Recent introduction and rapid dissemination of Chikungunya virus and Dengue virus serotype 2 associated with human and mosquito coinfections in Gabon, central Africa.
BACKGROUND
Chikungunya virus (CHIKV) and Dengue virus serotype 2 (DENV-2) were recently introduced in central Africa, along with Aedes albopictus. Simultaneous outbreaks of CHIKV and DENV-2 have subsequently occurred, in Cameroon in 2006 and Gabon in 2007.


METHODS
To study the spread of the 2 viruses, we conducted active surveillance of acute febrile syndromes throughout Gabon between 2007 and 2010. Diagnostic methods included quantitative real-time reverse-transcription polymerase chain reaction, and molecular characterization was based on partial envelope gene sequences.


RESULTS
Between 2007 and 2010, 4287 acutely febrile patients were investigated for CHIKV and DENV-2 infections, of whom 1567 were CHIKV-positive, 376 DENV-2-positive, and 37 coinfected. We diagnosed 153 CHIKV and 11 DENV-2 cases in 2008, and 5 CHIKV and 9 DENV-2 cases in 2009. In 2010, CHIKV and DENV-2 caused a second large simultaneous outbreak. Among 2826 acutely febrile patients examined during this outbreak, 1112 were CHIKV-positive, 288 DENV-2-positive, and 28 coinfected. Mosquitoes were collected near the homes of coinfected patients, and 1 Aedes albopictus specimen was found to be positive for both CHIKV and DENV-2.


CONCLUSIONS
These findings show the rapid dissemination of CHIKV and DENV-2 within a nonimmune population in a tropical African country, probably facilitated by the spread of Aedes albopictus. This has resulted in major simultaneous outbreaks with numerous coinfections in both human and mosquito.
Unité des Maladies Virales Emergentes, Centre International de Recherches Médicales de Franceville, Gabon. melaniecaron.cirmf@gmail.com
Mélanie
M
Caron
Christophe
C
Paupy
Gilda
G
Grard
Pierre
P
Becquart
Illich
I
Mombo
Branly Bikie Bi
BB
Nso
Fabrice
F
Kassa Kassa
Dieudonné
D
Nkoghe
Eric Maurice
EM
Leroy
D000293:Adolescent; D000328:Adult; D000330:Aedes / Q000821:virology*; D000368:Aged; D000369:Aged, 80 and over; D018354:Alphavirus Infections / Q000453:epidemiology* / Q000821:virology; D000818:Animals; D002646:Chikungunya virus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D060085:Coinfection; D003715:Dengue / Q000453:epidemiology* / Q000821:virology; D003716:Dengue Virus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D004196:Disease Outbreaks; D005260:Female; D005681:Gabon / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014759:Viral Envelope Proteins / Q000235:genetics; D055815:Young Adult
D014759:Viral Envelope Proteins