Parasite Species Composition Research Articles

First report of Heterakis pedioecetes Mawson, 1956 (Ascaridomorpha: Heterakoidea) and Synhimantus (Dispharynx) nasuta (Rudolphi, 1819) (Spiruromorpha: Acuarioidea) from the Indo-Chinese green peafowl Pavo muticus imperator (Galliformes: Phasianidae).

The Indo-Chinese green peafowl Pavo muticus imperator (Galliformes: Phasianidae) is an endangered bird species. However, our present knowledge of the species composition of nematode parasites of this bird remains limited. In the present study, two nematode parasites Heterakis pedioecetes Mawson, 1956 (Ascaridomorpha: Heterakoidea) and Synhimantus (Dispharynx) nasuta (Rudolphi, 1819) (Spiruromorpha: Acuarioidea) were reported from P. muticus imperator for the first time. The detailed morphology of these two nematode species was further studied using light and scanning electron microscopy, and some previously unreported morphological features were revealed. These supplementary morphological and morphometric data contributed to a more accurate identification of these two common avian nematodes.

Inter-annual and seasonal variations of the metazoan parasite communities of the blue sea catfish Ariopsis guatemalensis (Siluriformes: Ariidae), in a tropical coastal lagoon

Parasitological studies of long-term inter-annual variations provide more precise and reliable information about the biological structure of fish parasite communities, and constitute a reference data base for future studies. A total of 1103 blue sea catfish Ariopsis guatemalensis from a tropical eutrophic coastal lagoon were examined for parasites over a 22-year period (from May 2000 to October 2022), to test the hypothesis that parasite communities of this host, should exhibit greater variations in their structure and species composition mainly over long-term periods. Three species of monoxenous (single-host life cycle), and nine of heteroxenous (multi-host life cycle) parasites were identified. The results indicated that parasite species composition of this catfish has remained stable over a 22-years period. However, the community structure has registered notable changes over periods of several years, mainly due to the replacement of the numerically dominant species. Temporal variations in the infection dynamics of component parasite species, were possibly caused by a combination of biotic and abiotic factors, influenced by the seasonal dry/rainy cycle, which can affect the availability of intermediate host populations, as well as the feeding and reproductive behavior of the host.

A Comparison of the Prevalence of Gastrointestinal Parasites in Wild Boar (Sus scrofa L.) Foraging in Urban and Suburban Areas

The aim of this study was to compare the species composition of gastrointestinal parasites in wild boar feeding in the city of Szczecin with those in its suburban area, as well as to determine the prevalence and intensity of this parasite infection. The intestines and stomachs of 57 wild boars were supplied by a municipal hunter from the city of Szczecin. Both analysed groups of animals were infected with the following parasites: Eimeria debliecki, E. suis, E. polita, E. scabra, Isospora suis, Ascaris suum and Oesophagostomum dentatum. Wild boar from the city were characterised as having a significantly higher prevalence of total Eimeria (p = 0.04) and a lower prevalence of noted species of nematodes (p = 0.15) compared to those from the suburban area. Since the wild boars were mainly infected with Eimeria, it should be assumed that they may pose a real health threat to farm pigs and other farm animals for which Eimeria is a pathogenic parasite. The occurrence of coccidiosis leads to serious health problems and economic losses for breeders. Although the prevalence of A. suum was low, it should be taken into account that this nematode is able to both infect and complete their life cycle in humans.

Ecological and phylogenetic components of flatfish ectoparasites (Pleuronectiformes: Paralichthyidae) from the Southern Gulf of Mexico.

For many years, parasite ecologists have debated the relative importance of phylogeny and ecology as drivers of parasite community structure. Here, we address this issue using data on the metazoan ectoparasite communities of different flatfish species. Twenty species of flatfish were collected along the continental shelf of the Southern Gulf of Mexico and examined for ectoparasites. Eight flatfish species were parasitized by at least one ectoparasite species. In total, 326 ectoparasites, representing 11 species (4 monogeneans, 4 copepods, 1 isopod, 1 branchiurid, and 1 leech) were removed from 1622 hosts examined. The highest prevalence (37.5%) occurred in Bomolochus sp1 from Trinectes maculatus, while the lower (0.1%) for Argulus sp., Gnathia sp. and Trachellobdella lubrica from Cyclopsetta chittendeni. Changes in the ectoparasite community structure per host species and region were evaluated using a Permutational Multivariate Analysis of Variance and represented by a multidimensional scaling analysis. Significant differences in the parasite species composition among regions and hosts were detected, but no significant interaction between regions and hosts occurred. A multivariate pairwise t-test detected significant differences in the parasite infracommunities between the Yucatan Shelf and the other two regions; in addition, significant differences were detected between C. chittendeni and the Syacium species as well as between Ancylopsetta dilecta and Syacium papillosum. In this case, there is no relationship between the patterns of ectoparasitic community structure and the inherent phylogenetic affinity of the hosts; instead, the variations in ectoparasitic communities are determined by a regional ecological component.

On the species composition of fish parasites in rivers and lakes in the south of Western Siberia

The fish from 11 lakes and 4 rivers of four regions of the south of Western Siberia (Novosibirsk, Tomsk, Kemerovo and Omsk regions), were examined from May to November 2015. A total of 817 specimens 14 fish species to five families: Coregonidae (1 species), Thymallidae (1), Cyprinidae (8), Lotidae (1), Percidae (3) were inspected for ectoparasites and endoparasites were infestation. In the present study taxonomic composition of ectoparasites includes representatives of four families of crustaceans (Lernaeopodidae, Lernaeidae, Argulidae and Ergasilidae) and leeches (Glossiphoniidae). Monogeneans were represented by three families: Dactylogyridae, Tetraonchidae and Diplozoidae. Cestodes of two families Ligulidae and Dilepididae were discovered. Fish infected with сestodes family Diphyllobothriidae were no found. The species composition of trematodes is the most diverse (7 genera to 4 families). Metacercariae of the families Diplostomatidae (genera Diplostomum , Posthodiplostomum , Tylodelphys ), Bucephalidae (genus Rhipidocotyle ), Prohemistomatidae (genus Paracoenogonimus ), and Opisthorchiidae (genus Metorchis and Opisthorchis ) were identified. Opisthorchis felineus , and Metorchis bilis , are two opisthorchiid species potentially perilous to human health, and domestic pets (cats, dogs) were found. Metacercariae of O. felineus , in all regions (Novosibirsk, Tomsk, Kemerovo and Omsk), in all surveyed rivers: Kiya, Tom, Irtysh and Ob were found. The opisthorchiid metacercariae potentially perilous to human health in three species (dace, ide, roach) out of eight studied (Cyprinidae) were found. The trematodes of the family Diplostomatidae were found in 8 fish species. The highest rates of infection were observed in roach and pike perch.

Вплив нематоди Contracaecum (Ascaris) на риб водойми-охолоджувача Запорізької атомної електростанції

Purpose: To determine species composition and localization of anisakidosis pathogens, infestation of fish species in the Zaporizhzhia NPP cooling reservoir, and identify trends in their infestation compared to monitoring epizootic studies of the last year. Methodology. In the course of the work, we used the generalized results of the studies conducted in the summer and autumn of 2021. The fish species composition in the ZNPP cooling reservoir as well as the species composition of parasites of Anisakidae family and their localization were determined. The studies were carried out using the method of incomplete parasitological dissection of fish at the laboratory. Nematode larvae were detected by visual inspection. The parasites were identified using identification keys. The detected parasites were washed with a saline and stored in 70% ethanol. For the quantitative analysis of the parasitofauna, we used such parameters as prevalence (%) and intensity (ind./ fish). Findings. The parasitological analysis showed that Contracaecum (Ascaris) larvae were found in European, channel and redtail catfishes, which were localized as cysts or free-living in the abdominal cavity. The infestation intensify reached 86 ind./fish, and prevalence reached 100%. The parasites caused hyperemia (redness) and inflammation of internal organs. At the same time, no Contracaecum larvae were found in common and silver carps. Compared to 2020, the infestation of fish was less pronounced, namely: no monogenean Dactylogirus were found on the gills of carps as well as ciliates including Trichodina and Apiosoma, which were found in small amounts on the body surface and gills of common and silver carps. The Contracaecum larvae invasion intensity in catfish decreased by 17 %. Originality. For the first time, a large tendency to the spread of Contracaecum larvae among fish of the ZNPP cooling reservoir was detected, namely in European, channel and redtail catfishes. The importance of the threat of this invasion for fish was established. Practical value. The obtained results can be used to identify timely trends in the infestation of fish by Anisakidae and to develop sanitary and preventive measures in the reservoir. Key words: nematodes, parasites Contracaecum (Ascaris), fish, ZNPP, anisakidosis, prevalence, invasion intensity, anisakids (Anisakidae).

Evaluation of the zoonotic potential of invasions of carnivores in a number of regions of St. Petersburg and the Lenigrad region

The last large-scale study of the parasite fauna of cats and dogs in St. Petersburg was carried out by Prozorov A.M. However, since then, according to sociological surveys, the number of animals in large cities of Russia has increased significantly, and no new studies on parasitic diseases of carnivores have been conducted. As the number of pets increases, so does the parasite population. Of particular danger are zoonotic invasions, in particular toxocariasis, dipilidiosis and toxoplasmosis. In the process of studying the species composition of parasites of carnivores, material from 608 animals from a number of districts of St. Petersburg and the Leningrad region was examined. As a result, the extensiveness of invasion in carnivores was established, which amounted to 23.7% (in cats 11.5%, in dogs - 12.2%). Cat toxocariasis is registered in every district and is in first place in terms of frequency of occurrence, with the exception of the Kalininsky district of St. Petersburg. The most common infestation of dogs, as well as in cats, in all the studied areas was toxocariasis, the prevalence of invasion of which in animals from centers for helping homeless animals and owners is 26.5% and 7.7%, respectively, which contributes to the contamination of the environment with toxocara eggs. Dipylidiasis is rare in carnivores (extensiveness of invasion was 0.2%) but has not been completely ruled out. The analysis led to the conclusion that the danger of infection with zoonotic invasions is preserved, therefore, it is necessary to carry out timely fight against diseases and carnivorous people, both in the centers for helping homeless animals, and in the owners of dogs and cats. It is also necessary to increase the level of people's knowledge about parasites, methods of infection and prevention, most common in humans and animals, invasive infections.

Parasite communities of the golden snapper Lutjanus inermis (Perciformes: Lutjanidae): inter-annual variations during strange climatic events.

Strange oceanographic events such as El Niño and La Niña may have indirect effects on the local transmission processes of intestinal parasites due to the reduction or increase in populations of potential intermediate or definitive hosts. A total of 713 individuals of Lutjanus inermis (Peters) were collected over an 8-year period (October 2015 to July 2022) from Acapulco Bay, Mexico. Parasite communities in L. inermis were quantified and analysed to determine if they experienced interannual variations in species composition and structure as a result of local biotic and abiotic factors influenced by oceanographic events, such as El Niño-Southern Oscillation (ENSO), or La Niña, the cool phase of the ENSO climate pattern. Twenty-six taxa of metazoan parasites were recovered and identified: two Monogenea, eight Digenea, two Acanthocephala, four Nematoda, one Cestoda, seven Copepoda, and two Isopoda. Species richness at the component community level (8 to 17 species) was similar to reported richness in other species of Lutjanus Bloch. Parasite communities of L. inermis exhibited high inter-annual variation in the abundance of component species of parasite. However, the species richness and diversity were fairly stable over time. Climatic episodes of El Niño and La Niña probably generated notable changes in the structure of local food webs, thus indirectly influencing the transmission rates of intestinal parasite species. Changes in species composition and community structure of parasites possibly were due to variations in feeding behaviour during the events and differences in the host body size.

Factors determining community structure of metazoan parasites from brown-spotted grouper, Epinephelus chlorostigma (Valenciennes, 1828) in Southern Saudi Arabia

Several factors influence the structure of parasite communities, which are important components of the biodiversity of various ecosystems. Some of these factors may be related to the environment and/or to the host. The present study evaluated the influence of host size and season on the structure of the metazoan parasite community of the brown-spotted grouper, Epinephelus chlorostigma. One hundred thirty-two fish were collected between March 2018 to February 2019 from the Red Sea, Saudi coast, Southern Saudi Arabia. Eight parasite species were recorded: one copepod (Sarcotaces sp.), one isopod (Argathona rhinoceros), two monogeneans (Pseudorhabdosynochus epinepheli and Megalocotyloides epinepheli), three digeneans (Prosorhynchus epinepheli, Helicometrina nimia, and Erilepturus hamati), and one nematode (Cucullanus epinepheli). The overall prevalence was 43.2% Digeneans were the most frequent parasite species and represented (50.55%) followed by monogeneans (45.05%), crustacean (3.42%), and nematode (0.98%) of the total individual parasites collected from 57 infected fish. Parasite community structure and species composition varied significantly among host size. Positive associations were found between infection parameters of parasite species and host size. Our results suggest that parasite infection parameters were affected by host size and season. Further long-term research is required to conclude the factors determining the structuring of the parasite community of E. chlorostigma.

The Fish Parasite Community in a Hypertid Estuary Penzhina River (Basin of the Sea of Okhotsk)

The species composition of parasites in the estuary of the Penzhina River was studied (114 species). The influence of the specific conditions of the estuary on the parasite fauna was shown. High flow rates, mixing of fresh and sea waters, and the abundance of organic matter determine the predominance among parasites of species with morphological adaptations for reliable fixation on fish tolerant to changes in salinity and associated with benthos in the life cycle. Transitions of parasites to atypical hosts have been noted. The component communities of parasites of most fish species are characterized by high indices of diversity and evenness and low indices of dominance. In the marginal populations of pike and whitefish, they are strongly depleted with pronounced dominants and their change in ontogeny. The Arctic and Pacific elements of the ichthyoparasite fauna testify to the influence of the Arctic and Pacific oceans on its formation.

ВИДОВОЕ РАЗНООБРАЗИЕ ГЕЛЬМИНТОВ ПИЩЕВАРИТЕЛЬНОЙ СИСТЕМЫ ЛЕЩА И ПЛОТВЫ САРАТОВСКОГО ВОДОХРАНИЛИЩА

The data on helminths of the digestive system of the bream Abramis brama Linnaeus, 1758 and the common roach Rutilus rutilus Linnaeus, 1758 (Osteichthyes, Cyprinidae) from the middle part of the Saratov reservoir (Koltsovo-Mordovinskaya fl oodplain) are given. In 2013–2016, 40 specimens of A. brama and 47 specimens of R. rutilus were studied by standard parasitological methods. Bream has 8 species of worms of different systematic groups, including Cestoda – 2, Trematoda – 1, Chromadorea – 3, Acanthocephala – 2. The community of intestinal and liver parasites of roach includes 5 species: Cestoda – 1, Aspidogastrea – 1, Chromadorea – 2, Acanthocephala – 1. The degree of invasion of fi sh by helminths circulating through food webs is low. The bream is dominated by the carp-specifi c nematode Rhabdochona denudata (Dujardin, 1845) Railliet, 1916 (Spirurida, Rhabdochonidae) (invasion intensity 27.5 %, invasion intensity 1–126 ind., abundance index 5.8 ind.). No dominant parasites were found in the common roach, three species (Contracaecum microcephalum (Rudolphi, 1819), Aspidogaster limacoides Diesing, 1835 and Raphidascaris acus (Bloch, 1779)) have the status of subdominants. During the research period, there were signifi cant fl uctuations in the qualitative and quantitative indicators of fi sh invasion (species composition of parasites, their occurrence and average number), which is determined by the feeding characteristics of bream and roach in each specifi c year.

ДИАГНОСТИКА ГЕМОПАРАЗИТОВ У PELOPHYLAX LESSONAE

This article describes the distribution, developmental cycle, clinical manifestations and diagnosis of haemoparasitic diseases in amphibians. An overview of the etiology and detection methods of haemoparasites is presented. The article presents the results of the complex clinical and laboratory examination of the series of clinical cases of haemoparasites in the experimental group of amphibians (n=6) of pond frog species Pelophylax lessonae, caught on 07.05.2022. As a control we used 5 specimens of pond frogs, caught on 02.07.2022 in the same biotope as the experimental group. Both groups were kept in artificial conditions. The experimental group was kept from 07.05.2022 to 28.07.2022, the control group was kept from 02.07.2022 to 28.07.2022. Dry peripheral blood smears were fixed with 96° ethanol and stained with Romanowsky-Giemsa (pH 6.8). Microscopic examination of blood smears of each individual of both groups revealed the presence of haemoparasites. It was found that the species composition of parasites is represented by one species - sporozooners Hepatozoon magna. By the method of calculating the extensiveness, the average intensity of invasion and the parasites abundance index found that the indicators of the experimental group were much higher than the control, the extensiveness of invasion: (83,3%, against 40%), the average intensity of invasion: (37 against 25), the parasites abundance index: (30,8 against 10). Based on the results of the studies, the dependence of the spread of haemoparasites on housing conditions and period was revealed. It has been suggested that the longer a group of individuals has been kept under artificial conditions, the higher its indices of extensiveness, average invasion intensity and parasite abundance index are.

Гельминтозы пищеварительного тракта овец в степной зоне Забайкалья

The infection of sheep with helminthiases of the digestive tract in the steppe zone of the Trans- Baikal Territory, the species composition of parasites and the degree of infestation by them were studied. Based on the results of complete helminthological dissections (PHV) and incomplete helminthological dissections (IGV), 20 species of helminths were collected and identified, of which 2 species belong to the cestode class and 18 species belong to the nematode class. The most common helminthiases are nematodirosis, ostertagiosis, trichostrongylosis, strongyloidiasis, and bunostomiasis, esophagostomiasis, and chabertiosis were found much less frequently. In some farms, strongyliasis of the digestive system is very widespread, affecting sheep with an extensiveness of invasion (EI) up to 96,7 %, and moniesiasis infects with EI up to 60,2 %.

Результаты археопаразитологического и палинологического исследования культурных слоев античного поселения Артезиан (Восточный Крым)

The article presents the results of archaeoparasitological and palynological research of the cultural layers located in the ancient Artesian settlement in the Eastern Crimea. The study revealed the species composition of parasites and palynological spectrum in the cultural layers. Parasite eggs distribution over the layers indicates high content of eggs in almost all periods of the citadel’s existence. High abundance of geohelminth eggs in the studied samples, which might belong to both humans and domestic animals, indicates the unsatisfactory sanitary state of the settlement and the constant risk of infection with geohelminthiasis and intestinal infections possessing the same fecal-oral route of transmission. Features of the studied spore-pollen spectra do not allow a detailed reconstruction of the vegetation dynamics in the vicinity of the Artezian fortress at the turn of the millennium. The major reason is complexity of spectra formation: in addition to pollen deposited from the air (pollen rain), a significant proportion consists of pollen grains brought from other sources. Furthermore, interpretation of the spore-pollen spectra is complicated by presence of a large number of microcharcoals and burnt pollen grains. Despite the above-mentioned challenges in the study of samples from the cultural layers of the Artezian archaeological site using spore-pollen method, we have determined that the inhabitants of the settlement probably used animal dung as fuel, and that at the turn of the millennium, forestless open landscapes covered with steppe vegetation were predominant around the settlement. An important result of the study is the demonstration of unexplored opportunities to investigate cultural layers by archaeoparasitological and palynological methods and of the obtained data use as a source of bioarchaeological information.

Parasite communities of the spotted rose snapper Lutjanus guttatus (Perciformes: Lutjanidae) off the Mexican Pacific coasts: Spatial and long-term inter-annual variations.

A total of 802 individuals of Lutjanus guttatus (Steindachner, 1869) specimens were collected over a 10-year period (August 2012 to February 2021) from four locations on the south-central Pacific coast of Mexico. Their parasite communities were quantified and analyzed to determine if they experience significant spatial and inter-annual variations. Thirty-two taxa of metazoan parasite were recovered and identified: four species of Digenea, four Monogenea, one Cestoda, two Acanthocephala, seven Nematoda, one Hirudinea, and nine of Crustacea (six Copepoda, and three Isopoda). Species richness was greatest among the digenean group, which represented 25% of the total species recovered, followed by the nematodes (22% of total species). Species richness at the component community level (10 to 20 species) was similar to reported richness in other Lutjanus spp. The component communities and infracommunities exhibited a similar pattern: low species richness and diversity, and dominance by a single species, mainly the monogenean Haliotrematoides guttati. Parasite community structure and species composition varied through the years, as well as between sampling locations. Variations were possibly caused by a combination of biotic and abiotic factors which generated notable changes in the infection levels of several component species. However, the similarity in the parasite species composition was high locally for short-term periods (one or two years). This result, therefore, suggests that parasite communities of L. guttatus may be more predictable locally, but only for short-term periods.

Parasitological monitoring of European bison in the West Pomeranian voivodeship on the basis of coproscopical examination

The aim of the study was to determine the level of parasitic infections in West Pomeranian European bison on the basis of coproscopic examinations. A total of 172 faecal samples of European bison from the Mirosławiec, Drawsko and Jałowcówka herds were examined by the flotation and sedimentation methods as well as the Baermann technique. Faecal examinations revealed the presence of gastrointestinal nematode eggs belonging to the family Trichostrongylidae and the genera Nematodirus, Aonchotheca, Trichuris and Strongyloides, eggs of tapeworms of the genus Moniezia, trematodes Fasciola hepatica and Paramphistomum cervi as well as larvae of the lungworm Dictyocaulus viviparus and seven species of coccidia of the genus Eimeria (E. bovis, E. pellita, E. zuernii, E. auburnensis, E. cylindrica, E. ellipsoidalis, and E. brasiliensis). The composition of parasite species in the population of European bison in the West Pomeranian voivodeship was similar to that observed in other free-living European bison populations in Poland.

Confounding factors affecting faecal egg count reduction as a measure of anthelmintic efficacy.

Increasing anthelmintic resistance (AR) in livestock has stimulated growing efforts to monitor anthelmintic effectiveness (AE) on livestock farms. On-farm assessment of AE relies on measuring the reduction in faecal egg count (FEC) following treatment; and if conducted rigorously, qualifies as a formal FEC reduction test (FECRT) for AR. Substantial research effort has been devoted to designing robust protocols for the FECRT and its statistical interpretation; however, a wide range of factors other than AR can affect FEC reduction on farms. These are not always possible to control, and can affect the outcome and repeatability of AE measurements and confound the on-farm classification of AR using FECRT. This review considers confounders of FEC reduction, focusing on gastrointestinal nematodes of ruminants, including host and parasite physiology and demography; pharmacokinetic variation between drugs, parasites and hosts; and technical performance. Drug formulation and delivery, host condition and diet, and seasonal variation in parasite species composition, can all affect AE and hence observed FEC reduction. Causes of variation in FEC reduction should be attenuated, but this is not always possible. Regular monitoring of AE can indicate a need to improve anthelmintic administration practices, and detect AR early in its progression. Careful interpretation of FEC reduction, however, taking into account possible confounders, is essential before attributing reduced FEC reduction to AR. Understanding of confounders of FEC reduction will complement advances in FECRT design and interpretation to provide measures of anthelmintic efficacy that are both rigorous and accessible.

Endoparasites of pet reptiles and amphibians from exotic pet shows in Texas, United States.

Reptiles and amphibians are becoming increasingly more common in the exotic pet trade and as such veterinary care is also rising. Parasitic infections can pose a serious threat to pet reptiles and amphibians and are a common finding in these exotic pets. The purpose of the present study was to determine the species composition of parasites among reptiles and amphibians entering the pet industry. Excreta were collected from 283 reptiles and amphibians (181 geckos, 23 chameleons, 21 frogs, 16 tortoises, 11 snakes, 1 caiman, and 31 other lizard species), representing 58 different species. Samples were collected from animals being sold at exotic pet shows in Texas, USA, where breeders from throughout the United States gathered to showcase their exotic pets. Excreta samples were tested using double centrifugation flotation with Sheather's sucrose solution. Endoparasites were identified in 51.9% of samples. The most prevalent helminth parasite among reptiles and amphibians were Pharyngodonidae (44.5%) nematodes. Oocysts of coccidians such as Isospora, Eimeria, and Choleoeimeria, and cysts of the ciliate Nyctotherus were also identified. The prevalence rates of endoparasites among animal groups ranged from 0 to 87.5%. The highest prevalence of infection was found in Testudines (87.5%), followed by Chamaeleonidae (87%), other lizards (76.7%), Amphibia (71.4%), Serpentes (63.6%), and then Gekkonidae (55.2%). No endoparasites were detected in the one Crocodylia sampled. Our results show that parasitic infections, many of which can cause clinical disease and mortality, are common in exotic reptiles and amphibians being sold or traded as pets in the United States, underlining the need for veterinary care and routine diagnostic screening for parasitic infections.

Helminth communities of Coregonus lavaretus (Salmonidae: Coregoninae) from Lake Kamennoye (Kostomuksha State Nature Reserve, Russia)

Macroecological models are useful for assessing trends in variability for developing monitoring strategies of successional changes and anthropogenic transformation of aquatic ecosystems. Modelling of the relationships of the generalised population indices also makes possible to reveal qualitative differences in the structure of parasite component communities. We analysed helminth communities of Coregonus lavaretus from a natural water body, Lake Kamennoye (Kostomuksha State Nature Reserve, Russia). The component community of metazoan parasites of C. lavaretus was represented by nine helminth species. Infection with cestodes (two species), nematodes (three species), and trematodes (one species) reflects the presence of zooplankton, aquatic insects and molluscs in the diet of fish, while infection with trematode larvae (three species) occurs by percutaneous penetration. The complete ITS1-5.8S-ITS2 cluster of the rRNA gene was sequenced in order to identify trematode larvae. Metacercariae of Diplostomum sp. LIN 5 were the most abundant among them. Using populational approaches, we described the species richness and the diversity of infra- and component communities of the parasites. We also described the species composition and the structure of the component community, the distribution and the accumulation rate of species richness, and the relationships between the infection intensity and the prevalence. Five species (Diplostomum sp. LIN5, Tylodelphys immer, Crepidostomum farionis, Proteocephalus longicollis, and Raphidascaris acus) were considered as the core species of the component community, while other helminths were considered as satellite species. We conclude that infra-communities play a key role in the formation of species richness, structure and abundance of the parasitic component community of C. lavaretus. Infra-communities in younger age groups of C. lavaretus are characterised by the paucity and a relatively high diversity of the species composition of parasites, which is probably a consequence of their diverse diet. In older fish, the species richness of infra-communities increases but the species diversity of the parasites declines, indicating a pronounced dietary specialisation. An analysis of species richness and population characteristics indicates that in Lake Kamennoye, the parasite communities of C. lavaretus are fairly stable, which reflects the stability of the entire lake ecosystem.

Malaria parasite species composition of Plasmodium infections among asymptomatic and symptomatic school-age children in rural and urban areas of Kinshasa, Democratic Republic of Congo

BackgroundMalaria remains a major public health concern in the Democratic Republic of Congo (DRC), and school-age children are relatively neglected in malaria prevalence surveys and may constitute a significant reservoir of transmission. This study aimed to understand the burden of malaria infections in school-age children in Kinshasa/DRC.MethodsA total of 634 (427 asymptomatic and 207 symptomatic) blood samples collected from school-age children aged 6 to 14 years were analysed by microscopy, RDT and Nested-PCR.ResultsThe overall prevalence of Plasmodium spp. by microscopy, RDT and PCR was 33%, 42% and 62% among asymptomatic children and 59%, 64% and 95% in symptomatic children, respectively. The prevalence of Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale spp. by PCR was 58%, 20% and 11% among asymptomatic and 93%, 13% and 16% in symptomatic children, respectively. Among P. ovale spp., P. ovale curtisi, P. ovale wallikeri and mixed P. ovale curtisi + P. ovale wallikeri accounted for 75%, 24% and 1% of infections, respectively. All Plasmodium species infections were significantly more prevalent in the rural area compared to the urban area in asymptomatic infections (p < 0.001). Living in a rural as opposed to an urban area was associated with a five-fold greater risk of asymptomatic malaria parasite carriage (p < 0.001). Amongst asymptomatic malaria parasite carriers, 43% and 16% of children harboured mixed Plasmodium with P. falciparum infections in the rural and the urban areas, respectively, whereas in symptomatic malaria infections, it was 22% and 26%, respectively. Few children carried single infections of P. malariae (2.2%) and P. ovale spp. (1.9%).ConclusionSchool-age children are at significant risk from both asymptomatic and symptomatic malaria infections. Continuous systematic screening and treatment of school-age children in high-transmission settings is needed.