Prevalence of Angiostrongylus vasorum, Aelurostrongylus abstrusus and Crenosoma vulpis larvae in native slug populations in Germany

Metastrongyloid parasites represent sparsely studied parasites of dogs and cats in Germany. Recent European surveys indicate that these parasites are spreading in Europe. Actual data on prevalence of Angiostrongylus vasorwn in dogs and foxes reveal several endemic foci in Germany. However, actual data on the prevalence of A. vasorum and other metastrongyloid lungworm larvae in a wide range of slug and snail intermediate hosts, such as Anion lusitanicus, are missing for Germany. To fill this gap, we conducted an epidemiological survey on native German slugs in selected regions of Hesse and Rhineland-Palatinate. The focus was on slugs, because in study areas slugs appear to be more abundant than snails. Slugs were collected throughout different seasons of the year in areas that were previously proven to be hyperendemic for A. vasorum fox infections. Overall, a total of 2701 slugs were collected and examined for lungworm larvae via artificial digestion. The number of A. vasorum larvae per slug varied considerably (1-546 larvae per specimen). Some hotspot areas with high A. vasorum prevalence in slugs (up to 19.4%) were identified. The overall A. vasorum prevalence varied with season with largest number of slugs infected in summer (9.1%) and lowest number in winter (0.8%). The current study revealed a total A. vasorum prevalence of 4.7% in slugs based on microscopic analyses. Confirmation of lungworm species was made by specific duplex-real-time PCRs. Hence, these data demonstrate that final hosts are at a permanent risk for A. vasorum infections during all seasons when living in investigated areas. Besides A. vasorum, other lungworm larvae were also detected, such as Crenosoma vulpis (the fox lungworm, 2.3%) and Aelurostrongylus abstrusus (feline lungworm, 0.2%).