Expansion of spatial and host range of Puumala virus in Sweden: an increasing threat for humans?

Hantaviruses are globally distributed and cause severe human disease. Puumala hantavirus (PUUV) is the most common species in Northern Europe, and the only hantavirus confirmed to circulate in Sweden, restricted to the northern regions of the country. In this study, we aimed to further add to the natural ecology of PUUV in Sweden by investigating prevalence, and spatial and host species infection patterns. Specifically, we wanted to ascertain whether PUUV was present in the natural reservoir, the bank vole (Myodes glareolus) further south than Dalälven river, in south-central Sweden, and whether PUUV can be detected in other rodent species in addition to the natural reservoir. In total, 559 animals were collected at Grimsö (59°43'N; 15°28'E), Sala (59°55'N; 16°36'E) and Bogesund (59°24'N; 18°14'E) in south-central Sweden between May 2013 and November 2014. PUUV ELISA-reactive antibodies were found both in 2013 (22/295) and in 2014 (18/264), and nine samples were confirmed as PUUV-specific by focus reduction neutralization test. Most of the PUUV-specific samples were from the natural host, the bank vole, but also from other rodent hosts, indicating viral spill-over. Finally, we showed that PUUV is present in more highly populated central Sweden.

Development of feeding selectivity and consistency in food choice over 5 years in fallow deer.

In order to better understand the development and maintenance of feeding selectivity, several feeding experiments were performed with fallow deer (Dama dama L.). In experiments performed when the fawns were between ten and 27 days old, it was found that all fawns showed preferences for sucrose but aversions towards tannic acid and ascorbic acid. However, differences in selectivity towards tannic acid were present already before the fawns became functional ruminants and these individual differences lasted 5 years. Moreover, individuals that ingested overall less tannic acid, searched more thoroughly between food sources. When the foraging behaviour was compared with age (11-41 days old and 65-97 days old), it was found that the time a fawn spent eating, increased with age, and the time spent on exploration, smelling and tasting plants decreased with age. Furthermore, the fawns increased their intake of grass and herbs, while the intake of soil and dead plant material decreased with age.