Meiogymnophallvs minutus (Cobbold, 1859) comb, nov., from Cardium edule L. and Haematopus ostralegus occidentalis Neumann is shown to be synonymous with Lecithodendrium somateriae (non Levinsen, 1881) Jameson, 1902 in partim, Cercaria margaritae Lebour, 1907, Oymnophalloides oedemiae (Jameson & Nicoll, 1913) James, 1964, Cercaria cambrensis Cole, 1938, and Gymnophallus nereicola Rebecq & Prévot, 1962. The intensity of infestation of cockles, with the metacercariae, increases with the size and particularly with the age of this host and varies with the seasonal migrations of the final host. The connexion between the metacercaria and the adult is demonstrated experimentally. Domestic ducklings used as experimental hosts were susceptible to infection when fed with minced cockles but not when fed on baby chick crumbs.

We are very grateful to Professor E. W. Knight-Jones for the provision of working facilities and for help with the manuscript and to the Science Research Council for a grant to one of us (E.A.B.) which made the work possible.

The daily food intake and related changes in body weight were measured in young rats which were fed on synthetic diets containing 1% (3 experiments), 2% (4 experiments) and 20% (1 experiment) casein respectively. Some rats were infected with Nippostrongylus brasiliensis and allowed to feed ad libitum, some remained uninfected and were allowed to feed ad libitum while others, which were matched by initial weight with rats from the infected group, remained uninfected and were given only the same amount of food as that consumed during the previous 24 h by their infected partners. No significant differences were detected between the rats before the start of the infection. Thereafter, the food intake of the infected undernourished rats was usually found to be significantly lower and the loss of body weight significantly greater than those of the uninfected rats. In infection periods of relatively long duration, the pair-fed uninfected rats did not lose as much weight as their infected partners even though their food intake (1% and 2% casein) was the same. Although the food intake, and consequently the weight, of infected rats fed on the diet containing 20% casein were significantly less than in their uninfected partners, no significant differences were observed between the weights of the infected and pair-fed rats fed on this diet.

Spatial distribution is understood to connote distribution of density (including zero density) over the land surface at a given time. Combining fact and conjecture, the following is a theory of spatial distribution of Ixodes ricinus in Britain. The tick passes practically the whole of its 3-year life span on the ground, spending a total of only 3 weeks on hosts. A considerable amount of vegetational cover is necessary for efficient survival on the ground; the more important limiting circumstances in lesser cover seem to be humidity (conditioned by temperature) in summer, perhaps temperature (alone) in winter, and the activity of predators. A host is necessary for mating as well as food purposes. Though small at best, the tick's chances of achieving a host are greater the more hosts on the ground. In practice this means the more sheep, since the latter are by far the main hosts. For the most part, spatial distribution to-day can be explained adequately in terms of interplay between amount of ground-cover and of host-potential, with cover the master factor. Thus poor cover keeps the heavily stocked lowland pastures free of permanent tick population even when opportunity of colonization is offered. The tick is confined to the hills and moorlands with their deep vegetation layers. There, within limits, it is more numerous on a pasture the more universal the distribution of adequate cover (because it drops at random from the host) and the higher the host-potential. Among hill and moorland pastures, however, there are some cases where, despite ample cover and hostpotential, either (1) no ticks are present, or (2) the tick population is lower than it ought to be. These cases can be explained on grounds of lack of opportunity for colonization (1); or colonization so recent that population has not attained the level of ‘dynamic equilibrium’ with the environment (2). The question of ‘spread’ (colonization) is discussed fully in the text. The sheep flock is the main agent in spreading ticks. Spread is comparatively slow and relatively small in extent nowadays. There has very probably been considerable increase both in tick population densities and in infested areas since the advent of intensive hill and moorland grazing with farm stock some centuries ago.

The population structure and recruitment of Argulus coregoni was monitored at a Finnish fish farm during the open water periods of 1999 and 2001 by weekly sampling of attached argulids. In 2001 the numbers of rainbow trout examined increased in the autumn when the A. coregoni population was declining. When the water temperature exceeded 10 °C, at the end of May, A. coregoni egg hatching commenced. A mean number of 98 (S.D.±5·4) juvenile A. coregoni was recorded on each fish, before the start of female egg laying in July 1999. The abundance of lice was lower in 2001. The main recruitment of A. coregoni juveniles occurred in early summer, but the hatching of eggs continued until September. However, no pulses of hatching were recorded later in the summer and the numbers of lice on fish substantially decreased after mid-July in both years. On average, only 0·6 (S.D.±0·72) parasites/fish were found between August and late October 2001 and none in November. We suggest that there is 1 main A. coregoni generation annually in Central Finland. Environmental conditions, especially temperature, affects the population cycle of A. coregoni: we found a more synchronous and intense population cycle during the summer 1999, when the early summer was warmer than in 2001. The overall sex ratio (female[ratio ]male) of A. coregoni was nearly 1[ratio ]1 in June 1999, but was male biased (1[ratio ]1·4) in June 2001. It was also shown that from July onwards, many females detached from the fish host in order to lay their eggs on the bottom of the pond. Large males were often bigger than the largest females between mid-July and early September 2001, when as many as 3·7 (S.D.±1·48) times more males than females were present in the lice samples.

Neurocysticercosis (NCC) is the most common parasitic disease of the central nervous system (CNS) caused by the larval form of the tapeworm Taenia solium. NCC has a long asymptomatic period with little or no inflammation, and the sequential progression to symptomatic NCC depends upon the intense inflammation associated with degeneration of larvae. The mechanisms involved in these progressive events are difficult to study in human patients. Thus it was necessary to develop an experimental model that replicated NCC. In this review, we describe studies of a murine model of NCC in terms of the release/secretion of parasite antigens, immune responses elicited within the CNS environment and subsequent pathogenesis. In particular, the kinetics of leukocyte subsets infiltrating into the brain are discussed in the context of disruption of the CNS barriers at distinct anatomical sites and the mechanisms contributing to these processes. In addition, production of various inflammatory mediators and the mechanisms involved in their induction by the Toll-like receptor signaling pathway are described. Overall, the knowledge gained from the mouse model of NCC has provided new insights for understanding the kinetics of events contributing to different stages of NCC and should aid in the formulation of more effective therapeutic approaches.

Schistosomiasis and soil-transmitted helminthiasis occur throughout the developing world and remain a major public health problem in the poorest communities with enormous consequences for development. The extent of the problem has long been neglected because these diseases rarely kill at a young age and also because of their insidious nature. Today there exists a momentum and an unprecedented opportunity for a cost-effective control of these neglected tropical diseases. The control of these diseases has become a priority on the agenda of many governments, donors and international agencies. This paper highlights the progress made and future control activities in Cameroon and Côte d'Ivoire, where schistosomiasis and soil-transmitted helminthiasis control measures have been implemented over the past decade with limited budgets. In Cameroon, deworming activities were increased to encompass all ten regions in 2007 as a result of a co-ordinated effort of the Ministry of Health and the Ministry of Education with national and international partners. In Côte d'Ivoire, focal control activities were achieved with support from various partners. Prospects, opportunities and challenges for the control of neglected tropical diseases in these two countries are discussed.

The relative importance of temporal and spatial effects was assessed in helminth communities of bank voles (Myodes glareolus) in 3 woodland sites in N.E. Poland in the late summers of 1999 and 2002. Among common species the rank order of sites in relation to prevalence and abundance of infection was maintained between surveys. Site effects accounted for most of the deviance (in statistical models), and time was less important, so the exact location from which voles were sampled was of critical importance. The only exception was Syphacia petrusewiczi. In contrast, for derived measures such as species richness and diversity, most deviance was accounted for by host age, and the interaction between site and year was significant, implying that rank order of sites changed between years. Temporal effects on derived measures were generated primarily by a combination of relatively small changes in prevalence and abundance of the common, rather than the rare, species between the years of the study. In the medium-term, therefore, helminth communities of bank voles in N.E. Poland had a stable core, suggesting a substantial strong element of predictability.

Infrapopulation dynamics of the nematode Rhabdias cf. hylae within naturally-infected Bufo marinus in north Queensland, Australia, were detailed. Over 80% of 580 toads were infected with Rh. cf. hylae with a mean intensity of 16·1. Distribution of Rh. cf. hylae within the toad population was aggregated, with an increase in the variance-to-mean ratio with increasing toad size. Intensity of infection and length of nematode were both correlated with length of toad in the smaller size classes. Length of nematode was not related to intensity of infection at any time. Mean intensity of infection rose significantly in small toads following initial infection after metamorphosis. Over the same period, average length of nematode did not increase implying constant re-infection of the toads. Larger toads were not reinfected to the same extent, and the number of uninfected toads in the larger size class increased which indicated a natural loss of infections. Changes in parameters of Rh. cf. hylae infection within B. marinus were attributed to seasonal rainfall and its subsequent effect on the behaviour of the toad.

In 2009, a haplotype closely related to European strains of Echinococcus multilocularis was detected in a dog from the Quesnel region of British Columbia, Canada. We now report the establishment of this same haplotype in 7 coyotes (Canis latrans) trapped within 40 km of Quesnel, BC. In addition, 3 coyotes and 1 red fox (Vulpes vulpes) harboured adult cestodes morphologically compatible with that of E. multilocularis (overall prevalence 33% in 33 carnivores). None of 156 potential intermediate hosts, including 131 representatives of two highly suitable rodent species, Peromyscus maniculatus and Microtus pennsylvanicus, trapped from a region 120–210 km south of Quesnel were infected. This report confirms the establishment and local transmission of a European-type strain of E. multilocularis (the causative agent of human alveolar hydatid disease), in wildlife in a forested region of North America where this cestode had not been previously detected, with significance for public and animal health.

In the present study, we describe the complete mitochondrial (mt) genome of the Atlantic salmon parasite Gyrodactylus salaris, the first for any monogenean species. The circular genome is 14 790 bp in size. All of the 35 genes recognized from other flatworm mitochondrial genomes were identified, and they are transcribed from the same strand. The protein-coding and ribosomal RNA (rRNA) genes share the same gene arrangement as those published previously for neodermatan mt genomes (representing cestodes and digeneans only), and the genome has an overall A+T content of 65%. Three transfer RNA (tRNA) genes overlap with other genes, whereas the secondary structure of 3 tRNA genes lack the DHU arm and 1 tRNA gene lacks the TΨC arm. Eighteen regions of non-coding DNA ranging from 4 to 112 bp in length, totalling 278 bp, were identified as well as 2 large non-coding regions (799 bp and 768 bp) that were almost identical to each other. The completion of the mt genome offers the opportunity of defining new molecular markers for studying evolutionary relationships within and among gyrodactylid species.

Strongyloides stercoralis is a parasite that can cause death in immunocompromised people. A proper diagnosis is hence essential. The real-time polymerase-chain reaction (RT–PCR) is a novel, promising diagnostic method, that detects the DNA of the parasite in stool samples. In this retrospective study, we compared the sensitivity of agar plate coproculture (APC), an in-house immunofluorescence test (IFAT) and an in-house RT–PCR for the diagnosis of S. stercoralis infection. The study sample was composed by 223 samples. Samples resulting positive to APC, IFAT and RT–PCR were 20, 140 and 25, respectively. When sensitivity was calculated against a composite reference standard, serology confirmed the best performance (sensitivity 95%), followed by RT–PCR (57%) and APC (45%). In conclusion, in a non-endemic setting, serology is the best screening method, while the combination of APC and RT–PCR does not seem a reasonable approach to increase sensitivity. Both methods can have a role as confirmatory tests for selected cases.

Cortisone treatment of BL chickens given oocysts of Eimeria mivati resulted in the production of greater numbers of oocysts in the faeces and a prolonged patent period.

Schizonts were seen in sections of the intestines of treated birds up to the 24th day after oocyst inoculation although none was seen in control chickens after the 8th day. These late schizonts resembled those of the 3rd and 4th generations recorded for this species but may be those of a generation not yet described.

The depletion of intestinal lymphoid tissue in cortisone-treated birds is noted. The findings are discussed with reference to host-parasite relationships.

We wish to thank the scientific assistants and senior poultry attendant of the department for their help throughout the work.

A trypanosome identified as Trypanosoma (Schizotrypanum) dionisii Bettencourt & França, 1905, has been isolated from Pipistrellus pipistrellus (Chiroptera) in England. At least five out of eight P. pipistrelhis were infected. 2. In the blood of P. pipistrelhis, the parasite closely resembled T. (S.) cruzi. When grown in vitro in monophasic or diphasic media at 28°C, epimastigotes and trypomastigotes developed. The latter were of two types — very long, thin forms and less numerous shorter individuals. 3. The trypanosomes multiplied as amastigotes within HeLa and mouse L cells in vitro. After 6–9 days in HeLa cells at 37°C, they transformed into small trypomastigotes and emerged from the cells. Higher infection rates (up to about 4%) were obtained in cell cultures inoculated with flagellates from older monophasic cultures, which contained more of the long, slender trypomastigotes. 4. Trypanosomes also entered (or were phagocytosed by) up to 60% or more of mouse peritoneal macrophages in vitro. Multiplication occurred by binary and multiple fission of amastigotes in at least some of the parasitized macrophages and transformation into trypomastigotes was seen after 7 or more days at 37°C. Development in macrophages was less synchronous than in HeLa cells.

A quantitative study has been made of the relationship between Moniliformis dubius and Periplaneta americana.

1. Eggs removed from the body cavity of the worm hatch at a higher rate after dessication and after a short period of time following removal.

2. There is an exponential decline in the additional number of cystacanths recovered as the dose is increased linearly.

3. Female cockroaches are more susceptible to high levels of infection than males.

4. Direct injection into the haemocoele produces a similar recovery rate to that from oral infection.

5. Previous infection does not seem to affect the success of a superimposed infection.

6. Rates of development and growth are described.

7. The effect of the parasite on the concentration of free amino acids in the haemolymph was found to be negligible.

I would like to thank Miss S. Arnold and Mr D. Barnard for technical assistance, Mr E. Walters for help with statistical analysis, Dr D. W. T. Crompton for many helpful discussions and Dr P. J. Whitfield for reading this paper. This work has been carried out during the tenure of a Science Research Council Studentship.

The uptake of bloodstream forms of Trypanosoma cruzi, Y and CL stocks, by mouse peritoneal macrophages and their intracellular differentiation and multiplication has been compared in vitro. After 48 h the number of macrophages showing intracellular amastigote forms was higher when the Y stock was used. The number of parasitized cells increased with the time of contact between parasites and macrophages. Prior treatment of the parasites with anti-T. cruzi antibodies and/or complement increased the number of infected macrophages, but did not interfere with their subsequent differentiation within the macrophages. The number of parasitized cells was greater when macrophages were obtained from mice previously treated with lipopolysaccharide, peptone or thioglycollate. Uptake was not appreciably affected when macrophages were pre-treated with trypsin or anti-macrophage serum, or when the parasites and macrophages were incubated in the presence of cytochalasin B. In the same experimental conditions, epimastigotes of T. cruzi were not able to differentiate into amastigotes. Their uptake was potentiated by previous treatment with specific antibodies and/or complement and was blocked by cytochalasin B. These results confirm that epimastigotes derived from T. cruzi cultures are phagocytosed and suggest that bloodstream forms penetrate actively into macrophages.

Antigens sharing determinants with surface membranes and soluble proteins of adult Schistosoma mansoni have been detected in culture media after incubation of radioactively labelled worms. The relative quantities of these antigens were measured with specific antisera raised in rabbits and with serum from an immune rhesus monkey. It was found that 12–16% of TCA-precipitable radioactivity in the culture medium consisted of membrane antigens and 6–8% consisted of antigens sharing determinants with proteins found in the soluble fraction of adult worms. Over half the membrane antigens were present in particulate form, while other antigens were present in solution. Surface labelling the adult worms with [125I]confirmed that some of the particles in the culture medium were derived from the surface membrane of the adult worm and electron microscope examination of such particles showed that large membrane fragments were present. These results support the hypothesis that anti-bodies against schistosome membrane antigens are induced by particulate membrane antigens released by the parasite.

Trichinella spiralis infections influenced the establishment and maintenance of behavioural dominance among outbred male mice. Infected animals assumed a subordinate status when challenged by normal or more lightly infected conspecifics both in an unfamiliar test arena and in their established home cages. These effects were demonstrable during the acute and the chronic phases of infection. The significance of this phenomenon to the survival of the mouse host and the transmission of the parasite is discussed.

African trypanosomes can undergo antigenic variation and evade the host immune response. Whether the antigenic variants arise in an ordered sequence or randomly has been in dispute but has not been statistically tested. The coefficient of concordance (W), a statistic designed to detect similarities between sequences of objects, was applied to the literature data. The tendency towards a reproducible order of variants was strong, although in several of the studies the number of experimental animals was so low that no conclusions could be drawn. A computer model was used to determine whether this degree of order could arise with random generation of variants followed by selection. The model simulated a trypanosome clone with 90 possible variants, widely differing variant-specific growth rates, random variant origin and variant eradication by an anamnestic host immune response. Parameters varied were maximum parasitaemia, growth rate differential between ‘fast’ and ‘slow’ variants, and parasitologist ability to detect minor variants. Random generation and selection by growth rate alone could not produce the degree of variant orderliness reported in the literature. However, experiments with larger numbers of host animals and direct investigation of variant growth rates and competitive interactions are necessary before the random generation-selection hypothesis can be proven or disproven.

Polistes atrimandibularis is a species of obligate social wasp parasite, which introduces into nests of the host species P. biglumis, where it rears its own brood relying on the workers of the host species. Wasps of the host species discriminate between nestmates and non-nestmates by means of their epicuticular hydrocarbons. To overcome the host recognition systems, parasites have to modify their epicuticular recognition cues. Compared to individuals of the host species, parasites have 3–4 times less epicuticular hydrocarbons, although they share with their hosts the habitat and even the nests. We hypothesize that a dilution of the recognition cues in social parasites could have a facilitating role in entering host nests, in integrating within their host colony and in sneaking into secondary colonies to steal larvae and pupae.

RNA interference (RNAi) is a powerful research tool that has enabled molecular insights into gene activity, pathway analysis, partial loss-of-function phenotypes, and large-scale genomic discovery of gene function. While RNAi works extremely well in the non-parasitic nematode C. elegans, it is also especially useful in organisms that lack facile genetic analysis. Extensive genetic analysis of the mechanisms, delivery and regulation of RNAi in C. elegans has provided mechanistic and phenomenological insights into why RNAi is so effective in this species. These insights are useful for the testing and development of RNAi in other nematodes, including parasitic nematodes where more effective RNAi would be extremely useful. Here, we review the current advances in C. elegans for RNA delivery methods, regulation of cell autonomous and systemic RNAi phenomena, and implications of enhanced RNAi mutants. These discussions, with a focus on mechanism and cross-species application, provide new perspectives for optimizing RNAi in other species.