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Nematode burdens and variation in morphological characteristics were assessed in eighty-eight animals from three host species (Apodemus sylvaticus, Apodemus flavicollis, and Myodes glareolus) from eight localities in Serbia. In total, 15 species of nematodes were identified, and the overall mean parasite species richness (IndPSR) was 1.61 per animal (1.98 in A. flavicollis, 1.43 in M. glareolus, and 0.83 in A. sylvaticus). Furthermore, the studied host species significantly differed in individual parasite load (IndPL) and in the following morphological characters: spleen mass, body condition index (BCI), and body mass. We aimed to analyze the relationship between the burden of intestinal nematodes, on one hand, and the body conditions of the host and its capability to develop immune defends on the other. Spleen mass was considered as a measure of immune response. In all host species, larger animals with a better condition (higher BCI) were infected with more parasites species (IndPSR), while parasite load was not related to BCI. Only in A. flavicollis were males significantly larger, but females of the same sizes were infected with more parasite species. This female-biased parasitism is contrary to the theoretical expectation that males should be more parasitized, being larger, more active, with a wider home range. Although the spleen size was significantly correlated with body condition and body mass, IndPSR was not related to spleen mass in any studied species, but in M. galareolus, we found that a smaller spleen was related to higher infection intensity (IndPL).

Background Mammalian mandible and cranium are well-established model systems for studying canalization and developmental stability (DS) as two elements of developmental homeostasis. Nematode infections are usually acquired in early life and increase in intensity with age, while canalization and DS of rodent skulls could vary through late postnatal ontogeny. We aimed to estimate magnitudes and describe patterns of mandibular and cranial canalization and DS related to age and parasite intensity (diversity) in adult yellow-necked mice ( Apodemus flavicollis ). Results We found the absence of age-related changes in the levels of canalization for mandibular and cranial size and DS for mandibular size. However, individual measures of mandibular and cranial shape variance increased, while individual measures of mandibular shape fluctuating asymmetry (FA) decreased with age. We detected mandibular and cranial shape changes during postnatal ontogeny, but revealed no age-related dynamics of their covariance structure among and within individuals. Categories regarding parasitism differed in the level of canalization for cranial size and the level of DS for cranial shape. We observed differences in age-related dynamics of the level of canalization between non-parasitized and parasitized animals, as well as between yellow-necked mice parasitized by different number of nematode species. Likewise, individual measures of mandibular and cranial shape FA decreased with age for the mandible in the less parasitized category and increased for the cranium in the most parasitized category. Conclusions Our age-related results partly agree with previous findings. However, no rodent study so far has explored age-related changes in the magnitude of FA for mandibular size or mandibular and cranial FA covariance structure. This is the first study dealing with the nematode parasitism-related canalization and DS in rodents. We showed that nematode parasitism does not affect mandibular and cranial shape variation and covariance structure among and within individuals. However, parasite intensity (diversity) is related to ontogenetic dynamics of the levels of canalization and DS. Overall, additional studies on animals from natural populations are required before drawing some general conclusions.

Foxes and jackals from the Vojvodina Province of Serbia were examined for the presence of echinococcosis. Animals were collected as part of routine rabies monitoring and autopsied; their intestines were checked for parasites. Out of 112 examined foxes, echinococcosis was found in 20 (17.9 %); of 28 examined jackals, 4 were infected (14.3 %). Morphological analysis confirmed the presence of Echinococcus multilocularis . This is the first record of E. multilocularis in foxes or other carnivorous mammals in Serbia.

Genetic background underlying wild populations immune response to different parasites is still not well understood. We studied immune response to multiple infections and to competition between different parasite species at different developmental stages in population of yellow-necked mouse, Apodemus flavicollis. Quantitative real-time PCR was used to investigate associations of MHC II-DRB, IL-10 and Tgf-β genes expressions with presence of intestinal parasites at different developmental stages. Furthermore, we were interested whether the host related characteristics (sex, age, body condition, presence of B chromosomes or expression of other genes) or characteristics of present parasites (number of adult parasites of each identified species, egg count of each parasite genus, total number of nematode individuals) affect differential expression of the studied genes. A significant invert association between the expression of MHC II-DRB and Tgf-β gene was found, which together with absence of IL-10 association confirmed modified Th2 as the main type of immune response to nematode infections. Effect of recorded parasites and parasite life-cycle stage on expression levels of MHC II-DRB gene was detected only through interactions with host-related characteristics such as sex, age, and the presence of B chromosomes. The presence of B chromosomes is associated with lower expression level of Tgf-β gene. Although the influence of host genetic background on parasite infection has already been well documented, this is the first study in mammals that gave presence of B chromosomes on immune response full consideration.

Vršeno je istraživanje intestinalnih nematoda žutogrlog miša (Apodemus flavicollis Melchior, 1834) uzorkovanog sa 18 lokaliteta na teritoriji Srbije, južno od Save i Dunava, sa ciljem proširenja i upotpunjavanja saznanja o ovoj komponenti parazitofaune glodara u ovom delu Evrope. Fauna nematoda crevnog trakta je analizirana sa više aspekata: kvantitativnog, aspekta zajednica, biološkog, aspekta biodiverziteta i aspekta polne strukture. Pored toga, ispitan je uticaj odabranih spoljašnjih i unutrašnjih faktora na prevalencu i abundancu parazitske infekcije. Zabeleženo je prisustvo devet vrsta intestinalnih nematoda, pri čemu je broj vrsta po lokalitetu varirao od 1 do 7. Ukupna prevalenca infekcije iznosila je 81,6%. Najčešće vrste u uzorku bile su Heligmosomoides polygyrus i Syphacia stroma, koje su se odlikovale najvišim prevalencama i intenzitetima infekcije. Distribucija nematoda unutar domaćina je bila agregirana. Broj vrsta po domaćinu varirao je od 1 do 5, ali su najzastupljenije bile infekcije jednom ili dvema vrstama. Najčešća kombinacija vrsta bila je H. polygyrus-S. stroma; međutim, odsustvo podataka iz ranijih istraživanja i adekvatnih polaznih modela sprečava donošenje zaključaka o mogućim interakcijama i asocijacijama između vrsta. Monoksene nematode su bile brojnije i imale veću prevalencu od heteroksenih nematoda, što oslikava razlike u njihovim životnim ciklusima. Među monoksenim nematodama, geohelminti u užem smislu su se odlikovali najvećim prevalencama, a ageohelminti najvećom abundancom, u skladu sa životnim strategijama koje teže ka disperziji ili akumulaciji.Šenonov indeks diverziteta cele uzoračke populacije iznosio je 1,44 što je visoka vrednost u odnosu na one iz drugih delova Evrope. Nije uočena značajna negativna korelacija između udaljenosti lokaliteta i vrednosti Sorensenovog indeksa,ukazujući da je prostorni faktor značajan u strukturiranju zajednica intestinalnih nematoda i na lokalnom nivou. Odnos polova je bio neravnomeran, uglavnom u korist ženki, u skladu sa podacima drugih autora. Ženke su ujedno bile krupnije od mužjaka, saglasno sa ranijim nalazima za parazitske nematode. Nadmorska visina nije uticala na abundancu intestinalnih nematoda. Pol domaćina je uticao na prevalencu dve vrste: prevalenca S. stroma je bila veća kod mužjaka, a prevalenca Trichuris muris kod ženki. Kao značajan faktor uticao je na abundancu samo kod vrste Aonchotheca annulosa; abundanca ove vrste bila je veća kod mužjaka. Rezultati sugerišu da je uticaj pola domaćina na nivo parazitske infekcije izuzetno kompleksan fenomen. Prevalenca i abundanca infekcije intestinalnim nematodama je bila veća kod domaćina sa B hromozomima. Lokalitet je bio značajan faktor u variranju abundance nematoda. Uzrast i prisustvo drugih vrsta nematoda su takođe ispoljavali značajan efekat. Povećanje abundance nematoda sa uzrastom se vezuje za dužu izloženost starijih jedinki parazitima. Iako je registrovan uticaj abundance jedne vrste na abundancu druge, on ne predstavlja čvrst dokaz za postojanje interakcija između vrsta.

Genetic background underlying wild populations immune response to different parasites is still not well understood. We studied immune response to multiple infections and to competition between different parasite species at different developmental stages in population of yellow-necked mouse, Apodemus flavicollis. Quantitative real-time PCR was used to investigate associations of MHC II-DRB, IL-10 and Tgf- beta genes expressions with presence of intestinal parasites at different developmental stages. Furthermore, we were interested whether the host related characteristics (sex, age, body condition, presence of B chromosomes or expression of other genes) or characteristics of present parasites (number of adult parasites of each identified species, egg count of each parasite genus, total number of nematode individuals) affect differential expression of the studied genes. A significant invert association between the expression of MHC II-DRB and Tgf- beta gene was found, which together with absence of IL-10 association confirmed modified Th2 as the main type of immune response to nematode infections. Effect of recorded parasites and parasite life-cycle stage on expression levels of MHC II-DRB gene was detected only through interactions with host-related characteristics such as sex, age, and the presence of B chromosomes. The presence of B chromosomes is associated with lower expression level of Tgf- beta gene. Although the influence of host genetic background on parasite infection has already been well documented, this is the first study in mammals that gave presence of B chromosomes on immune response full consideration.