The intestinal parasitic nematode, Baylisascaris transfuga, was recorded in wild rodents for the first time. Representatives of four murid species (15 Myodes rufocanus, 10 M. rutilus, 3 M. glareolus and 27 Microtus oeconomus) were collected in the White Sea coastal habitats in the south of the Kola Peninsula, Russia in July 2015 and examined for parasites. Encapsulated nematode larvae were detected in the mesentery and the large intestine wall of one grey-sided vole (M. rufocanus) and one tundra vole (M. oeconomus). Based on morphology, the larvae were identified as belonging to the genus Baylisascaris Sprent 1968. The partial 18S rDNA sequence of the larvae from the voles was obtained and fully corresponded to the sequence of Baylisascaris transfuga in the NCBI GenBank. The ITS rDNA and CoxI mtDNA sequences these larvae were also similar to the respective B. transfuga sequences in GenBank. The presence of B. transfuga in wild rodents suggests that rodents can participate in the B. transfuga life cycle.

Previously we have characterized the complete gene encoding a pyruvate decarboxylase (PDC)/indolepyruvate decarboxylase (IPDC) of Phytomonas serpens, a trypanosomatid highly abundant in tomato fruits. Phylogenetic analyses indicated that the clade that contains the trypanosomatid protein behaves as a sister group of IPDCs of γ-proteobacteria. Since IPDCs are key enzymes in the biosynthesis of the plant hormone indole-3-acetic acid (IAA), the ability for IAA production by P. serpens was investigated. Similar to many microorganisms, the production of IAA and related indolic compounds, quantified by high performance liquid chromatography, increased in P. serpens media in response to amounts of tryptophan. The auxin functionality was confirmed in the hypocotyl elongation assay. In tomato fruits inoculated with P. serpens the concentration of free IAA had no significant variation, whereas increased levels of IAA-amide and IAA-ester conjugates were observed. The data suggest that the auxin produced by the flagellate is converted to IAA conjugates, keeping unaltered the concentration of free IAA. Ethanol also accumulated in P. serpens-conditioned media, as the result of a PDC activity. In the article we discuss the hypothesis of the bifunctionality of P. serpens PDC/IPDC and provide a three-dimensional model of the enzyme.

Lernaeenicus radiatus, a mesoparasitic pennellid copepod, has long been known in the northwest Atlantic with metamorphosed females infecting the muscle of marine fish. The study herein is the first to identify a definitive first host, black sea bass Centropristis striata, for L. radiatus supporting larval development to adults and sexual reproduction in the gills. This finding suggests a two-host life cycle for L. radiatus, with black sea bass as the first host. Heavy infections in the gill were associated with considerable pathology related to a unique and invasive attachment process that penetrated the gill and selectively attached to the gill filament cartilage. The morphology of the developing copepod was highly conserved with that of a related pennellid copepod, Lernaeocera branchialis, though was distinguished by the attachment process, unique pigmentation and other morphologic features described herein. Sequencing the small and large subunits of the ribosomal RNA and mitochondrial cytochrome c oxidase subunit I genes demonstrated L. radiatus to share closer identities with Lernaeocera and Haemobaphes spp. pennellid copepods rather than other Lernaeenicus spp. available in GenBank to date. Taxonomy of L. radiatus is discussed in relation to life cycles, tissue tropism, morphology and genetics of other closely related pennellid copepods.

The genus Androlaelaps was raised by Antonio Berlese in 1903 for those Laelaptidae in which leg ii of the male and female is furnished with spurs on the femur, genu and tibia. Amongst the mites taken on a Uganda unstriped grass-rat (Arvi-canthis abyssinicus rubescens Wroughton), numbers of two new species of this genus were found and are here described under the names Androlaelaps oudemansi and A. arvicanthis.

Some years ago, in endeavouring to obtain various stages in the life history of the liver-fluke in South Africa for teaching purposes, I found that, although the parasite is fairly common on some farms in this country, the intermediate host had not yet been definitely ascertained. In Europe, as is well known, the intermediate host is the fresh-water snail Limnaea truncatula, but this species has not been recorded with certainty from South Africa. The commonest fresh-water snail here is Physa (Isidora) tropica and a preliminary examination of a few specimens of this mollusc from Muizenberg Lake revealed abundant stages of fluke very closely resembling those of the liver-fluke. Additional specimens procured from the neighbourhood also afforded abundant material of the same stages. The only difficulty in accepting this as a solution of the problem was that, though placed in the most favourable conditions, the free swimming form (cercaria) was never observed to encyst.

1. Experimental systems are described for studying the interaction of compounds with various species of trichomonad. In vitro systems have been used to study the effects of compounds on trichomonads growing in culture and to determine the speed of action of compounds on non-dividing populations. In vivo experiments have utilized vaginal infections in hamsters and subcutaneous, intraperitoneal, intra-muscular and caecal infections in mice. In vitro assays have also been carried out on serum and urine obtained from non-infected rats or monkeys dosed with compounds showing in vitro activity.

2. The types of activity which can be obtained experimentally are illustrated by reference to a number of local remedies already available and to representatives of a number of chemical types, notably acridines, quinoxaline N-oxides, anthrapyrimidines, nitrofurans, thiazoles, imidazoles and pyrazoles.

We thank Dr R. F. Jennison and Mr H. Francis for clinical trial results, Drs J. K. Landquist, G. V. McHattie and D. Richardson for synthesis of some of the compounds mentioned, Dr G. E. Paget for toxicity data, Dr W. M. Duncan for data on the metabolism of 5667, Dr J. M. Pryce for pK determinations and Mrs M. Ryley, P. Ward, A. Fletcher, D. Wood and Miss V. Rowe for technical assistance at various stages in the work.

Depending on the extent of evolutionary divergence among parent taxa, hybrids may suffer from a breakdown of co-adapted genes or may conversely exhibit vigour due to the heterosis effect, which confers advantages to increased genetic diversity. That last mechanism could explain the success of hybrids when hybridization zones are large and long lasting, such as in the water frog hybridization complex. In this hybridogenetic system, hybrid individuals exhibit full heterozygosity that makes it possible to investigate in situ the impact of hybridization. We have compared parasite intensity between hybrid Rana esculenta and parental R. lessonae individuals at the tadpole stage in two populations inhabiting contrasted habitats. We estimated intensity of Gyrinicola sp. (Nematoda) in the gut, Echinostome metacercariae in the kidneys and Haplometra cylindracea in the body cavity (both species belong to Trematoda). Despite high sampling effort, no variation in parasite intensity was detected between taxa, except a possible higher tolerance to H. cylindracea in hybrid tadpoles. The low effect of hybridization suggests efficient gene co-adaptation between the two genomes that could result from hemiclonal selection. Variation in infection intensity among ponds could support the Red Queen hypothesis.

In this paper four new mites are described and figured, one being a new species of the subfamily Macronyssidae, one in the subfamily Laelaptinae and two in the family Trombiculidae.

The cidal properties of some phenolic, halogenated diphenyl, salicylanilide, benzimidazole and diaminophenoxyalkane anthelmintics, against 6-week-old worms of Fasciola hepatica were assessed in vitro. In a conventional fluke culture medium containing RPMI 1640, supplemented with serum with or without rabbit erythrocytes or pink-ghosts, only the halogenated diphenyl and salicylanilide compounds showed activity at concentrations equal to or less than 100 μm. However, when basal, serum and cell-free RPMI 1640 was used, all compounds other than diamphenethide were highly active, their minimum lethal concentrations being some 25–125 times lower under these conditions. The inclusion of rabbit liver microsomes in the basal culture medium resulted in diamphenethide exhibiting cidal activity equivalent to that seen when its free-amine active metabolite was assayed. The possibility that the activity of many of these compounds was masked in vitro because of their serum binding properties is discussed. Recommendations are made that in vitro screens for new fasciolicides should be carried out in serum-free medium and that additional replicates containing mammalian liver microsomes and liver cytosolic extracts be included as means for the metabolic activation of certain otherwise undetectable prodrugs.

1. The nauplius, the metanauplius and the first copepodid larva, of Lernaea chackoensis were reared in vitro and are described.

2. The four copepodid larvae obtained by artificial infection of Barbus stigma and Oryzias rubristigma are described.

3. The young females infesting the adult host fishes are described, noting the changes which take place after the copulation of the female larva.

4. The accelerated development of this tropica form and the need for a temporary host to complete the life cycle are discussed.

It has been estimated that up to a third of global malaria deaths may be attributable to malarial anaemia, with children and pregnant women being those most severely affected. An inefficient erythropoietic response to the destruction of both infected and uninfected erythrocytes in infections with Plasmodium spp. contributes significantly to the development and persistence of such anaemia. The underlying mechanisms, which could involve both direct inhibition of erythropoiesis by parasite-derived factors and indirect inhibition as a result of modulation of the immune response, remain poorly understood. We found parasite-derived factors in conditioned medium (CM) of blood-stage Plasmodium falciparum and crude isolates of parasite haemozoin directly to inhibit erythropoiesis in an ex vivo model based on peripheral blood haematopoietic stem cells. Erythropoiesis-inhibiting activity was detected in a fraction of CM that was sensitive to heat inactivation and protease digestion. Erythropoiesis was also inhibited by crude parasite haemozoin but not by detergent-treated, heat-inactivated or protease-digested haemozoin. These results suggest that the erythropoiesis-inhibiting activity in both cases is mediated by proteins or protein-containing biomolecules and may offer new leads to the treatment of malarial anaemia.

An experiment was carried out to investigate the effect of soil moisture stress upon the hatching behaviour of Nematodirus battus. The method involved the use of polyethylene glycol solutions to maintain a steady osmotic pressure around a soil containing N. battus eggs, which were ready to hatch. Different concentrations of polyethylene glycol (creating different moisture stresses) were found to affect the numbers and the rate of egg hatching markedly.

Scientific evidence strongly suggests that parasites are directly or indirectly associated with carcinogenesis in humans. However, studies have also indicated that parasites or their products might confer resistance to tumour growth. Plasmodium protozoa, the causative agents of malaria, exemplify the ambivalent link between parasites and cancer. Positive relationships between malaria and virus-associated cancers are relatively well-documented; for example, malaria can reactivate the Epstein-Barr Virus, which is the known cause of endemic Burkitt lymphoma. Nevertheless, possible anti-tumour properties of malaria have also been reported and, interestingly, this disease has long been thought to be beneficial to patients suffering from cancers. Current knowledge of the potential pro- and anti-cancer roles of malaria suggests that, contrary to other eukaryotic parasites affecting humans, Plasmodium-related cancers are principally lymphoproliferative disorders and attributable to virus reactivation, whereas, similar to other eukaryotic parasites, the anti-tumour effects of malaria are primarily associated with carcinomas and certain sarcomas. Moreover, malarial infection significantly suppresses murine cancer growth by inducing both innate and specific adaptive anti-tumour responses. This review aims to present an update regarding the ambivalent association between malaria and cancer, and further studies may open future pathways to develop novel strategies for anti-cancer therapies.

In regions where Chagas disease is endemic, canine Trypanosoma cruzi infection is highly correlated with the risk of transmission of the parasite to humans. Herein we evaluated the novel TcTASV protein family (subfamilies A, B, C), differentially expressed in bloodstream trypomastigotes, for the detection of naturally infected dogs. A gene of each TcTASV subfamily was cloned and expressed. Indirect enzyme-linked immunosorbent assays (ELISA) were developed using recombinant antigens individually or mixed together. Our results showed that dogs with active T. cruzi infection differentially reacted against the TcTASV-C subfamily. The use of both TcTASV-C plus TcTASV-A proteins (Mix A+C-ELISA) enhanced the reactivity of sera from dogs with active infection, detecting 94% of the evaluated samples. These findings agree with our previous observations, where the infected animals exhibited a quick anti-TcTASV-C antibody response, coincident with the beginning of parasitaemia, in a murine model of the disease. Results obtained in the present work prove that the Mix A+C-ELISA is a specific, simple and cheap technique to be applied in endemic areas in screening studies. The Mix A+C-ELISA could help to differentially detect canine hosts with active infection and therefore with high impact in the risk of transmission to humans.

Young lambs (6–8 weeks of age) were infected with 50000 infective stage larvae of the trichostrongyle nematode Nematodirus battus. Initial mean adult worm burdens of 23884±1678 (S.E.M.) at day 14 post-infection (p.i.) were reduced significantly (P < 0·01) to a mean burden of 5383±1397 by day 21 p.i. Blood samples were taken and serum analysed using ELISA and Western blotting techniques for IgG antibodies specific for N. battus. Pre-infection serum from young naive animals showed IgG recognition of adult and larval N. battus whole worm homogenate. Recognition of adult antigens became reduced during the first 14 days after infection, followed by a subsequent increase beginning between days 14 and 18 p.i. and peaking at day 28 p.i. IgM recognition of N. battus antigens showed a single response peak, starting between days 14 and 18 p.i., without the pre-infection elevated titre as observed with IgG. These results show that young lambs can mount a significant serum response to a primary infection with N. battus during rejection of adult worms and that lambs receive from their dams IgG antibodies that are capable of recognizing adult and larval N. battus during the first few weeks of life.

The availability of complete genome sequences is a revolution in the study of microorganisms. A fully annotated genome sequence provides an interactive tool for scientists and influences the approach and focus of research. In this article I discuss the impact of genome sequencing projects of bacteria. Much useful data have been obtained but the experimental methods needed to fully exploit the information continue to develop. Some of the approaches and particular applications relevant to bacteria of clinical importance are discussed.

In previous studies, ultrastructural observations revealed a large number of gap junctions (GJs) in the neck and immature proglottid tissues of Taenia solium tapeworms. In these helminths, cytoplasmic glycogen sacs are connected by numerous discrete GJs to other cells throughout the maturing strobilar tissue. Discontinuous sucrose gradients were used to purify membrane fractions containing GJs, which were identified by ultrastructural analysis. A trans-membrane peptide sequence from a highly conserved innexin region was used to construct a 20-amino acid synthetic peptide and used to raise polyclonal antibodies in rabbits that recognized both a 55 and a 67 kDa protein in a Western blot of the GJ-enriched pellet. Immunohistochemistry of larval and adult worm sections incubated with antiserum to the synthetic peptide and a secondary anti-rabbit IgG bound to fluorescein, revealed strong binding to the tegumentary surface of the worm, as well as patchy fluorescent areas in the parenchyma. The results indicate that both the tegument of cysticerci and adult T. solium contain innexin-rich membranes, which may function as a tegumentary transport system for small molecules.

Genome sequencing has greatly contributed to our understanding of parasitic protozoa. This is particularly the case for Cryptosporidium species (phylum Apicomplexa) which are difficult to propagate. Because of their polymorphic nature, simple sequence repeats have been used extensively as genotypic markers to differentiate between isolates, but no global analysis of amino acid repeats in Cryptosporidium genomes has been reported. Taking advantage of several newly sequenced Cryptosporidium genomes, a comparative analysis of single-amino-acid repeats (SAARs) in seven species was undertaken. This analysis revealed a striking difference between the SAAR profile of the gastric and intestinal species which infect mammals and one species which infects birds. In average, total SAAR length in gastric species is only 25% of the cumulative SAAR length in the genome of Cryptosporidium parvum, Cryptosporidium hominis and Cryptosporidium meleagridis, species infectious to humans. The SAAR profile in the avian parasite Cryptosporidium baileyi stands out due to the presence of long asparagine repeats. Cryptosporidium baileyi proteins with repeats ⩾20 residues are significantly enriched in regulatory functions. As postulated for the related apicomplexan species Plasmodium falciparum, these observations suggest that Cryptosporidium SAARs evolve in response to selective pressure. The putative selective mechanisms driving SAAR evolution in Cryptosporidium species are unknown.