Parasite's Cycle Research Articles

Targeting cysteine proteases in trypanosomatid disease drug discovery.

Chagas disease and human African trypanosomiasis are endemic conditions in Latin America and Africa, respectively, for which no effective and safe therapy is available. Efforts in drug discovery have focused on several enzymes from these protozoans, among which cysteine proteases have been validated as molecular targets for pharmacological intervention. These enzymes are expressed during the entire life cycle of trypanosomatid parasites and are essential to many biological processes, including infectivity to the human host. As a result of advances in the knowledge of the structural aspects of cysteine proteases and their role in disease physiopathology, inhibition of these enzymes by small molecules has been demonstrated to be a worthwhile approach to trypanosomatid drug research. This review provides an update on drug discovery strategies targeting the cysteine peptidases cruzain from Trypanosoma cruzi and rhodesain and cathepsin B from Trypanosoma brucei. Given that current chemotherapy for Chagas disease and human African trypanosomiasis has several drawbacks, cysteine proteases will continue to be actively pursued as valuable molecular targets in trypanosomatid disease drug discovery efforts.

Case-series study of hepatic echinococcal cysts in Serbia: viability of scolices, seropositivity and epidemiological characteristics.

Cystic echinococcosis (CE) is an endemic helminthic disease caused by infection with Echinococcus granulosus metacestodes. Although CE is endemic in the Balkan region, the exact epidemiology remains unknown. We conducted a case-series study with the aim of evaluating the correlation between seropositivity, socio-epidemiological data, pre-operative treatment with albendazole and viability of protoscolices in human hepatic hydatid cysts. Consecutive patients with hepatic CE underwent surgery to extract E. granulosis cysts. The viability of protoscolices was measured by their ability to absorb 0.1% eosin. Socio-epidemiological data were collected and serological testing was performed. In the present study, 38 patients (28 adults and 10 children) with hepatic CE were treated surgically. The scolex viability test was positive in 30/38 (79%) samples. All patients with non-viable cysts had seronegative results. The viability test was positive in 11/12 (91.6%) adult patients with pre-operative albendazole treatment and in 9/10 (90%) children. Statistically more patients were from an urban area compared with a rural area (65.8% vs. 15.7%). The increasing number of stray dogs shedding E. granulosus eggs in urban public areas in the Balkans might be the reason for the significant difference in the rate of infection between urban and rural areas in the present study. In addition, uncontrolled slaughtering of livestock, common in rural settlements, and feeding the infected viscera to dogs, favour the maintenance of the parasite cycle. We believe that the results of our study will encourage physicians, veterinarians and health authorities to initiate a programme to prevent and control CE in the Balkan region.

Mining a differential sialotranscriptome of Rhipicephalus microplus guides antigen discovery to formulate a vaccine that reduces tick infestations

BackgroundTicks cause massive damage to livestock and vaccines are one sustainable substitute for the acaricides currently heavily used to control infestations. To guide antigen discovery for a vaccine that targets the gamut of parasitic strategies mediated by tick saliva and enables immunological memory, we exploited a transcriptome constructed from salivary glands from all stages of Rhipicephalus microplus ticks feeding on genetically tick-resistant and susceptible bovines.ResultsDifferent levels of host anti-tick immunity affected gene expression in tick salivary glands; we thus selected four proteins encoded by genes weakly expressed in ticks attempting to feed on resistant hosts or otherwise abundantly expressed in ticks fed on susceptible hosts; these sialoproteins mediate four functions of parasitism deployed by male ticks and that do not induce antibodies in naturally infected, susceptible bovines. We then evaluated in tick-susceptible heifers an alum-adjuvanted vaccine formulated with recombinant proteins. Parasite performance (i.e. weight and numbers of females finishing their parasitic cycle) and titres of antigen-specific antibodies were significantly reduced or increased, respectively, in vaccinated versus control heifers, conferring an efficacy of 73.2%; two of the antigens were strong immunogens, rich in predicted T-cell epitopes and challenge infestations boosted antibody responses against them.ConclusionMining sialotranscriptomes guided by the immunity of tick-resistant hosts selected important targets and infestations boosted immune memory against salivary antigens.

ABORDAGEM DA SAÚDE ÚNICA NA OCORRÊNCIA DE ENTEROPARASITAS EM HUMANOS DE ÁREA URBANA NO NORTE DO PARANÁ

As enteroparasitoses causadas por helmintos e protozoários infectam humanos e animais no mundo todo, e sua prevalência está relacionada à falta de hábitos de higiene pessoal em consequência do seu ciclo oral-fecal. No Brasil, como não são doenças de notificação obrigatória, é possível que sua prevalência esteja subnotificada. Em Londrina, não existem dados sobre a prevalência dessas parasitoses na população urbana adulta, que ofereçam suporte para delinear programas de saúde preventiva na comunidade. Foram coletadas amostras de fezes de 187 humanos residentes na área urbana de Londrina para pesquisa de enteroparasitas. Dados epidemiológicos foram coletados por meio de um questionário epidemiológico aplicado a todos os participantes. As variáveis associadas ao risco foram analisadas conforme foram relatadas pelos indivíduos parasitados. Foram discutidos: gênero, idade, renda familiar mensal, lavagem das mãos antes da alimentação e após utilizar o banheiro, água de consumo, ocorrência de diarreia nos últimos sete dias, abastecimento de água e rede de esgoto. Foram detectados ovos ou cistos de parasitas em 8/187 (4,27%) amostras investigadas. A ocorrência do protozoário Giardia spp. foi verificada em 7/187 (3,74%) amostras e o helminto Enterobius vermiculares em 1/187 (0,53%). Devido ao ciclo destes parasitas envolver a saúde humana, animal e do ambiente, é sugerido que a ocorrência das enteroparasitoses reduza por meio da abordagem de Saúde Única na área urbana de Londrina, PR.

Plasmodium falciparum Maf1 Confers Survival upon Amino Acid Starvation.

ABSTRACTThe target of rapamycin complex 1 (TORC1) pathway is a highly conserved signaling pathway across eukaryotes that integrates nutrient and stress signals to regulate the cellular growth rate and the transition into and maintenance of dormancy. The majority of the pathway’s components, including the central TOR kinase, have been lost in the apicomplexan lineage, and it is unknown how these organisms detect and respond to nutrient starvation in its absence. Plasmodium falciparum encodes a putative ortholog of the RNA polymerase (Pol) III repressor Maf1, which has been demonstrated to modulate Pol III transcription in a TOR-dependent manner in a number of organisms. Here, we investigate the role of P. falciparum Maf1 (PfMaf1) in regulating RNA Pol III expression under conditions of nutrient starvation and other stresses. Using a transposon insertion mutant with an altered Maf1 expression profile, we demonstrated that proper Maf1 expression is necessary for survival of the dormancy-like state induced by prolonged amino acid starvation and is needed for full recovery from other stresses that slow or stall the parasite cell cycle. This Maf1 mutant is defective in the downregulation of pre-tRNA synthesis under nutrient-limiting conditions, indicating that the function of Maf1 as a stress-responsive regulator of structural RNA transcription is conserved in P. falciparum. Recent work has demonstrated that parasites carrying artemisinin-resistant K13 alleles display an enhanced ability to recover from drug-induced growth retardation. We show that one such artemisinin-resistant line displays greater regulation of pre-tRNA expression and higher survival upon prolonged amino acid starvation, suggesting that overlapping, PfMaf1-associated pathways may regulate growth recovery from both artemisinin treatment and amino acid starvation.

Cercariae (Digenea: Strigeidae, Diplostomidae) in Biomphalaria straminea (Planorbidae) from a rice field in Northeastern Argentina

The rice fields can provide habitats for many species of aquatic invertebrates, as insects, molluscs, crustaceans; and vertebrates, as fish, amphibians, reptiles and birds, which may act as hosts in the life cycles of digenean parasites. In this context, the goal of the present study was to describe the cercariae found in Biomphalaria straminea from a rice field in Northeastern Argentina. This freshwater snail inhabits a wide variety of environments, favoring shallow, temporary and standing or slow-flowing freshwater bodies. For this study, snails were collected from the cultivated parcels and irrigated channels during the flooding periods (from the time of sowing to soon after harvesting of the rice) between December 2010 and May 2011 and December 2011 and April 2012, in a rice field from Corrientes province, one of the main rice producers of Argentina. A total of 5 510 snails were examined of which 26 were infected with three different larval trematodes belonging to Strigeidae, Furcocercaria V (0.40 %) and Furcocercaria XX (0.04 %), and Diplostomidae, Furcocercaria XIX (0.04 %). Furcocercaria XX and Furcocercaria XIX were present in one rice cultivation cycle, while Furcocercaria V was present in both rice cultivation cycles. The prevalence of the different furcocercariae was somewhat higher in the second rice cultivation cycle. The cercariae described are new records for Argentina that added to 53 cercariae previously reported for Biomphalaria spp. in different aquatic environments of country. The study of the digenean larval in rice fields is important because contribute to the knowledge of the biodiversity of these environments.

Rabbits killing hares: an invasive mammal modifies native predator–prey dynamics

AbstractInvasive species management requires practical evidence of the impacts of introduced species over ecosystem structure and functioning. Theoretical ecology and empirical data support the potential of introduced mammals to drive native species to extinction, indeed the majority of practical evidence comes from insular environments, where conditions may differ from the mainland. We analyzed the effects of an introduced lagomorph, the eastern cottontail Sylvilagus floridanus on two native mammals, the European hare Lepus europaeus and the red fox Vulpes vulpes. We used relative abundances collected over 8 years at 30 protected areas in Italy. A generalized linear mixed model was fit to test various hypotheses about the relationships between cottontails, foxes and climatic conditions over the abundance of native hares. In our model, hare and cottontail abundances did not show a negative relationship and we believe that no direct competition occurs between the two species. However, the relationship between fox and hare abundances, positive when cottontails were scarce, became more and more negative as cottontails increased: this supports the hypothesis that indirect dynamics like apparent competition exists between the two lagomorphs. Climatic conditions, expressed through the North Atlantic Oscillation, did not affect the relationship between cottontail and hare abundances. As the impact of parasites on mammal populations is generally climate dependent, we believe that cottontails do not play a direct role in the cycle of parasites affecting hares. Our results provide a clue that an invasive mammal, the eastern cottontail, is modifying the predator–prey relationship between two native species in a non‐insular environment. The existence of such dynamics should lead wildlife managers to account for the effect of introduced species in their decision making, directing control activities on cottontails and not on native foxes.

The evolution of transmission mode.

This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode have been inferred through experimental and phylogenetic studies, including changes in transmission associated with host shifts and with evolution of the unusually complex life cycles of many parasites. Understanding the forces that determine the evolution of particular transmission modes presents a fascinating medley of problems for which there is a lack of good data and often a lack of conceptual understanding or appropriate methodologies. Our best information comes from studies that have been focused on the vertical versus horizontal transmission dichotomy. With other kinds of transitions, theoretical approaches combining epidemiology and population genetics are providing guidelines for determining when and how rapidly new transmission modes may evolve, but these are still in need of empirical investigation and application to particular cases. Obtaining such knowledge is a matter of urgency in relation to extant disease threats.This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.

Ethanolic extracts of Inula viscosa, Salix alba and Quercus calliprinos, negatively affect the development of the entomopathogenic nematode, Heterorhabditis bacteriophora – A model to compare gastro-intestinal nematodes developmental effect

Heterorhabditis bacteriophora can represent a model system for herbal medication against gastro-intestinal strongylid parasites in determining the recovery and development due to their unique parasitic infectious cycle. The fact that plant extracts impair nematode development is known but their differential impact on stages of the life cycle of H. bacteriophora has never been investigated. We examined the developmental stages resumed from eggs, young juveniles (J1–3), infective juveniles (IJs), young and adult hermaphrodites of H. bacteriophora upon exposure to crude ethanolic extracts of Inula viscosa, Salix alba, and Quercus calliprinos at concentrations of 600, 1200, and 2400ppm. Our results showed that plant extracts were highly toxic to the survival of the eggs and young juveniles J1 to J3 at all concentrations. The plant extracts inhibited their development and were associated with low reproduction parameters (i.e. fecundity and viability of eggs). The IJs, J4, young and developed hermaphrodites displayed concentration-dependent negative effect on development with less egg count, poor vulval muscle development, loss of egg laying capacity and progeny development by matricidal hatching. Plant extract of I. viscosa at low (600ppm) concentration did not impair vulval development. These results suggest that these plant extracts show potential for the control of parasitic rhabditids.

Small rodents as paratenic or intermediate hosts of carnivore parasites in Berlin, Germany.

Rodents are important intermediate and paratenic hosts for carnivore parasites, including the important zoonotic agents Toxoplasma, Echinococcus and Toxocara. Monitoring of such parasites in rodents can be used to detect increasing risks for human and veterinary public health. Rodents were trapped at four sites in Berlin, two near the city center, two at the periphery. PCRs were conducted to detect Coccidia (target ITS-1) and specifically Toxoplasma gondii (repetitive element) in brain and ascarids (ITS-2) in muscle or brain tissue. During necropsies, metacestodes were collected and identified using ITS-2 and 12S rRNA PCRs. An ELISA to detect antibodies against Toxocara canis ES antigens was performed. Within the 257 examined rodents, the most frequently observed parasite was Frenkelia glareoli predominantly found in Myodes glareolus. T. gondii was only detected in 12 rodents and Microtus spp. (although strongly underrepresented) had a significantly increased chance of being positive. Neither Echinococcus nor typical Taenia parasites of dogs and cats were found but Mesocestoides litteratus and Taenia martis metacestodes were identified which can cause severe peritoneal or ocular cysticercosis in dogs, primates and humans. Using PCR, the ascarids T. canis (n = 8), Toxocara cati (4) and Parascaris sp. (1) were detected predominantly in muscles. Seroprevalence of T. canis was 14.2% and ELISA was thus more sensitive than PCR to detect infection with this parasite. Non-parametric multidimensional scaling and cluster analysis revealed that parasite communities could be grouped into an urban and a peri-urban cluster with high frequency of ascarid-positive rodents in urban and high frequency of F. glareoli in peri-urban sites. Prevalence rates of parasites in rodents with potential impact for human or veterinary public health are considerable and the monitoring of transmission cycles of carnivore parasites in intermediate rodent hosts is recommended to estimate the health risks arising from wild and domesticated carnivores.

A novel flow cytometric application discriminates among the effects of chemical inhibitors on various phases of Babesia divergens intraerythrocytic cycle.

Human babesiosis is a global emerging infectious disease caused by intraerythrocytic parasites of the genus Babesia. Its biology has remained largely unexplored due to a lack of critical tools and techniques required to define the various stages and phases of the parasite's cycle in its host RBC and the interplay between host and parasite. This article presents a powerful set of tools combining stage synchronization of the parasite with a platform that encompasses both a flow cytometric evaluation of the subpopulation structure of the parasite population together with a morphological assessment of the population parasites using light microscopy of conventional Giemsa stained smears. Together, these yield specific information on the effect of any drug/condition of interest and its targeted biological process, allowing the characterization of the adaptive response of parasites to a particular stressor agent. Three inhibitors were used in this study, each targeting a specific phase of the parasite's lifecycle, neuraminidase for host cell invasion, N-acetyl-L-leucyl-L-leucyl-L-norleucinal for parasite development and EGTA for parasite egress from the host cell. Results presented prove the power of this combination platform in discriminating the specific targets among the life-cycle processes of the parasite-invasion, development/proliferation and egress. This will expand the range of queries that can now be successfully addressed in this parasite, opening avenues for the development of new methods to control babesiosis, either by chemicals (screening for new chemotherapy drugs or defining levels of parasite resistance) or physical methods (light irradiation or heat shock used in pathogen reduction/elimination methods). © 2017 International Society for Advancement of Cytometry.

HGF Secreted by Activated Kupffer Cells Induces Apoptosis of Plasmodium-Infected Hepatocytes.

Malaria liver stage infection is an obligatory parasite development step and represents a population bottleneck in Plasmodium infections, providing an advantageous target for blocking parasite cycle progression. Parasite development inside hepatocytes implies a gross cellular insult evoking innate host responses to counteract intra-hepatocytic infection. Using primary hepatocyte cultures, we investigated the role of Kupffer cell-derived hepatocyte growth factor (HGF) in malaria liver stage infection. We found that Kupffer cells from Plasmodium-infected livers produced high levels of HGF, which trigger apoptosis of infected hepatocytes through a mitochondrial-independent apoptosis pathway. HGF action in infected hepatocyte primary cultures results in a potent reduction of parasite yield by specifically sensitizing hepatocytes carrying established parasite exo-erythrocytic forms to undergo apoptosis. This apoptosis mechanism is distinct from cell death that is spontaneously induced in infected cultures and is governed by Fas signaling modulation through a mitochondrial-dependent apoptosis pathway. This work indicates that HGF and Fas signaling pathways are part of an orchestrated host apoptosis response that occurs during malaria liver stage infection, decreasing the success of infection of individual hepatocytes. Our results raise the hypothesis that paracrine signals derived from Kupffer cell activation are implicated in directing death of hepatocytes infected with the malaria parasite.

Leishmaniasis: General Aspects Related with the Disease, the Parasite Cycle, Available Drugs, Novel Prototypes and Vaccines

A leishmaniose foi considerada por muito tempo uma doenca negligenciada por apenas possuir casos registrados em paises subdesenvolvidos. Com o passar dos anos e fatores como a globalizacao, que proporcionou grande migracao de pessoas e animais, a doenca se tornou endemica em paises onde nao havia muitos casos confirmados. Os tratamentos atuais contra essa doenca sao eficazes, porem os efeitos colaterais e o preco do tratamento completo em algumas partes do mundo acabam impedindo o tratamento da doenca ou nao permitindo o tratamento completo, resultando em evolucao para os estagios mais graves da doenca, podendo levar o paciente a obito. Neste contexto, diversos grupos de pesquisa tem buscado novos candidatos a farmacos a partir de fontes naturais ou de medicamentos com funcao antiparasitaria. Neste artigo sao discutidas as principais formas de tratamento da doenca atualmente, assim como novos compostos bioativos que vem sendo desenvolvidos buscando alternativas com menores efeitos colaterais e mais efetivas em comparacao com os tratamentos atuais, alem do entendimento geral sobre a doenca e seu ciclo.

Occurrence of two novel actinospore types (Cnidaria: Myxosporea) in Brazilian fish farms, and the creation of a novel actinospore collective group, Seisactinomyxon.

The involvement of oligochaetes in the life cycles of fresh water myxozoan parasites in Brazil was investigated. Of 333 oligochaetes collected in a fish farm in the State of São Paulo, three (0.9%) released Aurantiactinomyxon type spores. From 86 worms collected in a fish farm in Mato Grosso do Sul State, 1 (0.9%) released actinospores with a novel morphology for which we propose the name Seisactinomyxon. Infected oligochaetes were identified by morphology: all belonged to family Naididae, with Pristina americana the host for Aurantiactinomyxon and Slavina evelinae the host of Seisactinomyxon. This is the first report of the involvement these two species of oligochaetes in the life cycle of myxozoans. Small subunit rDNA sequences of the Aurantiactinomyxon (1204 nt) and Seisactinomyxon (1877 nt) did not match any previously sequenced myxozoan. Phylogenetic analyses showed that both actinospore types fell in a clade formed by six Myxobolus spp. that parasitize Characiformes fishes.

Leishmanicidal Activity of Oleuropein: Leishmania donovani Promastigote Cell Death through a Possibly ROS-Independent Mechanism

The development of potent and inexpensive antiparasitic agents for common use is imperative due to the absence of an effective and safe treatment for visceral leishmaniasis, a devastating parasitic disease. Oleuropein, a secoiridoid, exerts an antileishmanial effect on promastigotes of Leishmania infantum, L. major and L. donovani, as well as on amastigotes of L. donovani in in vitro and in vivo experimental models. In this study, our aim was to characterize how oleuropein drives parasites into cell death. Our hypothesis is that oleuropein promotes an apoptotis-like cell death which restrains the inflammatory processes that facilitate parasitic dissemination. Logarithmic-phase L. donovani promastigotes were treated with oleuropein for 24, 48 and 72 h, and parasitic cell cycle, parasitic membrane asymmetry and intracellular generalized oxidative stress were assessed via flow cytometry. Morphological alterations were analyzed with confocal microscopy. Cell-cycle analysis revealed that oleuropein fragmented parasite DNA within the first 24 h of incubation. In vitro treatment of promastigotes with oleuropein resulted in several morphological alterations and significant annexin V binding. Interestingly, oleuropein treatment did not increase the levels of intracellular reactive oxygen species until 48 h of incubation. Our findings suggest that oleuropein promotes apoptosis-like cell death in L. donovani promastigotes that is not being mediated by an induced endoparasitic oxidative stress.

Parásitos del pez luna Mola mola (Pisces: Molidae). Primer registro en aguas de la costa centro sur de Chile

In this study, we report parasitological findings in one Mola mola specimen examined and collected as by catch-off Tome, south central Chile, during october 2014. Adult stages of digeneans, Accacladium serpentulum and Accacladocoelium macrocotyle, cestode Anchistrocephalus microcephalus, and copepod Cecrops latreillii were isolated. Besides, at the larval stage, the third larval stage (L3) of nematode Anisakis sp. Type I, sensu Berland, 1961, and plerocerci larvae of cestode Molicola horridus were also observed. The results demonstrated the participation of M. mola as a definitive and intermediate or paratenic host in the life cycles of different parasites identified in the present study.

Investigation into the Physiological Significance of the Phytohormone Abscisic Acid in Perkinsus marinus, an Oyster Parasite Harboring a Nonphotosynthetic Plastid.

Some organisms have retained plastids even after they have lost the ability to photosynthesize. Several studies of nonphotosynthetic plastids in apicomplexan parasites have shown that the isopentenyl pyrophosphate biosynthesis pathway in the organelle is essential for their survival. A phytohormone, abscisic acid, one of several compounds biosynthesized from isopentenyl pyrophosphate, regulates the parasite cell cycle. Thus, it is possible that the phytohormone is universally crucial, even in nonphotosynthetic plastids. Here, we examined this possibility using the oyster parasite Perkinsus marinus, which is a plastid‐harboring cousin of apicomplexan parasites and has independently lost photosynthetic ability. Fluridone, an inhibitor of abscisic acid biosynthesis, blocked parasite growth and induced cell clustering. Nevertheless, abscisic acid and its intermediate carotenoids did not affect parasite growth or rescue the parasite from inhibition. Moreover, abscisic acid was not detected from the parasite using liquid chromatography mass spectrometry. Our findings show that abscisic acid does not play any significant roles in P. marinus.

Parasite communities and infection levels of the invasive Chinese sleeper Perccottus glenii (Actinopterygii: Odontobutidae) from the Naab river basin, Germany.

The Chinese sleeper (Perccottus glenii), an invasive Asian fish, was first registered in Germany in 2009 (westernmost extent of its invasive range). We sampled Chinese sleepers from two localities on the Bücherlgraben creek (a tributary of the River Naab) in south-eastern Germany in November 2015 and examined them for parasite infection. Twelve taxa were registered, including ciliates (unidentified Trichodina), a monogenean, three cestode species, two digenean taxa, two acanthocephalan species, two nematode species and one mollusc glochidia. Infracommunities consisted of 1-5 species, with 10% of fish uninfected. Three parasite species (Acanthocephalus anguillae, Gyrodactylus luciopercae and Pseudocapillaria tomentosa) were recorded on Chinese sleepers for the first time. The results highlight the important role of the Chinese sleeper as a second intermediate host in the life cycle of heron and grebe parasites. The Chinese sleeper parasite community displayed low homogeneity at both localities sampled, with allogenic parasites (metacercariae and mesocercoids) mostly shared. Differences between localities were mainly caused by autogenic parasites. No invasive parasites associated with the Chinese sleeper were observed in the study area, all parasites being representatives of European fauna. This supports the hypothesis of introduction via the aquarium trade or through transport with commercial fish.

Analysis of results of technique competition for parasitic disease diagnosis in Class A tertiary hospitals in Jiangxi Province, 2015

To understand the capability of parasitic disease diagnosis among professionals from the clinic laboratory of Class A tertiary hospitals in Jiangxi Province. The teams that took part in the competition were formed from 20 Class A tertiary hospitals, with 2 contestants per team. The competition contents included written examination and skill operation. The written examination involved the life cycle of parasites, immunological basis, detecting techniques, etiological diagnosis etc., and the skill operation involved making and dying thin and thick blood smears, making Kato-Katz's fecal thick smears, as well as microscopic examinations of smears. A total of 40 participants took part in the competition. Their total average score was 97.3±22.4 with the pass rate of 15.0%, in which the mean score of theoretical knowledge was 56.6±12.8 with the pass rate of 52.5%, and the mean score of skill operation was 40.8±12.4 with the pass rate of 5.0%. In the written examination, the scoring rate of the life cycle of soil-transmitted helminths was the highest (90.0%), and the rate of the basic knowledge of food-borne parasites was the lowest (31.5%). Both the pass rates of blood smear making and examination were higher than those of Kato-Katz's thick smears, and the differences were statistically significant (both P < 0.05). The detection rates of Plasmodium vivax, Plasmodium falciparum, Plasmodium ovale and negative slides of the contestants were 38.8%, 45.0%, 35.0% and 25.0% respectively. As to the microscopic examination of helminth eggs, the detection rate of Trichuris trichiura egg was the highest (87.5%), and the rate of the Sparganum mansoni egg was the lowest (2.5%). The scores of Kato-Katz's thick smear making and examination of the contestants from the provincial level hospitals were higher than those from the city level hospitals (both P < 0.05), and the score of those from teaching hospitals in Kato-Katz's thick smear making was higher than that of those from non-teaching hospitals (P < 0.05). The technique level of professionals from the clinic laboratory of the Class A tertiary hospitals cannot meet the needs of the diagnosis of parasitic diseases in Jiangxi Province, which should arouse the attention of the health authorities and hospitals.

The phylogeny and life cycle of two species of Profilicollis (Acanthocephala: Polymorphidae) in marine hosts off the Pacific coast of Chile.

Resolving complex life cycles of parasites is a major goal of parasitological research. The aim of this study was to analyse the life cycle of two species of the genus Profilicollis, the taxonomy of which is still unstable and life cycles unclear. We extracted individuals of Profilicollis from two species of crustaceans (intermediate hosts) and four species of seagulls (definitive hosts) from sandy-shore and estuarine habitats along the south-east Pacific coast of Chile. Mitochondrial DNA analyses showed that two species of Profilicollis infected intermediate hosts from segregated habitats: while P. altmani larvae infected exclusively molecrabs of the genus Emerita from fully marine habitats, P. antarcticus larvae infected the crab Hemigrapsus crenulatus from estuarine habitats. Moreover, P. altmani completed its life cycle in four seagulls, Chroicocephalus maculipennis, Leucopheus pipixcan, Larus modestus and L. dominicanus, while P. antarcticus, on the other hand, completed its life cycle in the kelp gull L. dominicanus. Accordingly, our results show that two congeneric parasites use different and spatially segregated species as intermediate hosts, and both are capable of infecting one species of definitive hosts. As such, our analyses allow us to shed light on a complex interaction network.