Primers and DNA probes designed for use in the specific detection of the paramyxean parasites Marteilia sydneyi and Marteilia refringens were tested for their potential to cross-react with closely related species in Polymerase Chain Reaction (PCR) and in situ hybridization. PCR primers and a DNA probe designed within the ITS1 rRNA of M. sydneyi were specific for M. sydneyi when compared with related species of Marteilia and Marteilioides. PCR primers designed within the 18S rRNA of M. refringens were specific in the detection of this species in PCR while a DNA probe (named Smart 2) designed on the same gene cross-reacted with M. sydneyi in tissue sections of Saccostrea glomerata as well as Marteilioides sp. infecting Striostrea mytiloides. Though not species specific, the Smart 2 probe provided a stronger signal in detection of all stages of M. sydneyi than the ITS1 probe. The ITS probe is proposed for use as a confirmatory diagnostic tool for M. sydneyi.

The population of malaria-causing parasites is characterized by great genetic diversity. Knowledge of the polymorphism generation mechanism is a central issue for developing effective vaccines against malaria and understanding the parasite population structure. Plasmodium vivax genetic diversity has been explained in terms of two major factors: natural selection and intragenic recombination. A modular organization was found within P. vivax Duffy binding protein in the present work. Four Colombian isolates have identical sequences to Salvador-1 strain amongst dpb regions III–VI analysed, suggesting a high identity between Central and South American isolates. Geographically clustered sectors, corresponding to cysteine-rich regions (II and VI), show a high sequence diversity that could reflect a possible immune response evasion mechanism; both positive and negative selection were detected in these regions. In contrast, other dbp gene regions display a non-geographical clustering pattern, lower sequence diversity and predominant negative selective pressure. Recombination was homogeneously detected all along the molecule. These findings suggest that diversification vs. homogenizing forces, drive dbp gene evolution and determine its mosaic region organization.

Heliciculture is an excellent alternative to obtain edible snails but its viability is seriously threatened by pathogens. A parasitological survey was conducted in 3 mixed system-based heliciculture farms in Galicia (NW Spain), with the species Tetrahymena rostrata, Tetrahymena limacis, Tetratrichomonas limacis, Cryptobia helicogenae, Brachylaima aspersae (metacercariae and sporocysts), Alloionema appendiculatum, Nemhelix bakeri, and Riccardoella limacum being commonly found infecting Helix aspersa aspersa (petit-gris) snails. With the exception of C. helicogenae, N. bakeri, and B. aspersae sporocysts, all species were also detected in Helix aspersa maxima (gros-gris) snails, although generally with lower parameters. Most monoxenous infections, and consequently multiple parasitism, exhibited a rising trend during the first 2 months of intensive mating, with tendencies being slowed down or even reversed during the third month as a result of accumulated mortality and a sampling-derived reduction in host density. No parasites were vertically transmitted and infections were initially acquired from invading gastropod and micromammal reservoirs during fattening. Finally, artificial hibernation reduced significantly the prevalence of most species. These results confirm the importance of parasites in heliciculture and emphasize the need to prevent the entry of wild reservoirs into the farms and to rapidly remove the carcasses of dead snails from the reproduction units and fattening pens.

Understanding how individual parasite traits contribute to overall fitness, and how they are modulated by both external and host environment, is crucial for predicting disease outcome. Fungal (chytrid) parasites of phytoplankton are important yet poorly studied pathogens with the potential to modulate the abundance and composition of phytoplankton communities and to drive their evolution. Here, we studied life-history traits of a chytrid parasite infecting the planktonic, bloom-forming cyanobacterium Planktothrix spp. under host genotype and thermal variation. When expressing parasite fitness in terms of transmission success, disease outcome was largely modulated by temperature alone. Yet, a closer examination of individual parasite traits linked to different infection phases, such as (i) the establishment of the infection (i.e. intensity of infection) and (ii) the exploitation of host resources (i.e. size of reproductive structures and propagules), revealed differential host genotype and temperature × host genotype modulation, respectively. This illustrates how parasite fitness results from the interplay of individual parasite traits that are differentially controlled by host and external environment, and stresses the importance of combining multiple traits to gain insights into underlying infection mechanisms.

The development of a new species, Bacillidium vesiculoformis n. sp. (Microspora, Mrazekiidae), is described from the freshwater oligochaete Nais simplex (Oligochaeta, Naididae). Initial stages of parasite development consist of a monokaryotic merogony within a haemocyte of the intestinal blood sinus. The resulting hypertrophied haemocyte is attached to the chloragocytes of the sinus by fine cytoplasmic extensions with the sinus around the cell becoming greatly enlarged. The meronts within the haemocyte form diplokaryotic sporonts that undergo sporogenesis directly within the cytoplasm of the host cell. The infected cell becomes packed with spores and developmental stages, causing it dramatically to increase in size, eventually rupturing the oligochaete and cell. Sporogony appears to be disporoblastic. Released spores were observed to have an adhesive quality. Transmission studies conducted with mature spores failed to transmit the parasite horizontally although vertical transmission was observed. Phylogenetic analysis of the parasite demonstrated that B. vesiculoformis clustered with microsporidian parasites of bryozoa and two other microsporidians, Janacekia debaiseuxi and an unidentified Bacillidium sp.

New ideas for diagnostics in clinical parasitology are needed to overcome some of the difficulties experienced in the widespread adoption of detection methods for gastrointestinal parasites in livestock. Here we provide an initial evaluation of the performance of a newly developed automated device (Telenostic) to identify and quantify parasitic elements in fecal samples. This study compared the Telenostic device with the McMaster and Mini-FLOTAC for counting of strongyle eggs in a fecal sample. Three bovine fecal samples were examined, in triplicate, on each of the three fecal egg-counting devices. In addition, both manual (laboratory technician) and automated analysis (image analysis algorithm) were performed on the Telenostic device to calculate fecal egg counts (FEC). Overall, there were consistent egg counts reported across the three devices and calculation methods. The Telenostic device compared very favourably to the Mini-FLOTAC and McMaster. Only in sample C, a significant difference (P < 0.05) was observed between the egg counts obtained by Mini-FLOTAC and by the other methods. From this limited dataset it can be concluded that the Telenostic-automated test is comparable to currently used benchmark FEC methods, while improving the workflow, test turn-around time and not requiring trained laboratory personnel to operate or interpret the results.

Pasteuria penetrans is a Gram-positive endospore-producing bacterium that is a parasite of root-knot nematodes. Attachment of endospores to the cuticle of the nematode is the first stage in the infection process. Western blot analysis with monoclonal and polyclonal antibodies that recognize the 30 kDa heparin-binding domain (HBD) and the 45 kDa gelatin-binding domain (GBD) fragments of human fibronectin (Fn) revealed a series of polypeptides of approximately 40, 45 and 55 kDa present in crude cuticle extracts of Meloidogyne javanica 2nd-stage juveniles. The results suggest that the structure of the nematode fibronectin is different to the fibronectins so far characterized. Pre-treatment of endospores of Pasteuria with either the HBD or the GBD was found to inhibit binding to the nematode cuticle. The larger GBD fragment was the most effective at blocking adhesion. Pre-treatment of the GBD fragment with gelatin prevented the GBD fragment from inhibiting endospore attachment to the nematode cuticle.

The causative agent of urogenital schistosomiasis, Schistosoma haematobium, was thought to be the only schistosome species transmitted through Bulinus snails on Unguja and Pemba Island (Zanzibar, United Republic of Tanzania). For insights into the environmental risk of S. haematobium transmission on Pemba Island, malacological surveys collecting Bulinus globosus and B. nasutus, two closely related potential intermediate hosts of S. haematobium were conducted across the island in November 2016. Of 1317 B. globosus/B. nasutus collected, seven B. globosus, identified through sequencing a DNA region of the mitochondrial cytochrome oxidase subunit 1 (cox1), were observed with patent infections assumed to be S. haematobium. However, when the collected cercariae were identified through sequencing a region of the cox1 and the nuclear internal transcribed spacer (ITS1 + 2), schistosomes from five of these B. globosus collected from a single locality were in fact S. bovis. The identified presence of S. bovis raises concerns for animal health on Pemba, and complicates future transmission monitoring of S. haematobium. These results show the pertinence for not only sensitive, but also species-specific markers to be used when identifying cercariae during transmission monitoring, and also provide the first molecular confirmation for B. globosus transmitting S. bovis in East Africa.

Additional biomarkers are essential for control of Trypanosoma evansi (T. evansi) infection in dromedary camels. Two groups of 30 camels each, one naturally infected with T. evansi and other normal healthy were executed. The basis for the infection was the positive findings of clinical examination, blood smears and latex agglutination test. Blood samples of both groups and its harvested serum were used for the estimation of present serobiochemical parameters. The present findings revealed significant decrease (P ⩽ 0·05) in triacylglycerol, cholesterol, high density lipoprotein cholesterol with significant increase (P ⩽ 0·05) in low density lipoprotein cholesterol, beta hydroxyl butyric acids, non-esterified fatty acids, haptoglobin, serum amyloid A, ceruloplasmin, fibrinogen, interleukins, tumour necrosis factor-α, interferon gamma, malondialdehyde, superoxide dismutase, reduced glutathione and catalase of infected camels compared with the control. The present study suggests lipid profile, acute phase proteins, proinflammatory cytokines and oxidative stress parameters as biomarkers for T. evansi infection in camels.

Despite the great interest to quantify the structure of host–parasite interaction networks, the real influence of some factors such as taxonomy, host body size and ecological opportunity remains poorly understood. In this paper, we investigate the general patterns of organization and structure of interactions in two anuran–parasite networks in the Brazilian Pantanal (seasonally flooded environment) and Atlantic Forest (non-flooded forest). We present theoretical models to test whether the structures of these host–parasite interaction networks are influenced by neutrality, host taxonomy and host body size. Subsequently, we calculated metrics of connectance, nestedness and modularity to characterize the network structure. We demonstrated the structure networks were influenced mainly by body size and taxonomy of the host. Moreover, our results showed that the seasonally flooded environment present networks with higher connectance/nestedness and lower modularity compared to the other environment. The results also suggest that seasonal floods may promote ecological opportunities for new species associations.

Trichobilharzia ocellata cercariae attach readily to the foot skin of their duck host, but poorly to preen-gland contents. The attachment to duck foot disappears when the skin surface lipids are extracted, and can be restored by reapplication of the lipids to the skin. Hydrophilic skin extracts are without any effect. Thin-layer chromatographic fractionation of duck-foot skin surface lipids reveals cholesterol and ceramides as attachment stimuli. A stimulation of cercarial attachment by these hydrophobic host signals is supported by the host identification pattern of the cercariae, which secures a close contact with encountered substrates.

In the system investigated the spleen was essential in most rats for the acquisition of immunity and its maintenance in the presence of the piroplasm.

It is stressed that model immunological systems involving the role of the spleen do not simulate the complexity of a parasitic infection. The roles of the spleen as an antibody producer, and as a site of phagocytosis and haemopoiesis are discussed in relation to the control of Babesia rodhaini by the rat. The possibility that the piroplasm may be able to undergo antigenic variation is considered.

Mice infected with Nematospiroides dubius generate weaker immune responses to concurrently administered sheep red blood cells (SRBC), than non-infected controls. The experiments described in this paper demonstrate that both adult and larval stages of N. dubius cause non-specific immunodepression of the response to SRBC. Mice which had been infected with larvae exposed to 25 krad. of irradiation, which prevents development to the adult luminal stages, produced as weak haemagglutination responses to SRBC as mice infected with normal worms even when SRBC were administered 6 weeks after infection. The removal of adult N. dubius by treatment with pyrantel 9, 11 and 15 days after infection with normal larvae did not restore the host's ability to respond to SRBC given on day 14. It was only when the mice had been without worms for 17 days that their capacity to respond normally to SRBC was restored. Mice infected with 60 or 400 transplanted adult worms produced depressed haemagglutination and plaque-forming responses to concurrently injected SRBC when compared with normal or sham-operated controls. The significance of these results is discussed in relation to the possible role of non-specific immunodepression in facilitating the survival of N. dubius in the host.

Fleas are insects that undergo a complete metamorphosis in the course of their development from egg to adult. The eggs laid by the mother are not, as are the eggs of lice, attached in any way to the skin, fur or feathers of the animal on which the parents are parasitic. They fall into the nest, or drop to the ground within the lair or “ run ” of the host. Hatching takes from three to ten days according to the temperature. The larvae are active, whitish maggots, eyeless and legless, which are not parasitic, but feed on organic matter in the host's bed, or in the dust that collects on the ground in its proximity.

The dry weight and nitrogen content of Hymenolepis diminuta were studied after a period of 15 days‘ growth in rats receiving different diets. The special diets were fed during the last 7 days of this period, that is, while the major part of growth is occurring but before shedding proglottids.

Replacement of all the protein (casein) of the diet by carbohydrate resulted in greater development of the worm. However, replacement of casein by fat had no effect on worm development, indicating that removal of protein is not a significant factor, whereas addition of carbohydrate is effective.

Since exchange of casein by the nutritionally incomplete protein zein did not affect worm development significantly, protein quality appears not to be a factor in growth of H. diminuta.

The addition of tryptophan and lysine to the meal containing zein, in order to raise its nutritional value to that of casein, did not influence the growth of the parasite. However, the feeding of the same amounts of these two amino acids at times other than those of giving zein depressed the growth of the parasite. This was not due to type of protein (zein) fed in the rest of the diet, since a similar phenomenon occurs when casein is the dietary protein, or when a protein-free diet rich in carbohydrate is given. Addition of these amino acids, singly, either to diets containing protein or deficient in protein, had significant actions on worm growth, which was sometimes stimulated and in other circumstances reduced.

The nitrogen balance of the host was unaffected by the worm burden.

We are deeply indebted to Dr C. A. Hopkins for providing facilities, for infection of rats with the cestode, and for his helpful advice. Miss M. Cowan provided skilled technical assistance during the feeding of the animals and analysis of the host and parasite tissues. One of us (D.F.M.) gratefully acknowledges the Award of a Commonwealth Bursary from the Royal Society and the Nuffield Foundation.

Morphological, histopathological, and immunological studies of seven strains of rickettsial disease have placed them in two widely separated groups, for which typhus and spotted fever seem the most logical names.

Diseases of the spotted fever group are carried by ticks (Arachnoidea) and characterised by distinctive histopathological lesions—thrombonecrosis of arterioles and venules, with micro-organisms of definite and characteristic morphology, invading smooth muscle cells, as well as endothelium, mesothelium, and macrophages. Tissue culture studies show massive invasion and distention of cell nuclei, while cytoplasmic invasion of host cells is relatively sparse.

Diseases of the typhus group are carried by lice and fleas (Insecta) and characterised by the facts that the intracellular parasite which causes them invades only endothelium and mesothelium, distends the cytoplasm of its host cells without ever invading nuclei, and in guinea pigs causes only proliferative endangeitis without thrombonecrosis.

In the spotted fever tick, organisms are intranuclear as well as intracytoplasmic, invade nearly all types of tissue, and are transmitted hereditarily. In typhus-infected lice and fleas, organisms are intracytoplasmic only, infect only the lining cells of the gut, and are not transmitted hereditarily.

Neither focal brain lesions nor scrotal sac exudation is of importance in the differential diagnosis, since both occur in certain strains of spotted fever, as well as in typhus. Definite necrosis of the scrotum is of importance, since it is dependent upon the above-described arteriolar thrombonecrosis and is peculiar to spotted fever.

A review of the literature shows that rickettsial diseases and their etiological agents are being classified in an inaccurate and unjustifiably complex manner, specific names often being given to organisms without the presentation of evidence sufficient to establish them as new varieties.

A plea is made for the study of unclassified or unsatisfactorily classified diseases in all parts of the world by the methods described, and for their classification on the basis of morphologic and histopathologic observations on insect and mammalian hosts and of immunological studies on the latter, rather than on variations in clinical pictures in man and in experimental animals.

The criteria for the differential diagnosis between typhus and spotted fever are presented in tabular form and illustrated wherever possible. All reported rickettsial diseases as well as their etiological agents are classed on the basis of the criteria presented, and, with the exception of the incompletely studied mite-borne group, the available evidence strongly suggests that all are varieties of typhus and spotted fever.

The morphological, histopathological, and immunological differences between typhus and spotted fever are so great that these two diseases, as well as their causative organisms, should be widely separated from one another, and given definitely distinguishing names.

It is suggested that the well-established name, Rickettsia prowazeki, be applied to intracytoplasmic micro-organisms in Insecta causing all diseases of the typhus group, and that Dermacentroxenus rickettsi (the name originally given by Wolbach) be applied to hereditarily transmitted micro-organisms invading nuclei in Arachnoidea and in tissue cultures, causing all diseases of the spotted fever group. Specific varieties, when established by the demonstration of definite and constant biological differences, should be indicated by variety names, as Rickettsia prowazeki mooseri (for endemic flea-borne typhus in all parts of the world).

Schistosoma mansoni cercariae were incubated for 3–5 h at 37°C in various test solutions, and the rate and extent of conversion of th ecercariae to schistosomula were determined. Criteria used to identify schistosomula included: (1) loss of cercariai tail, (2) viability of organisms in saline but not in water, (3) pre-acetabular gland evacuation and (4) ability to survive in culture.

In tests for chemotherapeutic activity, mice were infected with Eperythrozoon coccoides, treated with drugs for 2 days, splenectomized, and treated with drugs for a further 2 days. Blood films were examined from the second day after splenectomy, when control mice showed heavy blood infections.

Neoarsphenamine, aureomycin and terramycin were active.

Tryparsamide, Chloromycetin, alloxan and polyoxyethylene ether, D2, were slightly active.

Many drugs, listed in Table 3, were inactive.

Neoarsphenamine cleared E. coccoides from the blood very rapidly. This action was inhibited by dimercaprol (BAL).

E. coccoides closely resembles Haemobartonella muris in its sensitivity to drugs. Both micro-organisms probably have affinities with the Rickettsiae.

1. Copulation between individuals of the two species O. moubata, and O. savignyi may occur, and the stimulus of coition may induce oviposition, the eggs being non-fertile.

2. There is no evidence of parthenogenesis in this species, nor do these ticks undergo ecdysis after reaching maturity.

3. An increase in temperature of 8° C. from 22° C. (a) doubles the.rate of oviposition, (b) decreases the fertility of the eggs by 30 per cent., (c) reduces the longevity of the female tick from 715 to 397 days, i.e. by 40 per cent, and (d) approximately halves the period required for metamorphosis, under laboratory conditions. Under these conditions at 37° C., reproduction is inhibited, and the longevity of the female is reduced by 80 per cent.

4. An individual may undergo from four to eight ecdyses before reaching maturity, the great majority of the males appearing after the fifth ecdysis and the females about equally after the fifth and sixth ecdyses.

5. Engorgement can take place one or two days after emergence, at any stage, the average time required being three-quarters of an hour. There is great variation in the extent of engorgement at each stage, but this is not correlated with the ecdysis period. The largest meal may be taken either before or after an individual reaches maturity.

6. Moisture has an adverse influence on the vitality of the individual, excess of moisture inhibiting growth.

7. An approximation to the stage of development attained can be made after the study of the structure of the hypostome, leg and spiracle. The larval and first four nymphal stages are fairly well differentiated, much more so than the later stages, but variation due to nutrition requires further study.

A new species of ascaridoid nematode, Baylisascaris tasmaniensis, is described from three marsupial carnivores of Tasmania, namely Sarcophilus harrisi, Dasyurus viverrinus, and Dasyurops maculatus. The new species is differentiated from other species in the genus Baylisascaris and the phylogenetic affinities within the genus are discussed in relation to the origin of the placental and marsupial carnivores.