Rapid assessment of West Nile virus circulation in a German zoo based on honey-baited FTA cards in combination with box gravid traps

Abstract

Background For over a decade, monitoring of West Nile virus (WNV) in Germany has consisted of a bird monitoring programme as well as a mosquito-based surveillance programme employing CO2-baited encephalitis vector surveillance (EVS) traps for mass trapping and screening of mosquitoes. In contrast to the EVS traps, the Reiter/Cummings type box gravid trap collects gravid female mosquitoes, which have already taken a blood meal, increasing the likelihood of being infected with pathogens. The traps can be equipped with a honey-baited Flinders Technology Associates® (FTA) card to encourage sugar feeding by the trapped mosquitoes. FTA cards contain nucleic acid preserving substances, which prevent the degradation of viral RNA in the expectorated mosquito saliva and allows for testing the card for flavivirus RNA. This study aimed to assess the suitability of the method for WNV surveillance in Germany as an alternative to previous methods, which are expensive, time-consuming, and predominantly target host-seeking populations less likely to be infected with WNV. Methods In the Thüringer Zoopark Erfurt, snowy owls (Nyctea scandiaca) and greater flamingos (Phoenicopterus roseus) died of WNV infections in July and August 2020. In response, five Reiter/Cummings type box gravid traps were positioned during the daytime on the 10th, 13th, and 16th of September in five different locations. The FTA cards and mosquitoes in the chamber were collected, kept in a cool chain, and further processed for virus detection using a modified generic flavivirus reverse transcription PCR. Results A total of 15 trappings during September collected a total of 259 female mosquitoes, 97% of which were Culex pipiens sensu lato, as well as 14 honey-baited FTA cards. Eight mosquitoes tested PCR-positive for WNV. Four FTA cards tested PCR-positive for mosquito-borne flaviviruses, two of which were confirmed as WNV, and the remaining two confirmed as Usutu virus. Conclusion The suitability of the FTA cards in preserving viral RNA in the field and rapid turnaround time from collection to result is combined with a simple, cost-effective, and highly specific trapping method to create an arbovirus surveillance system, which circumvents many of the difficulties of previous surveillance programmes that required the analysis of mosquitoes in the laboratory. Graphical Abstract

Nucleic Acid Preservation Card Surveillance Is Effective for Monitoring Arbovirus Transmission on Crocodile Farms and Provides a One Health Benefit to Northern Australia

“…As expected, transmission was most prevalent between January to May which is generally considered the period of peak arbovirus activity. We and others have previously validated FTA TM cards as an effective arbovirus surveillance system for several mosquito-borne viruses in a range of environments and locations [27,30,32,[49][50][51][52]. However, this was the first report of its use to monitor virus transmission in the context of farmed crocodilians and to guide the frequency and timing of mosquito control strategies (e.g., spraying).…”

Vaccination of Zoo Birds against West Nile Virus—A Field Study

“…The trial was conducted from October 2020 to February 2022 and was flanked by mosquito control programs in 2020 and 2021 [ 46 ].…”

“…Furthermore, (iv) WNV was detected in an asymptomatically deceased greater flamingo. In addition to the WNV genome detection in zoo birds, WNV lineage 2 was found in eight mosquitoes and USUV (European lineages) in three mosquitoes trapped in the vicinity of the zoo in September [ 46 ]. At the same time, two male keas and one rainbow lorikeet ( Trichoglossus moluccanus ) showed clinical signs including apathy, beak lock, feather loss, reduced feed intake, and vomiting.…”

“…The birds survived after treatment. In parallel, a natural and biological mosquito control in relevant biotopes was carried out in 2020 by reduction of water retention and using BTI ( Bacillus thuringiensis israelensis ) in open water areas, which was scientifically accomplished by the German Mosquito Control Association (KABS) [ 46 ].…”

Towards environmental detection of Chagas disease vectors and pathogen

“…Flinders Technology Associates (FTA) cards consist of filter paper impregnated with a proprietary chemical mixture that lyses cells, inhibits overgrowth of bacteria and other microorganisms, denatures proteins and immobilises nucleic acids in a matrix, designed for long-term storage at room temperature 40 . In the context of vector-borne diseases, FTA cards have been used for successful preservation of different pathogens, including arboviruses 41 – 44 , Plasmodium falciparum , P. vivax and P. berghei 41 , 45 , 46 , Mansonella ozzardi 47 Theileria pava 48 , Trypanosoma brucei s.l. 49 and T. cruzi 50 , 51 , as well as infected vector species, such as Aedes ( Ae. )…”