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The recently introduced Aedes albopictus in Tunisia has the potential to transmit chikungunya, dengue and Zika viruses.

ABSTRACT: The mosquito Aedes albopictus was detected for the first time in Tunisia in 2018. With its establishment in the capital city of Tunis, local health authorities fear the introduction of new human arboviral diseases, like what happened in Europe with unexpected local cases of chikungunya, dengue and Zika. Even though this mosquito is competent to transmit the arboviruses mentioned above, the transmission level will vary depending on the couple, mosquito population and virus genotype. Here, we assessed the vector competence of Ae. albopictus Tunisia by experimental infections with chikungunya (CHIKV), dengue (DENV), and Zika (ZIKV) viruses. We found that Ae. albopictus Tunisia was highly competent for CHIKV (transmission efficiency of 25% at 21 post-infection) and to a lesser extent, for ZIKV (8.7%) and DENV (8.3%). Virus was detected in mosquito saliva at day 3 (CHIKV), day 10 (ZIKV) and day 21 (DENV) post-infection. These results suggest that the risk of emergence of chikungunya is the highest imposing a more sustained surveillance to limit Ae. albopictus populations in densely populated urban dwellings and at the entry points of travelers returning from CHIKV-endemic regions.

SUBMITTER: Bohers C

PROVIDER: S-EPMC7556531 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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The recently introduced Aedes albopictus in Tunisia has the potential to transmit chikungunya, dengue and Zika viruses.

Bohers Chloé C Mousson Laurence L Madec Yoann Y Vazeille Marie M Rhim Adel A M'ghirbi Youmna Y Bouattour Ali A Failloux Anna-Bella AB

PLoS neglected tropical diseases 20201002 10

The mosquito Aedes albopictus was detected for the first time in Tunisia in 2018. With its establishment in the capital city of Tunis, local health authorities fear the introduction of new human arboviral diseases, like what happened in Europe with unexpected local cases of chikungunya, dengue and Zika. Even though this mosquito is competent to transmit the arboviruses mentioned above, the transmission level will vary depending on the couple, mosquito population and virus genotype. Here, we asse ...[more]

PMID: 33007002

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Project description:Dengue is a mosquito-borne disease that has been an epidemic in China for many years. Aedes albopictus is the dominant Aedes mosquito species and the main vector of dengue in China. Epidemiologically, dengue mainly occurs in Guangdong Province; it does not occur or rarely occurs in other areas of mainland China. This distribution may be associated with climate, mosquito density, and other factors in different regions; however, the effect of temperature on the vector competence of Ae. albopictus for dengue viruses (DENV) remains unclear. In this study, Ae. albopictus was orally infected with dengue virus 2 (DENV-2) and reared at constant temperatures (18, 23, 28, and 32°C) and a fluctuating temperature (28-23-18°C). The infection status of the midguts, ovaries, and salivary glands of each mosquito was detected by polymerase chain reaction (PCR) at 0, 5, 10, and 15 days post-infection (dpi). DENV-2 RNA copies from positive tissues were quantified by quantitative real time PCR (qRT-PCR). At 18°C, DENV-2 proliferated slowly in the midgut of Ae. albopictus, and the virus could not spread to the salivary glands. At 23 and 28°C, DENV-2 was detected in the ovaries and salivary glands at 10 dpi. The rates of infection, dissemination, population transmission, and DENV-2 copies at 28°C were higher than those at 23°C at any time point. At 32°C, the extrinsic incubation period (EIP) for DENV-2 in Ae. albopictus was only 5 dpi, and the vector competence was the highest among all the temperatures. Compared with 28°C, at 28-23-18°C, the positive rate and the amount of DENV-2 in the salivary glands were significantly lower. Therefore, temperature is an important factor affecting the vector competence of Ae. albopictus for DENV-2. Within the suitable temperature range, the replication of DENV-2 in Ae. albopictus accelerated, and the EIP was shorter with a higher temperature. Our results provide a guide for vector control and an experimental basis for differences in the spatial distribution of dengue cases.

Project description:Background & objectivesThere are reports about the susceptibility of Aedes mosquitoes to ZIKV from various countries, however, no such information is available from Indian sub-continent, although, high level of group cross-reactivity of ZIKV with other flaviviruses has been reported. During outbreak situations, many cases of Dengue (DEN) and Chikungunya (CHIK) are reported. In such scenario, vector mosquitoes are likely to get co-infection/secondary-infection with one or other virus. The present study was carried out to determine the susceptibility of Indian strain of Aedes aegypti to Zika virus (ZIKV) strain (MR-766) and the effect of co-infection/super-infection with either dengue virus (serotype-2) (DENV) or chikungunya virus (CHIKV) on ZIKV replication.MethodsAe. aegypti mosquitoes used in this study were reared for many generations since 1980 at laboratory colony maintained at the ICMR-National Institute of Virology, Pune, India. Transmissibility of ZIKV from infected mosquitoes to suckling mice was also studied. Mosquitoes were experimentally infected with ZIKV and super-infected with either DENV or CHIKV via membrane-feeding route and incubated for 14 days at 28±2°C and humidity of 85±5 per cent. Replication of these viruses in mosquitoes was confirmed using real-time reverse transcription-polymerase chain reaction and immunofluorescence assay. Twenty infected mosquitoes were allowed to feed upon four suckling CD1 mice for about 30 min. Transmission of the ZIKV by infected mosquitoes to suckling mice was confirmed by the appearance of clinical signs and the presence of viral RNA in different organs.ResultsConcomitant infection of mosquitoes with all the three viruses showed simultaneous propagation of all three viruses, confirmed by real time RT-PCR and IFA. Infection of mosquitoes with CHIKV followed by ZIKV showed positivity in individual head squashes (7%) for both viruses using IFA; only 8.3 per cent showed dual positivity with primary infection of ZIKV followed by DENV; 8.3 per cent dual infection positivity was observed when infected with DENV followed by ZIKV; 5 per cent showed dual infection was observed when infected with ZIKV followed by CHIKV. Ae. aegypti was found to be susceptible to ZIKV strain as ZIKV could be detected from the second post-infection day (PID) in infected mosquitoes. Transmission of ZIKV to mice by the bite of infected Ae. aegypti establishes this species as a potential vector.Interpretation & conclusionsFrom super-infection experiments, it was concluded that ZIKV might have a relative advantage in replication dynamics over DENV. Vertical transmission was not observed for ZIKV in experimentally infected mosquitoes (n=920 larvae). Further studies are required to understand the possibility of silently circulating ZIKV in India, which remain non-detected because of lack of surveillance.

Project description:BackgroundAedes albopictus is the secondary vector for dengue virus (DENV) in the Philippines, and also harbors chikungunya (CHIKV) and Zika (ZIKV) viruses. This study aimed to determine the minimum infection rates (MIRs) of CHIKV, DENV serotypes, and ZIKV in Ae. albopictus collected from selected two-site categories by altitude (highland [H] and lowland [L] sites) in Cebu city, Philippines during the wet (WS) and dry seasons (DS) of 2021-2022, and to explore the relationships between these arboviral MIRs and the local weather.MethodsThe viral RNA extracts in pooled and reared adult Ae. albopictus collected during the DS and WS from two-site categories were subjected to RT-PCR to amplify and detect gene loci specific for CHIKV, DENV-1 to DENV-4, and ZIKV and analyzed with the weather data.ResultsThe range of CHIKV MIRs was higher in the WS (13.61-107.38 infected individuals per 1,000 mosquitoes) than in the DS (13.22-44.12), but was similar between the two-site categories. Rainfall (RF) influenced the CHIKV MIR. The MIR ranges of both DENV-2 (WS: H = 0, L = 0; DS: H = 0-5.92; L = 0-2.6) and DENV-4 (WS: H = 0, L = 0-2.90; DS: H = 2.96-6.13, L = 0-15.63) differed by season but not between the two-site categories. Relative humidity (RH), RF, and temperature did not influence DENVs' MIRs. The MIR range of ZIKV was similar in both seasons (WS: 11.36-40.27; DS: 0-46.15) and two-site categories (H = 0-90.91, L = 0-55.56). RH and temperature influenced ZIKV MIR.ConclusionsRF influenced CHIKV MIR in Ae. albopictus, whereas RH and temperature influenced that of ZIKV. Season influenced the MIRs of CHIKV and DENVs but not in ZIKV. Ae. albopictus were co-infected with CHIKV, DENVs, and ZIKV in both highland and lowland sites in Cebu city. Recommendations include all-year-round implementation of the Philippine Department of Health's 4S enhanced strategy and installation of water pipelines in rural highlands for vector and disease control. Our findings are relevant to protect public health in the tropics in this climate change.

Project description:BackgroundAedes aegypti, commonly known as "the yellow fever mosquito", is of great medical concern today primarily as the major vector of dengue, chikungunya and Zika viruses, although yellow fever remains a serious health concern in some regions. The history of Ae. aegypti in Brazil is of particular interest because the country was subjected to a well-documented eradication program during 1940s-1950s. After cessation of the campaign, the mosquito quickly re-established in the early 1970s with several dengue outbreaks reported during the last 30 years. Brazil can be considered the country suffering the most from the yellow fever mosquito, given the high number of dengue, chikungunya and Zika cases reported in the country, after having once been declared "free of Ae. aegypti".Methodology/principal findingsWe used 12 microsatellite markers to infer the genetic structure of Brazilian Ae. aegypti populations, genetic variability, genetic affinities with neighboring geographic areas, and the timing of their arrival and spread. This enabled us to reconstruct their recent history and evaluate whether the reappearance in Brazil was the result of re-invasion from neighboring non-eradicated areas or re-emergence from local refugia surviving the eradication program. Our results indicate a genetic break separating the northern and southern Brazilian Ae. aegypti populations, with further genetic differentiation within each cluster, especially in southern Brazil.Conclusions/significanceBased on our results, re-invasions from non-eradicated regions are the most likely scenario for the reappearance of Ae. aegypti in Brazil. While populations in the northern cluster are likely to have descended from Venezuela populations as early as the 1970s, southern populations seem to have derived more recently from northern Brazilian areas. Possible entry points are also revealed within both southern and northern clusters that could inform strategies to control and monitor this important arbovirus vector.

Dataset Information

The recently introduced Aedes albopictus in Tunisia has the potential to transmit chikungunya, dengue and Zika viruses.

Publications

The recently introduced Aedes albopictus in Tunisia has the potential to transmit chikungunya, dengue and Zika viruses.

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