Volume 55 (2018): Issue 3 (September 2018)

Immunosuppression caused by parasitic infections represents the foremost way by which the parasites overcome or escape the host’s immune response. Glucan is a well-established natural immunomodulator with the ability to significantly improve immune system, from innate immunity to both branches of specific immunity. Our review is focused on the possible role of glucan’s action in antiparasite therapies and vaccine strategies. We concluded that the established action of glucan opens a new window in treatment and protection against parasitic infections.

The serotoninergic and FMRFamidergic nervous system of the attachment organs of trematodes were examined using immunocytochemical techniques and confocal scanning laser microscopy. Adult trematodes from eight families as well as cercariae and metacercariae from ten families were studied. TRITC-conjugated phalloidin was used to stain the muscle fibres. The serotonin- and FMRFamide-immunoreactive (IR) nerve cells and fibres were revealed to be near the muscle fibres of the oral and ventral suckers of the trematodes and their larvae. The results indicate the important role of neurotransmitters, serotonin and neuropeptide FMRFamide in the regulation of muscle activity in the attachment organs of trematodes and can be considered in perspective for the development of new anthelmintic drugs, which can interrupt the function of the attachment organs of the parasites.

Parasitic helminthes can suppress and/or regulate the host immune response to allow long-term survival and chronic infection where toll-like receptors (TLRs) expressed on macrophages play essential roles in response to parasitic infection. Semi-quantitative PCR and flow cytometry studies about the modulation of TLRs and cytokine profiles in macrophages following T. spiralis infection were performed. TLRs, MyD88 and NF-κB were up-regulated by T. spiralis infection and essential to the parasite life cycles. Cytokines profiles (IL-6, IL-10, IL-12, TNF-α) were modulated during T. spiralis infection. Results suggest that T. spiralis infection may regulate the expression of TLR4 on macrophages and TLR4/MyD88/NF-κB signaling pathways. This study provides further insights into the mechanisms of TLR-mediated post-inflammatory response during T. spiralis infection.

This study was carried out to estimate the minimal number of eggs present in adult E. coelomaticum uterus. Samples were collected during post-mortem inspection and were submitted to light microscopy (bright field). The length, width, the total area of the parasite, uterus, and eggs were measured. The ImageJ software was used to calculate the area of the different parameters analyzed in this study. It was possible to observe that the uterus corresponds on average to 51.9 % of the total area of the parasite (ranging from 45 to 64 %). The number of eggs present in the uterus of parasites ranged from 5,946 to 15,813. To estimate the number of eggs three scenarios were considered, where the first taken into account the number of whole eggs observed in the image. In the second way to estimate the number of eggs, all the structures were considered (whole eggs and fractions that could be delimited) and compared with manual counting. Finally, in the last scenario, was considered an occupancy rate of 100 % of the uterine area per eggs, since there are overlapping eggs and these cannot be correctly delimited and accounted for. This study describes an important tool for quantifying eggs in a nondestructive manner and aggregate information until then is not explained by other works.

As part of routine monitoring of foxes (Vulpes vulpes) and jackals (Canis aureus) on the territory of Vojvodina province (northern Serbia), an analysis of respiratory and cardiopulmonary parasitic nematodes was conducted. Both host species harbored Eucoleus aerophilus, E. boehmi and Crenosoma vulpis, whereas Angiostrongylus vasorum was found only in foxes. A high prevalence of infection (72.6 %) was noted for E. aerophilus in foxes. The remaining parasite species occurred less frequently in both host species. In all species where it could be quantified, a high degree of parasite aggregation within host individuals was noted. Single species infections were most common, whereas two and three species infections occurred less frequently in both host species. The distribution of abundance of E. aerophilus was affected by host sex, with abundances higher in male foxes. Sampling site and year influenced abundance variation in E. boehmi.

Species diversity and composition of the parasite communities of barbel (Barbus barbus) at the infracommunity and component community levels were studied in the Lower Danube River, Bulgaria. During the two-year investigations, five parasite species have been found in 92 host fish: Bathybothrium rectangulum (Cestoda), Acanthocephalus anguillae and Pomphorhynchus laevis (Acanthocephala) and larval stages of Contracaecum sp. and Raphidascaris acus (Nematoda). Bathybothrium rectangulum and R. acus found in barbel represented new host records in Bulgaria. Parasite communities of barbel were species-poor and highly unbalanced. Pomphorhynchus laevis represented the dominant (core) species (prevalence 98.9 %), the second most frequent component parasite was Contracaecum sp. (P = 14.1 %) and remaining three species occurred only accidentally in barbels. Differences in species richness, prevalence, intensity of infection and ecological indices between individual seasons (spring, summer, autumn) were statistically significant, but considerably affected by unequal species structure of communities with highly prevailing P. laevis. Low parasite species diversity of barbel and low values of most ecological indices, when compared with previous studies in this area (or other Bulgarian parts of the River Danube) might indicate that environmental conditions are impaired and thus, not favourable for the development of barbel parasites (primarily to their intermediate host survival) in the Lower Danube River of Bulgaria.

Snakehead fishes are widely consumed throughout South East Asia, China and India because of their good taste of meat and high nutrient values such as presence of prostaglandins, thromboxane and Omega-6 fatty acid. Parasitic infection constitutes significant economic loss in fish production. The aim of this work was to study the seasonal variation of helminths in snakeheads. In the presented study, a three-year survey has been performed. A total of 1013 individuals of Channa punctatus and 247 individuals of Channa striatus were examined. A total of 3783 helminths were collected, with an average of 3.02 helminths/fish. 43.50 % individuals of C. punctatus and 59.10 % of C. striatus were found to be infected with acanthocephalans, trematodes, nematodes and cestodes per year. The prevalence and mean abundance of Pallisentis sp. was at its peak in summer. However the prevalence of trematodes, nematodes and cestodes was at peak during autumn. Mean abundance of nematodes was at peak in summer. Interestingly, the males were found more infected as compared to the females and the infection rate in males peaked in summer. In comparison to other weight groups, medium size hosts (21 – 40 g) were found more consistently infected. Thus the results indicate that there are seasonal variations in parasitic helminths infecting C. punctatus and C. striatus which also depend upon sex and weight. These variations may be attributed to various environmental and biological factors including parasite life cycle and immune level of host.

Chrysocyon brachyurus, the largest South American canid, is a native species of the Brazilian cerrado. The present study is aimed to report the occurrence of the trematode, Athesmia foxi, in the liver of a new host, C. brachyurus, and to describe its morphology and pathology. One C. brachyurus individual was necropsied and examined for the presence of parasites. Worms were collected from the bile ducts and based on morphological and morphometrical characteristics, such as a relatively large, slender, aspinose, elongated shape with vitellarium present on the upper left side of the body were identified as A. foxi. On the host, hepatic lesions limited to the bile ducts and periportal regions, were characterized as chronic-active cholangitis, biliary hyperplasia, and fibrosis. This is the first report of A. foxi parasitizing C. brachyurus, demonstrating that this parasite has no host specificity and can be widely distributed. A. foxi lesions noted in C. brachyurus are similar to those noted in various other mammalian hosts.

Fifty-one yellow-necked mice from the Obedska bara locality were analysed for the presence of intestinal nematode parasites in order to assert whether there was a host sex bias in infection. Previous research indicated that males would be the more infected sex, either due to the immunosuppressive effect of testosterone or their different allocation of resources towards immune defence. Quantitative infection parameters were compared between host sexes for all nematode species and nematodes in general. In addition, the influence of host sex, age, total body length, body mass and presence of other nematode species on parasite abundance was analysed. No statistically significant differences between males and females were noted for any of the studied quantitative parameters, leading to an absence of sex-biased parasitism in this study.

We have investigated freshwater cyprinid fish for its current infection status with plerocercoid of ligulid tapeworm in the Republic of Korea. A total of 6,049 (517 Euiam Lake and 4,071 Hoengseong Lake in Gangweon-do and 1,461 Chungju Lake in Chungcheongbuk-do) fish were examined by dissecting the peritonial cavity between March 2015 and December 2016. Totally 45 (0.74 %) fish in of 5 (26.3 %) species (8 Squalidus japonicus coreanus, 6 Squalidus gracilis majimae, 7 Opsariichthys uncirostris amurensis, 15 Zacco platypus and 9 Erythroculter erythropterus) were infected with plerocercoids of ligulid tapeworm. The infection density with plerocercoids in Erythroculter erythropterus was 12 – 26 per fish infected in Erythroculter erythropterus, and 1 – 2 in other 4 fish species. The plerocercoid was ivory-white and 26.2 – 57.8 cm long. The prevalence value in this survey was 0.9 % (45/6,049). The genetic analysis in this study was conducted to identify plerocercoid species. Based on genetic analysis with data in GenBank, these plerocercoids were identified as the L. intestinalis.

A survey of entomopathogenic nematodes was conducted in Croatia between 2016 and 2017. The steinernematids were recovered in two out of 100 soil samples from agricultural land characterized as loamy soils with acidic reaction. Molecular and morphological identification was used to distinguish the nematodes. The isolates were identified as two different strains conspecific with Steinernema feltiae. The variations in morphometrical characteristics of infective juveniles (IJs) and males were observed among Croatian strains and with the original description. The analysis of ITS region revealed the greatest similarity of Croatian strains with Slovenian B30 and English A2 strains, which together comprised a monophyletic group in evolutionary analysis. This is the first record of steinernematids, namely S. feltiae in Croatia.