Population dynamics, pathogen detection and insecticide resistance of mosquito and sand fly in refugee camps, Greece

Abstract

Background: As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece. Displaced populations, travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease (VBD). This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present, in light of designing effective and efficient context specific vector and disease control programs. Methods: A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece. Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control (CDC) light traps and oviposition traps. Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition, population dynamics, pathogen infection rates, and insecticide resistance status in the major vector species. Results: Important disease vectors including Anopheles sacharovi, Culex pipiens, Aedes albopictus and the Leishmania vectors Phlebotomus neglectus, P. perfiliewi and P. tobbi were recorded in the study refugee camps. No mosquito pathogens (Plasmodium parasites, flaviviruses) were detected in the analysed samples yet high sand fly Leishmania infection rates are reported. Culex pipiens mosquitoes displayed relatively high knock down resistance (kdr) mutation allelic frequencies (ranging from 41.0 to 63.3%) while kdr mutations were also detected in Ae. albopictus populations, but not in Anopheles and sand fly specimens. No diflubenzuron (DFB) mutations were detected in any of the mosquito species analysed. Conclusions: Important disease vectors and pathogens in vectors (Leishmania spp.) were recorded in the refugee camps indicating a situational risk factor for disease transmission. The Cx. pipiens and Ae. albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings. In contrast, pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx. pipiens and Ae. albopictus larvicide applications. Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.

Bioassay and molecular monitoring of insecticide resistance status in Aedes albopictus populations from Greece, to support evidence-based vector control

“…Study localities, sample collections and mosquito handling Adult and immature stage Ae. albopictus mosquitoes were collected during the summer of 2017, 2018 and 2019, in a total of 19 urban and peri-urban localities in Greece, in the regions of Thessaloniki [33] and Rodopi (Northern Greece), Attica and Argolida (Central Greece), the Island of Chios (North Eastern Aegean Islands complex) [33], Patras and Kalamata (Western Greece), the Island of Kefalonia (Ionian Islands complex) and Crete (Chania, Rethymno and Heraklion-Southern Greece) ( Fig.1, Table 1). The localities we selected to include in the analysis were chosen based on: their geographical location (in order to cover a large geographical area of Greece), the history of insecticide applications, previous insecticide resistance ndings in other mosquito species and the availability of Ae.…”

“…Samples from Diavata, Lagkadikia and Souda refugee camps were collected and analysed in Fotakis et al, 2020 [33].…”

“…Results are presented cumulatively for the different sampling localities in each region, except for Thessaloniki. ¥: Samples from Diavata and Lagkadikia refugee camps (Thessaloniki) and Chios were analysed in Fotakis et al, 2020[33]. V: 1016V susceptible allele.…”

Phenotypic and molecular analysis of insecticide resistance in Aedes albopictus populations from Greece

“…Adults and immature stages of Ae. albopictus were collected during the summer of 2017, 2018 and 2019, in a total of 19 urban and peri-urban localities in Greece, in the regions of Thessaloniki [32] and Rodopi (Northern Greece), Attica and Argolida (Central Greece), the Island of Chios (North Eastern Aegean Islands complex) [32], Patra and Kalamata (Western Greece), the Island of Kefalonia (Ionian Islands complex) and Crete (Chania, Rethymno and Heraklion-Southern Greece) ( Table 1).…”

Structure-guided paradigm shifts in flavivirus assembly and maturation mechanisms

“…Efforts to combat the spread of most flaviviruses have been limited to simple contact prevention measures, with mosquito netting and protective clothing initiatives being the most widely utilized tactics. Unfortunately, with the increased restriction of pesticide use in developing countries, as well as an increase in mosquito resistance to available pesticides, efforts to control the spread of flavivirus vectors has been diminishing over the last 30 years, and with it an increase in flavivirus infections has been observed ( Fotakis et al, 2020 ; Wang et al, 2013 ). While YFV and JEV can both be effectively combatted through vaccination, there are no vaccines for WNV or ZIKV, and the single available DENV vaccine (from Sanofi Pasteur) has recently demonstrated untoward side effects through ADE, limiting its use and global acceptance ( Barrows et al, 2018 ) .…”