Exposure of Wildlife to the Schmallenberg Virus in France (2011-2014): Higher, Faster, Stronger (than Bluetongue)!

The Schmallenberg virus (SBV) has recently emerged in Europe, causing losses to the domestic livestock. A retrospective analysis of serodata was conducted in France for estimating seroprevalence of SBV among six wildlife species from 2011-2012 to 2013-2014, that is during the three vector seasons after the emergence of the SBV in France. Our objective was to quantify the exposure of wildlife to SBV and the potential protective effect of elevation such as previously observed for bluetongue. We also compared the spatiotemporal trends between domestic and wild animals at the level of the departments. We tested 2050 sera using competitive ELISA tests. Individual and population risk factors were further tested using general linear models among 1934 individuals. All populations but one exhibited positive results, seroprevalence up to 30% being observed for all species. The average seroprevalence did not differ between species but ranged from 0 to 90% according to the area and period, due to the dynamic pattern of infection. Seroprevalence was on average higher in the lowlands compared to areas located up to 800 m. Nevertheless, seroprevalence above 50% occurred in areas located up to 1500 m. Thus, contrary to what had been observed for bluetongue during the late 2000s in the same areas, SBV could spread to high altitudes and infect all the studied species. The spatial spread of SBV in wildlife did not fully match with SBV outbreaks reported in the domestic livestock. The mismatch was most obvious in mountainous areas where outbreaks in wildlife occurred on average one year after the peak of congenital cases in livestock. These results suggest a much larger spread and vector capacity for SBV than for bluetongue virus in natural areas. Potential consequences for wildlife dynamics are discussed.

Molecular and biological characteristics of Toxoplasma gondii isolates from wildlife in France.

Toxoplasma gondii isolates have been classified into 3 genetic types. Little is known about genotypes of T. gondii isolates in wild animals in Europe. In this report, genotypes of T. gondii isolates from wildlife in France are described. Sera from wildlife were tested for antibodies to T. gondii with the modified agglutination test, and the hearts from animals with titers superior or equal to 1:6 were bioassayed individually in mice. T.gondii was isolated from 9 of 14 seropositive red foxes (Vulpes vulpes), 12 of 33 roe deer (Capreolus capreolus), 1 of 4 deer (Cervus elaphus), 1 of 7 mouflons (Ovis gmelini musimon) and 1 of 2 common mallards (Anas platyrhynchos). No isolate was obtained by bioassay in mice of 1 fallow deer (Dama dama) and of 3 European brown hares (Lepus europaeus). Genotyping of the 24 isolates using PCR-RFLP and microsatellite markers indicated that all were type II and none of these Toxoplasma isolates was virulent for mice.

Serological and molecular comparison of Mannheimia haemolytica and Pasteurella trehalosi strains isolated from wild and domestic ruminants in the French Alps.

Over a period of 17 years, 84 bacterial isolates identified as Mannheimia haemolytica or M. glucosida, and 52 isolates identified as Pasteurella trehalosi were detected in the lungs of domestic and wild ruminants in the French Alps. The isolates were serotyped according to their surface capsular antigens, and those sharing common antigens were further characterized by pulsed field gel electrophoresis. The results showed that the bacterial isolates included in the study clustered according to the host species from which they were isolated. These findings indicate that the transmission of serotypes of M. haemolytica, M. glucosida or P. trehalosi from an animal host in which they are common to another species sharing the same geographical space may be a rare epidemiological event.