Amputation experiments upon immature stages of Argas persicus (Oken 1818), Amblyomma hebraeum Koch 1844, and Hyalomma aegyptium (Linnaeus 1746) show that the mouthparts and legs of these ticks may be more or less regenerated when mutilated shortly after the ticks have abandoned the host in a fully engorged condition.

It has been observed that fluorescent membrane-impermeant molecules can enter the cercariae as they penetrate mouse skin. The hypothesis to be tested was that such molecules, which included Lucifer Yellow and a variety of fluorescent dextrans, entered the parasite through the nephridiopore and excretory tubules as well as through the surface membrane. FITC-labelled poly-L-lysine (molecular weight 10 kDa), added at 4°C during syringe transformation, was found to enter the nephridiopore and labelled the excretory bladder and sometimes the excretory tubules. This finding indicates that macromolecules (10 kDa) can enter the nephridiopore. It was found that linoleic acid (a normal constituent of skin) greatly stimulated uptake of Lucifer Yellow and dextrans into the excretory/subtegumental region of 2-h-old schistosomula. This correlated with an increased uptake of membrane-impermeant propidium iodide at 37°C. Since increased uptake of propidium iodide occurs when membranes become permeable, the surface membrane could also be a pathway of transport of the membrane-impermeant molecules into the schistosomulum.

The new species herein described are of interest, although we can only deal with females, as is so frequently the case with this genus. One species (I. kempi), allied to the North American I. angustus, comes from a hitherto unexplored region on the north-east frontier of India, having been collected by the Abor Expedition. Two species (I. daveyi and I. oldi) are from Africa, and offer a peculiarity of structure in that they possess anal grooves having the form of a horse-shoe, an appearance only hitherto observed in three other species of Ixodes, all of which are African. The fourth species (I. ricinoides) is from China, and is allied to our I. ricinus:

The following note is published by way of supplement to the foregoing paper on “Tick Paralysis” by Hadwen, as it records a positive experiment carried out in Cambridge upon a dog experimentally infested with Dermacentor venustus obtained from Canada.

Taenia multiceps is a cestode (family Taeniidae) that in its adult stage lives in the small intestine of dogs and other canids. The metacestode, known as Coenurus cerebralis, is usually found in the central nervous system including brain and spinal card in sheep and other ruminants. The presence of cysts typically leads to neurological symptoms that in the majority of cases result in the death of the animal. Coenurosis could cause high losses in sheep farms because the disease commonly affects young animals. A total of 20 C. cerebralis isolates collected from naturally infected sheep in Mardin province of Turkey were characterized through the polymerase chain reaction and sequencing of a fragment of cytochrome c oxidase subunit 1 (CO1) gene. The results showed that the CO1 gene sequences were highly conserved in C. cerebralis isolates. Phylogenetic analysis based on partial CO1 gene sequences revealed that C. cerebralis isolates were composed of three different variants.

Enzyme-linked immunosorbent assays (ELISAs) were developed in order to detect coproantigens (CAgs), coproantibodies (CAbs) and faecal immune complexes (FIC) in rats experimentally infected with Trichinella spiralis. The usefulness of these assays was compared to that of a conventional ELISA for detection of serum antibodies (Abs) to muscle larvae excretory–secretory products (ML–ESP). The ELISA for CAgs was the first parameter to give a positive result but the detection was limited only to day 2 p.i. CAbs against ML–ESP and adult worm excretory–secretory products (AW–ESP) was first positive on day 4 p.i. Anti-ML–ESP remained positive until day 12 p.i. while CAbs against AW–ESP remained positive throughout the study period. Specific IgE and IgA were found. FIC were detected between days 2 and 8 p.i. Serum Abs began to appear on day 10 p.i. Therefore, the ELISA for CAbs was a suitable assay for the detection of the enteral and early phases of the infection.

Juvenile female Litomosoides sigmodontis secrete a protein (Juv-p120) highly modified with dimethylethanolamine (DMAE). In an attempt to establish the source of this decoration worms were pulsed with [3H]-choline and [3H]-ethanolamine and the radio-isotope labelled products analysed. Both isotope labels were successfully taken up by the worms, as demonstrated by labelling of phospholipids with [3H]-choline, being predominantly incorporated into phosphatidylcholine and [3H]-ethanolamine into phosphatidylethanolamine. Isotope labelling of phosphatidylethanolamine was particularly striking with the worms taking up ~30 times as much labelled ethanolamine as choline. It was possible to detect faint labelling of Juv-p120 with [3H]-ethanolamine after prolonged exposure periods but, unlike the situation with the phospholipids, it was much more readily labelled with [3H]-choline. When pulsing with [3H]-ethanolamine it was also possible to detect isotope-labelled phosphatidylcholine, which may ultimately account for the low levels of labelling of Juv-p120. Overall our results raise the previously unconsidered but intriguing possibility that in L. sigmodontis, choline may be the precursor of DMAE.

Hepatojarakus bandicoti sp.nov. has been described from Bandicota bengalensis (type host), Millardia meltada, Tatera indica and Mus musculus bactrianus. The genus Hepatojarakus Yeh, 1955, has been retained in the family Trichostrongylidae Leiper, 1912. This is the second record of Hepatojarakus and the first from India.

The study of pathogenicity of haemoprotozoa and the pathogenesis of the diseases they cause requires quantitative descriptions. Statistical and mathematical methods are introduced to describe infectivity, parasitaemia, total body parasitosis and the severity of diseases.

A range of monoclonal antibodies specific for Plasmodium falciparum were tested in vitro for their abilities to inhibit the multiplication of a partially synchronized culture of P. falciparum, to augment the phagocytosis of the parasites by macrophages, and to enhance the killing of parasites by peritoneal cells depleted of adherent cells. Seven of 17 monoclonal antibodies, ranging from culture supernatant fluid and ascitic fluid to purified IgG, showed dose- and time-dependent inhibition of parasite growth in vitro. At a concentration of 0·6 mg/ml, the inhibitory capacity of these monoclonal IgGs was above 94% over a 3-day culture period, much higher than that of the relevant polyclonal IgG. Four of 6 monoclonal antibodies tested augmented the phagocytosis of the parasites by macrophages, which occurred as a result of opsonization of the parasites. Four of 7 monoclonal antibodies examined showed cytotoxic activity on malaria parasites. Peritoneal cells depleted of adherent cells were capable of killing the parasites in the presence of monoclonal antibodies. These results indicate that there may be ‘monofunction’, ‘bifunction’, and ‘multifunction’ types of monoclonal antibodies against P. falciparum. The putative protective antigen of malaria parasites purified by ‘multifunctional monoclonal antibody’ affinity chromatography may have potential interest as a vaccine against the parasite or as an immunodiagnostic reagent for human malaria.

Of the surface antigens identified by radio-iodination, two-dimensional gel analyses showed no similarities between those of Schistosoma haematobium and Schistosoma mansoni, thus providing a basis for the species specificity of these antigens described previously (Simpson, Knight, Hagan, Hodgson, Wilkins & Smithers (1985) Parasitology 90, 499–508). The surface antigens of S. haematobium were glycosylated and comprised an acidic polypeptide of Mr 17000 as well as a complex set of polypeptides of approximate pI 6–7, which resolved in the Mr range 20000–30000. At least one of the lower Mr forms of this complex is also present in the adult worm. Limited cross-reaction was observed with S. mansoni infection sera and this may be due to a shared carbohydrate epitope. In contrast, extensive cross-reaction was observed using sera from mice immunized with S. bovis. This pattern parallels the species-specificity of vaccine-induced immunity. Extensive cross-reaction was also observed within cell-free translation products of m-RNA from adult worms of S. haematobium and S. mansoni by use of heterologous human infection sera. The few antigens which were species-specific may represent surface antigens.

The interaction between host and infecting organism plays an important role in the survival of both of these components. The mechanisms whereby survival of one, or both, is achieved can be considered at various anatomical levels and degrees of complexity; those involving whole tissues together with events occurring at the cellular and subcellular levels. The involvement of sequestration, or the ‘standing apart’ of an invading organism from the host, as a mechanism of survival can also be examined at these various levels.

When I first began to think about this presentation I flirted with the idea of reversing the title to read: ‘Immunologists as Parasites’. I could clearly see some of the sectional headings such as ‘The Spreading Cancer of Tumour Immunology’ and ‘Does the International Immunology Scene represent an IDIOT-ype–Anti-IDIOT-ype network’?. But although this might have been fun it would certainly have been unfair to those immunologists who are currently working on Parasite Immunology, a very difficult and demanding field.

A hypothesis to explain some features of Ascaris flexures is given. It is based on the co-operation of muscle cells in domains which may assume two states. In one state the muscles are long and it is mainly the non-contractile parallel elements that are in tension. The other state has short muscles exerting tension mainly in the contractile elements. The living animal changes shape if new domains are formed or if domain boundaries move. The hypothesis is applied to laboratory experiments and observations.

The rediscovery of Elleipsisoma thomsoni Franca 1912 from Talpa europaea is reported. This organism, whose identity as a parasite was initially doubted, is shown to be an intra-erythrocytic protozoan parasite. Light microscope observation confirmed the original description and 22/53 (42·5%) moles examined from a locality near Blackpool were positive. Organ impression smears demonstrated that E. thomsoni was concentrated in the heart and lungs, occasionally in the kidneys, liver and spleen. Electron microscope studies conclusively showed that the parasite was a member of the phylum Apicomplexa. A typical apical complex was present with rhoptries, micronemes, polar ring and microtubules but, in contrast to the genera Plasmodium, Babesia and Theileria, a conoid was also present. The parasitized red cells were larger than normal mature erythrocytes and the remaining cytoplasm of the erythrocyte was less dense than that of non-infected red cells. The problem of studying this enigmatic parasite and its life-cycle are described.

Peritoneal leucocytosis, with an increased percentage of eosinophils, was found in mice which had been infected with Schistosoma mansoni for 7 weeks or longer. Specific IgG against worm and egg antigens increased in peritoneal fluids and their corresponding sera respectively 5 and 7 weeks after infection. An intraperitoneal challenge with schistosomula elicited neutrophilia in all mice regardless of immune status, as well as infiltration of eosinophils and macrophages in infected mice. The secondary eosinophilia occurred in mice previously infected for 1 week or longer, whereas the infiltration of macrophages occurred only after worms from the primary infection had started laying eggs. Unlike the eosinophilia the macrophage response required infection with bisexual populations of cercariae. Injection of previously infected mice with Escherichia, Trichinella or Toxocara failed to increase the proportions of eosinophils and macrophages. Schistosomula-induced eosinophilia could be elicited in passively sensitized mice. Intraperitoneal injection of PBS extract of adult worms elicited eosinophilia in infected mice and neutrophilia in normal mice. Two chromatographic fractions induced eosinophilia and the third only neutrophilia. The relevance of these observations to host response to S. mansoni infections is discussed.

The humidity reaction of the larvae of Xenopsylla cheopis Rothsch. was studied in an air-chamber with a 0–100% relative humidity gradient.

Highly significant differences (P < 0·001) between the reactions in the various R.H. ranges was found. The most preferred relative humidity along this gradient was 100%. Relatively few larvae were collected at each R.H. in the range between 0 and 90% R.H.

The reaction of the larvae under the experimental conditions was seen to be of orthokinetic type.

Chickens which have recovered from an initial Histomonas infection are better hosts for Heterakis gallinarum than chickens which are fully susceptible to Histomonas. Not only do they support more nematodes but the immature worms, measured 12 and 14 days after infection, are larger.

Acknowledgements are due to Miss C. N. Hebert who carried out the statistical analysis and to Mr C. C. Norton for technical assistance.