Browsing by Subject "VECTOR COMPETENCE"

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  • Jansen, Stephanie; Heitmann, Anna; Lühken, Renke; Jöst, Hanna; Helms, Michelle; Vapalahti, Olli; Schmidt-Chanasit, Jonas; Tannich, Egbert (2018)
    The invasive mosquito species Aedes japonicus japonicus (Ae. japonicus) is widely distributed in Central Europe and is a known vector of various arboviruses in the laboratory, including flaviviruses such as Japanese Encephalitis virus or West Nile virus. However, the vector competence of Ae. japonicus for the recently emerging Zika virus (ZIKV) has not been determined. Therefore, field-caught Ae. japonicus from Germany were orally infected with ZIKV and incubated at 21, 24, or 27 degrees C to evaluate the vector competence under climate conditions representative of the temperate regions (21 degrees C) in the species' main distribution area in Europe and of Mediterranean regions (27 degrees C). Aedes japonicus was susceptible to ZIKV at all temperatures, showing infection rates between 10.0% (21 degrees C) and 66.7% (27 degrees C). However, virus transmission was detected exclusively at 27 degrees C with a transmission rate of 14.3% and a transmission efficiency of 9.5%. Taking into account the present distribution of Ae. japonicus in the temperate regions of Central Europe, the risk of ZIKV transmission by the studied Ae. japonicus population in Central Europe has to be considered as low. Nevertheless, due to the species' vector competence for ZIKV and other mosquito-borne viruses, in combination with the possibility of further spread to Mediterranean regions, Ae. japonicus must be kept in mind as a potential vector of pathogens inside and outside of Europe.
  • EFSA Panel Anim Hlth Welf AHAW; Nielsen, Soren Saxmose (2020)
    Rift Valley fever (RVF) is a vector-borne disease transmitted by different mosquito species, especially Aedes and Culex genus, to animals and humans. In November 2018, RVF re-emerged in Mayotte (France) after 11 years. Up to the end of October 2019, 126 outbreaks in animals and 143 human cases were reported. RVF mortality was 0.01%, and the number of abortions reported in polymerase chain reaction (PCR)-positive ruminants was fivefold greater than the previous 7 years. Milk loss production in 2019 compared to 2015-2018 was estimated to be 18%, corresponding to an economic loss of around Euro191,000 in all of Mayotte. The tropical climate in Mayotte provides conditions for the presence of mosquitoes during the whole year, and illegal introductions of animals represent a continuous risk of (re)introduction of RVF. The probability of RVF virus (RVFV) persisting in Mayotte for 5 or more years was estimated to be <10% but could be much lower if vertical transmission in vectors does not occur. Persistence of RVF by vertical transmission in Mayotte and Reunion appears to be of minor relevance compared to other pathways of re-introduction (i.e. animal movement). However, there is a high uncertainty since there is limited information about the vertical transmission of some of the major species of vectors of RVFV in Mayotte and Reunion. The only identified pathways for the risk of spread of RVF from Mayotte to other countries were by infected vectors transported in airplanes or by wind currents. For the former, the risk of introduction of RVF to continental France was estimated to 4 x 10(-6) epidemic per year (median value; 95% CI: 2 x 10(-8); 0.0007), and 0.001 epidemic per year to Reunion (95% CI: 4 x 10(-6); 0.16). For the latter pathway, mosquitoes dispersing on the wind from Mayotte between January and April 2019 could have reached the Comoros Islands, Madagascar, Mozambique and, possibly, Tanzania. However, these countries are already endemic for RVF, and an incursion of RVFV-infected mosquitoes would have negligible impact. (c) 2020 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.