Publikationsdatenbank

Fly-based wildlife disease surveillance in remote tropical habitats - two exemplary targeted microorganisms with zoonotic potential: Bacillus cereus biovar anthracis and adenoviruses (2018)

Art

Hochschulschrift

Autor

Hoffmann, Constanze (WE 7)

Quelle

Berlin, 2018 — VI, 155 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/23071

Kontakt

Institut für Mikrobiologie und Tierseuchen

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 51843 / 66949
mikrobiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

The surveillance of wildlife diseases is relevant for three main reasons. First, wildlife diseases constitute a source of human emerging infectious diseases (EIDs); second, wildlife diseases pose a potential threat to livestock; and third, they are of conservation concern. This applies especially to resource-poor areas with high biodiversity (e.g. tropical Africa and Asia). As most wildlife disease surveillance tools available are cost-, time- and resource-intensive, we investigated the feasibility of a fly-based approach for wildlife disease surveillance in resource-poor countries. Two sample pathogens were targeted: Bacillus cereus biovar anthracis (Bcbva), a spore-forming highly pathogenic bacterium causing anthrax, and adenovirus (AdV), a low-pathogenic virus that is generally shed with feces. Studies were performed at different spatial scales with different resolutions and dimensions. On a small scale, an in-depth study of Bcbva over time and space and an initial AdV screening were performed in a remote tropical rainforest (Taï National Park, Côte d’Ivoire). On a large scale, Bcbva screening was implemented at ten sites throughout sub-Saharan Africa. Both pathogens were detectable in flies using molecular methods. Based on the genetic information obtained, phylogenetic analysis revealing the pathogens’ diversity was performed. In the small-scale study, Bcbva was present in 5% of flies (detection by polymerase chain reaction (PCR)) and isolation of viable bacilli was successful. It was shown that Bcbva prevalence varies over time and space: prevalence in flies peaked from December to March and was higher within the research area. Fly meal analysis supported the overall finding that anthrax in the tropics exploits hosts that differ from those in savannah regions. Phylogenetic analysis based on whole fly genomes, as well as carcass and bone samples, showed exceptionally high genetic diversity. It was also shown that flies were more effective than carcass monitoring in detecting anthrax victims. Using flies, three different AdVs (two simian and one murine) circulating in the region were identified. However, prevalence in flies was far below prevalence reported for feces, calling into question the applicability of fly-based surveillance of AdVs. In the large-scale study, a Bcbva screening identified one potential new Bcbva site in Grebo National Forest, Liberia. Surprisingly, flies from two sites where Bcbva had been detected previously all tested negative. Most likely, differences in the fly species collected accounted for the phenomenon. In can be concluded that the feasibility of fly-based wildlife disease surveillance depends on three factors: the nature of the pathogen of interest, the ecosystem studied and the possible availability of alternative surveillance techniques. In the case of Bcbva, the use of flies was highly beneficial. For AdV, other surveillance tools such as fecal sampling might be more efficient. The extent to which this new approach is applicable to other wildlife pathogens remains to be investigated.