Parasites of the liver:A global problem?

Parasitic liver diseases can be caused by trematodes,cestodes,nematodes,and protozoa.This pathology is significant because millions of people in different parts of the world have liver parasites,which can manifest themselves in the development of inflammation,liver cysts,cholecystitis,cholelithiasis,pancreatitis and liver cirrhosis that are often threatening their lives.The International Agency for Research on Cancer considers three species of trematodes,Schistosoma haematobium,Opisthorchis viverrini and Clonorchis sinensis,to be carcinogens.Complex modern examination methods,in some cases including extensive screening of large populations,are required for diagnosing liver parasites.Treatment of parasitic liver diseases is differentiated and can involve a combination of surgical and therapeutic measures.There is no doubt that the clinical and epidemiological scale allows one to regard parasitic liver diseases as a global healthcare problem.

Evaluation of Immunological Markers in Children Infected with Intestinal Parasites in Three Communities, Nigeria

Helminthiases are neglected parasites that induce changes in the host’s immune response. The study assayed some immunological markers in helminth infections in children and adolescents. Stool and blood samples were collected from 276 subjects resident in three rural communities of Rivers and Imo States. Of these, 98 (35.5%) were infected with one or more of 3 parasitic species, of which Ascaris lumbricoides 39 (39.8%), Ancylostoma duodenale 30 (30.6%) and Trichuris trichiura 29 (29.6%) were recovered. Intestinal helminth parasites were identified using formol-ether concentration. Of the infected subjects, 66 had single species infections and 32 had multiple infections with two or three helminth species and children of the 6 - 10 years age group had the highest incidence. Sera of 60 infected subjects and 30 controls were evaluated to define immunological serum levels of IgE, IL-5, IFN-γ and C3 using the ELISA technique, while white blood cell differential counts and neutrophil-lymphocyte ratio (NLR) were evaluated using haematology auto-analyser. Elevation of IL-5, IgE, WBC and eosinophil levels were demonstrated in the infected groups (p < 0.01), higher in the multiple infected groups, compared to the control. Their concentrations across the different age groups were also significantly different (p = 0.0001), the highest in 6 - 5 years and the lowest in 0 - 5 years. Differences in IFN-γ and C3 levels among non-parasitized, single-parasitized and poly-parasitized groups were not statistically significant. Neutrophil, lymphocyte and NLR levels between control and helminth infected subjects were not significantly different. The result suggested that IgE, IL-5, total WBC and eosinophil increased in helminth infections, more in poly-parasitized and 6 - 10 years children.

Taxonomic Study of Five Parasitic Polypores of the Hymenochaetaceae Family of TIN Vegetation in Western Burkina Faso

The aim of this work is to inventory and study the lignicolous parasitic macrofungi of the Tin plant formation. The mycological outings from July to September 2018 and 2019, collected forty-four (44) basidiomes through a random sampling device over an area of 40,000 m2 including 1000 m long by 40 m2 wide. The standard methods and techniques used in mycology for taxonomic studies were used to describe and classify the carpophores collected in three families: Hymenochaetaceae, Ganodermataceae and Polyporaceae, into eight genera: Onnia (4.55%), Amauroderma (4.55%), Ganoderma (20.45%), Phellinus (52.27%), Inonotus (4.55%), Phellinopsis (6.82%), Grammothele (2.27%) and Trametes (4.55%). The genera Phellinus and Ganoderma were the most abundant. Finally, eight species were identified: Inonotus cf. ochroporus, Inonotus cf. pachyphloeus, Phellinus cf. cryptarum, Phellinus cf. hartigii, Phellinus cf. hippophaecola;Phellinus cf. robustus, Phellinus cf. igniarius, et Amauroderma cf. fasciculatum. Seven fungal species belong to the family Hymenochaetaceae and only the species Amauroderma cf. fasciculatum is a Ganodermataceae. However, all these fungal species are shown to be parasites of trunks and/or branches of the following woody: Parkia biglobosa (50%), Anogeissus leiocarpus (25%), Annona senegalensis (12.5%) and Mangifera indica (12.5%). Authors attest that the presence of phytoparasitic polypores in a plant formation is an indicator of aging hence the urgency to put in place the appropriate measures to safeguard and restore Tin’s plant formation.

Do brood parasitic Common Cuckoos develop brood patches during the breeding season?

Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,vascularization,and edema.However,little is known about whether avian brood parasites that do not incubate their eggs exhibit brood patch development during the breeding season.In this study,we measured the size of the ventral apterium in 114 Common Cuckoos(Cuculus canorus)captured in the field throughout the breeding season and examined the appearance of the ventral apterium to confirm the development of brood patches.We also examined whether morphological traits and various factors correlated with the size of the ventral apterium(sternal apterium and abdominal apterium)and how it changed during the breeding season.We found no clear signs of brood patch development in Common Cuckoos captured throughout the breeding season,indicating that they likely did not develop brood patches on the ventral apterium during this period.We also found that ventral apterium size was positively correlated with wing length and body weight.In addition,Common Cuckoos with newly growing feathers on the boundary of the ventral apterium with pteryla were frequently observed as seasons progressed to the end.In conclusion,Common Cuckoos exhibit neither brood patch development nor the vestigial characteristics of ancestral brood patches,except for the growth of feathers on boundary the ventral apterium.Further studies examining brood patches across different groups of avian brood parasites are valuable for enhancing our understanding of the developmental and physiological adaptations of avian brood parasites.

Yr5-virulent races of Puccinia striiformis f.sp.tritici possess relative parasitic fitness higher than current main predominant races and potential risk

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is one of the most destructive fungal diseases of wheat,and seriously threatens safe production of the crop worldwide.In China,new races historically appeared and rapidly developed to be predominant races and have resulted in ineffectiveness and replacement of wheat resistance cultivars as well as massive reduction in yield.In the present study,the relative parasitic fitness of the two newlyemerged Yr5-virulent races(TSA-6 and TSA-9)were compared with those of four currently predominant Chinese races(CYR31,CYR32,CYR33,and CYR34)based on evaluation on 10 Chinese wheat cultivars.As a result,there were significant differences in the relative parasitic fitness parameters among overall tested races based on multiple comparison(LSD)analysis(P<0.05).The principal component analysis(PCA)of overall parasitic fitness parameters indicated that the sporulation ability,infection and spore survivability,expansion capacity,and potential pathogenicity were the most important parasitic fitness attributes of the tested races.Based on the establishment of extracted three principal components and a comprehensive factor score mathematical models,evaluations of the parasitic fitness attributes of tested races showed that the level of relative parasitic fitness of the tested six races was:CYR32(1.15)>TSA-9(0.95)>TSA-6(0.92)>CYR34(0.29)>CYR31(–1.54)>CYR33(–1.77).The results indicated that two Yr5-virulent races TSA-9 and TSA-6 possessed relative parasitic fitness higher than races CYR34,CYR31,and CYR33,but lower than race CYR32,and have potential risks in developing to be predominant races.Therefore,continual monitoring of both Yr5-virulent races,and their variants is needed.The use of wheat cultivars(lines)with Yr5 resistance gene singly in wheat breeding is essential for being avoided,and is suggested to combine with other effective stripe rust resistance genes.

A review of selected parasitic plants in Nigeria:converting harms to benefits

Parasitic plants are challenging to agricultural crops and forestry development,which are sources of major revenues in several countries,including Nigeria.Nevertheless,parasitic plants are important to human society as they have an abundance of bioactive compounds with pharmacological relevance.Thus,it becomes expedient to know the benefits of these plants and potential means of management.This review discusses four selected parasitic plants in Nigeria,namely Viscum album,Striga hermonthica,Tapinanthus bangwensis and Cuscuta campestris.Relevant information about their pharmacological relevance and biocontrol was obtained from credible databases,including the National Library of Medicine,SCOPUS,and Google Scholar.The review showed that all four plants have been extensively studied for their antioxidant and antitumor properties.Also,antimicrobial and anti-inflammatory activities are common pharmacological values among parasitic plants.These are largely due to the presence of abundant beneficial classes of phytocompounds.Furthermore,there is an increasing number of biocontrol studies on the use of microorganisms,such as Phaeobotryosphaeria visci,Sphaeropsis visci,Pandoraea pulminicol,Colletotrichum gloeosporioides,and Fusarium oxysporum in controlling and managing these seemingly disastrous plants.It is hoped that this review will spur further studies into the conservation and proper management of parasitic plants using strategically developed biocontrol.

Opportunistic and other intestinal parasites among HIV/AIDS patients attending Gambi higher clinic in Bahir Dar city,North West Ethiopia

Objective:To determine the magnitude of opportunistic and non-opportunistic intestinal parasitic infections among HTV/AIDS patients in Bahir Dar.Methods:Cross-sectional study was conducted among HIV/ AIDS patients attending Gambi higher clinic from Aprill- May 30,2009. Convenient sampling technique was employed to identify the study subjects and hence a total of 248 subjects were included.A pre-tested structured questionnaire was used to collect sociodemographic data of patients.Stool samples were examined by direct saline,iodine wet mount, formol-ether sedimentation concentration and modified Ziehl-Neelsen staining technique. Results:Out of 248 enrolled in the study,171(69.0%)(90 males and 81 females) were infected with one or more intestinal parasites.The highest rate of intestinal parasites were observed among HIV/AIDS patients(80.3%,151/188),and the infection rate of HIV negative individuals was 33.3%(20/60).Cryptosporidum parvum(43.6%),Isospora belli(15.5%) and Blastocystis hominis (10.5%) were opportunistic parasites that were found only in HIV/AIDS patients.Conclusions: Opportunistic parasite infections are common health problem among HIV/ AIDS patients in the study area.Therefore,early detection and treatment of these parasites are important to improve the quality of life of HIV/AIDS patients.

Molecular basis for identification of species/isolates of gastrointestinal nematode parasites

Gastrointestinal（GI） parasitism is the most serious constraint throughout the world in small ruminants which causes significant production loss in animals.GI parasites are major contributor to reduce productivity in terms of meat,milk and wool in animals.Control of GI parasite is done primarily by anthelmintic treatment where choice and schedule of treatment is done after identification and quantitation of individual parasite.Identification of GI parasites is done through microscopic method by identifying specific morphological characteristics of egg and larva（L3）.Since most of parasite eggs are having similar morphological characteristics, identification up to species level through microscopy is not possible in most of cases.To address this issue,molecular techniques are the viable alternative for identification of species as well as molecular level differences within a species（isolates） of parasites.Different DNA based molecular techniques viz.PCR,AFLP,RAPD,RFLP,PCR-SSCP,real time PCR,DNA microarray etc.have been used for identification and to assess the genetic diversity among parasite population.For identification of species,the characteristic sequence of genomic DNA of different species should differ to allow the delineation of species,but at the same time,no/minor variation within the species should exist.In contrast,for purpose of identifying population variants（strains/isolates）, a considerable degree of variation in the sequence should exist within a species.Various target regions,including nuclear ribosomal DNA（rDNA）,mitochondrial DNA（mtDNA） or repetitive DNA elements（microsatellite loci）,which show considerable variation in the number of repeats within individuals have been employed to achieve the identification of parasites species or strain.

Survey on gastrointestinal parasites and detection of Cryptosporidium spp. on cattle in West Java,Indonesia

Objective:To evaluate the presence of gastrointestinal parasites on cattle in Indonesia because the prevalence of parasites varies between counlries depending on the terrain surrounding livestock farms and investigations in Indonesia have never been performed.Methods:Fecal samples from cattle at 35 farms in 7 districts in West Java,Indonesia,has been examined using the floatation or sedimentation methods,and a immunofluorescence assay and experimentally inoculation to mice for Cryptosporidium or Giardia spp.Results:153 of 394 examined cattle(38.8%)were infected with gastrointestinal parasites.The prevalence of Eimeria spp.,Nematoda spp.(including Oesophagustomum and Bunostomum-like),Fasciola gigantica and Paramphistomum spp.was 22.4%,11.2%,12.5%and 3.8%,respectively.Cryptosporidium andersoni(C.andersoni)was also found in two samples.One isolate of this parasite was confirmed to be transmitted to mice,in contrast to the isolates from other countries.Conclusions:although this survey is preliminary,the results shows that the infection of gastrointestinal parasites in Indonesia was not high,but these infected cattle could be as a potential source leading to economic losses in livestock production.

Oomycetes and fungi:important parasites on marine algae

Considering that the field is largely unexplored and its importance to aquaculture,outline of oomycetes and fungi parasiting on marine algae was provided in this paper,including 15 species of oomycetes,six species of chytrids,31 Ascomycota species and one species of mitosporic fungi.In natrue,both the oomycetes and chytrids frequently occurred and induced prevalences of disease which could destroy the populations of host plants greatly.However,the parasites in Ascomycota on algae have never occurred as epidemics so far.Some issues relating to the field were discussed such as performing tests to satisfy Koch＇s postulates,investigations of host specificity,interactions between host and parasite and the potential effects of environmental factors on occurrence of a disease,which are urgent in need of further investigations.

Temporal-spatial patterns of intestinal parasites of the Hooded Crane(Grus monacha) wintering in lakes of the middle and lower Yangtze River floodplain

Background: Parasites have adverse effects on the life and survival of many migratory waterbirds, especially birds on the endangered species list. Hooded Cranes are large migratory colonial waterbirds wintering in wetlands,which are prone to parasite infection, thus monitoring the diversity of parasites is important for sound wetland management and protection of this species.Methods: From November 2012 to April 2013, we collected 821 fresh faecal samples from the three lakes(Poyang,Caizi and Shengjin Lake) in the lower and middle Yangtze River floodplain, and detected with saturated brine floating and centrifugal sedimentation methods. Parasite eggs were quantified with a modified Mc Master's counting method.Results: In this study, 11 species of parasites were discovered, i.e., two coccidium(Eimeria gruis, E. reichenowi), five nematodes(Capillaria sp., Strongyloides sp., Ascaridia sp., Trichostrongylus sp., Ancylostomatidae), three trematodes(Echinostoma sp., Echinochasmus sp., Fasciolopsis sp.) and one cestode(Hymenolepis sp.). About 57.7% of the faecal samples showed parasitic infection. All species of parasites were found at the three sites except Hymenolepis which was not found at Poyang Lake. While most samples were affected by only one or two species of parasites, infection by Eimeria spp. was the most common(53.1%). From One-Way ANOVA analysis of the three lakes, parasite species richness index(p = 0.656), diversity index(p = 0.598) and evenness index(p = 0.612) showed no significant difference. According to the statistical analysis of our data, there were no significant difference in parasite species richness index(p = 0.678) and evenness index(p = 0.238) between wintering periods, but a strong difference in diversity index(p < 0.05).Conclusions: Our study suggests that in the wintering Hooded Crane populations, parasite diversity is more sensitive to changes in the overwintering periods than to locations. This also indicates that with the limitations of migration distance, the parasites may not form the differentiation in Hooded Crane populations of the three lakes.

Parasites may exit immunocompromised northern pig-tailed macaques (Macaca leonina)infected with SIVmac239

Parasites can increase infection rates and pathogenicity in immunocompromised human immunodeficiency virus （HIV） patients. However, in vitro studies and epidemiological investigations also suggest that parasites might escape immunocompromised hosts during HIV infection Due to the lack of direct evidence from animal experiments, the effects of immunocompromised hosts parasitic infections on remain unclear. Here we detected 14 different parasites in six northern pig-tailed macaques （NPMs） before or at the 50th week of simian immunodeficiency virus （SIV） infection by ELISA. The NPMs all carried parasites before viral injection. At the 50th week after viral injection, the individuals with negative results in parasitic detection （i.e., 08247 and 08287） were characterized as the Parasites Exit （PE） group, with the other individuals （i.e., 09203, 09211, 10205, and 10225） characterized as the Parasites Remain （PR） group. Compared with the PR group, the NPMs in the PE group showed higher viral loads, lower CD4＋ T cells counts, and lower CD4/CD8 rates. Additionally, the PE group had higher immune activation and immune exhaustion of both CD4~ and CD8~ T cells. Pathological observation showed greater injury to the liver, cecum, colon, spleen, and mesenteric lymph nodes in the PE group This study showed more seriously compromised immunity in the PE group, strongly indicating that parasites might exit an immunocompromised host.

Prevalence of Gastrointestinal Parasites of Horses and Donkeys in and around Gondar Town, Ethiopia

A cross sectional study was conducted from October 2010 to June 2011 in and around Gondar town to identify the species and determine prevalence of gastrointestinal parasites in donkeys and horses. Gross examination, direct fecal smear, sedimentation and floatation techniques were utilized to identify the eggs and larvae of parasites in feces. A total of 384 horses and donkeys were examined for gastrointestinal parasites. The overall prevalence of gastrointestinal parasites was 92.71% (356 from 384) with 80.95% (85 from 105) and 97.13% (271 from 279) in horses and donkeys, respectively. Prevalence of Strongyle, Parascaris equorum, Oxyuris equi, Gastrodiscus aegyptiacus and Gastrophilus intestinalis was 66.67%, 43.8%, 0.95%, 2.86%, and 0.95%, respectively in horses. Prevalence of gastrointestinal parasites was 87.81%, 42.29%, 4.30%, 5.73%, 1.43%, 3.58% and 0.72% for Strongyles, Parascaris equorum, Oxyuris equi, Fasciola, Tricuris, Gastrodiscus aegyptiacus and Gastrophilus intestinalis in donkeys, respectively. There was a statisticcally significant difference between species, housing and among feed types in prevalence of equine gastrointestinal parasites

Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films

Objective:To determine the frequency of malaria parasite detection from the buffy coal blood films by using capillary tube in falciparum malaria patients with negative conventional thick films.Methods:Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study.The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases,Bangkok,Thailand for 28 day.Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia,then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film.The first negative conventional thick films were compared with buffy coat thick films for parasite identification. Results:Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients(27.8%) with asexual forms of Plasmodium falciparum.Conclusions:The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8%of patients whose conventional thick films show negative parasitemia.

Nanobiotechnology for the Detection and Control of Waterborne Parasites

Nowadays, the fast development of nanobiotechnology, has led to rapid diagnosis of important infectious diseases such as arboviruses-borne diseases, vector-borne infections and waterborne parasites diseases and others in order to reduce and avoid further dissemination of the infections within the general population. Furthermore, new nanomedicines based on the application of silver and gold nanoparticles which are less toxic, more effective, and that does not generate resistance could help to solve the problems of parasitic disease like leishmaniasis and chagas disease. It turns out that the combination of nanoparticles with antibiotics not only reduces the toxicity of both agents towards human cells but also enhances their ability to destroy bacteria by facilitating the binding of antibiotics to the microbes. Moreover, combining nanoparticles with antimicrobial peptides and essential oils with nanoparticles generates genuine synergy against microbial resistance.

Effects of Plant Tannin Extracts Supplementation on Animal Performance and Gastrointestinal Parasites Infestation in Steers Grazing Winter Wheat

Twenty-six stocker cattle (286.1 ± 25.7 kg) were used to quantify the effect of commercial plant tannin extracts (control vs. mimosa and chestnut tannins) on animal performance, gastrointestinal parasites control and plasma metabolite changes in heifers grazing winter wheat forage (Triticum aestivum L. var. “cutter”). The forage biomass and crude protein content were generally similar among treatments. Initial live-weight (LW) was similar among treatments, although final LW (P = 0.1) and average daily gain (ADG;P P Ostertagia was lower (P P P < 0.02) for chestnut tannins group than for control, and intermediate for mimosa tannins. However, cholesterol level was similar among treatment after 20 days cessation of tannins treatments. Our data suggest that heifers grazing winter wheat forage supplemented with plant tannins rather than control (non-tannins group) increased ADG (8% to 19%) for mimosa and chestnut tannins groups, respectively with no detectable detrimental effects on animal health. The increase in ADG may be due to decrease fecal parasites infections.

Protozoan parasites in irritable bowel syndrome:A case-control study

AIM To investigate the putative role of protozoan parasites in the development of irritable bowel syndrome(IBS).METHODS The study included 109 IBS consecutive adult patients fulfilling the Rome Ⅲ criteria and 100 healthy control subjects. All study subjects filled a structured questionnaire, which covered demographic information and clinical data. Fresh stool samples were collected from patients and control subjects and processed within less than 2 h of collection. Iodine wet mounts and Trichrome stained smears prepared from fresh stool and sediment concentrate were microscopically examined for parasites. Blastocystis DNA was detected by polymerase chain reaction, and Cryptosporidium antigens were detected by ELISA.RESULTS A total of 109 IBS patients(31 males, 78 females) with a mean age ± SD of 27.25 ± 11.58 years(range: 16-60 years) were enrolled in the study. The main IBS subtype based on the symptoms of these patients was constipation-predominant(88.7% of patients). A hundred healthy subjects(30 males, 70 females) with a mean ± SD age of 25.0 ± 9.13 years(range 18-66 years) were recruited as controls. In the IBS patients, Blastocystis DNA was detected in 25.7%, Cryptosporidium oocysts were observed in 9.2%, and Giardia cysts were observed in 11%. In the control subjects, Blastocystis, Cryptosporidium and Giardia were detected in 9%, 0%, and 1%, respectively. The difference in the presence of Blastocystis(P = 0.0034), Cryptosporidium(P = 0.0003), and Giardia(P = 0.0029) between IBS patients and controls was statistically significant by all methods used in this study.CONCLUSION Prevalence of Blastocystis, Cryptosporidium and Giardia is higher in IBS patients than in controls. These parasites are likely to have a role in the pathogenesis of IBS.

Coevolution of acoustical communication between obligate avian brood parasites and their hosts

The mutually antagonistic processes producing adaptations and counter-adaptations in avian brood parasites and their hosts provide a model system for the study of coevolution;this topic has long been an area of focus in ornithology and evolutionary biology.Although there is an extensive body of literature dealing with avian brood parasitism,few empirical studies have considered the effects of the coevolutionary processes associated with brood parasitism on the acoustic characteristics of parent–offspring communication.Under the strong selection pressures associated with brood parasitism,parasitic birds may,for instance,produce deceptive songs.The host may in turn evolve the ability to recognize these sounds as deceptive.At present,the mechanisms underlying the different competitive strategies employed by hosts and parasitic birds remain unclear.Here,we reviewed previous studies that investigated acoustic traits in scenarios of brood parasitism,highlighting possible adaptive functions.Using a meta-analysis,we identified no heterogeneity among studies of begging call adaptations in parasitic nestlings.However,our results may have been affected by the small number of applicable papers available for analysis.Our meta-analysis also suggested that studies of acoustic communication and transmission in adult hosts were highly heterogenous,suggesting that research methods were inconsistent among studies.Finally,we identified knowledge gaps and proposed several lines of future research.

Expansion of Small Terrestrial Mammals and Their Parasites into the Barun Valley (Makalu Mt. Region, Nepal Himalaya) Linked with Changes in Glaciation and Human Activities

The article is based on collection of small terrestrial mammals(Soriculus nigrescens,Episoriculus caudatus, Neodon sikimensis,Alticola stoliczkanus, Niviventer eha and Ochotona roylei) collected in the Barun Valley, east Nepal in the pre-monsoon period of 1973.Zoogeographic and ecological characteristics and altitudinal stratification of these species are analysed, depending both on abiotic(geomorphological and climatic) and biotic(vegetation, and human presence and activities)factors. All the captured mammals were examined for ecto- and endoparasities. Infestations of Trombiculid mites and Ixodid ticks were tightly linked to the local habitat where these ectoparasites must survive during their nonparasitic phase. Analysis of their occurrence completes the reconstruction of migration routes during the expansion of small mammals into the Barun Valley and the exacerbating influence of human activities(summer pasturing,mountaineering expeditions and trekking parties).An indicator of anthropogenic influence was the occurrence of synantropic flies. The potential medical importance of these findings is discussed.It is assumed a possible occurrence of arboviruses transmitted by ticks and also rickettsioses(transmitted by ticks and chigger mites). As far bacteriological infections, plague cannot be excluded.

MICROHABITAT DISTRIBUTION OF METAZOAN PARASITES ON GILLS OF SILURUS ASOTUS IN JIANGKOU RESERVOIR, JIANGXI PROVINCE, CHINA

This paper deals with the proportional distribution, niche breadth and niche overlap of two metazoan parasites(copepods species, Ergasilus anchoratus Markewitsch, 1946 and Pseudergasilus parasiluri Yamaguti, 1936) and monogeneans (in the genus Silurodiscoides Gussev, 1976) found on gills of the fish, Silurus asotus L. from Jiangkou Reservoir in Jiangxi Province,China. E.anchoratus was the common and dominant metazoan parasite on gills of the fish in this locality as indicated by the higher infection levels, and distributed almost evenly on gill arches without any observed gill arch preference, as shown by the wide proportional distribution and broad niche breadth. P. parasiluri and monogeneans in Silurodiscoides were found also without any significant gill arch preference although they had a rather narrow niche breadth. The observed significant overlap between P. parasiluri and Silurodiscoides spp. may be simply due to the lower infection levels of the parasites. The observed pattern of unrestricted distributions of the parasitic copepods on gills of the fish may be accounted for, at least in part, by the moving ability of the copepods, and may also indicate that the parasite does not exhibit any feature of gill arch preference. However, further experimental research is needed to verify the microhabitat distribution of the parasites.