Human neurocysticercosis (NCC) is a worldwide neglected disease caused by Taenia solium metacestode and responsible for various complications and neurological disorders. This study aimed to evaluate the use of specific immunoglobulin Y (IgY) produced by laying hens immunized with a hydrophobic fraction of Taenia crassiceps metacestodes (hFTc) in NCC diagnosis. Egg yolk IgY antibodies were fractionated, purified and characterized. Enzyme-linked immunosorbent assay (ELISA) was carried out to evaluate the production kinetics and avidity maturation of anti-hFTc IgY antibodies throughout the IgY obtention process. Antigen recognition tests were carried out by Western blotting and immunofluorescence antibody test using purified and specific anti-hFTc IgY antibodies for detection of parasitic antigens of T. crassiceps and T. solium metacestodes. Sandwich ELISA was performed to detect circulating immune complexes formed by IgG and parasitic antigens in human sera. The results showed high diagnostic values (93.2% sensitivity and 94.3% specificity) for immune complexes detection in human sera with confirmed NCC. In conclusion, specific IgY antibodies produced from immunized hens with hFTc antigens were efficient to detect T. solium immune complexes in human sera, being an innovative and potential tool for NCC immunodiagnosis.

No external signs of activation of cystacanths in the alimentary tract were observed until 25 min after oral ingestion. Peak percentage evagination was observed after 60 min.Activation and establishment of cystacanths were never found in the ventriculus or anterior to it, but several crushed specimens were found in the ventriculus, which is a mechanical hazard to the parasite.Infections established by cannulation at the yolk-stalk are greater than infections produced by ingested parasites; thus the ventricular environment does not need to be experienced by the freed cystacanth for activation to take place.

1. Accurate measurements were made of adults, larvae and eggs of Rhabditis pellio, representing an average selection for comparison with Johnson's figures.

2. The most satisfactory method of culturing the nematodes was in hanging drops, in a medium free from an excess of putrefying bacteria.

3. A medium poor in food was found to prolong life (up to 40 days), while a rich medium quickened up the life processes thereby causing death sooner. It is probably partial starvation which prevents the larvae from becoming mature while in the living earthworm.

4. In a medium favourable for prolonging life, the males were found to live about one-third as long as the females (F generation). It is probable that the females only live for about 4–8 days in a decaying earthworm after attaining maturity.

5. The maximum number of eggs laid per female was 257 (F generation) and 197 (F1 generation). It is probable that between 150 and 300 eggs are laid per female in the natural state. No information was obtained regarding the effect of the various media on egg production.

6. In most cases the females died when spent of eggs.

7. Vivipary is considered to be due to a favourable environment probably aided by a high temperature.

8. Larvae were found to be more susceptible to cultural conditions than the adults, especially those (F generation) which were not bred from females in culture media. The growth-rate of F1 generation larvae was found to be slightly faster in a natural medium, such as earthworm broth, than in peptone.

9. The chief food is considered to be bacteria.

10. During this work R. pellio behaved entirely as a bisexual species. A few cases of copulation were observed, showing that some of the males had not lost their “sexual instinct.”

11. Rhabditis pellio is considered to be a species in which hermaphroditism is just commencing and in which true males and females exist together with hermaphrodite females whose numbers fluctuate, the degree of hermaphroditism possibly bearing some relation to the sex ratio.

12. The sex ratio was about 1 ♂: 2 ♀♀, in both the F and F1 generations, but varied considerably. There were a few cases in which the male proportion was equal, or higher, than the female.

13. Four different species of British earthworms were examined, each being infected by Rhabditis pellio to a varying extent. Eisenia foetida was, however, rarely infected. Size of the earthworm, in proportion, played no part regarding the degree of infection. There is an indication that the head (segment I to the beginning of the clytellum) is the most heavily infected region.

14. A few specimens (larval stage) of an Ascarid, a species of Porrocaecum, a parasite of small mammals and birds, were found in three of the species of earthworms examined.

15. A probable course of the life history is given, based on this work and that of Johnson (1913).

The importance of parasites as a selective force in host evolution is a topic of current interest. However, short-term ecological studies of host–parasite systems, on which such studies are usually based, provide only snap-shots of what may be dynamic systems. We report here on four surveys, carried out over a period of 12 years, of helminths of spiny mice (Acomys dimidiatus), the numerically dominant rodents inhabiting dry montane wadis in the Sinai Peninsula. With host age (age-dependent effects on prevalence and abundance were prominent) and sex (female bias in abundance in helminth diversity and in several taxa including Cestoda) taken into consideration, we focus on the relative importance of temporal and spatial effects on helminth infracommunities. We show that site of capture is the major determinant of prevalence and abundance of species (and higher taxa) contributing to helminth community structure, the only exceptions being Streptopharaus spp. and Dentostomella kuntzi. We provide evidence that most (notably the Spiruroidea, Protospirura muricola, Mastophorus muris and Gongylonema aegypti, but with exceptions among the Oxyuroidae, e.g. Syphacia minuta), show elements of temporal-site stability, with a rank order of measures among sites remaining similar over successive surveys. Hence, there are some elements of predictability in these systems.

The life cycle of the parasitic copepod Lernaeocera branchialis involves 2 hosts, typically a pleuronectiform host upon which development of larvae and mating of adults occurs and a subsequent gadoid host, upon which the adult female feeds and reproduces. Both the copepodid and adult female stages must therefore locate and identify a suitable host to continue the life cycle. Several mechanisms are potentially involved in locating a host and ensuring its suitability for infection. These may include mechano-reception to detect host movement and chemo-reception to recognize host-associated chemical cues, or kairomones. The aim of this study was to identify the role of kairomones in host location by adult L. branchialis, by analysing their behaviour in response to fish-derived chemicals. Experiments demonstrated that water conditioned by immersion of whiting, Merlangius merlangus, elicited host-seeking behaviour in L. branchialis, whereas cod- (Gadus morhua) conditioned water did not. Lernaeocera branchialis are considered a genetically homogeneous population infecting a range of gadoids. However, their differential response to whiting- and cod-derived chemicals in this study suggests that either there are genetically determined subspecies of L. branchialis or there is some form of environmental pre-conditioning that allows the parasite to preferentially recognize the host species from which it originated.

The diseases included under the general term of piroplasmosis are amongst the most devastating which affect domesticated animals, and they are, consequently, of great economic importance. As far as known, all forms of piroplasmosis are tick-transmitted.

It has been pointed out by Warburton (1912) that the degree of variation within the species of the genus Rhipicephalus is very considerable, and in view of this fact it is important to investigate the range of a species and the value of the differential structural characters upon which species are based. The great majority of the Rhipicephali are inornate and this, in conjunction with the general lack of distinguishing structural features and the wide variation found within the species, renders determinations difficult. As Rhipicephalus pulchellus, however, possesses a characteristic and well-marked ornamentation, which is subject to but slight variation, any specimen, at least in the case of the males, may be determined without difficulty.

The parasite reaction phenotype of 80 lambs was determined with natural infection on pasture. These lambs were then assigned to outcome groups and randomized into treatment groups. Developing some simple but unusual analytical techniques it was possible to demonstrate that mixed natural infections of trichostrongyles with the chief biomass component Haemonchus contortus cayugensis protected against superinfections with 35000 infective larvae but protected against superinfections with 1000 infective larvae per day only within the limits characteristic of the enclosing barn ecosystem. The limits of the barn ecosystem were less constraining on more diathetic sheep than the natural pasture infection. Internal evidence from the experiment suggests that the interaction of sheep × pasture × infective trichostrongylid larvae constrains the parasite biomass in the host in more diathetic animals at significantly lower levels. Anaphylactoid ‘self-cure’ did not occur in this experiment but something like premunition certainly did.

This essay deals in turn with the six main mechanisms that are believed to be involved in the passage of small molecules across the cell membrane of yeasts and fungi. Such solutes include amino acids, carbohydrates, purines and pyrimidines and other nutrients, among which are the ions K+, , or . The subject has been reviewed extensively (see, for example, Eddy, 1982; Cooper, 1982; Serrano, 1984; Harold, 1986). Transport systems relate to chemotherapy in two ways. First, they may themselves be potential targets for drug action. Second, they may deliver a drug to its intracellular target, the drug being an illicit passenger in a transport system with a different primary role. Most of our knowledge about yeast and fungal transport is currently based on studies with relatively few species selected because they are known to be amenable to genetic and biochemical analysis. The organisms include representative strains of Neurospora crassa or of Saccharomyces cerevisiae and selected species of Rhodotorula and Schizosaccharomyces. Fungal organisms pathogenic to man, such as Candida albicans, those causing either systemic fungal infections (see Kerridge, 1986; Shepherd, Poulter & Sullivan, 1985), or the numerous fungal diseases of plants have been little used as models of nutrient transport, despite their clinical or economic importance. Whether all these ecologically diverse organisms, which in evolutionary terms are only distantly related, employ only the transport mechanisms so far discovered in Saccharomyces cerevisiae is an open question.

A new isolate of Trypanosoma musculi has been derived from organisms recovered from Mus spretus captured in Lisbon, Portugal. The time-course and profiles of infection with this isolate in inbred mice have been compared with those obtained with the existing Partinico II isolate. Infections with the Portuguese isolate are less intense, and controlled more quickly than those with the Partinico isolate. As with the latter, there are marked mouse strain-dependent influences on infection with the Portuguese isolate, but these strain-dependent characteristics differ considerably with each isolate. For example, NIH mice were the most susceptible to the Partinico II isolate, but virtually refractory to the Portuguese isolate. Mice exposed to infection with one isolate show complete immunity to both homologous and heterologous challenge infections. These striking interactions between host and parasite genotype are discussed in terms of immunological influences on infection.

Sera from goats and cattle that were infected with two Trypanosoma vivax clones (ILDat 1.2 and ILDat 2.1) derived from different stocks were analysed for antibody activity against the variable surface glycoproteins (VSGs) of the infecting clones by enzyme-linked immune assays (ELISA) and immune lysis. To obtain purified VSG, lysed trypanosomes were separated on dodecyl sulphate-polyacrylamide gels. The gels were copper stained and the VSG protein band was excised from the gel. After destaining, the proteins were electroeluted from the gel slices and used as antigens in ELISA. High titres of IgM and IgG1 antibodies and lytic antibodies against the VSG of the infecting clone were detected. The IgG1 response appeared about 4 days later than the IgM response. IgG2 antibodies were only detected in goats and cattle that were infected with ILDat 1.2. Two goats and two calves that were infected with ILDat 1.2 showed recurrent peaks in lytic activity and of IgM and IgG1 antibody activity to the VSG of the infecting variable antigenic type (VAT). Two goats that were infected with ILDat 2.1 showed a similar pattern, but in two other goats there was a recurrent peak only in the IgM class. Recurrent peaks of antibody activity to the VSG of ILDat 1.2 and ILDat 2.1 were not detected in the sera of goats that had been inoculated with irradiated trypanosomes or that had been infected with an unrelated T. vivax clone. The recurrence of antibody peaks against the VSG of infecting VATs suggests that trypanosomes with completely or partially identical surface determinants reappear during T. vivax infection of ruminants.

Rhinonyssids are obligate haematophagous mites that parasitize the nasal cavity of vertebrates, and occur in a wide range of birds worldwide. Two species of nasal mites are known to occur in penguins: Rhinonyssus sphenisci, which has been recorded from Humboldt and Magellanic penguins (Spheniscus humboldti and S. magellanicus, respectively), and Rhinonyssus schelli, which has been recorded in Adélie and Gentoo penguins (Pygoscelis adeliae and P. papua, respectively). We examined the nasal cavity of African penguins (Spheniscus demersus) that died while under care at a rehabilitation centre (N = 40) or that were found dead at breeding colonies (N = 67). Nasal mites were found in the nasal cavity and/or paranasal of sinuses of 21 penguins, some of which had signs of mild-to-moderate sinusitis. Prevalence was higher in juveniles (29%) and adults (27%) than in chicks (10%). Mean intensity was 5.9 ± 12.9 mites per infected host (range 1–60). The mites presented morphological characteristics that were at times consistent with either R. sphenisci or R. schelli, and therefore we conservatively classified them as ‘R. sphenisci sensu lato’. Our morphometric results raise the question of whether the specific status of R. schelli is justified.

The cDNA probe, Lmet2, was labelled with digoxigenin and used in a chemiluminescent system to detect fewer than 100 membrane-immobilized Leishmania parasites. The probe was found to hybridize primarily with members of the L. donovani complex but a slight cross-reaction was also observed with greater than 5 x 104L. major. This cross-reaction was reduced by hybridizations in 50% formamide at 37 °C. Formamide also significantly reduced non-specific binding of the digoxigenin-labelled probe to the membrane support which, in hybridizations without formamide, masked the specific hybridization signal. This background was not observed with the corresponding radio-isotope labelled probe. With hybridizations in formamide the sensitivity achieved by the chemiluminescent system after exposure to film for 3 h was greater than that achieved by the isotopic system even after autoradiography for 24 h.

In my previous paper (Parasitology, XI. 1919) on the life history of a Calliphorine fly, Melinda cognata Meig., the larvae of which live as parasites in a snail (Helicella virgata), I gave a complete account of all the Dipterous larvae feeding upon molluscs.

Two repetitive DNA sequences have been characterized from Schistosoma mansoni which were transcribed into mRNAs and translated to give two families of cross-reactive proteins. One DNA element, which was present as a 230 bp Pst I fragment was arranged in tandem arrays of at least 17 copies in the genome. The second element, which could be localized to a 1800 bp Pst I fragment, was dispersed in the genome. The 1800 bp repeat was found on the mRNA encoding the 45 kDa polypeptide precursor of a potential surface antigen. This precursor was post-translationally modified to give a 50 kDa antigen (Sm50) which was expressed from the cercaria to the adult worm and in the egg. However, a proportion of this antigen was differentially modified in females and eggs to give a 60 kDa form. Two copies of the 230 bp repeat and one copy of the 1800 bp repeat were found on a second cDNA clone. The antiserum raised against the fusion protein of this clone recognized a family of cross-reactive proteins ranging from 14 to 70 kDa in size. The members of this family were also differentially expressed between the sexes. Consequently, two families of antigens have been identified which were both encoded by repetitive DNA elements and whose members were both differentially expressed in adult male and female worms.

Cysticercosis caused by the metacestode larval stage of Taenia hydatigena formerly referred to as Cysticercus tenuicollis is a disease of veterinary importance that constitutes a significant threat to livestock production worldwide, especially in endemic regions due to condemnation of visceral organs and mortality rate of infected young animals. While the genetic diversity among parasites is found to be potentially useful in many areas of research including molecular diagnostics, epidemiology and control, that of T. hydatigena across the globe remains poorly understood. In this study, analysis of the mitochondrial DNA (mtDNA) of adult worms and larval stages of T. hydatigena isolated from dogs, sheep and a wild boar in China showed that the population structure consists of two major haplogroups with very high nucleotide substitutions involving synonymous and non-synonymous changes. Compared with other cestodes such as Echinococcus spp., the genetic variation observed between the haplogroups is sufficient for the assignment of major haplotype or genotype division as both groups showed a total of 166 point-mutation differences between the 12 mitochondrial protein-coding gene sequences. Preliminary analysis of a nuclear protein-coding gene (pepck) did not reveal any peculiar changes between both groups which suggests that these variants may only differ in their mitochondrial makeup.

A male specimen of the monkey, Cercopithecus aethiops pygerythrus (Cuvier), caught near Bedford, Eastern Cape, was sent to us by Dr P. A. D. Winter of the Polio Research Foundation, Rietfontein. On arrival at Rietfontein this monkey showed slight symptoms of a mange, described by Dr Winter as follows: 'The lesion was scaly with underlying patches of erythema. Over the lesion the hair was thin. On scraping, much of the scaly material could be taken away, revealing irregular, raised erythematous patches. These patches were distributed particularly on the dorsal aspects of the limbs and there were also several of them on the chest, abdomen and head.

Immunological data indicate that different subsets of T-helper cells work best against different types of infection. Concomitant infection of a host may thus impose either conflicting or synergistic immune response requirements, depending upon the extent to which the component optimal immune responses differ. Drawing upon empirically-determined optimal responses to single-species infections, an optimality model is here used to generate testable hypotheses for optimal responses to concomitant infection. The model is based upon the principle that the joint immune response will minimize divergence from each of the optima for single-species infections, but that it will also be weighted by the importance of mounting the correct response against each infectious organism. The model thus predicts a weighted average response as the optimal response to concomitant infection. Data on concomitant infection of murine hosts by the parasites Schistosoma mansoni and Toxoplasma gondii will provide the first test of the optimality model. If the weighted average hypothesis holds true, then there are no emergent immunological properties of concomitant infections and we may be able to understand immune responses to concomitant infection directly via our understanding of single-species infections.

An egg-adapted line of Eimeria necatrix has now been passaged 40 times in the chorio-allantoic membranes of embryonated eggs. Between the 21st and 40th passage in eggs the parasite was subjected to a selection for precocious development, and its pre-patent period in this host is now 123–125 h. The parasite continued to adapt to the chorio-allantoie this tissue caused the growth of the host embryo to be markedly stunted. In chickens, both the reproduction and the pathogenicity of the egg-adapted line decreased with increasing numbers of passages in eggs. A comparison of teh immunogenicity of te egg-adapted line and its parent strain in chickens kept on litter, showed that substantially more oocysts of the egg-adapted line had to be given to induce complete protection.