African trypanosomes are parasitic protozoa causing sleeping sickness in humans and related diseases in domestic animals against which no entirely satisfactory forms of chemotherapy are yet available. It was previously shown that related species of trypanosomes, as well as procyclic (insect) forms of Trypanosoma brucei are extremely sensitive to the action of phenothiazine neuroleptic drugs in vitro. In this work, we have carried out a more detailed investigation of the effects of thioridazine, one of the most potent neuroleptic phenothiazine drugs known, on the morphology of the infective bloodstream forms of T. brucei, with particular reference to the parasite's prominent pellicular membrane complex. Our data show that this drug induces rapid changes in cell shape that appear to involve some reorganization of the microtubular membrane skeleton, but does not affect the structural integrity of the microtubular complex. Another early consequence of drug action involved damage to nuclear and cytoplasmic membranes and the appearance of tubular arrays of coated membrane within the flagellar pocket. It was also revealed that the drug induces a rapid release of the variant-specific glycoprotein (VSG) which makes up the surface coat protecting bloodstream forms of the parasite against the host immune system. Our evidence suggests that this release of VSG involves cleavage of the protein's glycosyl-phosphatidylinositol (GPI) membrane anchor by endogenous GPI-specific phospholipase C, probably as a consequence of minor damage to the parasite plasma membrane induced by the drug.

In a recent contribution to Parasitology (present volume, p. 26) a short description of the male of this species was given. The type-material consisted of a single male from the Silurid fish, Heterobranchus anguillaris, from Cairo. Through the kindness of Dr W. N. F. Woodland, of the Wellcome Bureau of Scientific Research, the writer has recently had the opportunity of examining further material belonging evidently to the same species, the host being Synodontis eupterus and the locality Khartoum. This material consists of several males, one mature and two immature females, all mounted as microscopic preparations in glycerine-jelly. A few further details may now be added to the description of the species.

There are many reasons why detection of parasites of medical and veterinary importance is vital and where novel diagnostic and surveillance tools are required. From a medical perspective alone, these originate from a desire for better clinical management and rational use of medications. Diagnosis can be at the individual-level, at close to patient settings in testing a clinical suspicion or at the community-level, perhaps in front of a computer screen, in classification of endemic areas and devising appropriate control interventions. Thus diagnostics for parasitic diseases has a broad remit as parasites are not only tied with their definitive hosts but also in some cases with their vectors/intermediate hosts. Application of current diagnostic tools and decision algorithms in sustaining control programmes, or in elimination settings, can be problematic and even ill-fitting. For example in resource-limited settings, are current diagnostic tools sufficiently robust for operational use at scale or are they confounded by on-the-ground realities; are the diagnostic algorithms underlying public health interventions always understood and well-received within communities which are targeted for control? Within this Special Issue (SI) covering a variety of diseases and diagnostic settings some answers are forthcoming. An important theme, however, throughout the SI is to acknowledge that cross-talk and continuous feedback between development and application of diagnostic tests is crucial if they are to be used effectively and appropriately.

A new species of phryxid (Isopoda, Bopyridae) found attached in the pterygostome region of a pontoniid shrimp, Periclimenes grandis (Stimpson), is described. The only specimen, found at Mazizini, Zanzibar, has been placed in a new genus, which is defined here. The parasite, Orophryxus shiinoi gen.nov., sp.nov., is the only bopyrid which has been found attached in the pterygostomial region.

1. Chickens were infected with Coccidia, considered to be Eimeria meleagridis, from turkeys.

2. Turkeys were subsequently infected with oocysts obtained from the chickens.

3. Slight variation from normal measurements of the coccidia in chickens is attributed to development in an abnormal host.

4. E. acervulina from chickens was not infective to a coccidia-free turkey chick.

Ookinetes are the motile and invasive stages of Plasmodium parasites in the mosquito host. Here we explore the role of intracellular Ca2+ in ookinete survival and motility as well as in the formation of oocysts in vitro in the rodent malaria parasite Plasmodium berghei. Treatment with the Ca2+ ionophore A23187 induced death of the parasite, an effect that could be prevented if the ookinetes were co-incubated with insect cells before incubation with the ionophore. Treatment with the intracellular calcium chelator BAPTA/AM resulted in increased formation of oocysts in vitro. Calcium imaging in the ookinete using fluorescent calcium indicators revealed that the purified ookinetes have an intracellular calcium concentration in the range of 100 nm. Intracellular calcium levels decreased substantially when the ookinetes were incubated with insect cells and their motility was concomitantly increased. Our results suggest a pleiotropic role for intracellular calcium in the ookinete.

Numerous genetic variants of the Echinococcus antigen B (AgB) are encountered within a single metacestode. This could be a reflection of gene redundancy or the result of a somatic hypermutation process. We evaluate the complexity of the AgB multigene family by characterizing the upstream promoter regions of the 4 already known genes (EgAgB1-EgAgB4) and evaluating their redundancy in the genome of 3 Echinococcus species (E. granulosus, E. ortleppi and E. multilocularis) using PCR-based approaches. We have ascertained that the number of AgB gene copies is quite variable, both within and between species. The most repetitive gene seems to be AgB3, of which there are more than 110 copies in E. ortleppi. For E. granulosus, we have cloned and characterized 10 distinct upstream promoter regions of AgB3 from a single metacestode. Our sequences suggest that AgB1 and AgB3 are involved in gene conversion. These results are discussed in light of the role of gene redundancy and recombination in parasite evasion mechanisms of host immunity, which at present are known for protozoan organisms, but virtually unknown for multicellular parasites.

A recent accession to the collection of the British Museum (Natural History) contains a number of ticks taken in 1927 from a captive Komodo dragon (Varanus komodoensis) in the Zoological Gardens, London. Figures of the two species of ticks concerned were prepared by Mr A. J. E. Terzi for the late Dr W. L. Sambon who intended to describe them as new but died before he had done so. The two species have since been described by other authors, but Mr Terzi's excellent figures are reproduced here (Figs. 1–4), together with a note on the synonymy of one of the species.

1. The feeding of the tick Ixodes ricinus was studied in relation to the reproductive condition of the host, in this case the hedgehog Erinaceus europaeus.

2. Hedgehogs in hibernation, in full breeding condition, and injected with male and female sex hormones, were parasitized with unfed nymphs and female ticks in midwinter.

3. Attachment and engorgement of the ticks was successfully accomplished on both sexually active and inactive hosts. The longer time required to complete engorgement on the hibernating hedgehogs may be explained by their lower blood temperature.

4. Parasitization by this tick does not appear to be related to the reproductive condition of the host animal, and the amount of sex hormone in the host's blood has no apparent immediate effect on the fecundity of the tick.

The paper provides an overview of recent studies on the use of 75Se to tag larval schistosomes and to monitor their migration and distribution patterns in naive mice and those previously exposed to cercariae. The principles and techniques of radioassay and autoradiography in studying various aspects of 75Se-labelled larval schistosomes are described. The main shortcoming of radioassay in monitoring location and movement of labelled schistosomula is that some of the label dissociates from the schistosomula and accumulates in host tissues, notably the liver. Dissociated label is indistinguishable from schistosomula-bound label making monitoring of parasite migration extremely difficult. This difficulty is overcome by compressed tissue autoradiography where labelled schistosomula can be seen as reduced silver foci on an autoradiographic film, whereas dissociated label is too diffusely distributed to produce such reduced silver foci. Furthermore, using autoradiography, quantitative information on parasite migration in normal and immunized laboratory animals can be obtained that would be impossible using traditional recovery techniques. In addition to using 75Se tracer in migration studies, the radio-isotope has potential for elucidating various aspects of schistosome transmission ecology and snail population dynamics in natural waters.

The role of the larva of the alder fly Sialis lutaria as a host for Neoechinorhynchus rutili (Acanthocephala) has been investigated. Brown trout (Salmo trutta) infected with N. rutili were found to be feeding on S. lutaria larvae which contained juvenile acanthocephalans in their haemocoels. These acanthocephalans have been identified as N. rutili. A previous report of this host-parasite relationship indicated some form of host response to the larval acanthocephalan. Stained wax sections of S. lutaria larvae infected with N. rutili did not show any evidence of either a host response or encapsulation. Samples of S. lutaria larvae revealed an interesting pattern of infection. Only larvae of a particular size range were infected. An experiment to infect commercially obtained rainbow trout (Salmo gairdneri) with N. rutili by feeding them with infected S. lutaria larvae was successful. Since S. lutaria larvae are known to be prey items for trout it appears that this route of infection could commonly occur in the natural environment. Larval S. lutaria is considered as an additional intermediate host to several ostracod species which have been shown to play a role in the transmission of N. rutili.

The genus Lecithocladium was erected by Lühe in 1901, with L. excisum (Rud. 1819) as the type species. In addition to the type species, the genus contains L. excisiforme Cohn, 1902, L. gulosum Linton, 1910, L. longicaudum Shen, 1934, L. psenopsis, L. magnacetabulum and L. pagrosomi Yamaguti, 1934, and L. johnii Yamaguti, 1938. L. barbatum Cohn, 1902, has been transferred to the genus Dinurus Looss, 1907, and L. crenatum (Molin, 1859) is regarded by Looss as a ‘species inquirenda’, while Lühe maintains that it is synonymous with L. excisum. The author (1937) has added two more species from Indian hosts to the genus. These are more fully described in the present paper.

Having at our disposal material from various sources obtained from the intestines of monitor lizards, it appeared useful to prepare drawings and descriptions of the less known species of parasites.

Taenia saginata cyst fluid proteins from 4, 8, 12 and 16-week-old cysticerci were analysed by a combination of direct I radio-isotope labelling, immunoprecipitation using a panel of sera from infected cattle infected with T. saginata and SDS–PAGE. Protein antigens of 12, 14, 16, 20 and 26 kDa were identified in all of the cyst fluids examined. These were immunogenic and were precipitated by serum taken from cattle from 8 weeks after infection onwards and were therefore considered to be of diagnostic potential. A 185 kDa protein antigen found only in the cyst fluid of 4-week-old cysticerci and a 43 kDa protein antigen first detected in cyst fluid from 8-week-old cysticerci were also identified but were considered to be of more limited diagnostic potential due to their restricted presence. An apparently non-immunogenic 67 kDa protein, found in all the cyst fluids examined, may have been host serum albumin.

Despite immense efforts, vaccine against visceral leishmaniasis has yet not been developed. Earlier our proteomic study revealed a novel protein, cofactor-independent phoshoglycerate mutase (LdiPGAM), an important enzyme in glucose metabolism, in T helper cells type 1 (Th1) stimulatory region of soluble Leishmania donovani antigen. In this study, LdiPGAM was biochemically and molecularly characterized and evaluated for its immunogenicity and prophylactic efficacy against L. donovani. Immunogenicity of recombinant LdiPGAM (rLdiPGAM) was initially assessed in naïve hamsters immunized with it by analysing mRNA expression of inducible nitric oxide (NO) synthase (iNOS) and other Th1/T helper cells type 2 cytokines, which revealed an upregulation of Th1 cytokines along with iNOS. Immunogenicity of rLdiPGAM was further evaluated in lymphocytes of treated Leishmania-infected hamsters and peripheral blood mononuclear cells of Leishmania patients in clinical remission by various parameters, viz. lymphoproliferation assay and NO production (hamsters and patients) and levels of various cytokines (patients). rLdiPGAM induced remarkable Lymphoproliferative response and NO production in treated Leishmania-infected hamsters as well as in patients and increase in interferon gamma (IFN-γ), interleukin-12 (IL-12p40) responses in Leishmania patients in clinical remission. Vaccination with rLdiPGAM exerted considerable prophylactic efficacy (73%) supported by increase in mRNA expression of iNOS, IFN-γ and IL-12p40 with decrease in transforming growth factor beta and interleukin-10. Above results indicate the importance of rLdiPGAM protein as a potential vaccine candidate against visceral leishmaniasis.

1. The eggs of Thelastoma bulhõesi are shown to have a sticky outer coat of acid mucopolysaccharide.

2. The acid mucopolysaccharide is secreted by the lower uterus wall and by the vagina uterina.

3. A protein substance of unknown function has been observed in invaginations in the ovijector of T. bulhõesi.

4. This protein substance appears to be secreted by the lower part of the vagina uterina and passed along into the ovijector.

5. Possible functions of the mucopolysaccharide coat on the eggs, and of the protein substance in the ovijector, are discussed.

I wish to express my thanks to Dr P. Tate for many invaluable suggestions and for his constant encouragement during this investigation.

It is a common observation that in individual Ixodes ricinus L. ticks, size variations occur; such variation is reflected in the records of early workers (Wheler, 1899; Neumann, 1899: quoted by Nuttall, Warburton, Cooper & Robinson, 1911). The present paper attempts to examine the true specific importance of size variation by basing the study on measurements of the relatively inelastic scuta after the principle of using head capsule measurements for insectan larval instars.

1. A strain of Culex pipiens which is autogenous and stenogamic has been found at Hayling Island, England, and compared with British anautogenous strains.

2. Definite characteristics in adults of both sexes and in larvae have been found which separate the autogenous from the anautogenous British strains of C. pipiens.

3. The autogenous strain differs from the anautogenous strains in (a) the lighter colour of the thorax of the adults; (b) the greater average number of hairs on the ninth tergite of the adults; (c) the relative shortness of the male palps in comparison with the proboscis; (d) the larger average number of branches in each of the four siphonal tufts of the fourth instar larvae; (e) the lower siphonal index of the fourth instar larvae; and (f) the greater width of the egg relatively to its length.

When incubated in vitro for 24 h, intact eggs, chemically shelled eggs (obtained by treating intact eggs with NaOCl), activated larvae (eggs in which the outer shell and inner envelope were removed), and oncospheres (activated larvae treated with papain to remove the embryophore) absorb and metabolize radioactive glucose. Intact eggs, which are covered by the impermeable shell, absorb only small amounts of exogenous radioactive glucose, while chemically shelled eggs, activated larvae, and oncospheres absorb much larger amounts. Only very small amounts of the exogenous glucose are incorporated into the ethanol-precipitable carbohydrate fraction (which would include glycogen) by any of the preparations of eggs/larvae. However, the glucose is incorporated into higher molecular weight end-products that are liberated into the incubation medium. There is a temporal shift in the ability of activated larvae and oncospheres to metabolize exogenous glucose. Activated larvae and oncospheres absorb but do not metabolize glucose during the first 8 h post-activation. Between 8 and 16 h post-activation, however, virtually all of the absorbed glucose is metabolized into higher molecular weight end-products that are liberated into the incubation media. This temporal shift suggests that activation of oncospheres and cysticercoid morphogenesis are accompanied by distinct changes in carbohydrate metabolism.

Colour changes that occur during tanning of intact and punctured Globodera rostochiensis females and of isolated cuticle are described. Experiments with catechol and enzyme inhibitors show that the tanning enzyme, a phenoloxidase, is located in the cuticle, soluble in aqueous media and relatively abundant. Substrate for the enzyme is limited in the cuticle. Pseudocoelomic fluid of yellow females promoted tanning and contains either phenolic substrate(s) for the enzyme or part of a biochemical system responsible for release of the substrate. The substrate or biochemical system is thermolabile. Apparently, the tanning enzyme and its substrate(s) are partitioned in living females but the partitioning breaks down after death and the cuticle tans to form the cyst.