Our study aimed at examining the phylogenetic position of the newly-found Setaria nematodes obtained from the red deer (Cervus elaphus) based on sequences of the mitochondrial cytochrome c oxidase subunit 1 (COX-1). Alignment and phylogenetic analyses, as well as SEM microscopic analysis, revealed the presence of two Setaria species: S. cervi and S. tundra. Setaria tundra was noted in only one individual, a calf of the red deer, while S. cervi was observed in three stages, two hinds and one calf of the red deer. According to our knowledge, it is the first case of S. cervi in the red deer in Poland confirmed in molecular studies and also the first case of S. tundra infection in the red deer.

The results of 4 different assays for haemocytic immune responsiveness in the cockroach, Periplaneta americana, have shown that the presence of larvae of Moniliformis moniliformis within the haemocoele depresses the insect's immune reactivity. Thus, the proportion of haemocytes that phagocytose fluorescent latex beads in vivo, the proportion of haemocytes that can be stimulated in vitro by the β1,3-glucan, laminarin, to produce phenoloxidase, and the number of haemocytic aggregates produced in vivo in response to zymosan stimulation, are significantly depressed compared with control, unparasitized cockroaches. Also, when cockroaches are injected intra-haemocoelically with hatched oncospheres of the tapeworm, Hymenolepis diminuta, a higher prevalence and intensity of tapeworm larvae are found in insects already parasitized by M. moniliformis. All of these assays show that depression rather than total suppression of the immune response occurs; in the wild, this may be sufficient to ensure that the cockroach does not succumb to unrelated infections during the long developmental period of the parasite.

The commonly accepted view regarding the manner of entry of larvae of Wuchereria bancrofti (Cobb.) into the body cavity of its mosquito host is that microfilariae from human blood enter the stomach of the mosquito along with the blood meal and after casting their sheath in the stomach, they penetrate through the wall of the stomach, enter the haemocele and then find their way into the thoracic muscles. The time taken for the penetration of the stomach wall according to Looss (1914) is 6–12 hours. According to Bahr (1912) the worms appear in the thoracic muscles in 24 hours, while Lebredo (1905) recorded that in exceptional cases, worms were seen in the thorax 13 hours after feeding, but ordinarily the time interval was longer.

Infective-stage larvae of trichostrongyle nematodes, either resistant or susceptible to thiabendazole (TBZ), were incubated in eserine, an acetylcholinesterase inhibitor. Paralysis occurred in larvae treated with eserine but significant differences were observed in the percentage of larva immobilized between TBZ-resistant and TBZ-susceptible strains of the nematodes. These differences are probably related to the presence of higher levels of acetylcholinesterase in the TBZ-resistant strains than in the susceptible strains. This could be used as a rapid and inexpensive method of detecting resistance to TBZ in trichostrongyles.

The morphology of the adult blood fluke Schistosoma hippopotami sp.nov. from Hippopotamus amphibius L. is described and compared with that of other species of the genus Schistosoma.

Cod (Gadus morhua), an important fish species in the Baltic Sea, is the paratenic host for many parasite species, including the zoonotic nematodes, Anisakis sp. and Contracaecum osculatum. We aimed to identify which invertebrate species (found in situ in the fish stomach) are responsible for infection of cod with zoonotic nematodes. We found that Crangon crangon and Gammarus sp., both invertebrate prey species of cod, were infected with Anisakis simplex and C. osculatum, respectively. These host–parasite systems are reported here for the first time, implicating C. crangon and Gammarus sp. as sources of infection of Baltic cod with zoonotic nematodes.

An analysis of natural infections of Toxocara mackerrasae in Rattus fuscipes trapped in rain forests in south-eastern Queensland is given and Hydromys chrysogaster is listed as a new host.

T. mackerrasae larvae in egg-infected mice are incapable of somatic migration but some complete development to the young adult stage can occur entirely within the alimentary tract. T. mackerrasae is capable, in low numbers, of developing to maturity in experimentally infected Rattus spp.

The work was financed by grants from the University of Queensland and the National Health and Medical Research Council of Australia. I wish to thank Professor J. F. A. Sprent for his criticisms and suggestions during the preparation of this text.

Individual animals are often infected not only by different parasite species, but also by multiple genotypes of the same parasite species. Genetic relatedness among parasites sharing a host is expected to modulate their strategies of resource exploitation, growth and virulence. We experimentally examined the effects that genetic diversity and infection intensity had on host mortality, infectivity and growth of the marine trematode Maritrema novaezealandensis in amphipod hosts. The presence of 2 versus 1 parasite genotype during infection did not influence subsequent host mortality, had different effects on infectivity among genotypes and did not influence growth or variation in parasite growth. Density-dependent growth reductions revealed that the number of parasites infecting a host was more important than their genetic relatedness. Temperature, host size, and host sex influenced the degree to which density-dependent factors affected parasite growth. Our results suggest that the effects of parasite relatedness vary among parasite genotypes in this trematode species, and reveal that many factors play an important role during parasite development and transmission.

The kinetoplast DNA (kDNA) of kinetoplastidae was the first mitochondrial DNA (mtDNA) to be discovered, and with its unusual network structure, consisting of more than 104 catenated DNA circles, it is without equal in nature. Analysis of networks from various genera (reviewed by Borst & Hoeijmakers (1979a) and Englund (1980)) has shown that they always consist of two components: mini-circles and maxi-circles (see Table 1). The mini-circles are the major component and deterraine the size and sliape of networks. They vary in size between 1 and 3 kilo-base pairs (kb = 1000 base pairs (bp)), they are heterogeneous in sequence, their sequence evolves rapidly and their function is not yet known. The maxi-circles, on the other hand, are homogeneous in sequence, their sequence is conserved and they probably represent the counterpart of mtDNA in other organisms.

Ten larval Cestodes, eight from aquatic and two from terrestrial hosts, have been described. Of these, eight species are new, and in the case of Cysticercus “A,” both larva and adult are new. By direct animal experiment the life-histories of three forms have been definitely established, while by careful comparison of the hooks of the scolex two larvae have been related to known adults. Cysticercus Hymenolepidis setigerae, previously recorded only from Copepods, is described here from an Ostracod host.

Effect of the parasite on the host. It is difficult to estimate the effect of Cestode larvae parasitic in Invertebrata, especially in the smaller forms such as the Entomostraca. In the latter, I have found that the intestine and musculature suffer most, and that the reproductive organs remain unattacked. The same remarks also hold for Oligochaete hosts. Dady (1901) considers that the influence of these cystic stages on their hosts is considerable, particularly on the musculature, sexual organs and intestine, and that death of the host may follow. Lindner (1921) states that little or no harm is done to Ostracods by the presence of tapeworm larvae, and also that the ovary of the female remains unattacked. The same author considers that, among the Entomostraca, destruction of the intestine occurs only in Copepods, the body cavity of Ostracods being so roomy that a harming of the intestine by growth of the parasite is unlikely. Schmidt (1894) finds that for Cysticercus Hymenolepidis anatinae, the host, Cypris ovata, was not particularly affected.

Chagas disease is a serious parasitic infection caused by Trypanosoma cruzi. Unfortunately, the current chemotherapeutic tools are not enough to combat the infection. The aim of this study was to evaluate the trypanocidal activity of benznidazole-loaded microparticles during the acute phase of Chagas infection in an experimental murine model. Microparticles were prepared by spray-drying using copolymers derived from esters of acrylic and methacrylic acids as carriers. Dissolution efficiency of the formulations was up to 3.80-fold greater than that of raw benznidazole. Stability assay showed no significant difference (P > 0.05) in the loading capacity of microparticles for 3 years. Cell cultures showed no visible morphological changes or destabilization of the cell membrane nor haemolysis was observed in defibrinated human blood after microparticles treatment. Mice with acute lethal infection survived 100% after 30 days of treatment with benznidazole microparticles (50 mg kg−1 day−1). Furthermore, no detectable parasite load measured by quantitative polymerase chain reaction and lower levels of T. cruzi-specific antibodies by enzyme-linked immunosorbent assay were found in those mice. A significant decrease in the inflammation of heart tissue after treatment with these microparticles was observed, in comparison with the inflammatory damage observed in both infected mice treated with raw benznidazole and untreated infected mice. Therefore, these polymeric formulations are an attractive approach to treat Chagas disease.

A n.gen. and n.sp. of a yeast-like micro-organism—Adlerocystis ornithodori—is described. This micro-organism is probably a symbiote of sperm cells of Ornithodoros tholozani. Another species, A. parkeri n.sp., is found in O. parkeri.

Adlerocystis sp. were also found in O. coriaceus, O. nicollei, O. erraticus, and O. savignyi.

The earliest stage of development of A. ornithodori was observed in the posterior lobe of the complex of accessory genital glands of the male, where it has the shape of a round cell. It is spindle-shaped when attached to the mature sperm in the spermatophore.

The development of A. ornithodori from a round cell to an elongated spindle-shaped organism, in vitro in the spermatophore, as well as in vitro, is described.

We wish to thank Dr W. Burgdorfer, the Rocky Mountain Laboratory, Mr R. Garcia, University of California, and Mr A. Avivi, the Israeli Institute of Biology, who provided ticks, as well as Mr E. B. Kennedy for taking the microphotographs and Mr N. Shultan from the Elyahu and Rosa Wunsch Electron Microscopy Laboratory for the electron micrograph, both from the Hebrew University Hadassah Medical School, Jerusalem.

Syngamus trachea, the gape nematode, has been used as a model to study the chemosensory function of amphids. Extracellular electrophysiological recordings were performed directly on amphids. The amphids were stimulated by blood serum from a host bird and by D-tryptophan. The spike frequency produced by the amphid increased significantly after the application of the serum and the application of D-tryptophan. Two types of amphidial neurones responded to the presence of the stimuli. These extracellular recordings have verified the chemosensory function of the amphids.

Myxidium oviforme is described from Irish salmon Salmo salar. Its close relationship with M. folium, M. moxostomatis and M. aplodinoti, and its possible economic importance are discussed.

Attempts to establish infections of M. oviforme in young, parasite-free salmon are described, and the reasons for their negative results discussed.

This work was carried out during the tenure of a Medical Research Council Scholarship for Training in Research Methods between October 1964 and September 1966, and forms part of a thesis submitted for the Ph.D. Degree of the University of London. Grateful acknowledgement is due to Dr J. G. Ross and Dr G. Lawson of the Veterinary Research Division of the Ministry of Agriculture for Northern Ireland for information on salmon infections in Ireland, to the Ministry of Agriculture and Fisheries for the provision of young salmon, and to Messrs Barnetts of Frying Pan Alley Ltd., London, for the provision of salmon livers.

In theory, the age at which maturation occurs in parasitic nematodes is inversely related to pre-maturational mortality rate, and cross-species data on mammalian nematodes are consistent with this prediction. Immunity is a major source of parasite mortality and parasites stand to gain sizeable fitness benefits through short-term adjustments of maturation time in response to variation in immune-mediated mortality. The effects of thymus-dependent immune responses on maturation in the nematode parasites Strongyloides ratti and Nippostrongylus brasiliensis were investigated using congenitally thymus-deficient (nude) rats. As compared with worms in normal rats, reproductive maturity of parasites (presence of eggs in utero) in nude rats occurred later in S. ratti but earlier in N. brasiliensis. Immune-mediated differences in maturation time were not associated with differences in worm length. Thymus-dependent immunity had no effect on pre-maturational mortality. Results are discussed in relation to theoretical expectations and possible explanations for the observed patterns in parasite maturation.

Sequences of the first and second internal transcribed spacers (ITS1 + ITS2) of nuclear ribosomal DNA were employed to determine whether the congeneric assemblages of species of the strongyloid nematode genus Cloacina, found in the forestomachs of individual species of kangaroos and wallabies (Marsupialia: Macropodidae), considered to represent species flocks, were monophyletic. Nematode assemblages examined in the black-striped wallaby, Macropus (Notamacropus) dorsalis, the wallaroos, Macropus (Osphranter) antilopinus/robustus, rock wallabies, Petrogale spp., the quokka, Setonix brachyurus, and the swamp wallaby, Wallabia bicolor, were not monophyletic and appeared to have arisen by host colonization. However, a number of instances of within-host speciation were detected, suggesting that a variety of methods of speciation have contributed to the evolution of the complex assemblages of species present in this genus.

Angiostrongylus cantonensis is the leading cause of eosinophilic meningitis worldwide, with life-threatening complications if not managed correctly. Previous in vitro studies have utilized change in motility patterns of adult female worms to assess the efficacy of anthelmintics qualitatively. However, it is the third stage larvae (L3) that are infectious to humans. With differential staining using propidium iodide penetration as the indicator of death, we can distinguish between dead and live larvae. This assay has enabled us to quantify the in vitro efficacy of nine clinically established anthelmintics on A. cantonensis L3. All drugs were tested at a 1 mm concentration. Piperazine and niclosamide were ineffective in inducing larval death; however, albendazole sulfoxide, pyrantel pamoate, diethylcarbamazine, levamisole and praziquantel were effective as compared to unexposed controls (P < 0.05). Ivermectin and moxidectin did not induce significant levels of mortality, but they considerably reduced larval motility almost immediately. This study indicates the need for further in vivo studies to determine the optimal dose and time frame for post-infection treatment with anthelmintics that demonstrated efficacy.

Eimeria spp. are the causative agents of coccidiosis, a major disease affecting the poultry industry. So far, only a few antigen genes of E. acervulina have been reported. In this study, a clone, named as cSZ-JN2, was identified from a cDNA expression library prepared from E. acervulina sporozoite stage with the ability to stimulate the chicken immune response. The sequence analysis showed that the open reading fragment (ORF) of cSZ-JN2 was 153 bp in size and encoded a predicted protein of 50 amino acids of Mr 5·3 kDa. BLASTN search revealed that cSZ-JN2 had no significant homology with the known genes of E. acervulina or any other organism (GenBank). The recombinant cSZ-JN2 antigen expressed in E. coli was recognized strongly by serum from chickens experimentally infected with E. acervulina. Immunofluorescence analysis using antibody against recombinant cSZ-JN2 indicated that this protein was expressed in sporozoite and merozoite developmental stages. Animal challenge experiments demonstrated that the recombinant protein of cSZ-JN2 and DNA vaccine carrying cSZ-JN2 could significantly increase the average body weight gains, decrease the mean lesion scores and the oocyst outputs of the immunized chickens and presented anti-coccidial indices of more than 165. All the above results suggested that the cSZ-JN2 was a novel E. acervulina antigen and could be an effective candidate for the development of a new vaccine against E. acervulina infection.

Scuticociliates are histophagous marine parasites that cause mortality in fish. Acid phosphatases (AcPs) are considered virulence factors and they are used by different parasites to dephosphorylate host molecules. The aim of this work was to characterize the AcPs from 3 scuticociliate species, Uronema marinum, Miamiensis avidus and Parauronema virginianum, which parasitize marine finfish species. We identified AcP activity (pH 5·2) with differential cellular distribution in the 3 parasite species. Native gel electrophoresis of ciliate lysates revealed the presence of 1 high molecular weight AcP activity band in M. avidus (tartrate-sensitive), several low molecular weight AcPs in U. marinum and 1 low molecular weight band only in P. virginianum (tartrate-resistant). Scuticociliate AcP was inhibited by specific inhibitors of tyrosine protein phosphatases. AcP decreased upon starvation but rapid reactivation occurred following exposure to skin mucus. Groper (Polyprion oxygeneios) peripheral blood leucocytes (PBLs) and, to a lesser extent, red blood cells, also increased AcP activity. Protein tyrosine phosphatase PTP1b was primarily detected in the plasma membrane of M. avidus and ingestion of groper PBLs upregulated its expression. M. avidus recovered from experimentally infected groper had greater levels of PTP1b expression than the injected suspension. The present results highlight the importance of PTPs in histophagous parasites and their interaction with fish host's factors.

A gene coding for the 30 kDa Schistosoma mansoni cercarial protease was amplified using the polymerase chain reaction (PCR) from genomic DNA templates. Cloning and sequencing of several independent PCR clones revealed the presence of an intron additional to the one described in the original cloning of the gene. The 3 exons were cloned into expression vectors so that they could be expressed as separate glutathione-S-transferase (GST) translational fusions. Recombinant bacteria carrying these expression plasmids expressed the fusion proteins at high levels. Western blotting of bacterial lysates with sera raised against the native S. mansoni cercarial protease showed that all 3 exons were recognized. Thus we have produced recombinant bacteria capable of providing large amounts of an S. mansoni antigen for immunological studies and evaluation as a candidate vaccine.