Article

High susceptibility to Chikungunya virus of Aedes aegypti from the French West Indies and French Guiana.

Unité d'entomologie médicale, Institut Pasteur de Guyane, Cayenne, Guyane française.
Tropical Medicine & International Health (Impact Factor: 2.3). 01/2011; 16(1):134-9. DOI: 10.1111/j.1365-3156.2010.02613.x
Source: PubMed

ABSTRACT To estimate the vector competence of Aedes aegypti populations sampled from distinct anthropogenic environments in French Guiana, Guadeloupe and Martinique for the strain CHIKV 06.21.
F(1)/F(2) females were orally infected at titres of 10(6) and 10(7.5) pfu/ml in blood-meals. Disseminated infection rates (DIR) of mosquitoes were estimated using indirect fluorescent antibody assay on heads' squashes, 7 or 14 days post-infection (pi).
At a titre of 10(7.5) pfu/ml, DIR ranged from 88.9% to 100.0% and were not significantly different whether assessed at day 7 or 14 pi. At a titre of 10(6) pfu/ml, DIR observed 7 days pi ranged from 37.6 to 62.0%.
Ae. aegypti from French Guiana and French West Indies are highly competent to transmit CHIKV. An evaluation of DIR 7 days rather than 14 days pi is adequate to estimate vector competence. The titre of 10(6) pfu/ml allows us to distinguish Ae. aegypti populations originating from distinct environments (dense or diffuse housing) by their vector competence. This assessment is a prerequisite to better evaluate the potential risk of Chikungunya outbreaks once the virus is introduced from endemic regions.

Full-text

Available from: Ignace Rakotoarivony, Sep 16, 2014
0 Followers
 · 
253 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Following almost 30 years of relative silence, chikungunya fever reemerged in Kenya in 2004. It subsequently spread to the islands of the Indian Ocean, reaching Southeast Asia in 2006. The virus was first detected in Cambodia in 2011 and a large outbreak occurred in the village of Trapeang Roka Kampong Speu Province in March 2012, in which 44% of the villagers had a recent infection biologically confirmed. The epidemic curve was constructed from the number of biologically-confirmed CHIKV cases per day determined from the date of fever onset, which was self-reported during a data collection campaign conducted in the village after the outbreak. All individuals participating in the campaign had infections confirmed by laboratory analysis, allowing for the identification of asymptomatic cases and those with an unreported date of fever onset. We develop a stochastic model explicitly including such cases, all of whom do not appear on the epidemic curve. We estimate the basic reproduction number of the outbreak to be 6.46 (95% C.I. [6.24, 6.78]). We show that this estimate is particularly sensitive to changes in the biting rate and mosquito longevity. Our model also indicates that the infection was more widespread within the population on the reported epidemic start date. We show that the exclusion of asymptomatic cases and cases with undocumented onset dates can lead to an underestimation of the reproduction number which, in turn, could negatively impact control strategies implemented by public health authorities. We highlight the need for properly documenting newly emerging pathogens in immunologically naive populations and the importance of identifying the route of disease introduction.
    PLoS Neglected Tropical Diseases 09/2014; 8(9):e3120. DOI:10.1371/journal.pntd.0003120 · 4.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed.
    Viruses 11/2014; 6(11):4628-4663. DOI:10.3390/v6114628 · 3.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Given the recent emergence of chikungunya in the Americas, the accuracy of forecasting and prediction of chikungunya transmission potential in the U.S. requires urgent assessment. The La Reunion-associated sub-lineage of chikungunya (with a valine substitution in the envelope protein) was shown to increase viral fitness in the secondary vector, Ae. albopictus. Subsequently, a majority of experimental and modeling efforts focused on this combination of a sub-lineage of the East-Central-South African genotype (ECSA-V) - Ae. albopictus, despite the Asian genotype being the etiologic agent of recent chikungunya outbreaks world-wide. We explore a collection of data to investigate relative transmission efficiencies of the three major genotypes/sub-lineages of chikungunya and found difference in the extrinsic incubation periods to be largely overstated. However, there is strong evidence supporting the role of Ae. albopictus in the expansion of chikungunya that our R0 calculations cannot attribute to fitness increases in one vector over another. This suggests other ecological factors associated with the Ae. albopictus-ECSA-V cycle may drive transmission intensity differences. With the apparent bias in literature, however, we are less prepared to evaluate transmission where Ae. aegypti plays a significant role. Holistic investigations of CHIKV transmission cycle(s) will allow for more complete assessment of transmission risk in areas affected by either or both competent vectors.
    PLoS ONE 10/2014; 9(10):e110538. DOI:10.1371/journal.pone.0110538 · 3.53 Impact Factor