four of the five territories, while the last one, St. Barthelemy, was not affected until the end of the year. Attack rate estimates varied from 28 to 70 per 1000 inhabitants according to the territory, and hospitalisation rate varied from 4.3 to 10.3 per 1000 cases. Severity rate didn't reach 1 per 1000 cases in any of the territories. Compared to metropolitan France, the surveillance system presented several strengths, including the pre-existence of both an active sentinel network and an expert committee on emerging diseases in each territory. On the other hand, specific difficulties appeared, notably linked with logistical aspects of virological surveillance and the co-circulation of dengue virus in Guadeloupe and St. Barthelemy. Despite these difficulties, the different tools allowed early detection of the epidemics and follow-up of their evolution. All of them lead to very concordant results, suggesting that they are completely appropriate to monitor a potential new epidemic wave.