RESUMEN
The Eurasian lynx (subspecies Lynx lynx carpathicus) was reintroduced to Switzerland in the 1970's. Health monitoring of the reintroduced population started in the late 1980's. Since then, six lynx have been found affected by a myocardial disease. The earliest case was an animal that died after a field anesthesia. Two lynx were found dead, two were euthanized/culled because of disease signs, and one was hit by car. Two had a heart murmur at clinical examination. At necropsy, the first animal showed only lung edema but the other five had cardiomegaly associated with myocardial fibrosis. Three had multisystemic effusions. Histological examination of all six lynx showed mild to severe, multifocal, myocardial interstitial and perivascular fibrosis along with multifocal myocyte degeneration and loss, and replacement fibrosis. Moderate to severe multifocal arteriosclerosis with associated luminal stenosis of the small and medium-sized intramural coronary arteries and the presence of Anitschkow cells was also observed. The heart lesions may have led to sudden death in the first case and to a chronic right-sided heart failure in the remaining. None of the lynx showed lesions or signs suggestive of an acute or subacute infection. Given the common geographic origin of these animals and the severe loss of heterozygocity in this population, a genetic origin of the disease is hypothesized.
RESUMEN
BACKGROUND: In parallel to the increase of wild boar abundance in the past decades, an increase of exposure to the Aujeszky's disease virus (ADV) has been reported in wild boar in several parts of Europe. Since high animal densities have been proposed to be one of the major factors influencing ADV seroprevalence in wild boar populations and wild boar abundance has increased in Switzerland, too, a re-evaluation of the ADV status was required in wild boar in Switzerland. We tested wild boar sera collected from 2008-2013 with a commercial ELISA for antibodies against ADV. To set our data in the European context, we reviewed scientific publications on ADV serosurveys in Europe for two time periods (1995-2007 and 2008-2014). RESULTS: Seven out of 1,228 wild boar sera were positive for antibodies against ADV, resulting in an estimated seroprevalence of 0.57% (95% confidence interval CI: 0.32-0.96%). This is significantly lower than the prevalence of a previous survey in 2004-2005. The literature review revealed that high to very high ADV seroprevalences are reported from Mediterranean and Central-eastern countries. By contrast, an "island" of low to medium seroprevalences is observed in the centre of Europe with few isolated foci of high seroprevalences. We were unable to identify a general temporal trend of ADV seroprevalence at European scale. CONCLUSIONS: The seroprevalence of ADV in wild boar in Switzerland belongs among the lowest documented in Europe. Considering the disparity of seroprevalences in wild boar in Europe, the fact that seroprevalences in Switzerland and other countries have decreased despite increasing wild boar densities and the knowledge that stress leads to the reactivation of latent ADV with subsequent excretion and transmission, we hypothesize that not only animal density but a range of factors leading to stress - such as management - might play a crucial role in the dynamics of ADV infections.
