Toxoplasma gondii is an obligate intracellular parasite of phylum Apicomplexa. To facilitate high-efficiency invasion of host cells, T. gondii secretes various proteins related to the moving junction (MJ) complex from rhoptries and micronemes into the interface between the parasite and host. AMA1/RON2/4/5/8 is an important MJ complex, but its mechanism of assembly remains unclear. In this study, we used the CRISPR-Cas9 system to generate a derivative of T. gondii strain RH with a null mutation in TgRON4, thought to be an essential MJ component. Deficiency of TgRON4 moderately decreased invasion ability relative to that of the wild-type parasite. In addition, expression of the endogenous N-terminal fragment of RON5 decreased in the mutant. Together, the results improve our understanding of the assembly mechanism of the MJ complex of T. gondii and raise the possibility of developing new therapeutic drugs that target this complex.

Intestinal and faecal IgA responses against different developmental stages of Nippostrongylus brasiliensis were studied in Hooded Lister rats vaccinated subcutaneously with infective larvae or intragastrically with 4th-stage larvae, adult nematodes, adult worm somatic and metabolic antigens. It was found that intragastric administration of L4 or adult worms produced as high resistance to challenge as normal infection. Oral vaccination with adult nematode excretory–secretory (ES) and somatic antigens produced 69 and 17% protection respectively. All vaccination regimes induced a considerable IgA response against somatic and metabolic antigens of the intestinal stages. However, no correlation could be seen between the IgA levels and degree of protection. Analysis of intestinal mucosal, intestinal contents and faecal IgA specific to larval or adult antigens suggests that the IgA is probably induced by antigen(s) common to all intestinal stages. Also secretory IgA responses against surface antigens of intestinal L4 did not show stage specificity, although this was detected in sera.

The Dipterous Family, Tachinidae, comprises a very large number of species whose larvae live as parasites within other insects, particularly in their larval forms.

The stink organs are different in structure and position in the adult and the larval stages.

The stink organs of the adult are composed of (a) a pair of glands, (b) a central reservoir with two backwardly-directed lateral reservoirs, (c) a median kidney-shaped organ in the central reservoir, and (d) a pair of lateral external openings.

Each gland is a multicellular compound structure, opening into the central reservoir. It is described for the first time in this paper.

The whole of the stink organ of the adult is formed in the last larval stage from a pair of invaginations of the epithelial lining of the body-wall.

In the larval stages the stink organs are simple glands, situated dorsally in abdominal segments III to V.

The function of the stink organs is defensive and in the adult perhaps also sexual.

By many observers Negri bodies have been considered to be parasitic in nature (Negri, 1903; Babes, 1907). Williams and Lowden (1906) go further and describe the life cycle of these bodies, regarding them as belonging to the Sporozoa, and give to them the name of Neuroryctes hydrophobiae. Calkins (1910), although he states that the parasitic nature of these bodies is not proven, still evidently inclines to that view. In his criticism of the work of Williams and Lowden he comes to differ from them as regards the classification of the supposed organisms. He thinks that their variable forms, the uninucleate condition, the occurrence of a state of distributed chromatin, and the budding phenomenon, are characteristic not of Sporozoa but of parasitic Rhizopods. His opinion is that the distributed chromatin masses in the Negri bodies are in all probability representative of the idiochromidia which are so characteristic of Rhizopods.

The development of the tegument and cercomer of Paricterotaenia paradoxa polycephalic larvae was examined using electron microscopy. Larvae are formed by budding from the inner surface of the tegument of the degenerating hexacanth embryo. A new secondary tegument formed around the larvae is probably produced from the original hexacanth sub-tegumental cells. Microvilli covering the surface of young larvae are converted directly into microtriches, as the larvae develop, by addition of electron-dense material to the proximal part of the microvillus. Remnants of the original microvillus are visible at the distal surface of each new microthrix, but they eventually degenerate. The cercomer homologue is represented by scattered follicular cells, bearing microvilli, lying just within the containing cyst wall. The continuity of tegumentary tissue from one developmental stage to the next is discussed.

During some investigations in which, he has been engaged on the internal parasites of rats in the British Isles, Mr G. C. Dudgeon, of the Wellcome Bureau of Scientific Research, has kindly submitted to the writer examples of all the species of adult Cestodes found.

There is an increasing interest in improving neurocysticercosis (NCC) diagnosis through the search of new and alternative antigenic sources, as those obtained from heterologous antigens. The aim of this study was to obtain potential biomarkers for NCC diagnosis after gel filtration chromatography [gel filtration fraction (GFF)] from the total saline extract (SE) from Taenia saginata metacestodes, followed by protein identification and application in immunodiagnostic. SE and GFF proteic profiles were characterized in gel electrophoresis, and diagnostic performance was verified by testing 160 serum samples through enzyme-linked immunosorbent assay and immunoblotting. Sensitivity (Se), specificity (Sp) and other diagnostic parameters were calculated. Polypeptides of interest in the diagnosis of human NCC present at GFF were analysed by mass spectrometry (MS) and B-cell epitopes were predicted. GFF had the best diagnostic parameters: Se 93·3%; Sp 93%; AUC 0·990; LR+ = 13·42 and LR− = 0·07, and proved to be useful reacting with serum samples in immunoblotting. Proteic profile ranged from 64 to 68 kDa and enolase and calcium binding protein calreticulin precursor were identified after MS. The enolase and calcium-binding protein calreticulin precursor showed 18 and 10 predicted B-cell epitopes, respectively. In conclusion we identified important markers in the GFF with high efficiency to diagnose NCC.

A technique is described for the isolation of a pure suspension of second-generation schizonts of Eimeria necatrix and E. tenella. Most of the schizonts appeared viable as judged by their ability to exclude Trypan blue and the use of this criterion is examined. They were able to metabolize radio-isotope labelled glucose and accumulate thiamine against a concentration gradient. A formula allowing detailed consideration of the latter process is introduced. Crude extracts of these schizonts exhibited serine hydroxymethyl transferase activity which is significantly different from that of the host tissue in terms of optimal pH (8·3 for the parasite and 7·8 for the avian intestinal cells) and Michaelis constant (approximately 2·6 × 10−3m and 0·6 × 10−3m respectively). Differences in response to potential inhibitors are also shown.

Pooled sample testing (PST) as a strategy for avoiding testing the majority of individual negative samples has been proposed for screening of diseases in low prevalence areas. There has been no standard guideline for PST in screening of Schistosoma japonicum infection of Yunnan, China. To document the optimum pool size with acceptable sensitivity of PST for screening of Schistosoma japonicum infection in this setting, an experimental pooling of each of 31 positive sera by IHA with various numbers of 24 negative sera was done. The results were used to create a statistical model which was subsequently used for simulation to predict sensitivity of the pooled serum tests in the population with varying prevalence and pool size. We found that to keep the sensitivity of PST above 90%, 1:05 should be the maximum dilution, that is, the optimum pool size should not be greater than 6. Antigen will have rather little interference if the prevalence of infection is low e.g. 1% or the antigen:antibody ratio is 1:100 or below. Pooled serum testing by IHA is an acceptable sensitive method for detecting antibody for Schistosoma japonicum infection in this area.

This study assessed the impact of adding community-directed treatment (ComDT) to the routine health facility (HF)-based treatment on prevalence and intensity of soil transmitted helminth (STH) infections among children aged 12 to 59 months. Repeated cross-sectional surveys were conducted among randomly selected children of this age group from the intervention area (HF+ComDT area) and the comparison area (HF area) at baseline (n=986), 12 months (n=796) and 18 months (n=788) follow-up. The prevalence of Ascaris lumbricoides was significantly higher in the HF+ComDT as compared to the HF area at baseline (P=0·048), but not at 12 and 18 months follow-up. At baseline the HF+ComDT area had significantly higher intensities of A. lumbricoides compared to the HF area (P<0·001), but not at 12 and 18 months follow-ups. Prevalence and intensity of hookworm did not differ significantly between treatment arms at any time. Analysis of trends showed a significant decrease in prevalence of A. lumbricoides and hookworm in the HF+ComDT area (P<0·001), of hookworm in the HF area (P<0·05), but not of A. lumbricoides in the HF area. It is concluded that the ComDT approach generally enhanced the treatment effect among under-five year children and that this alternative approach may also have advantages in other geographical settings.

Intraspecific pairing of Haematoloechus medioplexus and Echinostoma revolutum adults and interspecific pairing of H. medioplexus and E. revoltum adults were studied in vitro at 21 ± 1 °C and 30 ± 1 °C in Petri-dish cultures containing an agar substrate and a Locke's 1:1 solution overlay. Salinity and temperature tolerance tests showed that both species survived for 24 h in a Locke's 1:1 solution at 21 ± 1 °C and 30 ±1 °C. For behaviour studies, worms were placed 2 cm apart and then observed at various intervals from 5 min to 4 h. H. medioplexus and E. revolutum showed significant intraspecific pairing at 30±1 °C, whereas only H. medioplexus paired significantly at 21±1°C. Significant interspecific pairing of H. medioplexus and E. revolutum occurred at 21 ±1 °C and 30 ±1 °C. Thin-layer chromatographic analysis showed that H. medioplexus adults released mainly free sterol, along with traces of triacylglycerols and free fatty acids into a non-nutrient medium.

The increase of contact between natural and rural areas is prominent in Brazil, due to agricultural activities and concern with the environmental conservation. In this context, domestic animals, wild fauna and humans are exposed to mutual exchange of parasites, microorganisms and diseases. We studied tick parasitism of wild carnivores and domestic dogs, and the environmental of questing ticks, in extensive cattle ranch areas intermingled with natural vegetation, and in a natural reserve, both in a region of Cerrado biome, Midwestern Brazil. From 2008 to 2015, we inspected 119 wild carnivores from nine species, and collected six tick species (Amblyomma sculptum, Amblyomma ovale, Amblyomma dubitatum, Amblyomma tigrinum, Dermacentor nitens and Rhipicephalus microplus). The most numerous and infested hosts were Cerdocyon thous, Lycalopex vetulus, Chrysocyon brachyurus, Puma concolor and Conepatus amazonicus. From 139 domestic dogs, we collected A. sculptum, Rhipicephalus sanguineus and R. microplus. From vegetation, samplings resulted in A. sculptum, A. dubitatum, A. ovale, Amblyomma rotundatum and R. microplus, with dominance of A. sculptum. Domestics and wild animals presented high overlapping of infestations by A. sculptum, a generalist and anthropophilic tick species. This tick is the most important vector of the Brazilian spotted fever, a lethal human disease. This fact elicits attention and requires efforts to monitor the presence of pathogens vectored by ticks circulating in this type of agroecosystem, including in other regions of the Brazil, because the most of the natural vegetation remaining have been increasingly immersed in pastures and agricultural matrix.

Two major groups of heat-stable proteins have been purified by heat denaturation from homogenates of eggs of the potato-cyst nematodes Globodera rostochiensis and G. pallida. SDS-polyacrylamide gel electrophoresis of protein homogenates from 6 G. rostochiensis populations and 7 G. pallida populations revealed 2 bands specific for G. rostochiensis and 3 bands specific for G. pallida. Two-dimensional electrophoresis showed that the 2 bands specific for G. rostochiensis consisted of 2 polypeptides differing slightly in isoelectric point, as did one of the bands specific for G. pallida. Conventional antisera made against protein homogenates of either Globodera species showed a complete cross-reaction with the species-specific proteins. The perspectives of the differences in protein composition between G. rostochiensis and G. pallida, established in this study, for a quantitative differentiation of mixed field populations of the two Globodera species, involving monoclonal antibodies, are discussed.

Two tapeworms, Taenia saginata and Echinococcus granulosus, cause serious economic and human health problems in several parts of the world. Some of these Problems might be solved if a cheap, easy and safe vaccination could be developed. Before a vaccination against adult tapeworms can be developed it is necessary to know how intestinal tapeworm populations are controlled by immune mechanisms. For this purpose laboratory modeis have been used involving mainly species of Hymenolepis in rodents and especially H. diminuta in mice and rats, which will be referred to below.

Among the shore crabs the genus Callianassa is quite cosmopolitan; its species are widely distributed and seem also to be peculiarly susceptible to parasitism. Wherever they have been examined carefully they have yielded semi-parasitic copepods, sometimes in considerable numbers. Such forms have been reported from both the east and west coast of North America, from the Mediterranean and from the British Isles. Recently 150 of these semi-parasites were sent to the United States National Museum from Salaverry near Trujillo on the coast of northern Peru. They were taken by Mr Floyd Sears, agent of the Grace Line at Salaverry, from the branchial chamber of a species of Callianassa on the Peruvian coast. They prove to be new species belonging to two genera of cyclopid copepods and are here described and figured.

An apparatus for artificial feeding of Rhipicephalus appendiculatus nymphae was modified to improve feeding performance. Heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. The feeding apparatus was incubated at 37 °C in an atmosphere of 3% CO2 concentration and a relative humidity of 75–80%. Under these conditions, 91% of the engorged nymphae attained a mean weight of 6–11 mg, and an average of 93% of those nymphae moulted into adults. When this system was used to feed nymphal ticks on blood infected with Theileria parva piroplasms, the mean prevalence of infection in the resultant female and male ticks was 86% and 54%, respectively. The feeding performance and T. parva infection levels were comparable to those of nymphal ticks fed on the blood donor cattle. The apparatus used in this study has potential for modification to suit the artificial feeding needs of other species of ixodid ticks and for use in investigations to examine other tick/pathogen relationships.

Dirofilaria immitis is a parasitic nematode that survives in the circulatory system of suitable hosts for many years, causing the most severe thromboembolisms when simultaneous death of adult worms occurs. The two main mechanisms responsible for thrombus formation in mammals are the activation and aggregation of platelets and the generation of fibrin through the coagulation cascade. The aim of this work was to study the anticoagulant potential of excretory/secretory antigens from D. immitis adult worms (DiES) on the coagulation cascade of the host. Anticoagulant and inhibition assays respectively showed that DiES partially alter the coagulation cascade of the host and reduce the activity of the coagulation factor Xa, a key enzyme in the coagulation process. In addition, a D. immitis protein was identified by its similarity to the homologous serpin 6 from Brugia malayi as a possible candidate to form an inhibitory complex with FXa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and mass spectrometry. These results indicate that D. immitis could use the anticoagulant properties of its excretory/secretory antigens to control the formation of blood clots in its immediate intravascular habitat as a survival mechanism.

As a potential ultimate cause of microhabitat restriction for ectoparasites of fish, it has been postulated that selection has favoured narrow microhabitats to facilitate mating. The evidence for this hypothesis is evaluated with males and females of the parasitic copepod Lernanthropus cynoscicola, by using methods commonly used in community ecology, and considering the influence of host ontogeny on site selection. No evidence supporting the mating hypothesis was found after comparison of niche measurements between both sexes. Furthermore, aggregation among individuals of the same sex was stronger than among males and females, and the co-occurrence of both sexes did not depart from that expected by chance; also, negative correlations between the intensity of infection of both sexes were observed. Restriction of the microhabitats cannot therefore be due to facilitation of mating. Moreover, both sexes displayed a sequential displacement over the gill arches and differential preferences by specific gill sections in response to an increasing host size, probably as a consequence of a host-size related cline of optimal conditions where fitness is improved. Thus, reproductive benefits other than increased chances of mating may have played a role in the evolution of restricted niches in parasites, and selection may have favoured a narrowing of the niche around sites where fitness is maximized.