The genus Petasiger which belongs to the family Echinostomidae was proposed by Dietz in 1909, with Petasiger exaeretus as the type species. The description given by Dietz of this species is incomplete and it is proposed therefore to present below a more detailed account of the anatomy, based on an examination of whole mounts and serial sections. The material was obtained from the small intestine of cormorants shot on the coast of Cardigan Bay between Aberystwyth and Llanrhystyd. Five cormorants were shot in July, and of these two contained a large number of Petasiger exaeretus in the small intestine.

We believe that the publication of a new key to the species of the genus Polyplax, so soon after that contained in Ferris's recent monograph (Ferris, 1951), is justified since it includes two new species and three species, praomydis Bedford, subtaterae Bedford and cummingsi Ferris, which appear to require some re-definition as Ferris placed all three in synonymy.

The multi-host lifestyle of parasitic trematodes necessitates their ability to communicate with their external environment in order to invade and navigate within their hosts' internal environment. Through recent EST and genome sequencing efforts, it has become clear that members of the Trematoda possess many of the elaborate signal transduction systems that have been delineated in other invertebrate model systems like Drosophila melanogaster and Caenorhabditis elegans. Gene homologues representing several well-described signal receptor families including receptor tyrosine kinases, receptor serine tyrosine kinases, G protein-coupled receptors and elements of their downstream signalling systems have been identified in larval trematodes. A majority of this work has focused on the blood flukes, Schistosoma spp. and therefore represents a narrow sampling of the diverse digenean helminth taxon. Despite this fact and given the substantial evidence supporting the existence of such signalling systems, the question then becomes, how are these systems employed by larval trematodes to aid them in interpreting signals received from their immediate environment to initiate appropriate responses in cells and tissues comprising the developing parasite stages? High-throughput, genome-wide analysis tools now allow us to begin to functionally characterize genes differentially expressed throughout the development of trematode larvae. Investigation of the systems used by these parasites to receive and transduce external signals may facilitate the creation of technologies for achieving control of intramolluscan schistosome infections and also continue to yield valuable insights into the basic mechanisms regulating motility and behaviour in this important group of helminths.

The aim of this review was to identify anti-inflammatory and antioxidant therapeutic agents and their effects on patients with chagasic myocarditis. A systematic review of the MEDLINE, EMBASE, WEB OF SCIENCE, SCOPUS, LILACS and CENTRAL databases (Cochrane Library) was carried out without language restrictions. The descriptors used were: ‘Chagas cardiomyopathy’, ‘treatment’, ‘Chagas disease’, ‘anti-inflammatory agents’, ‘Trypanosoma cruzi’ and ‘antioxidants’. A total of 4,138 articles was identified, six of which were selected for data extraction. Of these, four were related to antioxidant therapy with vitamins C and E supplementation, and two using anti-inflammatory therapy. The studies were carried out in Brazil and were published between 2002 and 2017. Antioxidant therapy with vitamin C and E supplementation increases the activity of antioxidant enzymes and reduces the oxidative markers. There is no conclusive data to support the use of vitamin supplementation and anti-inflammatory therapy in the treatment of chagasic cardiomyopathy. However, the studies indicate the possibility of vitamin supplementation as a new approach to the treatment of Chagas disease. Antioxidant therapy was proven to be a viable alternative for attenuating the oxidative damage caused by chronic chagasic cardiopathy, leading to a better prognosis for patients.

The distribution of two stages of the nematode Labiostrongylus longispicularis (Wood) in thirty-eight stomachs of the Red Kangaroo, Megaleia rufa (Desmarest) has been analysed statistically.

A quadratic regression was used where y = log of mean worm densities of stomach sections + 1 and x = numerical values of the mid-positions of the sections. The analysis revealed significant maxima in the proximity of the cardiac region. The maxima in stomachs with relatively large numbers of worms were found to be further away from the pylorus than in the stomachs with small numbers of worms. The mean maximum densities were about fifty worms per 100 g of stomach content in highly infected animals and about eight in low infections. It is suggested that freshly chewed food or saliva may be a factor regulating the distribution of worms.

The parasite was absent from the stomach's pyloric region where the pH is low.

Sex and size of the worm were independent of its position in the stomach.

The average number of eggs per adult female in the different stomach sections roughly corresponded to the density of worms in these sections, but the sample material was inadequate to show that this relationship was statistically significant.

The mean number of fertilized eggs per female worm was 3300.

Thanks are due to Professor E. J. Williams of the University of Melbourne and Mr B. V. Fennessy of the Division of Wildlife Research, C.S.I.R.O., for reading and criticizing the manuscript, and to Messrs E. R. Hesterman and C. Kogon for technical assistance.

1. In all species of the fusca group of tsetse flies (Glossina), except G. brevipalpis Newstead, a gelatinous structure, the genital fossa, is present at the anterior end of the uterus. On the surface of the genital fossa is a toughened structure known as the signum.

2. Probably chitin and certainly calcium are present in the substance of the signum of G. tabaniformis Westwood. An opaque concretion develops on the signum after the female has been fertilized. The concretions may be caused by a reaction between sperms or secretions from the male accessory glands and materials in the substance of the genital fossa; the possibility that the concretions are ‘mating scars’ produced by pressure of the harpes of the male on the signum is considered unlikely. Concretions are not present on the signa of all species.

3. A possible mechanism of fertilization in G. tabaniformis is discussed, and it is suggested that the signum may act as a protective shield for the anterior part of the uterus and common oviduct of the female from the harpes of the male which are inserted into the uterus during coitus. The views of Machado (1959) are discussed and it is agreed that the signum probably acts as a protective shield in all species in which it occurs and differences in the form of the signum between species may be related to differences in the form of the harpes of the male.

I wish to thank Dr J. Williamson for chromatography, Dr L. E. Stephen and Mr K. E. Broomfield for advice and assistance with the sectioning of the signa, Dr F. Peers for operating the Flame Photometer, Dr D. G. Godfrey for suggesting that the signa should be examined for calcium, and Mr W. Petana for taking the photomicrographs.

I am indebted to Dr K. C. Willett, Director of the West African Institute for Trypanosomiasis Research, for criticism of the manuscript.

An account is given of the methods used to produce radioactive oocysts of P. gallinaceum. The latter are demonstrated in stained sections and in autoradio-graphs. The photographs show oocysts in mosquitoes fed on solutions of radioactive phosphorus and radioactive sulphur.

Some two years ago a proposal was put forward by Wenyon (1923) to change the name of one of the well-known coccidial parasites of man—the parasite which, in my revision of the group (1919), I called Isospora hominis (Rivolta). for various reasons Wenyon concluded that there must really be two species of Isospora in man—not one, as I had assumed—and he proposed to transfer my amended name I. hominis to another organism, whose existence he deduced from the literature and from his own observations on the Coccidia of cats and dogs: but as this would leave the species which I had called “I. hominis” without a name, he proposed to rename it “Isospora belli”.

Lung flukes, Paragonimus ohirai, from Kinosaki, Japan, characterized by 3 electrophoretic variants, FF, FS and SS, of glutamic-oxaloacetic transaminase (GOT: EC 2.6.1.1) were crossed in the laboratory. In the case of a cross between FS and SS, a parent, FS, produced 9 SS and 16 FS clones in the offspring, numbers not significantly different from that expected (1:1) from Mendelian inheritance. From the other cross FS × FF, 20 clones originating from the respective 20 miracidia were obtained from a parent FS. The phenotype segregation ratio was 6 FF and 14 FS, which is not significantly different from Mendelian inheritance expectation. Only 3 clones were obtained from the other parent FF, but these segregated in a ratio of 2 FS: 1 FF. These breeding data indicate that the GOT isozymes of P. ohirai are controlled by 2 codominant alleles, GotF and Gots at a single locus whose products aggregate randomly, forming a dimer.

Trypanosoma evansi and Trypanosoma vivax have shown a very high immunological cross-reactivity. Anti-T. vivax antibodies were used to monitor changes in the T. evansi intracellular Ca2+ concentration ([Ca2+]i) by fluorometric ratio imaging from single parasites. A short-time exposure of T. evansi parasites to sera from T. vivax-infected bovines induced an increase in [Ca2+]i, which generated their complete lysis. The parasite [Ca2+]i boost was reduced but not eliminated in the absence of extracellular Ca2+ or following serum decomplementation. Decomplemented anti-T. evansi VSG antibodies also produced an increase in the parasite [Ca2+]i, in the presence of extracellular Ca2+. Furthermore, this Ca2+ signal was reduced following blockage with Ni2+ or in the absence of extracellular Ca2+, suggesting that this response was a combination of an influx of Ca2+ throughout membrane channels and a release of this ion from intracellular stores. The observed Ca2+ signal was specific since (i) it was completely eliminated following pre-incubation of the anti-VSG antibodies with the purified soluble VSG, and (ii) affinity-purified anti-VSG antibodies also generated an increase in [Ca2+]i by measurements on single cells or parasite populations. We also showed that an increase of the T. evansi [Ca2+]i by the calcium A-23187 ionophore led to VSG release from the parasite surface. In addition, in vivo immunofluorescence labelling revealed that anti-VSG antibodies induced the formation of raft patches of VSG on the parasite surface. This is the first study to identify a ligand that is coupled to calcium flux in salivarian trypanosomes.

A recombinant cysteine protease inhibitor, onchocystatin of the parasitic nematode Onchocerca volvulus, was tested for its role in microfilarial development in the simuliid vector. Onchocystatin was found to be present in female adults and skin microfilariae of the bovine parasite O. ochengi, the closest relative of O. volvulus. In addition the inhibitor could be detected as an excretory–secretory (E–S) product of the microfilariae. Co-injection of onchocystatin and the O. ochengi microfilariae into the surrogate vector Simulium ornatum s.l. significantly enhanced the recovery rates of the parasite within 24 h into the infection (P>0·001). The findings suggest a possible role of onchocystatin in the evasion by the parasite of the immune response of its vector.

As animals we have been a remarkably successful species; but also as animals we are vulnerable to environmental, in particular climate change. Such change is accelerating as a result of human activity, and global warming may already be taking place. Although we can foresee the trends, we cannot yet be specific about the results. Change usually proceeds by steps rather than gradients. But warming would probably include new risks to human health and contribute to an increase in human displacement. Of course climate change is only one among other complex problems facing human society, but it is closely related to them all, including population increase, environmental degradation and loss of biodiversity. We cannot prevent global warming but we can anticipate and mitigate some of its worst effects. Peoples and governments still need persuading of the need for action and of the magnitude of the issue at stake.

The microsporidian parasite Hamiltosporidium tvaerminnensis can infect Daphnia magna both horizontally (through environmental spores) and vertically (through parthenogenetic and sexually produced eggs). The spores of H. tvaerminnensis come in three distinguishable morphologies, which are thought to have different roles in the transmission of the parasite. In this study, we examined the role of the two most common spore morphologies (i.e. oval-shaped spores and pear-shaped spores) in horizontal transmission of H. tvaerminnensis. To this end, we infected hosts with solutions consisting of either mostly oval- or mostly pear-shaped spores, and quantified infection rates, parasite-induced host mortality and mean number of parasite spores produced per host. We found that spore morphology by itself did not influence infection rates and parasite-induced host mortality. Instead, host clone and parasite isolate interacted with spore morphology in shaping infection outcome and mortality. Thus, there appear to be strong genotype-by-genotype (G × G) interactions in this system. While there is no dispute that H. tvaerminnensis can transmit both vertically and horizontally, our findings do not support theoretical predictions that different spore morphologies hold different roles in horizontal transmission of H. tvaerminnensis.

The larva of Phaonia palpata closely resembles that of P. variegata in the structure of the buccopharyngeal armature and of the posterior spiracles. The absence of sharp teeth on the anterior ribbons and the presence of a blunt knob on the ventral edge of the oral bars distinguish the larva of P. palpata from larvae of other species of Phaonia.

In the course of an extensive parasitological examination of Indian food fishes the author recovered, amongst others, six specimens of an interesting trematode from the gut of a fish examined at Karachi in June 1936. The trematode, though obviously belonging to the family Allocreadiidae, represents a new genus, Horatrema, and a new subfamily, Horatrematinae. This new genus forms a connecting link between Cymbephallus Linton, in Manter, 1934, and Parva-creadium Manter, 1940, of the subfamily Allocreadiinae, and the type genus Notoporus of the family Notoporidae Yamaguti, 1938. It will be appreciated from the systematic discussion at the end of the paper that the taxonomic status of the family Notoporidae is untenable, and it is, therefore, reduced to the rank of a subfamily, Notoporinae, under the family Allocreadiidae. Further, in view of the presence of a cirrus-sac in Notoporus trachuri Yamaguti, 1938, it has been considered necessary to assign it to a new genus, Neonotoporus

In March 1932, while examining the gut contents of Bufo melanostictus, I came across a species of coccidian in two specimens. On consulting the literature, I found that while five species of Eimeria have been recorded from the intestinal region of anurous amphibians, none of them corresponds with the one I have observed. Moreover, I notice that for no one of these five species has the whole life history been described.

In the following notes no attempt has been made to enter into the pathology or etiology of the diseases described, as only isolated cases have been available for investigation.

I am much indebted to the Council of the Marine Biological Association of the United Kingdom for their kindness in granting me a table at their Plymouth Laboratory.

The following is a description of a new species of Accacoeliid Trematode found in the intestine of a sun-fish (Orthagoriscus mola Bloch), caught by a fisherman in June, 1933, at Salcombe, Devon. The fish was examined by Mr J. W. Poulton of Downing College, Cambridge, to whom my thanks are due for bringing me the parasites for identification. In addition to the species described in this paper the host contained the following forms: on the skin, Tristoma molae and Lepeophtheirus nordmanni; in the intestine, Ancistrocephalus microcephalus.

The follwing descriptions relate to two new species of the genera Haemaphysalis and Amblyomma, respectibely, and to a new variety of Amblyomma variegatum:

Haemaphysalis silacea sp. n. ♀, from South Africa (370).

Amblyomma variegatum var. n. nocens, ♂, from South Africa (371).

Amblyomma fiebrigi sp. n. ♂ and ♀, from South America (6).

1. A description is given of the egg of Gasterophilus intestinalis.

2. The chorion has been shown to consist of a number of tanned protein and lipoprotein layers.

3. The waterproofing of the egg is shown to be dependent on a primary wax layer on the inner membrane of the endochorion and a secondary layer on the vitelline membrane.

4. The respiratory requirements of the egg are supplied from a free-air space between the inner membrane and the tanned protein layer of the endochorion which communicates with the atmosphere by specialized pore canals opening into the follicular grooves.

Thanks are due to Dr P. Tate for suggesting the subject of this work and for his advice and encouragement during its progress.