Spatial and Seasonal Dynamics of Anopheles Mosquitoes in Saint-Georges de l'Oyapock, French Guiana: Influence of Environmental Factors.

Little is known about the Anopheles fauna of Saint-Georges de l'Oyapock, a persistent malaria-endemic municipality in French Guiana. This study aimed to update the knowledge of local Anopheles diversity, and their ecology and role in malaria transmission. Sampling sessions were implemented between September 2013 and October 2014. Four species were identified from the 3,450 specimens collected: Anopheles darlingi Root, An. braziliensis, An. triannulatus s.l., and An. nuneztovari s.l. Anopheles darlingi was the predominant species. Its involvement in malaria transmission was suspected due to 1) its abundance, 2) the presence of a density peak during the malaria emergence period, and 3) a dynamic correlated with malaria cases observed two months later. Present and past studies show that the influence of environmental conditions on malaria vector dynamics is high, and may vary drastically according to the local context. This supports evidence that control strategies must be designed at fine scales.

[Malaria in France: Mainland and territories]. / Le paludisme en France : métropole et outre-mer.

Malaria, which was eliminated first from Metropolitan France (mainland and Corsica), then in the French West Indies and the Reunion Island during the 20(th) century, remains endemic in two French territories: French Guiana and the Indian Ocean Mayotte island. Despite differences in the dominating plasmodial species and epidemiological patterns, these two territories have achieved marked quantitative improvements (in the reported number of cases and severe cases) thanks to efforts undertaken over the past decade. The situation, however, remains a concern from a qualitative standpoint with the emergence of resistance to antimalarial drugs and logistical and administrative issues which hinder access to treatment. Although malaria was eradicated in Metropolitan France half a century ago, competent vectors remain present in part or all of these territories and can give rise to limited outbreaks.

[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.

[Update on the epidemiology of malaria in French Guiana]. / Situation epidémiologique du paludisme en Guyane.

The last study describing the epidemiology of malaria in French Guiana was published 20 years ago. Yet French Guiana in the Americas along with Mayotte in the Indian Ocean is the only French territory with persisting endemic malaria. The purpose of this study is to provide an update based on official malaria surveillance data as well as on information from hospital records and various field surveys that have been carried out in recent years. Due to recurrent problems in collecting thorough, continuous, and consistent data, exact determination of incidence by plasmodium species has always been difficult in French Guiana. These problems include not only the remote location of endemic areas and intense unpredictable migration patterns but also poor data collection methods that do not always ensure consistency and homogeneity. Another factor hindering thorough collection of conventional epidemiological data is the requirement for rapid effective treatment in remote regions. The overall incidence of malaria in French Guiana appears to have remained stable since the beginning of the decade with an average of 3,920 case reports per year for an incidence rate of 20 per thousand, noting that three fourths of the 206,000 inhabitants of French Guiana live outside of endemic areas. Overall involvement of P. falciparum and P. vivax appears to be equal with P. malariae accounting for only 2.6% of cases. Trends in recent years indicate an increase in the number of cases involving P. vivax especially in the eastern zones, i.e. in the Oyapock focus where annual incidences in children have reached up to 500 per thousand and in the whole region located between Saint Georges and Cayenne. Conversely a decrease in endemic levels has been observed in western areas, especially for P. falciparum in the upper and middle focuses of the Maroni. Most zones now causing problems are located near migration points, particularly in relation with clandestine gold panning activities. In the coastal strip where the three main cities with most of the population are located, most reported cases are imported but local cases may occur. In general local transmission in these areas has been promptly controlled but trends indicate that incidence of these events may be rising. Anopheles darlingi is still recognized as the main vector but its role in transmission is less obvious in eastern areas where increasing evidence suggests that other species may contribute to maintaining endemic levels. These findings indicate that the extensive resources deployed in this French territory (public financing, health care network, public awareness campaigns, and training of health care personnel in diagnosis and treatment of malaria) have helped reduce the number of severe cases in an unfavorable epidemiological setting.