Cultured adult chick kidney (CK) cells inoculated with sporozoites of Eimeria tenella showed progressive alterations in their morphological and adhesive characteristics. Scanning electron microscopy (SEM) showed that during a 3-day period following the inoculation of parasites there was a gradual loss of contact between the cells. Initially, the cells remained connected by long cytoplasmic bridges but with the breakdown of these, the cells began to round up, losing complete contact with each other and remaining attached to the substratum by means of retraction fibres. By 3 days many cells had completely detached. The factors inducing these alterations were transmissable via the medium as the alterations were mimicked by non-parasitized cells in co-culture with parasitized cells. Studies with the reflection interference microscope (RIM) showed that the changes were accompanied by an increase in the cell-substrate separation distance and the loss of focal contacts. These changes were not effected by substances transmissable via the medium. Parasitized cells showed enhanced agglutination with Concanavalin A (Con A) which could be eliminated by pre-fixation. The possibility that changes to the host cell indicate a rearrangement of cytoskeletal apparatus is discussed.

[This paper is the final report on the Diptera collected by the Percy Sladen Trust Expedition under Professor J. Stanley Gardiner, F.R.S., in the Seychelles and other islands of the Western Indian Ocean in 1905 and 1908–9. Many reports on the insects collected have appeared in the special series of volumes devoted to that Expedition, Tr. Linn. Soc.London, ser. 2 (Zool.), xii–xviii (from 1907 onwards), but it has not been possible to include all the entomological contributions in that series. I am greatly indebted to the Editor of Parasitology for accepting the present work, which was offered for publication in this journal as it deals with a number of parasitic forms—Bombyliidae, Sarcophaginae, Tachininae, etc. A list of all the other reports on Diptera collected by this Expedition, with full references, is given in Ent. Monthly Mag., 58, 1922, p. 184.

The detection of egg-derived antigens in the serum and urine of Schistosoma mansoni-infected individuals and experimental animals would provide an alternative method to assess the tissue egg burden. The detected levels are, however, not only a function of the amounts of antigen produced, but also of the processing or clearance by the host. In the present study the immunolocalization pattern of antigens using 2 recently described monoclonal antibodies to repetitive carbohydrate epitopes of S. mansoni soluble egg antigen (114–5B1–A and 114–4D12–A) in various organs of the host was investigated. In the liver strong immunoreactivity could be detected around the entrapped eggs and in egg-shells, as well as in Kupffer cells accumulating both antigen and schistosomal pigment. In the spleen, immunohistochemistry revealed antigen in the plasma as well as in secondary lysosomes of macrophages. Strong labelling was found in the vesicles of the eosinophilic granulocytes: indirect evidence perhaps for the presence of antigen–antibody complexes. In conclusion, the secreted egg antigens were sequestered in the reticulo-endothelial macrophages of the liver and the spleen as already partly described for worm-derived antigens. The presence of large quantities of antigenic material in the spleen could suggest an important role of this organ in the clearance of antigen and might even provide an additional explanation for the hepatosplenomegaly mainly present in S. mansoni-infected children.

Host invasion and tissue migration of several helminths have been linked to expression and release of parasite-derived proteinases. The plerocercoid of the cestode Proteocephalus ambloplitis can migrate into the visceral organs or, in the case of bass, from them into the intestinal tract of the same individual fish. It does this within a few hours, aided by secretion of a substance from its apical gland. Proteinase activity in this plerocercoid, obtained from the host liver, was defined by pH optimum, by substrate and inhibitor specificity, and by electrophoretic and chromatographic techniques. Homogenates of plerocercoid contained a metalloproteinase exhibiting a molecular weight of 30000 determined by gelatin substrate gel electrophoresis. Peak activity of this proteolytic enzyme in gel filtration fractions when azocoll was used as substrate then corresponded to a molecular weight of 31500. The proteinase showed collagenolytic, haemoglobinolytic and slight elastinolytic activity, and it had a pH optimum at 9·0. Enzyme activity could be inhibited by various chelating agents. The metalloproteinase identified in this study constitutes the only enzyme class present in this larval stage of P. ambloplitis. We suggest that the plerocercoid's metalloproteinase is the substance secreted from the apical organ, necessary for the previously recognized tissue migration phase. This enzyme might also have a nutritional function.

The A subunit of NF-Y nuclear factor from Schistosoma mansoni was expressed in E. coli fused to a histidine tag and purified by affinity chromatography using a Ni2+-Agarose matrix. Antibodies against the recombinant protein were prepared and used for Western blot and immunolocalization. The presence of SMNF-YA in all stages of the parasite life-cycle was determined by RT-PCR and Western blot analysis. The immunolocalization of SMNF-YA showed the presence of this factor in a parenchymal cell population of cercariae and adult worms and in embryos within eggs. The expression of SMNF-YA was demonstrated to decrease in maturating spermatozoites whereas an accumulation of this factor was observed in the nucleus from oocytes during their maturation processes.

The experiments described show that plasmoquine is very effective in preventing or delaying attacks of malaria in birds infected with P. relictum by direct blood inoculation, but has little or no prophylactic action in birds infected by the bites of mosquitoes.

In the mosquito-induced malaria parasites may appear in the blood 3 or 4 days after the cessation of plasmoquine treatment and there is no appreciable delay as compared with untreated control birds.

Five strains of Entamoeba histolytica isolated from man and capable of growth at room temperature were tested for virulence by inoculation into the caeca of young rats. The results showed all strains to have a low infectivity and none produced caecal ulceration. Ten laboratory strains of E. histolytica were examined for growth at 25 °C, but none were established at this low temperature.

1. Trypanblau promises to be an efficient remedy for bovine piroplasmosis, since it exerts a direct and obvious effect upon the parasites.

2. The effect of the drug upon Piroplasma bovis is similar to that which it produces upon the canine parasite. The dividing forms are the first to disappear, and after a few hours the pyriform parasites also disappear from the peripheral circulation; the parasites which are detected in the blood after a few hours appear degenerated and rounded or irregular; within nine to 45 hours or less all the parasites have disappeared from the blood.

3. As in canine piroplasmosis the disappearance of the parasites from the blood may be temporary. The parasites also disappear and reappear in small numbers (after two to 11 days) in animals undergoing natural recovery. In three treated animals the parasites reappeared in exceedingly small numbers after five to six days; in two they had not reappeared after 16 and 18 days respectively. The animals show no symptoms and progress towards recovery.

4. It remains to be detercnined (1) how long the blood of treated cows may contain parasites after the apparent recovery, (2) if the parasites in such recovered animals are altered in virulence, (3) if the parasites are capable of infecting ticks.

5. The experiments were conducted on nine cows, of which four served as controls and five were treated with trypanblau. Of the controls two suffered from haemoglobinuria, and one of these died of piroplasmosis; the two other controls had no haemoglobinuria and were very mild cases. All of the treated cows had haemoglobinuria and recovered. In four of the treated cows haemoglobinuria occurred before treatment began.

6. As might be expected, the drug exerts a more rapid effect when injected intravenously. The parasites disappear more slowly after subcutaneous injection of the drug. (Judging from our recent experiments on dogs, the giving of the drug per os promises to be without effect. See This Journal, p. 231.)

7. Although doses of 150–200 c.c. of a saturated watery solution of the dye were used, it is probable that smaller doses will prove efficient. The drug appears to produce no ill-effects upon cattle.

8. The drug, being a dye, has the disadvantage of colouring the tissues, more especially the subcutaneous connective tissues. How long the colouration persists remains to be determined. In any case this disadvantage can scarcely weigh in the balance as against saving the life of the animal, especially when used for breeding purposes.

9. We hope that experiments, which are about to be conducted in the field in Africa and elsewhere, will demonstrate the value of the remedy in practice.

10. Trypanblau and similar drugs should be given a trial in the treatment of Carçeag in sheep and Biliary Fever in horses.

A quantitative assessment of the effect of larval Caryophyllaeus laticeps upon its intermediate host, Psammoryctes barbatus, was obtained by comparing the energy budgets of infected and uninfected tubificids from the same natural populationm throughout the course of a year. Measurements of the energy transformations during growth, reproduction and respiration of tubificids indicated some of the effects of the parasite.

Infection had no influence upon the life-span of the host, but progressively decreased its growth and prevented reproduction. By contrast no significant differences were detected between the respiration rates of infected and uninfected animals. Decrease in the production of infected host tissue became apparent as soon as the parasite was detectable. Over the first 6 months loss in production due to the parasite was 50%, and over the whole life-span 59·9%. The production: respiration ratio of infected tubificids was also lower, but differences in assimilation were probably only small. The overall effects of the parasite upon its host population are slight, and the loss in tubificid nutriment available for fish food due to the parasite is less than 5% and of little economic importance. The way in which the parasite actually influences its host's physiology is discussed, and the effect of C. laticeps upon its host's energy budget compared with that of a plerocercoid larva on its fish host.

I should like to thank Dr M. Palmer for the loan of her Warburg flasks, Mr J. Harris for taking samples for me when I was unable to do so,'and Mr G. G. Vickers for many helpful comments and discussions on ecological energetics. I am also grateful to Mr G. Baileyfor combusting the samples for me.

The successful rearing of Amblyomma sparsum, using rabbits as larval and nymphal hosts and either sheep or tortoise for feeding adults, is described and details of the duration of the various stages are given. The life cycle of this tick is compared with that of A. variegatum and A. nuttalli.

The authors are grateful to the Director of the Coryndon Memorial Museum, Nairobi, for the loan of a Leopard Tortoise, and to the Directors of the East African Veterinary Research Organization and of the Veterinary Services, Kenya, for permission to publish this note.

The life cycle of Nosema helminthorum proceeds as follows (see Fig. 39).

Emergence of the sporoplasm. The spores swallowed by the vertebrate host (sheep) reach the small intestine where the tapeworm (Moniezia) is already present. Here are extruded the filaments with the sporoplasms attached to their tips. These sporoplasms come in contact with the cuticle of the tapeworm at various places, round off and work their way through the cuticle into the tissues of the worm.

Schizogony. They next proceed between the subcuticular cells (3) and start multiplying by binary fission or by multiple division (4, 5, 6, 7). Some of the so-called schizonts are spherical with three to four nuclei (6), while others are elongate plasmodia which give rise to chains of daughter-schizonts by division (7). All these schizonts give rise eventually to faintly staining schizonts in which the nuclei appear to be less compact. Some of these now enter the second phase of schizogony in which elongate fusiform or spindle-shaped cells are ultimately produced (10, 14). The nuclei of these elongate cells divide and move to the opposite poles, and the cytoplasm constricts between them. In this way a chain of fusiform schizonts may be formed (11). The final products of these divisions are fusiform or spindle-shaped cells (11, 15) which are really the precursors of sporonts, in which the nuclei are divided but not separated. These nuclei remain closely associated and eventually fuse either before the sporont stage is reached or later.

Sporogony. The sporonts are ovoidal cells which are generally uninucleate after fusion of the double nuclei of the previous stage. The nucleus is at the centre. Soon a vacuole is formed at the posterior pole, and within it there appears a premetachromatic granule (16) which gives rise to the metachromatic body in the mature spore.

Spore formation. A chitinous spore wall is then secreted (17) and the filament is probably formed at this stage in the central axis of the cytoplasm. The rest of the cytoplasm transforms into the sporoplasm, which surrounds the filament like a girdle (18). The spore now becomes mature and is infective to a new host. It is passed out within the gravid segments of the worm and, when it reaches the exterior, is liberated when the segments degenerate. These spores are quite resistant and probably remain dormant during the winter; they are swallowed by Moniezia-infected lambs in spring, when the cycle is resumed.

It is unlikely that the oribatid mite, which is the vector of Moniezia, plays any role in the transmission of Nosema helminthorum. My experimental studies (to be published later) suggest that the only possible part played by the mite is to carry the spores, accidentally swallowed by it, protecting them till they reach the adult worm already present in the intestine of the vertebrate host.

1. Enzyme electrophoretic patterns from populations of snails, intermediate hosts of Schistosoma, have been examined.

2. Esterase patterns (α-naphthyl butyrate as substrate) have been used to differentiate snail populations of B. africanus and Biomph. pfeifferi.

3. Malate, β-hydroxybutyrate and α-glycerophosphate dehydrogenases may be of use in some cases to distinguish between species, e.g. B. africanus v. B. ugandae and Biomph. sudanica v. Biomph. pfeifferi.

Individual females of Gyrinicola batrachiensis produce 2 types of eggs: thin-shelled auto-infective eggs are produced in the ventral horn of the reproductive tract and thick-shelled eggs (transmission agents) are produced in the dorsal horn. Fine structure of oogenesis and egg-shell formation in the 2 horns of the reproductive tract were studied and compared. Early stages of oogenesis were similar in both horns but mature oocytes differed considerably. Those in the dorsal horn were larger than those in the ventral horn; they contained large numbers of lipid droplets, peripheral patches of glycogen and several types of cytoplasmic granules presumably acting as yolk or playing a role in shell formation. Mature oocytes in the ventral horn contained large amounts of glycogen, relatively few lipid droplets and large multivesicular bodies. Four shell layers formed around ova in the dorsal horn: a vitelline layer, a lipid layer, a chitinous layer and an outer protein coat similar to that described in other oxyurids. Only the vitelline layer formed around thin-shelled eggs. Thick-shelled eggs did not embryonate in utero but thin-shelled eggs nearest the vagina contained larvae. The first moult in eggs of G. batrachiensis was described in a previous communication and it is suggested here that the thin fibrous layer loosely applied to the cuticle of infective larvae in thin-shelled eggs is the moulted 2nd-stage cuticle.

Six species of South African parasitic copepods belonging to the family Chondracanthidae were restudied. A redescription was given of Acanthochondria lepidionis, Ghondracanthus colligens and Ch. neali. Ch. lophii reported by Barnard (1955a) is actually a new species; it was named Ch. barnardi and redescribed. Ch. congiopodi Barnard, 1955, is conspecific with Ch. tuberculatus Nordmann, 1832. A redescription of this species was given based on Barnard's collection. Ch. merluccii was only mentioned and not redescribed.

A protocol for the routine laboratory maintenance of the life-cycle of Diphyllobothrium dendriticum, using herring gulls (Larus argentatus), Cyclops abyssorum and rainbow trout Oncorhynchus mykiss ( = Salmo gairdneri) as the definitive, first and second intermediate hosts respectively, is described.

This paper describes chronic features of neuroangiostrongyliasis (NAS), a long-term outcome of the disease that has not been adequately described. Current and past literature is predominantly limited to acute manifestations of NAS, and mention of chronic, ongoing clinical symptoms is usually limited to brief notes in a discussion of severe cases. This study investigated the long-term outcomes in ten individuals who were diagnosed with acute neuroangiostrongyliasis in Hawaii between 2009 and 2017. The study demonstrates a significant number of persons in Hawaii sustain residual symptoms for many years, including troublesome sensory paresthesia (abnormal spontaneous sensations of skin experienced as ‘burning, pricking, pins and needles’; also described as allodynia or hyperesthesia) and extremity muscle pains. As a consequence, employment and economic hardships, domestic relocations, and psychological impairments affecting personal relationships occurred. The study summarizes common features of chronic disease, sensory paresthesia and hyperesthesia, diffuse muscular pain, insomnia, and accompanying emotional distress; highlights the frequently unsuccessful endeavours of individuals struggling to find effective treatment; proposes pathogenic mechanisms responsible for prolonged illness including possible reasons for differences in disease presentation in Hawaii compared to Southeast Asia.

Since the publication of the original paper by Audouin and Milne-Edwards (1826, Ann. Sci. Nat. vol. IX), no investigator appears to have thoroughly examined Nicothoe astaci. It therefore seemed to me desirable that this Copepod should be reinvestigated by modern methods in respect to the morphology of its appendages.

1. Trypanosoma lewisi was found in 25% of rats caught in and about Cambridge. Of these rats 12% were young, 33% adult, and 29% old. In this region the endetnicity was localised to certain areas.

2. Fleas (C. fasciatus and C. agyrtes) were constantly found associated with wild rats infected with T. lewisi. We think that these two species of fleas are the chief carriers of the parasite from rat to rat in this region.

3. We tried transmission experiments with fleas (C. fasciatus and C. agyrtes), lice (H. spinulosus), bugs (A. lectularia), ticks (O. moubata, nymphs and adults), and Gamasus sp., but only obtained a positive result by the agency of fleas.

4. In the transmission experiments the arthropod was transferred from an infected to an uninfected animal. 16% of 138 experiments with fleas were successful, 80—98% of the fleas used were non-infective, while 2—20% were infective.

5. Distant transmission occurs with fleas. This was observed by one of us in January, 1909.

6. ‘Mechanical’ transmission occurs sometimes with fleas.

7. Infective fleas do not transmit the power of infection to their young.

8. The mechanism of infection in the case of mechanical transmission is by the bite of the flea; in the case of the distant infection it is not so.

9. The infective forms of T. lewisi for distant transmission are probably the ‘small trypanosomes’ which we have described elsewhere (1910). The forms of T. lewisi found prior to the small trypanosomes in the developmental cycle are not infective.

10. The development of the trypanosomes in the flea is not interfered with by the flea feeding on a rat immune to the disease.

11. Seventeen experiments with lice were performed, but no transmission was obtained by their agency. 1139 lice were used. No confirmation of Baldrey's infective cycle in lice could be obtained.

12. We could trace no connection between transmission of infection by lice and the presence in them of ‘developmental forms.’

13. No transmission of T. lewisi by other arthropods was obtained. These negative results had no connection with the presence in the arthropods of ‘developmental forms.’

In conclusion we would like to thank Professor Nuttall for his kindness in inoculating our animals and providing us with the material for our experiments, and for his interest and advice in our work.

Larval Schistosoma mansoni have been shown to induce morphological changes to the internal calcium reserves (in particular the calcareous inclusions in Type A calcium cells and to the inner, nacreous layer of the shell) of Biomphalaria glabrata within 48 h of miracidial penetration. Control experiments have shown that these changes were not due to either the experimental procedures used, mechanical damage or to starvation effects. The effects were, however, analogous to experimentally induced acidosis, suggesting that the rapidly transforming miracidium-sporocyst quickly induces changes in the host's metabolism, presumably by the production and release of CO2 and waste metabolites into the haemolymph.

We develop the hypothesis that parasites do not invade extreme environments, i.e. hostile hosts, but rather ‘create’ them. We argue that parasites may have driven the evolution of the constitutive and adaptive immune system. This leads to several implications. First, parasites respond to ‘genes to kill’ by ‘genes to survive’ and this triggers an indefinite selection of measures and counter-measures. Second, these revolutionary arms races may lead to local adaptation, in which parasite populations perform better on local hosts. Third, the evolution of the immune system, whose responses are predictable, may allow parasites to specialize, to evade and even to manipulate. Finally we show that the correlations between the increase in the antibody repertoire, the expansion of MHC loci and parasite pressures support our hypothesis that both host complexity and parasite pressures can be invoked to explain the diversity of antibodies, T-receptors and MHC molecules.