Echinococcus multilocularis and other zoonotic parasites in Estonian canids
Date
2016-05-09
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Abstract
Zoonootilised parasiidid on jätkuvalt ohuks inimeste tervisele mitte ainult arengumaades vaid ka mujal, sh. Euroopa riikides. Inimene võib selliste haigustekitajatega nakatuda otsese kokkupuute teel nakatunud loomaga või tarbides parasiidi nakkusvõimeliste arengujärkudega saastunud vett ja toiduaineid. Kõige ohtlikumaks loomadelt inimestele kanduvaks parasiidiks võib pidada alveokokk-paelussi (Echinococcus multilocularis), kelle lõpp-peremeesteks on Euroopas põhiliselt punarebane ja väiksemal määral ka kährikkoer, kuid nakatuda võivad ka koerad ja kassid. Euroopas viimastel aastakümnetel järsult tõusnud arvukuse tõttu on rebased asunud elama ka inimasulatesse, tuues sinna kaasa ohtlikud parasiidid. Käesoleva töö peamiseks eesmärgiks oli uurida alveokokk-paelussi esinemist Eesti koerlastel nii linnas kui maal. Lisaks uurisime rebaste ja kährikkoerte üldist parasitofaunat. Linnaloomade uurimiseks töötasime välja uue väga tundliku mitte-invasiivse molekulaarse meetodi, mis võimaldab määrata nii peremehe kui ka ehhinokoki liigi väljaheiteproovist. Tulemustest selgus, et kuigi rebaste ja kährikkoerte üldine parasitofauna on paljuski sarnane, siis inimesele eluohtliku alveokokk-paelussi nakkus oli rebastel oluliselt kõrgem (31,5 %) kui kährikkoertel (1,6 %), kellel diagnoositi see paeluss Eestis esmakordselt. Ligi 20-kordne erinevus kahe peremehe nakatumises on tingitud nende erinevatest toidueelistustest, eelkõige nende võimest püüda närilisi, kes on alveokokk-paelussi vaheperemeesteks. Tartu linnast korjatud väljaheiteproovide analüüsil uue metoodikaga leidsime, et 7,1 % rebaseproovidest olid nakatunud alveokokk-paelussi munadega. Koeraproovide analüüs näitas, et neist 2,2 % oli nakatunud sama perekonna teise inimestki nakatava liigi, põistang-paelussiga (E. granulosus). Kokkuvõttes võib öelda, et oma kõrge arvukuse tõttu võib nii rebaseid kui ka kährikkoeri pidada olulisteks zoonootiliste parasiitide levitajateks Eestis.
Zoonotic parasites are still a threat to public health not only in developing countries, but also in industrialised countries including Europe. In general, humans can acquire such parasites from a direct contact with an infected animal or by consuming water and foodstuffs contaminated with the infective stages of a parasite. The most dangerous parasite that can be transmitted from animals to humans is Echinococcus multilocularis. In Europe, the red fox and to a lesser extent also the raccoon dog are the main definitive host species for this cestode. However, adult worms can additionally develop in domestic dogs and cats. In Europe, during the last decades the number of red foxes has increased rapidly and they have colonised urban areas, bringing along their zoonotic pathogens. The main aim of the thesis was to study the prevalence of E. multilocularis among Estonian canids in both rural and urban areas. In addition, we studied the general parasite fauna of red foxes and raccoon dogs. In order to study urban canids new highly sensitive non-invasive molecular method that can identify both host and Echinococcus species from faecal samples was developed. Although the general parasite fauna of rural foxes and raccoon dogs is very similar, infection with life-threatening E. multilocularis was significantly higher in red foxes (31.5 %) compared to raccoon dogs (1.6 %), in which the cestode was reported for the first time in Estonia. The almost 20-fold difference in prevalence between the two host species can be explained by the difference in food preferences, especially their ability to capture rodents that serve as the main intermediate host for E. multilocularis. Analyses of faecal samples collected from urban areas in Tartu showed that 7.1 % of fox samples tested positive for E. multilocularis and 2.2 % of dog samples tested positive for E. granulosus, another zoonotic species from the genus Echinococcus. In conclusion, due to the high number of red foxes and raccoon dogs, both canid species can be considered as important sources of zoonotic parasites in Estonia.
Zoonotic parasites are still a threat to public health not only in developing countries, but also in industrialised countries including Europe. In general, humans can acquire such parasites from a direct contact with an infected animal or by consuming water and foodstuffs contaminated with the infective stages of a parasite. The most dangerous parasite that can be transmitted from animals to humans is Echinococcus multilocularis. In Europe, the red fox and to a lesser extent also the raccoon dog are the main definitive host species for this cestode. However, adult worms can additionally develop in domestic dogs and cats. In Europe, during the last decades the number of red foxes has increased rapidly and they have colonised urban areas, bringing along their zoonotic pathogens. The main aim of the thesis was to study the prevalence of E. multilocularis among Estonian canids in both rural and urban areas. In addition, we studied the general parasite fauna of red foxes and raccoon dogs. In order to study urban canids new highly sensitive non-invasive molecular method that can identify both host and Echinococcus species from faecal samples was developed. Although the general parasite fauna of rural foxes and raccoon dogs is very similar, infection with life-threatening E. multilocularis was significantly higher in red foxes (31.5 %) compared to raccoon dogs (1.6 %), in which the cestode was reported for the first time in Estonia. The almost 20-fold difference in prevalence between the two host species can be explained by the difference in food preferences, especially their ability to capture rodents that serve as the main intermediate host for E. multilocularis. Analyses of faecal samples collected from urban areas in Tartu showed that 7.1 % of fox samples tested positive for E. multilocularis and 2.2 % of dog samples tested positive for E. granulosus, another zoonotic species from the genus Echinococcus. In conclusion, due to the high number of red foxes and raccoon dogs, both canid species can be considered as important sources of zoonotic parasites in Estonia.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
parasiidid, ehhinokokk, zoonoosid, koerlased, rebane, kährikkoer, Eesti, parasites, Echinococcus, zoonoses, canids, fox, raccoon dog, Estonia