The filarial worm Litomosoides carinii showed a rapid uptake of glucose during in vitro incubation. This uptake proceeded linearly with time, and was significantly higher under aerobic compared to anoxic conditions. Under an atmosphere of nitrogen the worms converted glucose almost quantitatively to lactate, whereas in the presence of oxygen appreciable quantities of acetate, acetoin and CO2, in addition to lactate, were formed. Although aerobically only 73% of the carbohydrate carbon could be accounted for by the latter products as well as by a net glycogen synthesis, attempts to identify other compounds presumed to be derived from glucose metabolism have been unsuccessful. The complete sequence of the glycolytic enzymes was detected in particulate-free cytosolic extracts of the filarial worm. With the exception of 6-phosphofructokinase, all glycolytic enzyme activities were considerably higher than those reported for rat liver. In addition, L. carinii possesses the entire set of enzymes catalysing the eight successive reaction steps of the tricarboxylic acid cycle. On a mitochondrial protein basis, the specific activities of these enzymes were similar to those present in rat liver. Various enzymatic activities of the mitochondrial respiratory chain were detected in the parasite. These include low levels of NADH and cytochrome c oxidases, but a high activity value for NADH dehydrogenase. Cell-free extracts and the mitochondrial fraction of the worms were found to exhibit an enzyme capable of catalysing the decarboxylation of pyruvate. Since this activity was stimulated 5- to 20-fold by the cofactors known to be required by the pyruvate dehydrogenase complex of other animal cells, pyruvate decarboxylation and thus acetate formation in the parasite may be mediated by an enzyme similar to, or identical with, the pyruvate dehydrogenase system. Isotopic carbon balance studies and experiments in which substrates specifically labelled with 14C were employed showed that substrate carbon can to some extent enter into respiratory CO2. From these and the enzymatic analyses it is suggested that complete oxidation of carbon substrate may be of relevance as an energy-conserving pathway in the filarial worm.

A study has been carried out to determine the activity of genistein against adult liver fluke, Fasciola hepatica. Flukes were incubated in vitro in genistein at a concentration of 0·27 mg/ml (=1 mm). They ceased to move after 3 h, at which point the experiment was terminated and the specimens prepared for examination by scanning and transmission electron microscopy. Surface changes to the flukes comprised swelling and blebbing, especially in the posterior region of the flukes, and there was particular disruption to the spines, accompanied by some spine loss. Fine structural changes to the tegumental syncytium indicated an accelerated release of secretory bodies at the surface, but a reduction in their production within the cell bodies. Autophagic activity was evident in the tegumental cells, a phenomenon that was also observed in the gastrodermal cells. Disruption to the testis and vitelline follicles was severe, with an apparent block in the normal developmental sequence of the spermatogenic and vitelline cells, respectively. Shell protein production by the vitelline cells was also disrupted. In separate experiments, somatic muscle strips were exposed to concentrations of genistein ranging from 1 μm to 1 mm. There were statistically significant increases in the frequency and/or amplitude of muscle contractions at concentrations of 10 μm, 100 μm and 1 mm. The results suggest that genistein is capable of causing severe morphological and neuromuscular disruption to adult flukes in vitro over a short time-span.

Faecal egg counts were examined in 2 flocks of naturally infected Scottish Blackface sheep in southern and central Scotland. The distribution of mean counts was right skewed and similar to a gamma distribution. The counts varied with month, with mean counts rising from May to July, then falling but rising again in October, although data within each year did not always show such a clear pattern. There was no significant difference in mean egg count between the 2 farms examined. The distribution of egg count variances was also right skewed and conformed to a gamma distribution. There was a strong relationship between the mean and the variance for each population, implying that variation among populations in variances largely mirrored variation in mean egg counts. Populations with high mean egg counts and variances did not necessarily have more adult nematodes but had a greater number of adult nematodes from species other than Teladorsagia circumcincta, particularly Cooperia spp., Trichostrongylus axei and Trichostrongylus vitrinus. The contribution of different parasite species to the egg count explains the relatively poor and inconsistent fit of the negative binomial distribution to faecal egg counts in lambs.

We compared the clinical outcome and vertical transmission of six canine Neospora caninum isolates using a pregnant BALB/c model. Four of the isolates were obtained from oocysts of naturally infected dogs (Nc-Ger2, Nc-Ger3, Nc-Ger6 and Nc-6Arg) and two were from diseased dogs with neurological signs (Nc-Bahia and Nc-Liv). The dams were inoculated with 2×106 tachyzoites of each isolate at day 7 of pregnancy. Morbidity, mortality and the antibody responses were evaluated in both the dams and the offspring, as was parasite transmission to the progeny. The mortality rates varied from 100% in Nc-Bahia and Nc-Liv-infected pups to 19% or less for those infected with the isolates from oocysts. The vertical transmission rates varied from 9 to 53% for N. caninum from oocysts, compared with 100% for the Nc-Liv and Nc-Bahia isolates. All dams showed specific IgG responses against tachyzoite and rNc-GRA7 antigens, confirming Neospora infection. The highest IgG levels were detected in mice inoculated with the Nc-Liv and Nc-Bahia isolates. These results demonstrate marked differences in virulence between the N. caninum isolates obtained from oocysts and neurologically affected dogs. This variability could help us to explain the differences in the outcome of the infection in definitive and intermediate hosts.

The effect of temperature (19–36 °C) and snail host density (0.014–10 snails/1) on the snail-finding capacity of Echinostoma caproni cercariae is described. The initial swimming speed increased whereas the length of the infective period decreased with increasing temperature. The combined effect resulted in the E. caproni cercarial snail-finding capacity being temperature independent in the range 19 to 36 °C at a snail density of 0·014 snails/1. A moderate temperature dependency was, however, seen at a lower snail density. The cercarial snail-finding capacity was snail-host density dependent in the density range 0.014 to 1 snail/1. The findings from this study show that a relatively low and biologically realistic snail host density must be used in experimental studies if realistic estimates of the dynamics of cercarial transmission are to be obtained.

Regional differences in the response of mice to infection with three strains of dermotropic Leishmania spp. were shown for skin covering the trunk. Lesions tended to appear earlier and to grow more rapidly on sites over the caudal half of the body than the cranial half, and caudal lesions were more likely than cranial ones to result in metastatic disease in susceptible strains of mice. Site-related variations in lesion development were observed in different strains of mice as well as in golden hamsters. The effect of these regional differences on the development of some parasite-specific, immunological reactions was examined, as were parasite thermosensitivity and location-related variations in host skin temperature as possible explanations.

Populations of hosts vary extensively in the types and numbers of parasites that the average individual contains. Understanding the factors that lead to this variation is an important goal for parasite ecologists. We characterized patterns of helminth component community structure in whitefish collected from a cluster of 7 lakes located on an isolated plateau in northern Alberta, Canada. Component communities were species rich (5–6 species per lake), high in mean helminth intensity (approximately 80–500 individuals/host), and high in between-lake similarity (50–100%), a pattern consistent with results from studies on whitefish sampled from other localities in Northern Canada and Europe. Multivariate analyses indicated that the structure of the component communities was associated with 2 opposing environmental gradients. One was defined primarily by water colour, the second by phosphorous concentration. Thus, 4 lakes were characterized by a combination of high colour, low productivity, low parasite intensities, and the absence of larval acanthocephalans. Habitat/species associations were less clear as intensities increased, but the 3 remaining lakes tended to have the opposite characteristics. These results provide evidence that variation in helminth component community structure in fish is associated with variation in physicochemical characteristics that are linked to aquatic productivity.

Egg-laying patterns and egg production in Heteraxine heterocerca from the gills and Benedenia seriolae from the skin of Japanese yellowtail Seriola quinqueradiata in Japan were investigated in vivo. Eggs were collected every 3 h from sexually mature H. heterocerca and B. seriolae infecting 3 S. quinqueradiata kept individually over 3 consecutive days and exposed to alternating periods of illumination and darkness (LD 12:12; light on 06.00, light off 18.00) and maintained at 23·8±0·1°C and 35 ppt salinity. A well-defined egg-laying rhythm was demonstrated for H. heterocerca while B. seriolae was shown to release eggs continuously. A total of 114 000 H. heterocerca eggs was collected and of these, 45·4 (42·5–49·9)% were collected during the first 3 h period following dark at 18.00 h. A total of 662 857 B. seriolae eggs was collected and these were distributed over each 3 h period ranging from 11·1 to 14·1% of the daily egg output. All eggs extracted from the uterus of each H. heterocerca were joined together forming an ‘egg-string’. The contrasting egg-laying patterns of H. heterocerca and B. seriolae suggest that each species makes use of a different infection strategy to infect the same host species, S. quinqueradiata.

Objective. Ornithonyssus sylviarum (northern fowl mite) and Menacanthus stramineus (chicken body louse) are key poultry pests currently controlled by exclusion or pesticide application. We studied how host beak condition affected their populations over time and how the lice and mites might interact on a host. Methods. Beak-trimmed or beak-intact white leghorn hens were infested initially with either mites or lice and subsequently challenged using the alternate ectoparasite species (reciprocal transfer), while other hens harboured only the initial ectoparasite species. Results. Beak-trimmed hens had far higher ectoparasite numbers relative to beak-intact hens, and the 2 ectoparasites showed evidence of grooming-mediated competitive asymmetry. On beak-trimmed hens, larger numbers of lice quickly nearly completely excluded mites in competition for enemy-free space (lower abdomen), while in the reciprocal transfer mites did not affect louse numbers on beak-trimmed hosts. The 2 ectoparasites co-existed on beak-intact hens, which were better able to defend the lower abdomen habitat by grooming. Conclusion. Lice are somewhat less damaging and much easier to control relative to mites, and might be used to eliminate mites in commercial, beak-trimmed flocks. Beak trimming impairs host grooming and contributes greatly to the high ectoparasite populations seen in commercial flocks. The study adds incentives for poultry breeders to develop more docile hen strains that can be held without beak trimming. This has advantages both to welfare advocates and producers who may no longer need to use insecticides for pest control or be concerned about worker exposure to pesticides.

The melanotic encapsulation response mounted by Drosophila melanogaster against macroparasites, which is based on haemocyte binding to foreign objects, is poorly characterized relative to its humoral immune response against microbes, and appears to be variable across insect lineages. The genus Zaprionus is a diverse clade of flies embedded within the genus Drosophila. Here we characterize the immune response of Zaprionus indianus against endoparasitoid wasp eggs, which elicit the melanotic encapsulation response in D. melanogaster. We find that Z. indianus is highly resistant to diverse wasp species. Although Z. indianus mounts the canonical melanotic encapsulation response against some wasps, it can also potentially fight off wasp infection using two other mechanisms: encapsulation without melanization and a non-cellular form of wasp killing. Zaprionus indianus produces a large number of haemocytes including nematocytes, which are large fusiform haemocytes absent in D. melanogaster, but which we found in several other species in the subgenus Drosophila. Several lines of evidence suggest these nematocytes are involved in anti-wasp immunity in Z. indianus and in particular in the encapsulation of wasp eggs. Altogether, our data show that the canonical anti-wasp immune response and haemocyte make-up of the model organism D. melanogaster vary across the genus Drosophila.

The collection of large numbers of nematodes from Macropus rufus from Toganmain and Wilcannia in New South Wales and Cunnamulla in Queensland and from M. canguru from Cunnamulla has made possible the revision of five species and the description of three new species. The work is divided into two sections:

(1) Strongylina. Filarinema flagrifer Mönnig, Zoniolaimus setifer Cobb, Z. cobbi Kung, Rugopharynx australis (Mönnig) and Papillostrongylus labiatus Johnston & Mawson are re-described: Pharyngostrongylus alpha Johnston & Mawson and P. beta Johnston & Mawson are recognized as synonyms of R. australis; Filarinema moennigi sp.nov. is described from Macropus rufus.

(2) Oxyurina. Macropoxyuris longigularis gen.nov., sp.nov., and M. brevigularis gen.nov., sp.nov., are described from M. canguru. Re-examination of paratype material of oxyurids previously recorded from marsupials has made possible the presentation of more detailed descriptions, and the following nomenclatural changes become necessary: Oxyuris (s.l.) acuticaudata Johnston & Mawson is a synonym of Austroxyuris finlaysoni Johnston & Mawson: Syphacia trichosuri Johnston & Mawson is considered as Oxyuris (s.l.) trichosuri; two new genera are proposed, Potoroxyuris, for Oxyuris (s.l.) potoroo Johnston & Mawson, and Paraustroxyuris for Passalurus parvus Johnston & Mawson. Figures are given of Passalurus ambiguus (Duj.).

The material studied was made available by the generosity of Dr R. Mykytowycz of the C.S.I.R.O. Division of Wildlife Research, Canberra, to whom I am most grateful.

I am also indebted to Dr R. J. Ortlepp, Division of Veterinary Services, Onderstepoort, South Africa, for the gift of a sample of Rugopharynx australis, to Dr M. J. Mackerras, then of the Queensland Institute of Medical Research, for material from Macropus canguru from centres in south eastern Queensland, and to Dr G. B. Sharman of the C.S.I.R.O. Division of Wildlife Research for information on the correct names of the host species.

1. Entamoeba moshkovskii was isolated from a sewage plant in North London.

2. The morphology and metacystic development is similar to that of E. histolytica and other histolytica-like amoebae, but with differences in minor details.

3. The cysts of E. moshkovskii remain viable when kept at 4° C. for periods up to 10 months providing they are not allowed to dry.

4. If the amoebae are placed in hypotonic solution, the amoebae attempt to eliminate excess water by means of contracting vacuoles, but they eventually die.

5. Experiments have shown that E. moshkovskii is an anaerobe.

6. The optimum temperature for growth is about 24° C. as encystation does not occur at 37° C.

7. E. moshkovskii is not infective to rats or to larvae of the common frog (Rana temporaria) and Salamandra maculosa.

The muscular system is so highly developed in the Ixodoidea, that it is no matter of surprise that it has been the subject of more or less detailed treatment in most of the publications dealing with tick anatomy; but, with a single exception, the existing descriptions do not extend beyond a general classification of the various muscles, with the addition of brief remarks, in some instances, on the histological structure of the muscle fibres. In the majority of cases, also, the observations only apply to the Ixodid ticks, and although the general arrangement of the musculature in the two families of the Ixodoidea is not fundamentally different, the comparative anatomy of the muscles offers some difficulty, owing to the great morphological differences which the two families present.

The growth curve, rate of neutral unbound lipid synthesis, and relationship between morphogenesis and lipid reserve have been studied at 30 °C. The feeding process, including a theoretical calculation of bacterial requirements of preinfective larvae, is presented, together with some measurements of the most important variables in ingestion, expulsion of water through the anus, and its dependence on larval posture is described.

Larval stages have been tracked on agar; L1 are so inactive that no tracks were obtained; L2 show short, irregular tracks, and infective larvae strong, long and straighter tracks. The locomotory activity of L2s is primarily for feeding, whereas L2s are adapted for dispersion and host location.

I thank Mr J. M. Smith for tracking the larvae and Mrs Helen Foreman for staining them, Dr Elizabeth U. Canning for making available the scanning microdensitometer and Professor G. S. Nelson and Dr D. A. Denham for enabling us to establish A. tubaeforme in cats. Finally the generous support of the British Medical Research Council is appreciated.

Malaria is a major health concern particularly in Africa which has about 90% of the worldwide annual clinical cases. The increasing number of drug-resistant Plasmodium falciparum justifies the search for new drugs in this field. Antimalarial activity of 2-substituted 6-nitro- and 6-amino-benzothiazoles and their anthranilic acids has been tested. An in vitro study has been performed on W2 and 3D7 strains of P. falciparum and on clinical isolates from malaria-infected patients. Toxicity has been assessed on THP1 human monocytic cells. For the most active drug candidates, the in vitro study was followed by in vivo assays on P. berghei-infected mice and by in vitro assays in order to determine the stage-dependency and the mechanism of action. Of 39 derivatives tested in vitro, 2 had specific antimalarial properties. Each compound was active on all stages of the parasite, but one was markedly active on mature schizonts, while the other was more active on young schizont forms. Both drugs were also active on mitochondrial membrane potential. In vivo data confirmed efficiency with a sustained decrease of parasitaemia. Products A12 and C7 may be considered as potential antimalarial worthy of further chemical and biological research.

The first two phases in the growth of Maritrema linguilla in Ligia oceanica, which occur in unencysted specimens in the pleopod sinuses, from day 0 to day 28 post-infection (p.i.), include a 3-fold increase in size, an enormous increase in the relative size of the excretory bladder, metamorphosis of papilliform extensions of the tegument into microvilli and development of single pointed spines and cystogenous gland cells. The third phase, from day 29 to day 38 p.i., following migration to the dorsal haemocoel, includes production of 3 cyst wall layers, the loss of single pointed spines and a considerable decrease in the relative size of the excretory bladder. The fourth phase from day 39 to day 42 p.i., involves a further increase in body size and the formation of digitiform spines. The fifth, sixth and final phases from day 43 to day 120 p.i. first include the completion of the last two cyst wall layers and then an increase in body size and development of the digestive, excretory and reproductive systems to almost adult dimensions but sperm, ova, vitelline globules and eggs are produced only in the final host.

The trematode and cestode parasites of fishes inhabiting British coastal waters have been the subject of several studies in the past, but the parasites of deep-sea fishes have received comparatively little attention due probably to the difficulty of obtaining fresh material. In order that such material might be obtained, excursions were made by the junior author in a commercial trawler to some of the deep-sea fishing grounds lying to the west of Ireland, namely, the Irish Atlantic Slope and the Porcupine Bank. Two excursions were made, the first in August 1938 and the second in July 1939, each extending over a period of about 12 days. In addition, a study has been made of the parasites of some fishes from the Irish Sea from 1936 to 1939. The results of both surveys are incorporated in this paper, and the areas investigated are indicated in Table 1.

The feeding behaviour of parasitic 3rd-stage larvae (L3) of the hookworms Ancylostoma caninum, A. ceylanicum and Necator americanus was examined. Less than 11% of A. caninum L3 recovered from the small intestines of dogs infected orally were feeding at 4–48 h post-infection (p.i.). and none of the A. ceylanicum L3 recovered from the intestines of orally infected hamsters had resumed feeding. All L4 of both species recovered at 36 and 48 h p.i. had resumed feeding. On the other hand, approximately 16% of the A. ceylanicum L3 recovered from the skin of percutaneously infected hamsters at 18 h were feeding, and the percentage feeding increased to nearly 58% at 44 h p.i. Necator americanus L3 recovered from the skin of percutaneously infected neonatal hamsters resumed feeding at 6–12 h p.i. and reached 90–94% by 18 h. Feeding began to decline at 66 h, and reached 29% at 120 h p.i. This decrease was associated with the migration of larvae from the skin to the lungs. By 192 h p.i. over 95% of the larvae had reached the small intestine, and all had moulted to the L4. The results indicate that parasitic L3 resume feeding in the skin during percutaneous infections, and suggest that feeding by hookworm L3 correlates with the resumption of development.

The aim of this study was to evaluate the CD4+/CD8+ ratio in peripheral blood of dogs with localized and generalized demodicosis. Sixteen dogs were examined, 8 with localized and 8 with generalized demodicosis, while 8 healthy dogs were used as controls. Peripheral blood was obtained and CD4+ and CD8+ T cells were determined by flow cytometry. Significantly higher numbers of CD8+ T cells and lower numbers of CD4+ T cells were found in dogs with generalized demodicosis compared to dogs with localized demodicosis and healthy controls. Significantly higher numbers of CD8+ T cells and lower numbers of CD4+ T cells were also found in dogs with localized demodicosis compared to healthy controls. The CD4+/CD8+ ratio was also found to be significantly lower in dogs with generalized demodicosis in comparison with dogs with localized demodicosis and healthy controls. It is concluded that significant alteration in the CD4+/CD8+ ratio may be implicated in the pathogenesis of generalized canine demodicosis.

Representatives of a total of twenty fish species, most of them marine, from the Black Sea coast in Rumania were investigated. Of these, ten species were found to harbour ectoparasitic trichodinids on their skin and gills. Three of them, Trichodina rectuncinata Raabe, 1959, from Gaidropsis mediterranaeus and Crenilabrus griseus, T. caspialosae (Dogiel, 1940) mihi from Alosa braschnikowi meotica and T. d. f. latispina from Gasterosteus aculeatus, were already known.

Three species could be established as new ones: T. puytoraci sp.nov. from Mugil auratus, M. cephalus and M. saliens, T. raabei sp.nov. from Pleuronectes flesus and T. lepsii sp.nov. from M. auratus. They are clearly differentiated from other species.

The following trichodinids were provisionally classified as forms (including one new one) of T. domerguei, thus enlarging this most complicated Trichodina species: T. domerguei, cf. latispina from Gobius syrman, T. domerguei f.n. maris-negri from Gaidropsis mediterranaeus, and T. domerguei f. partidisci from Mugil cephalus. Other populations of T. domerguei could not be properly classified because of lack of material.

The description of the new species of Tripartiella which have been mentioned in the introduction, will be given in a separate paper.

A short survey on marine trichodinids recorded up to the present is given.