Kährikkoer (Nyctereutes procyonoides) Eesti looduses zoonooside levitaja ja kiskjana toitumis-, parasitoloogiliste- ja telemeetriauuringute põhjal

Väitekirja elektrooniline versioon ei sisalda publikatsiooneInvasiivsed võõrliigid võivad uude keskkonda sattudes rikkuda kohalike ökosüsteemide tasakaalu ja vähendada looduslikku mitmekesisust. Sageli toovad nad päritolualadelt kaasa uusi haigustekitajaid või aitavad kaasa olemasolevate patogeenide levikule. Kõrge sigimispotentsiaali ning laia toiduspektri tõttu on üheks edukaimaks võõrliigiks Euroopas kährikkoer Nyctereutes procyonoides. Käesoleva töö raames uuriti kährikkoerte toitumist, parasitofaunat ning ruumikasutust, saamaks ülevaadet liigi rollist Eesti looduses. Toitumisuuringu tulemustest selgus, et sügisel ja talvel toituvad Eesti kährikkoerad peamiselt raipest ning söödaplatsidel leiduvast teraviljast ja muust taimsest materjalist. Lisaks leidsime, et kärntõve nakkusega loomad toituvad võrreldes tervete isenditega oluliselt harvem selgrootutest loomadest ning sagedamini raipest. Raadiotelemeetrilise uuringu tulemused näitasid, et erinevalt mujal Euroopas elutsevatest kährikkoertest on Eesti loomade kodupiirkonnad loodusmaastikus pea poole väiksemad võrreldes intensiivselt majandatavate aladega. Samas tuvastasime, et kärntõve nakkusega isendite kodupiirkonna suurus ning päevateekonna pikkus vähenevad haiguse intensiivistudes märkimisväärselt ning enne surma on loomad pea liikumisvõimetud. Võttes kokku Eestis ning mujal Euroopas teostatud uuringute tulemused, võib väita, et elupaigavaliku ja toitumise poolest on kährikkoer oportunist, kes võimalusel eelistab viibida veekogude läheduses. Sellest lähtuvalt võib ta kiskjana sesoonselt ning lokaalselt ohustada veelinde ja kahepaikseid, kuid laiemat ohtu kährikkoer kohalikule faunale ei kujuta. Parasitoloogilise uuringu käigus leiti Eesti kährikkoertel kokku 17 siseparasiiti, neist 9 on zoonootilised ehk võivad nakatada ka inimest. Kõige sagedamini esinenud zoonootilisteks parasiitideks olid inimesel nahakahjustusi tekitav Uncinaria stenocephala ja silmi ning lihaskudet kahjustav Alaria alata. Muuhulgas tuvastasime Eesti kährikkoertel esmakordselt ka eluohtliku alveokokk-paelussi Echinococcus multilocularis nakkuse. Kuna haiguste levik on suuresti seotud nende kandjate asutustihedusega, on oluline hoida kährikkoerte arvukus ning selle tõusu soodustavad tegurid kontrolli all.Invasive alien species may harm biodiversity, alter ecosystem structure and functions, inflict large economic costs and can cause serious problems to human health. Due to its omnivorous diet habits and very high reproductive potential the raccoon dog Nyctereutes procyonoides have become one of the most successful invasive alien mammals in Europe. The main objectives of this thesis were to investigate feeding habits, parasites and space use of raccoon dog to evalute its role in Estonian ecosystem. Our diet study revealed that in autumn and winter period the most important food sources for Estonian raccoon dogs are carrion and anthropogenic plants (e.g. cereals, vegetables, fruit) originating from supplementary feeding sites. Diet comparison of scabied and asymptomatic raccoon dogs showed that infected individuals consumed significantly less invertebrates, but more carrion. Telemetry study revealed that from May to October raccoon dogs inhabiting the natural area have considerably smaller home ranges compared to managed area, which contradicts earlier findings from other parts of Europe. As well, we found that sarcoptic mange has severe impact on raccoon dog space use: during a relatively short period before their death, an abrupt and drastic decline in their home range size and daily covered distances was identified. In conclusion, raccoon dog seems to be a true opportunist in terms of habitat use and feeding habits. They prefer to live in wet habitats, which means that as a predator the species could locally and seasonally harm waterfowl and frogs, but in general raccoon dogs do not pose a threat to local native fauna. Also we recorded that Estonian raccoon dogs harbour at least 17 helminth species. Among nine zoonotic parasites found in raccoon dogs, the fox tapeworm (Echinococcus multilocularis) can be considered the most dangerous to humans. The most prevalent parasite species, which can also occasionally infect humans and cause serious health problems, were Uncinaria stenocephala and Alaria alata. As spread of pathogens is directly correlated with population density of their carriers, it is important to reduce and control the number of raccoon and factors promoting their repro¬duction

First report of highly pathogenic Echinococcus granulosus genotype G1 in dogs in a European urban environment

BACKGROUND: Echinococcus granulosus and E. multilocularis are tapeworm parasites of major medical and veterinary importance, causing cystic and alveolar echinococcosis, respectively. Both diseases are listed among the most severe parasitic diseases in humans, representing 2 of the 17 neglected diseases prioritised by the World Health Organisation. However, little is known about the role of urban animals in transmission of both parasite species. FINDINGS: A sensitive non-invasive genetic method was used to monitor E. granulosus and E. multilocularis infection among dog faecal samples collected from an urban area in Estonia in 2012–13. Out of 181 dog faecal samples analysed, 2.2% tested positive for E. granulosus, determined by sequencing as genotype G1. None of the samples tested positive for E. multilocularis. CONCLUSIONS: We report contamination of an urban environment with highly pathogenic E. granulosus G1 disseminated by dogs, and a potential risk to human health

Home ranges of raccoon dogs in managed and natural areas

<div><p>Knowledge of space use is central to understand animals’ role in ecosystems. The raccoon dog <i>Nyctereutes procyonoides</i> is considered as one of the most influential alien mesopredator species in Europe, having the potential to cause loss of local biodiversity and act as a vector for zoonotic diseases. We collared 12 animals to study their home range and habitat use in two areas with different management regimes in Estonia: in a protected natural area and in an intensively managed area. From May to October raccoon dogs inhabiting the natural area had considerably smaller home ranges compared to the managed area, 193.3ha±37.3SD and 391.9ha±292.9SD, respectively. This result contradicts somewhat earlier findings in other European raccoon dog populations, where the home range sizes in natural areas in summer and autumn period have usually been larger compared to managed areas. In both study areas raccoon dogs preferred watersides, where amphibians and other semi-aquatic prey are abundant, to other habitats available in their home ranges. We also studied movements of a raccoon dog pair in the managed study area in winter period. Due to mild weather conditions during the study period, raccoon dogs changed their resting sites quite often, covering a relatively large 599 ha area from November 2012 to January 2013, indicating the absence of usual winter lethargy during the mild winters.</p></div

Locations of study areas in Estonia.

<p>a) protected natural area in Soomaa National Park (78 ha; 58°25´N, 25°1´E); b) intensively managed area nearby Ilmatsalu borough (103 ha; 58°2´N, 26°32´E).</p

The proportion (%) of different habitat types in Soomaa and Ilmatsalu study areas (Avail) and in 95% fixed kernel home ranges (K95) of raccoon dogs radio-tracked in summer and autumn period.

<p>The proportion (%) of different habitat types in Soomaa and Ilmatsalu study areas (Avail) and in 95% fixed kernel home ranges (K95) of raccoon dogs radio-tracked in summer and autumn period.</p

Sizes of 95% fixed kernel home ranges (K95) and 100% minimum convex polygon (MCP100) areas in hectares for each radio-tracked raccoon dog in Soomaa and in Ilmatsalu study area.

<p>Note that kernel home ranges were not calculated when there were less than 50 location point available for the animal.</p

First report of the zoonotic tapeworm Echinococcus multilocularis in raccoon dogs in Estonia, and comparisons with other countries in Europe.

International audienceThe raccoon dog (Nyctereutes procyonoides) is an alien species in Europe and an important vector of zoonotic diseases. However, compared to the red fox (Vulpes vulpes), less attention has been paid to the raccoon dog as a potentially important host for Echinococcus multilocularis, the infective agent of alveolar echinococcosis, which is an emerging infectious disease with a high mortality rate. We examined the small intestines of 249 Estonian raccoon dogs and found 1.6% of individuals to be infected with E. multilocularis. The relatively large difference between this prevalence and that found in sympatric red foxes (31.5%) sampled during the same time period might be due to differences in diet: red foxes consume significantly more arvicolid rodents - the main intermediate hosts of the parasite - especially during the coldest period of the year when raccoon dogs hibernate. Nonetheless, given the relatively high density of raccoon dogs, our results suggest that the species also represents an important definitive host species for E. multilocularis in Estonia. Compared with other countries in Europe where E. multilocularis-infected raccoon dogs have been recorded (Latvia, Lithuania, Poland, Germany, and Slovakia), the prevalence in Estonia is low. The longer hibernation period of raccoon dogs at higher latitudes may explain this pattern. Both mitochondrial and nuclear loci were analysed for Estonian isolates: based on EmsB microsatellite genotyping the Estonian isolates shared an identical genotype with E. multilocularis in northern Poland, suggesting a common history with this region. The data from more than a quarter of the mitochondrial genome (3558 bp) revealed two novel haplotypes specific to Estonia and placed them into the same haplogroup with isolates from other European regions. Considering that the raccoon dog is becoming increasingly widespread and is already relatively abundant in several countries in Europe, the role of the species must be taken into account when assessing the E. multilocularis related risks to public health

An Invasive Vector of Zoonotic Disease Sustained by Anthropogenic Resources: The Raccoon Dog in Northern Europe

<div><p>The raccoon dog (<i>Nyctereutes procyonoides</i>) is an introduced species in Europe with a continually expanding range. Since the species is capable of affecting local ecosystems and is a vector for a number of severe zoonotic diseases, it is important to understand its food habits. Raccoon dog diet was studied in Estonia by examining the contents of 223 stomach samples collected during the coldest period of the year, August to March, in 2010–2012. The most frequently consumed food categories were anthropogenic plants (e.g. cereals, fruits; FO = 56.1%) and carrion (e.g. carcasses of artiodactyls and carnivores; FO = 48.4%). Carrion was also the only food category that was consumed significantly more frequently by raccoon dogs exhibiting symptoms of sarcoptic mange than by uninfected animals. Small mammals, which represent intermediate hosts for the zoonotic tapeworm <i>Echinococcus multilocularis</i>, were more commonly recorded in samples also containing anthropogenic plants than expected by chance. Comparison of raccoon dog and red fox (<i>Vulpes vulpes</i>) diet in Estonia revealed higher overlap than found elsewhere in Europe, with ‘carrion’ and ‘anthropogenic plants’ making up the bulk of both species’ diet; however, raccoon dogs were more omnivorous than red foxes. Our results suggest that while the use of most food categories reflects the phenology of natural food sources, ‘anthropogenic plants’ and ‘carrion’ provide an essential resource for raccoon dogs during the coldest period of the year, with the latter resource especially important for individuals infected with sarcoptic mange. Since both of these food categories and small mammals are often found at supplementary feeding sites for wild boar (<i>Sus scrofa</i>), this game management practice may facilitate high densities of mesocarnivores and promote the spread of some severe zoonotic diseases, including alveolar echinococcosis, trichinellosis, rabies and sarcoptic mange.</p></div

Frequency of occurrence (FO) of different food items in the stomachs of raccoon dogs uninfected and infected with sarcoptic mange.

<p>Frequency of occurrence (FO) of different food items in the stomachs of raccoon dogs uninfected and infected with sarcoptic mange.</p

Co-occurrence of food items in raccoon dog diet.

<p>Numbers of samples in which a particular food type was recorded is shown in parentheses. Cells below the diagonal show the number of samples in which food types co-occurred. Cells above the diagonal show the standardised C-score (values below zero indicate co-occurrence; values above zero indicate separation). C-scores that deviate significantly from a random null model are shown in bold typeface. PL-A – anthropogenic plants, PL-N – natural plants, BI - birds, SM – small mammals, CA - carrion, AM - amphibians, FI - fish, IN - invertebrates, GA – garbage.</p