P. Renault

Epidemiology of chikungunya infection on Reunion Island, Mayotte, and neighboring countries

Since 2004, the frequency of chikungunya virus infections has been increasing in Africa, Indian Ocean islands, and Asia. The epidemic began on the Kenyan coast, and reached the Comoros at the end of 2004 before spreading to the South-western Indian Ocean islands (SWIOI) in 2005 and especially in 2006. The epidemic then spread to Asia where epidemic foci are still active today. This increase also affected temperate zone countries where imported cases were reported, and indigenous transmission was reported in Italy in 2007, and in France (Var) in 2010. This review provides an update on the knowledge gained from monitoring chikungunya infections in SWIOI. Despite significant differences in design and performance, the implementation of surveillance systems has allowed describing the evolution of epidemic waves in the affected areas. Synchronous epidemic waves were observed in SWIOI, despite the differences between the preventive measures locally implemented. Between 2005 and 2007, all SWIOI were in inter-epidemic situation, except for Madagascar where a persistent virus circulation in an endemic-epidemic pattern was observed. In 2009, and in 2010, two moderate indigenous outbreaks were identified on the Reunion Island by the inter-epidemic surveillance system. Strains analyses demonstrated a reintroduction of the virus from Madagascar. These limited outbreaks should be a reminder of the vulnerability of SWIOI to arbovirosis, since the entomological indexes for competent vectors are high and the virus keeps on circulating more or less actively in the area.

Malaria imported into Réunion Island: is there a risk of re-emergence of the disease?

After a long period of endemicity until the 1950s, the World Health Organization considered autochthonous malaria eliminated from Réunion in 1979. To prevent secondary transmission and re-emergence of autochthonous malaria, permanent epidemiologic and entomological surveillance and vector control measures are conducted. The objective of this study is to report sociodemographic characteristics of imported malaria patients and incidence rates from 2003-2008 using mandatory notification with the aim of identifying risk groups and destinations. During this period, 684 imported malaria cases were reported. Median age of patients was 34.4 years and 22.1% were children </= 15 years. Men represented 67.7% of cases and 59.1% of patients reported having taken chemoprophylaxis based on chloroquine alone. Incidence of malaria was considerably different by country destination. For Comoros, incidence was stable and high during the period accounting for 1481 cases per 100000 travels in 2008. The rate was lower for travels to Madagascar, South Africa and Mayotte and decreased over the period to 37, 19 and 3 per 100000 respectively, by 2008. To avoid re-emergence of malaria on the island and to protect themselves, travelers should reduce their risks of acquisition and importation of parasites by using adequate preventive measures. A special preventive program and social mobilisation should be a priority, essentially for the Comorian community in Réunion.

Surveillance épidémiologique de la leptospirose à la Réunion, 2004–2008: possible impact de l’épidémie de chikungunya sur la létalité de la leptospirose

In 2006, increased mortality due to leptospirosis in Reunion Island had alerted the authorities and justified the conduct of this study in order to update knowledge on the epidemiology of leptospirosis, whereas the latest epidemiological data published on the disease dated back to 2003. This study followed the scheme of a descriptive retrospective survey based on data from reporting and investigation of hospitalized cases of leptospirosis that occurred in Reunion between the 1st January 2004 and 31st December 2008. Data from the National Reference Center (NRC) have also been used. The annual number of reported cases (40 to 50) was stable over the period, which contrasted with the historical decreasing trend of incidence reported by the NRC. The circumstances of exposure were those usually associated with the disease on the island: about 80% of cases were infected between January and June, during the wet season; the main exposure factor identified was the practice of agriculture, declared or not; Leptospira icterohaemorrhagiae remained the most frequently isolated serovar, although regressing. Finally, our study has shown that excess mortality observed in 2006 did not result from an increased incidence but from a rise in the case fatality rate. This could be linked to the outbreak of chikungunya, which peaked in February 2006. In endemic areas of leptospirosis, health professionals should remain aware of the risk of occurrence of fatal cases during arbovirosis outbreaks.

Epidemiological surveillance of leptospirosis on Reunion Island in 2004-2008: possible impact of chikungunya infection on the case fatality rate of leptospirosis

In 2006, increased mortality due to leptospirosis in Reunion Island had alerted the authorities and justified the conduct of this study in order to update knowledge on the epidemiology of leptospirosis, whereas the latest epidemiological data published on the disease dated back to 2003. This study followed the scheme of a descriptive retrospective survey based on data from reporting and investigation of hospitalized cases of leptospirosis that occurred in Reunion between the 1st January 2004 and 31st December 2008. Data from the National Reference Center (NRC) have also been used. The annual number of reported cases (40 to 50) was stable over the period, which contrasted with the historical decreasing trend of incidence reported by the NRC. The circumstances of exposure were those usually associated with the disease on the island: about 80% of cases were infected between January and June, during the wet season; the main exposure factor identified was the practice of agriculture, declared or not; Leptospira icterohaemorrhagiae remained the most frequently isolated serovar, although regressing. Finally, our study has shown that excess mortality observed in 2006 did not result from an increased incidence but from a rise in the case fatality rate. This could be linked to the outbreak of chikungunya, which peaked in February 2006. In endemic areas of leptospirosis, health professionals should remain aware of the risk of occurrence of fatal cases during arbovirosis outbreaks.

Dengue à la Réunion et dans les îles du sud-ouest de l’océan Indien

South Western islands of the Indian Ocean are permanently threatened by dengue fever outbreaks. On the Reunion Island, two dengue outbreaks were biologically documented (1977-1978 and 2004). And since July 2004 there has been an inter-epidemic period for the island with sporadic cases and clusters. Between January 1, 2007 and October 5, 2009, the epidemiologic surveillance system detected five confirmed autochthonous cases, five confirmed imported cases (South-East Asia), and 71 probable cases. All the five autochthonous confirmed cases occurred in Saint-Louis during two consecutive clusters. In other South Western islands of the Indian Ocean, several dengue fever outbreaks have been reported. Importation of dengue virus from South-East Asia is a major risk for a new outbreak on the island. The introduction of a new serotype could lead to the emergence of new and severe clinical forms, including dengue hemorrhagic fever.

[Epidemic of influenza A(H1N1) 2009 in Reunion Island: epidemiological data].

In Reunion Island, a French subtropical island located in the southern hemisphere, the monitoring of the epidemiological dynamics of the epidemic linked to the emergence of pandemic virus A(H1N1) 2009 was achieved through the regular influenza surveillance system which has been reinforced on that occasion. It was mainly based on a network of sentinel physicians, combined with virologic monitoring, and on surveillance of severe cases and deaths. The data were analyzed and retroinformation was distributed according to a weekly frequency. The first imported case was confirmed on July 5, 2009 in a traveler arriving from Australia, whereas the first autochthonous cases were reported on July 23. The epidemic peak was reached in five weeks and the duration of the whole epidemic episode was 9 weeks. Pandemic virus has quickly supplanted seasonal viruses that had begun to circulate. The estimated attack rate for symptomatic cases of infection with virus influenza A(H1N1) 2009 was 12.85%. The hospitalization rate was 32 per 10,000 estimated cases, and 24 people had a serious form requiring care in ICU. Among death certificates received at the regional office for health and social affairs, 14 mentioned the influenza, including 7 in whom the pandemic virus has been laboratory confirmed. These deaths occurred in patients significantly younger than usually observed in Reunion Island during the seasonal influenza epidemics. Overall, the epidemic intensity and severity have been similar to those of seasonal influenza in Reunion Island.

L’épidémie de grippe à virus A(H1N1) 2009 à la Réunion: données épidémiologiques@@@Epidemic of influenza A(H1N1) 2009 in Reunion Island: epidemiological data

In Reunion Island, a French subtropical island located in the southern hemisphere, the monitoring of the epidemiological dynamics of the epidemic linked to the emergence of pandemic virus A(H1N1) 2009 was achieved through the regular influenza surveillance system which has been reinforced on that occasion. It was mainly based on a network of sentinel physicians, combined with virologic monitoring, and on surveillance of severe cases and deaths. The data were analyzed and retroinformation was distributed according to a weekly frequency. The first imported case was confirmed on July 5, 2009 in a traveler arriving from Australia, whereas the first autochthonous cases were reported on July 23. The epidemic peak was reached in five weeks and the duration of the whole epidemic episode was 9 weeks. Pandemic virus has quickly supplanted seasonal viruses that had begun to circulate. The estimated attack rate for symptomatic cases of infection with virus influenza A(H1N1) 2009 was 12.85%. The hospitalization rate was 32 per 10,000 estimated cases, and 24 people had a serious form requiring care in ICU. Among death certificates received at the regional office for health and social affairs, 14 mentioned the influenza, including 7 in whom the pandemic virus has been laboratory confirmed. These deaths occurred in patients significantly younger than usually observed in Reunion Island during the seasonal influenza epidemics. Overall, the epidemic intensity and severity have been similar to those of seasonal influenza in Reunion Island.

Surveillance épidémiologique de la leptospirose à la Réunion, 2004–2008: possible impact de l’épidémie de chikungunya sur la létalité de la leptospirose@@@Epidemiological surveillance of leptospirosis on Reunion Island in 2004–2008: possible impact of chikungunya infection on the case fatality rate of leptospirosis

In 2006, increased mortality due to leptospirosis in Reunion Island had alerted the authorities and justified the conduct of this study in order to update knowledge on the epidemiology of leptospirosis, whereas the latest epidemiological data published on the disease dated back to 2003. This study followed the scheme of a descriptive retrospective survey based on data from reporting and investigation of hospitalized cases of leptospirosis that occurred in Reunion between the 1st January 2004 and 31st December 2008. Data from the National Reference Center (NRC) have also been used. The annual number of reported cases (40 to 50) was stable over the period, which contrasted with the historical decreasing trend of incidence reported by the NRC. The circumstances of exposure were those usually associated with the disease on the island: about 80% of cases were infected between January and June, during the wet season; the main exposure factor identified was the practice of agriculture, declared or not; Leptospira icterohaemorrhagiae remained the most frequently isolated serovar, although regressing. Finally, our study has shown that excess mortality observed in 2006 did not result from an increased incidence but from a rise in the case fatality rate. This could be linked to the outbreak of chikungunya, which peaked in February 2006. In endemic areas of leptospirosis, health professionals should remain aware of the risk of occurrence of fatal cases during arbovirosis outbreaks.

COL7-04 Paludisme d’importation à la Réunion (2003-2007) et risque de réémergence de cas autochtone

Objectif L’eradication du paludisme a La Reunion etait declaree en 1979. Ce travail devait evaluer le risque de reemergence de cas autochtone par l’analyse des donnees epidemiologiques (declarations obligatoires 2003-2007) et entomologiques (releves d’indices d’ Anopheles arabiensis depuis 1985). Resultats Entre 2003 et 2007, 619 cas de paludisme d’importation ont ete notifies (163 en 2003, 76 en 2007). L’âge median des patients etait de 34 ans et le sex-ratio H/F de 2. La moitie des patients etaient immigrants de 1 re generation et 47,8 % etaient nes dans une zone d’endemie palustre (Madagascar, Comores ou Mayotte). Plasmodium falciparum etait responsable de 84,3 % des acces. Les pays de contamination etaient Madagascar dans 40,5 % des cas, les Comores ou Mayotte dans 29 %, et un autre pays africain dans 6,1 % des cas. Aucune chimioprophylaxie n’a ete suivie dans 45,2 % des cas. Le delai median entre le retour de la zone endemique et le diagnostic etait de 11 jours. Plus de la moitie des cas (59,4 %) ont ete hospitalises et 4 deces ont ete signales. Conclusion La presence et l’extension geographique d’ Anopheles arabiensis et l’importation de Plasmodium via des voyageurs en provenance de pays impaludes impose une surveillance entomologique et epidemiologique renforcee pour prevenir la reemergence de cette maladie a La Reunion. L’existence de gites naturels dans l’Est proche de zones residentielles (zone des 2 derniers cas autochtones) et la future creation de zones irriguees dans l’Ouest ou la proliferation vectorielle est continue toute l’annee montre que le risque de cas autochtone secondaire est toujours bien reel.