Vorkommen von Staupeviren und Zoonoseerregern bei Wildkarnivoren in Thüringen
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Beschreibung
Occurrence of Canine morbillivirus and zoonotic agents in Thuringian wild carnivores
Wildlife can act as a reservoir and vector for numerous pathogens and thereby poses a threat to humans and domestic animals. Environmental changes constantly alter the epidemiologic features of infectious diseases. A risk-based control of epizootic and zoonotic agents in line with the One-Health approach therefore requires the continuous gathering of regional data. From January 2014 to March 2016, the occurrence and distribution of Canine morbillivirus (CDV), Rabies lyssavirus (RABV), Mycobacterium (M.) bovis, Trichinella spp., Echinococcus (E.) multilocularis and Baylisascaris (B.) procyonis was investigated in populations of wild carnivores in central Germany. A convenience sample consisting of 936 red foxes (Vulpes vulpes), 195 raccoons (Procyon lotor), 54 European badgers (Meles meles), 39 beech martens (Martes foina), 4 raccoon dogs (Nyctereutes procyonoides), 1 European polecat (Mustela putorius) and 1 stoat (Mustela erminea) was obtained from all 23 districts of the Free State of Thuringia.
Distemper is one of the most important diseases of wild carnivores worldwide. To detect viral ribonucleic acid (RNA), nucleic acid was extracted from tissue samples with an automated, magnetic bead-based isolation system and then tested in a CDV-specific reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Over a time period of two years, the CDV period prevalence2014/2015 was estimated to be 21.6 % (95 % confidence interval (CI): 19.2 – 24.3 %), without a statistically significant difference between the two years. The detection rate undulated over time, with peaks of significantly increased prevalence in spring. There were also significant regional differences, with the highest probability of a CDV detection occurring in the east of Thuringia and measured period prevalences in the separate districts reaching from 8.3 – 52.4 %, with a median of 22.2 %. Additionally, the level of urbanization was determined as a significant factor: higher CDV prevalences were measured in cities with more than 50 000 inhabitants. Higher population densities of wild carnivores in urban areas lead to an increased, interspecies transmission. Sustained by the widespread red foxes, 90.0 % of all distemper cases were registered in wild canids: the statistically significant highest detection rate of 26.8 % (95 % CI: 24.9 – 29.8 %) was measured in the Canidae family. Furthermore, CDV was detected in 17 raccoons (95 % CI of the period prevalence in Procyonidae: 5.2 – 13.6 %), 9 European badgers and 2 beech martens (95 % CI of the period prevalence in Mustelidae: 6.0 – 20.0 %). The prevalence did not differ between sexes, age groups or the infestation status with endoparasites, but was significantly higher in malnourished animals and wild carnivores that were clinically ill or found dead. Respiratory, nervous and gastrointestinal forms of distemper were noted, cutaneous lesions were of subordinate relevance. Infected animals had more frequently contact to humans, domestic animals or their living space, potentially exposing them to pathogens. Due to the CDV enzootic in Thuringia, the multi-host nature of the disease and high prevalences particularly in urban environments, the vaccination of susceptible pets and zoo animals is of utmost importance.
Lymphatic tissue proved especially eligible for the detection of CDV RNA. Regarding the complex pathogenesis of distemper and the variety of possible forms and courses of the disease, a limited selection of tissue samples can lead to a decrease in sensitivity of diagnostic tests. The concurrent testing of the cerebellum, an epithelial-respiratory pool comprising the eyelid and lung tissue, and a lymphatic-intestinal pool consisting of the Lymphonodi jejunales and tissue of the ileum including Peyer's patches, ensures a sensitive detection of CDV while minimizing cost and effort.
The zoonotic diseases rabies, tuberculosis and trichinosis could not be detected. Thuringia therefore remains officially free of terrestrial rabies. Furthermore, unlike in other European countries, badgers do not act as a M. bovis reservoir in Thuringia and Trichinella spp. do not play a major role as pathogens for indigenous wild carnivores.
The fox tapeworm E. multilocularis and the raccoon roundworm B. procyonis are highly adapted to their definitive hosts but cause life-threatening diseases in dead end or intermediate hosts like humans: alveolar echinococcosis (AE) resp. baylisascariasis in form of visceral, neural or ocular larva migrans. Both helminths are highly prevalent in Thuringia – the two-year period prevalence2014/2015 was estimated to be 43.9 % for E. multilocularis (95 % CI: 40.3 – 47.5 %) in wild canids and 44.4 % (95 % CI: 36.5 – 52.4 %) for B. procyonis in raccoons. The prevalence of both pathogens showed a seasonality, with the significantly highest detection rate in autumn, and was lower in urban areas. While many questions regarding the zoonotic potential of B. procyonis remain unanswered, the data indicates that AE is on the rise in Thuringia.
Autor*in
Timo Jan Siempelkamp
Themen in »Vorkommen von Staupeviren und Zoonoseerregern bei Wildkarnivoren in Thüringen«
Arnivoren Baylisascaris procyonis Canine morbillivirus Echinococcus multilocularis Eingeweide Germany Lymphknoten Lyssavirus Mycobacterium bovis Mycobacterium tuberculosis Komplex Mycobacterium tuberculosis complex Mykobakterium bovis RNA Rabies lyssavirus Rabies lyssavirus