Session:

Emerging Infectious Diseases

Abstract No.:

46.023

Title:

Chikungunya surveillance on Réunion Island between 2005 and 2011

Author(s):

L. Filleul¹, P. Renault², M. Bâville³, S. Larrieu⁴; ¹French Institute for public health surveillance, Regional office "cire océan Indien", Saint Denis - REUNION/FR, ²Agence régional de santé océan Indien, CVAGS, Saint Denis (La Réunion)/FR, ³Agence régional de santé océan Indien, LAV, Saint Denis (La Réunion)/FR, ⁴Institut de veille sanitaire, Cire océan Indien, Saint Denis/FR

Abstract:

Background: In 2005-2006, Reunion Island was hit by the greatest chikungunya outbreak ever described. A specific surveillance system was set up in order to follow the epidemic. Since the end of the episode, this system is still working and has been evolving. Its objectives are to early detect any case of chikungunya virus infection, and to follow-up the epidemiologic situation.
Methods: During interepidemic periods, surveillance is based on active and exhaustive detection of cases. If an epidemic occurs, weekly incidence is estimated through data from a sentinel doctors network. Surveillance of severe forms and mortality is also performed whatever the epidemiologic situation.
Results: In 2005-2006, the estimated number of chikungunya virus infections diagnosed in general practionners clinics was 266 000, i.e. an attack rate of 34%. A total of 222 severe forms and 44 mother-to-child transmissions were identified. Since the end of the outbreak, two clusters occurred in the west of the island in 2009 and 2010. The second one was non-negligible, since 164 cases were identified, of whom 112 biologically-confirmed. No severe illness or death was reported.
Conclusion: Due the experience of the past few years and the reemergence of chikungunya virus on Réunion Island in 2010 illustrates the permanent threat of circulation of exotic pathogens in the Indian Ocean and the need for strong epidemiologic and laboratory surveillance. Furthermore, Ae. Albopictus mosquitoes have been described as the main vector responsible for transmitting chikungunya virus on Réunion Island, and entomologic surveillance has been reorganized to prevent this risk. According to seven years of surveillance, our surveillance system of chikungunya appeared have good sensitivity and reactivity adapted to detect very early clusters of the disease.