Transmission of arboviral diseases using a multiplexed serological - - PowerPoint PPT Presentation
Transmission of arboviral diseases using a multiplexed serological survey in French Guiana Claude FLAMAND, FETP, PhD Head of epidemiology unit of Institut Pasteur in French Guiana Pasteur International Network Meeting American Region Sa o
Head of epidemiology unit of Institut Pasteur in French Guiana Pasteur International Network Meeting – American Region Sāo Paulo, 3 -5 July 2019
EPIARBO Project
2 Kraemer & al. (ELife, 2015)
vectors vectors
3 vectors vectors
https://www.cdc.gov/chikungunya/geo/index.html
Chikungunya global distribution Zika global distribution
Growing number of major outbreaks of DENV All four DENV serotypes in much global tropical and sub-tropical regions Large outbreak of Chikungunya in the Caraibbean and the Americas in 2013-2014 Large outbreak of Zika virus in the Americas in 2015 Yellow fever in Brazil and Angola in 2016-2017
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Frequent clinical misdiagnosis Transmission dynamics poorly understood True Burden rarely known Outbreak occurence prediction remain difficult Control efforts limited to ressource-intensive vector control activities and difficult to target Low specificity of serosurveys in the context of co-circulation
Substantial asymptomatic infection Changing epidemiology Serological cross-reaction Impact of environmental drivers may vary according to geographical area and spatial scale
French overseas department, South America
Population size : 250,000 inhabitants (~1‰ Brazil)
Amazonian forest complex (3 inhab./km2) Two main inhabited geographical regions
A costal urbanized strip (90% population) Remote and river area along the frontiers
High levels of immigration : ~40% of the population Various ethnic groups
Creoles, European, Brazilians, Marrons, Amerindians,
Chinese,…
Total fertility rate : 3.5 children p. women (6,700 births/year)
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Presence of competent vector : Aedes aegypti Regular major DENV outbreaks (1991 – 2013)
~2-5% of the population (CC)
Recent outbreaks of emergent arbovirus
CHIKV (2014), ZIKV (2016)
No seroprevance data available
Impact of past epidemics Estimating future transmission risks Surveillance system coverage Assessing the impact of prevention strategies
Implementation of an househould serosurvey
Burden of diseases and spatial distribution of viruses
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Epidemiological cross-sectional study
Serum sample : Multiplexed microsphere-based IgG Immunassay (Relative fluorescence intensity)
Age-stratified Modelling approach
Reconstruction of history of circulation and the extent of cross-reactivity
Alphaviruses Flaviviruses
DENV1-DENV4
The example for CHIKV and MAYV
Infection status (MAYV, CHIKV) Titers (in log scale)
(0,0) tM = s0
M + N(0, eM)
tC = s0
C + N(0, eC)
(1,0) tM = s0
M + sM + N(0, eM)
tC = s0
C + sM C tM +
N(0, eC) (0,1) tM = s0
M + sC M tC
+N(0, eM) tC = s0
C + sC + N(0, eC)
(1,1) tM = s0
M + sM +N(0, eM)
tC = s0
C + sC + N(0, eC)
MAYV and CHIK from individual RFI
boosts the RFI for an assay and cross-react with the other assay
circulation using risk factors
Model-based classification vs simple optimized cut-off
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DENV 69.7% [66.2% – 71.0%] High level of infection Small variations in the areas exposed to Aedes aegypti ZIKV 23.1% [19.5% – 27.2%] Large transmission in the most important municipalities North-Western area+ CHIKV 20.3 [17.5% – 22.5%] West Maroni river highly infected North-western area++ Household transmission ++ MAYV 2.7% [ 2.1% – 3.4%] Sylvatic constant transmission Inland and amazonian forest area ++ Male >20 years ++
Determining the level of circulation of priority arboviruses at a country-level in South America Contribution of modelling techniques to assess viral circulation from detailed age-stratified seroprevalence data dealing with cross- reactivity issues Investigating DENV serotype-specific and YF seroprevalence Elucidating spatial differences in risks exploring more determinants
Development opportunity to elaborate new research projects and establish partnerships to improve the understanding of transmission dynamics in South America
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