Entomopathogenic nematodes (EPN) are useful biological control agents of insect pests. However, the infective juvenile (IJ) stage which is the only stage to occur outside the host is susceptible to environmental extremes such as desiccation. We have isolated desiccation-tolerant strains of the EPN Heterorhabditis megidis. In this paper we describe the surface properties of these desiccation-tolerant mutants. Heterorhabditid IJs retain the sheath of the previous larval stage. The mutant lines possess alterations in the surface properties of the sheath. Differences were observed in fluorescent lipid analogue insertion into the surface of the sheath. Furthermore, cationized ferritin-binding studies demonstrated that the mutant lines possessed an increase in net negative surface charge. Removal of the surface layer of the sheath resulted in the loss of the mutant phenotype and in a reduction in the desiccation tolerance of the parental strain. Therefore, the negatively charged ‘surface coat’ appears to play an important role in the desiccation tolerance of Heterorhabditis species.

The term ‘data mining’ can be used to describe any process where useful information is extracted from data with a large background of ‘noise’. In the context of a genome project, several stages involve data mining. Amongst the sequence data, ‘signals’ need to be detected that indicate the presence of interesting features. Often this involves differentiating between transcribed and non-transcribed bases to predict coding regions. After detection, defining the roles of these sequences involves sifting through multiple lines of evidence. If these roles are accurately reflected in genome annotation, they can be used by researchers to frame queries and interrogate the data further.

A number of authors have demonstrated that the schistosomicidal compound, Praziquantel (Pzq), depends for its action upon the immune status of the host (Sabah et al. 1985; Brindley & Sher, 1987; Doenhoff et al. 1987). We have attempted to define the synergistic interaction between immuno- and chemotherapy further, using the murine irradiated vaccine model of schistosomiasis mansoni. In vaccinated mice, resistance operates in the skin but not the lungs; drug targeted towards lung-stage worms exacerbates lung-phase immunity, however, as depicted by the increased number and size of inflammatory reactions in the pulmonary tissues. Parasites are often found trapped within such foci. In the present investigation, light and ultrastructural studies have been utilized to examine the nature and extent of damage inflicted upon lung-stage larvae recovered from day 6 Pzq-treated vaccinated mice. Such studies have revealed that damage involves muscle disorganization, internal disruption and occasionally, loss of the tegument; in the latter case, cells are often seen attached to the denuded lung worms. To identify the crucial cellular effector cell(s) involved in the synergy between immuno- and chemotherapy, cell depletion studies have been performed in vivo. It would appear from these experiments that eosinophils or lymphocytes rather than neutrophils or macrophages are important effector cells in this synergy. Histological studies argue in favour of eosinophils being the key effector cells.

The application of genome-scale approaches to study Trypanosoma cruzi–host interactions at different stages of the infective process is becoming possible with sequencing and assembly of the T. cruzi genome nearing completion and sequence information available for both human and mouse genomes. Investigators have recently begun to exploit DNA microarray technology to analyze host transcriptional responses to T. cruzi infection and dissect developmental processes in the complex T. cruzi life-cycle. Collectively, information generated from these and future studies will provide valuable insights into the molecular requirements for establishment of T. cruzi infection in the host and highlight the molecular events coinciding with disease progression. While the field is in its infancy, the availability of genomic information and increased accessibility to relatively high-throughput technologies represents a significant advancement toward identification of novel drug targets and vaccine candidates for the treatment and prevention of Chagas' disease.

Methods are described for the freezing of trichomonads, suspended in a liverinfusion broth, to – 20 °C and – 70 °C, and storage at these temperatures. After 9 months’ storage at – 70 °C, with dimethyl sulphoxide, six strains of T. vaginalis and three strains of T. foetus were alive; three trichomonas strains frozen earlier were also alive after 13 months. Four of the T. vaginalis strains survived equally well for 6 months at – 70 °C, in the presence of either dimethyl sulphoxide or glycerol.

Although trichomonads may be maintained by subculture in a modified Diamond medium, storage at – 70 °C is more economical and less tedious; – 20 °C is not a satisfactory storage temperature for T. vaginalis or T. foetus, even in the presence of dimethyl sulphoxide or glycerol.

The severity of subcutaneous lesions in mice produced by six freshly isolated strains of T. vaginalis, and two out of three stock culture strains of T. foetus, was enhanced by either the addition of agar to the suspending medium or administration of cortisone to the mice. One strain of T. foetus produced lesions only in the presence of agar, cortisone, on the dose schedule used, being ineffective.

After storage at – 70 °C or cultivation in agar medium for 6 months, the virulence of trichomonads of either species was little affected, and lesions in mice were enhanced by agar in a similar degree to that found originally.

For enhancing the severity of subcutaneous lesions in mice the agar method, involving only one injection, is simpler than the repeated administration of cortisone to infected mice; agar was shown to be more effective than cortisone with small infecting doses of one strain of T. vaginalis quantitatively tested.

The subcutaneous injection of mice with trichomonads suspended in a liver-infusion broth containing 0·06% agar regularly produces lesions of the degree of severity required for the evaluation of compounds for therapeutic activity.

We express our gratitude to Mr S. A. Price for constructive criticism and helpful suggestions during the preparation of the manuscript. Dr S. R. M. Bushby kindly provided details of the dimethyl sulphoxide method and apparatus in use in his laboratory for the low-temperature preservation of tumour cells and trichomonads. For supplying the trichomonas strains we are grateful to Dr L. P. Joyner, Miss M. Moore-Tucker and Mr C. S. Ledwich. We thank Mr W. A. Freeman for advice on the composition of the inoculum medium.

In the body-cavity of a Racket-tailed Drongo (Dissemurus paradiseus) which died at the Calcutta Zoological Gardens, and the blood of which was teeming with two species of microfilariae, were found males of two new species of filariae, together with a single female specimen. In a Hunting Cissa (Cissa chinensis), which died at about the same time, males of one of the species discovered in the Drongo were found again, accompanied by a single female different from that found before. Since this cissa also harboured two species of microfilariae in its blood, the identity of either of the females is doubtful. In another specimen of hunting cissa a single male specimen of an entirely different species, which I have made the type of a new genus, was found. Here again two species of microfilariae were discovered so that it is not possible to say which is the offspring of the adult found. It had been hoped that more infected specimens of these birds might be obtained so that the confusion as regards relationships of the females and offspring to the males might be cleared up, but there appears to be little hope of more being obtained in the near future.

The World Health Organization suggested that the prevalence of Schistosoma mansoni among 7- to 14-year-olds be used to guide treatment strategies in endemic areas. This study explores how well the prevalence in that age group predicted the overall prevalence in the community in data from stool examinations (Kato–Katz method) from 180000 people in 3 municipalities in Brazil in 1984 and 1985. The median prevalence was higher in 1984, before community treatment was introduced. There was a strong relationship between the prevalence among 7- to 14-year-olds and the overall prevalence in the community. We present sensitivities and positive predictive values for the use of prevalence in the indicator group to select communities for mass treatment as recommended by WHO. For a range of assumptions sensitivity and positive predictive value were never both above 80%. We suggest that the estimates of validity presented in this paper inform future evaluations of strategies for S. mansoni control.

Cysteine (20–100 mM) and reduced glutathione (20–80 mM) potentiated the development of the exsheathed third-stage larva of Haemonchus contortus to the fourth stage. The potentiating effect of cysteine was greatest during the short period before and after the exsheathment of the third-stage larva. Two hundred mM cysteine and 1 mM p–chloro-benzoate inhibited development. This inhibition was reversible. Ten mM iodoacetate and 0·5 and 5 mM n–ethyl-maleimide inhibited development of the larvae. The larvae appeared to be most susceptible to the inhibiting effects of these reagents during the period of development approaching the third moult. Development was either little affected or potentiated, when larvae were incubated with these reagents for short periods immediately after exsheathment.

Definitive diagnosis of hookworm infection is usually based on the microscopic detection of eggs in a stool sample; however, several cases display a low or irregular egg output. Serodiagnosis can be a useful tool to identify these cases, but conventional tests do not differentiate past from active infections. The aim of this study was to obtain and apply egg yolk polyclonal immunoglobulin (IgY) antibodies to detect immune complexes (ICs) in serum samples from patients infected with hookworm. Hens were immunized with Ancylostoma ceylanicum saline extract, their eggs were collected and then IgY antibodies were extracted and purified. Antibody purity was tested by 12% sodium dodecyl sulphate polyacrylamide gel electrophoresis and specificity was assessed by immunoblotting and immunofluorescence. IgY production was evaluated by kinetics enzyme-linked immunosorbent assay (ELISA). Sandwich ELISA tested the ability of IgY to detect ICs in serum samples, from which diagnostic parameters were calculated. Antibody responses increased steadily from day 7 to 42. In the immunoblotting assay, IgY recognized two protein complexes. The immunofluorescence assay showed no staining in control samples. The sandwich ELISA presented a very high diagnostic value, with a sensitivity of 90% and a specificity of 86.7%. Our pioneer strategy highlights the potential use of egg yolk IgY as a diagnostic test to detect active hookworm infection.

A simple but efficient apparatus for harvesting nematodes migrating from their insect hosts is described. Infected host larvae are supported, in contact with water, on a nematode-permeable diaphragm resting in the mouth of a large funnel. A battery of funnels can be connected in series and their water-level maintained by a common constant-level device.

1. Mepacrine has a damaging action upon both vegetative forms and cysts of Giardia intestinalis. The action upon the former is rapid; but the action upon the cysts is gradual, and it takes 4 days of incubation in a 0·06% mepacrine suspension before all normal cysts disappear. The degeneration of cysts is accelerated by raising the concentration of mepacrine to which they are exposed.

2. Mepacrine produces a characteristic degeneration of the cyst which can be seen both in vitro and in vivo. This appearance develops gradually. In affected cysts the wall appears unaltered; but the protoplasm becomes shrunken and yellow, occupying only a small part of the internal cyst space. Whether shrunken or not, protoplasm stained by mepacrine is probably too much injured to survive, although the intense yellow colour makes it difficult to demonstrate eosin staining.

3. When parasites showing the characteristic abnormality are seen in the faeces they should be recognized as degenerate cysts, and further specimens should be examined before the patient is pronounced free from infection.

4. The usual method of treating a Giardia infection with mepacrine in a dosage of 0·05–0·3 gm. daily according to age, given by mouth for 6 days successfully eradicates the parasite, which is killed in both cystic and vegetative stages, but this dose is near to the minimum effective and neither time nor dosage can safely be reduced if a reliable cure is wanted.

5. Caustic soda destroys the whole cyst fairly rapidly, while a detergent had a damaging action on the protoplasm. Alkaline detergent solutions may therefore be recommended for the cleansing of infected utensils and premises. Dettol and Lysol kill cysts within 30 min. (judged by eosin staining), and 1% solutions of these disinfectants appear as effective as 5%. Utensils should be left to soak in the disinfecting solution since some cysts are slower to be affected than are others.

6. Cysts of Giardia are fairly resistant to acid, and up to 50% of them survived 4 hr. incubation in hydrochloric acid at a concentration of 0·26 gm.%, which corresponds to the upper limit of normal human gastric acidity (Harrison, 1947).

7. The cysts were damaged in different ways by different substances. In some cases the cyst was unchanged in appearance and yet rendered susceptible to eosin staining, in others the nuclei alone stained with eosin. Sometimes the protoplasm shrank within an intact cyst wall, and sometimes the wall was attacked directly.

8. In each sample of faeces studied in these experiments the Giardia cysts present appeared to be of unequal vitality, since, whatever the test substance to which they were exposed, and whatever form of degeneration developed, some cysts were affected hours or days before others showed any changes. It is conjectured that the age of the parasite since encystment may influence its resistance to damage.

Grateful acknowledgements are made to the practitioners and Medical Officers who co-operated in the following-up of cases of Giardiasis after they had been treated by mepacrine.

Malaria remains one of the most devastating diseases. Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection resulting in high mortality and morbidity worldwide. Analysis of precise mechanisms of CM in humans is difficult for ethical reasons and animal models of CM have been employed to study malaria pathogenesis. Here, we describe a new experimental cerebral malaria (ECM) model with Plasmodium berghei ANKA infection in KunMing (KM) mice. KM mice developed ECM after blood-stage or sporozoites infection, and the development of ECM in KM mice has a dose-dependent relationship with sporozoites inoculums. Histopathological findings revealed important features associated with ECM, including accumulation of mononuclear cells and red blood cells in brain microvascular, and brain parenchymal haemorrhages. Blood–brain barrier (BBB) examination showed that BBB disruption was present in infected KM mice when displaying clinical signs of CM. In vivo bioluminescent imaging experiment indicated that parasitized red blood cells accumulated in most vital organs including heart, lung, spleen, kidney, liver and brain. The levels of inflammatory cytokines interferon-gamma, tumour necrosis factor-alpha, interleukin (IL)-17, IL-12, IL-6 and IL-10 were all remarkably increased in KM mice infected with P. berghei ANKA. This study indicates that P. berghei ANKA infection in KM mice can be used as ECM model to extend further research on genetic, pharmacological and vaccine studies of CM.

The effect was compared in CBA mice of adding Corynebacterium parvum, saponin, and Bordetella pertussis to living or killed Trypanosoma cruzi (Y strain) epimastigote vaccines on the induction of protective immunity against subcutaneous (s.c.) challenge with blood trypomastigotes. The addition of C. parvum to a low dose of T. cruzi vaccine, which alone was non-protective, generated a greater degree of protection than did saponin or B. pertussis. C. parvum alone increased resistance to infection to a variable and usually weak extent. The addition of C. parvum to larger doses of T. cruzi vaccine, which were themselves sufficient to elicit some degree of protection, improved resistance when the challenge was given 1 or 12 weeks after immunization, but lowered it at 3 weeks. It is concluded that the comparative efficacy of adjuvants for T. cruzi vaccines needs to be assessed on 3 parameters: (1) the dose of antigen, (2) the dose of adjuvant and (3) the time interval between immunization and challenge.

Mice pre-treated with Corynebacterium parvum and later challenged with Plasmodium vinckei become infected but do not die whereas control mice do. When pre-treated mice were challenged with 1, 10, 1 × 102, 1 × 104, 1 × 105 or 1 × 106 parasites, the pre-patent periods correlated directly with the number of parasites injected, but the subsequent parasitaemias reached similar levels. This suggests that parasite killing, resulting from pre-treatment with C. parvum, is not triggered until the parasite load has reached a particular threshold. The injection of alloxan monohydrate, which brings about the release of toxic oxygen inter mediates thought to be involved in non-specific immunity, has little effect on P. vinckei infections until the parasitaemia is relatively high. This indicates that oxygen-mediated parasite killing also does not occur until the parasitaemia has reached a particular threshold. It is suggested that it is only at relatively high parasitaemias that the factors involved in parasite killing are able to enter the infected red blood cells.

A total of 65 enzymes in the 8 European pathotypes of the potato cyst nematodes Globodera pallida and G. rostochiensis were examined by isoelectric focusing (IEF) for possible polymorphic variants which may aid rapid pathotype recognition. Quantitative variation was seen with glucose oxidase (EC 1.1.3.4), with high levels of this enzyme present in G. rostochiensis Ro3. Mannose phosphate isomerase (EC 5.3.1.8) also varied between the pathotypes with G. rostochiensis Ro4 and Ro5 differing from the other pathotypes in the relative absorbance of some bands. Phosphoglucomutase was examined on a narrow-range pH gel and additional differences to those described previously were detected.

The term “Myiasis” is generally used to indicate the presence of Dipterous larvae in the living body of man or other animals. “ The form of Myiasis most commonly met with in the United Kingdom,” writes Austen (1912), “is that of the alimentary canal, as the result of which living larvae or pupae, greatly to the distress and alarm of the patient, are discharged from the bowel. Cases of Myiasis of the nasal passages and frontal sinuses the external auditory meatus, the subcutaneous tissue, and the urinary passages are apparently of quite exceptional occurrence in the British Islands.” The following pages deal with three hitherto unrecorded cases, two of urethral and one of intestinal Myiasis.

Laboratory bred DSN hamsters were exposed to varying doses of infective larvae of Ancylostoma ceylanicum (orally) or Necator americanus (percutaneously) and were autopsied at times which corresponded to a period immediately before cessation of growth of worms or soon afterwards. A total of 829 (404 male and 425 female) A. ceylanicum and 1582 (781 male and 801 female) N. americanus were measured. At worm burdens of fewer than 100, the length of A. ceylanicum appeared to increase with infection intensity and no evidence was found that growth was retarded under crowded conditions. In an experiment comparing directly low (mean worm burden = 22) and heavy infections (mean worm burden = 180) significant negative associations between both weight and width, and worm burden were detected, but length again increased with worm burden. In contrast, 5 experiments with N. americanus indicated negative relationships between measures of worm size (length, width, wet and dry weight) and worm burden. It was concluded that N. americanus is subject to regulation by density-dependent processes within the host while A. ceylanicum is not sensitive to the same degree.

1. Dobell's observations on the production of pure mixed strains of Entamoeba histolytica have been repeated and confirmed.

2. It has been demonstrated that the method devised by Rao did not sterilize the cysts of E. histolytica but merely killed all non-sporing organisms, while the spores of all spore-forming bacteria were unaffected.