Refine
Year of publication
- 2023 (1)
Document Type
- Doctoral Thesis (1)
Language
- English (1) (remove)
Has Fulltext
- yes (1)
Is part of the Bibliography
- no (1)
Keywords
- aviäre Influenza (1) (remove)
Institute
Until today, more than 100 years after its first description in Italy, the highly pathogenic avian influenza virus (HPAIV) has not lost its fearsome character for wild birds, poultry and humans. On the contrary, the number of outbreaks with high casualty rates in wild birds and poultry has multiplied in recent years and cases of zoonotic infections are also increasingly reported from HPAI endemic areas. The epidemiology of these infections is complex and also involves surface water and possibly sediments of shallow standing waters, which could play a role as a vector medium and/or virus reservoir. The goal of this project was to expand current knowledge of the influence of water on the spread of AIV. As part of this project, we were able to ...
1. ...improve AIV detection methods using real time RT-PCR in terms of sensitivity and breadth of viruses detected. In addition, we succeeded in economizing the procedure so that fewer resources are required and results are obtained faster (publication I: [173]).
2. ...develop an ultrafiltration-based enrichment method for AIV from surface water and evaluate it with field samples from HPAI outbreak areas in wild bird habitats (Wadden Sea coast of Schleswig-Holstein) and previously unaffected regions (Antarctic Weddell Sea) (publication II: [174]). Furthermore, protocols for testing different environmental sample matrices for AIV screening were tested and compared to results of passive monitoring by dabbing diseased or dead wild birds. AIV was detected in more than half (61%) of 44 water samples. We received additional sediment samples from 36 of the 44 water samples. In 18 of 36 of the sediments tested, as well as in 4.16% of 1705 fecal samples tested AIV was detected. However, the studies of the environmental samples mostly yielded only generic AIV detections, with viral loads in the range of the detection limit. This massively hampered further investigations for sub- and pathotyping. In contrast, 79.41% of 68 samples from passive monitoring showed high to very high HPAIV viral loads which also allowed sub- and pathotyping.
3. ...demonstrate in animal experiments that even very low titers (0.1 TCID50 ml-1) of HPAI viral infectivity in water can induce productive infection in susceptible but clinically largely resistant mallard ducks (publication III: [175]). Furthermore, we were able to develop evidence that there is a difference in virus spread that depends on the type of (contaminated) water source. This means that infections on poultry farms with inverted or nipple drinkers may follow a different course than infections in the wild, which are mediated via larger surface waters.
Overall, the results of this project highlight the important role of surface and drinking water, as well as aquatic sediments, in the spread of AIV. The methods developed here for AIV detection extend the possibilities for surveillance of AIV infections; however, passive remains superior to active surveillance of HPAIV infections in several aspects. Examination of various environmental samples did not yield a significant advantage in terms of an early warning system that would indicate the presence or spread of HPAIV in wild bird habitats prior to the occurrence of lethal infections in wild birds.