Manipulative endoparasites can alter the behaviour and the physiology of their intermediate hosts in ways that increase the probability of successful transmission to the final host. This requires that the parasite is able to circumvent its host's immune defence. Successful immune evasion may depend on host–parasite coevolutionary history and the appearance of new hosts invading the local host population may promote local parasite maladaptation. To test this hypothesis, we examined the effect of 2 acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on the immunity of their local and new invasive gammarid intermediate hosts, respectively Gammarus pulex and Gammarus roeseli. We found that infection by each parasite was correlated with a decrease, at different degrees, of the standing level of immune defence in local hosts – measured as the phenoloxidase (PO) enzyme activity – whereas invasive hosts infected by P. laevis had their PO-enzyme activity enhanced. These results suggest that these acanthocephalans evade their local host immune response through immunosuppression but cannot evade the immune response of their new invasive host. The potential role of this maladaptation on the success of invasive species is discussed.

1. The cycle of vertical migration of the infective larvae of Haemonchus contortus on experimental plots of Lolium perenne S 24, kept out of doors, has been related to meteorological and micrometeorological factors.

2. The three main factors concerned with vertical migration are temperature, humidity and light intensity.

3. In the majority of cases the greatest number of larvae are on the grass blades in the early morning and in the evening, less being recovered at night and during the middle of the day. The time of the morning maximum becomes progressively earlier passing from winter to summer, and the time of the evening maximum progressively later. The reverse is true in the second half of the year.

4. Low and high temperatures accompanied by low humidity inhibit vertical migration on the grass.

5. High humidity (continuous precipitation) does not prevent migration, the two daily maxima are apparent, but the numbers climbing are less than in the absence of rain.

Infection by a parasite often induces behavioural changes in the host and these changes may benefit either the host or the parasite. However, whether these changes are active host defence mechanisms or parasitic manipulations or simply incidental byproducts of the infection is not always clear. It has been suggested that understanding the proximate mechanisms of these changes as well as comparative studies could help distinguish these alternatives better. Behavioural fever is a common response to an infection in many animals and we investigated the phenomenon in the novel host-parasite relationship between the honeybee and the temperature-sensitive microsporidian Nosema ceranae. Our results show that infected bees prefer higher temperatures and even though this seems to benefit the pathogen, the proximate mechanism underlying this change is the pathological stress underlying the infection. Especially because it is a new host-parasite relationship, it is best to label the observed behavioural change as a case of incidental benefit although this does not rule out selection acting on it. We discuss the importance of looking at the behavioural outcomes of host-parasite relationships and the importance of studying them at multiple levels for understanding their origin and maintenance.

Avian trichomonosis, caused by the flagellated protozoan Trichomonas gallinae, is a recently emerged infectious disease of British passerines. The aetiological agent, a clonal epidemic strain of the parasite, has caused unprecedented finch mortality and population-level declines in Britain and has since spread to continental Europe. To better understand the potential origin of this epidemic and to further investigate its host range, T. gallinae DNA extracts were collected from parasite culture and tissue samples from a range of avian species in Britain. Sequence typing at the ITS1/5.8S rRNA/ITS2 region resolved three distinct ITS region types circulating in free-ranging British birds. Subtyping by sequence analyses at the Fe-hydrogenase gene demonstrated further strain variation within these ITS region types. The UK finch epidemic strain was preponderant amongst columbids sampled, however, wide strain diversity was encountered in isolates from a relatively small number of pigeons, suggesting further strains present in columbid populations across the UK are yet to be identified. Fe-hydrogenase gene sequence data in isolates from birds of prey with disease were predominantly identical to the UK finch epidemic strain, demonstrating its presence as a virulent strain in UK birds of prey since at least 2009.

The double isotope labelling method of Arias, Doyle & Schimke (1969) and Dehlinger & Schimke (1971) was used to determine the relative rates of turnover of proteins in various tissue fractions and in the culture medium of adult Schistosoma mansoni. The majority of proteins in the surface membrane turned over at about the same rate. This is consistent with a model for membrane assembly and degradation involving multi-protein units. The proteins in the other fractions examined, except frozen-thawed supernatant fluid, also turned over at about the same rate. In the frozen and thawed supernatant fluid, the higher molecular weight (>40000 daltons) proteins turned over at a much greater rate than the lower molecular weight proteins (<40000 daltons). The antigens in the culture medium, both particulate and soluble, had a higher turnover rate than the worm tissue proteins. It is concluded that the culture medium antigens are released as the result of two distinct processes: (a) surface membrane turnover and (b) a rapid secretory process. It is possible that the high molecular weight proteins found in the frozen-thawed supernatant fluid are involved in the rapid secretory process. The culture media of 6-day and 16-day schistosomula were also examined by the double isotope method. The culture medium of the adult worm and 16-day schistosomula contains more material presumed to be secreted than does that from the 6-day schistosomula. This may explain the poor immunogenicity of young schistosomula.

Parasite community ecology has recently focused on understanding the forces structuring these communities. There are few surveys, however, designed to study the spatial repeatability and predictability of parasite communities at the local scale in one host. The purpose of our study was to address the relationship between infracommunity and component community richness, and to describe spatial variations on the local scale, of helminth parasite communities in an avian host, the red-legged partridge (Alectoris rufa). We sampled 235 wild partridges from 8 separate localities, with different partridge population densities, in the Ciudad Real and Toledo provinces of central Spain, and we determined their overall and intestinal helminth species. We found that habitat variables (mean temperature and land use) were not significantly associated with any component community. The partridge population abundance index was directly correlated with the prevalence and mean intensity of infection but not with component community species richness. There was a curvilinear relationship between infracommunity and component community species richness, as well as negative interspecific associations, for the helminth species assemblage parasitizing the intestine. A nestedness/anti-nestedness pattern, considered as part of a continuum, was associated with prevalence, mean intensity and partridge population abundance index, but not with component community richness. Increases in the partridge population abundance index and the prevalence and mean intensity of infection were associated with increases in helminth community nestedness. Although negative interactions between helminth species could not be ruled out as forces structuring helminth communities, our results suggest that parasite community structure in the red-legged partridge was primarily determined by the extrinsic influence of parasite habitat heterogeneity and its amplification of the differing probabilities of colonization of parasite species.

Kudoid parasites are significant pathogens of marine fish. In the past, specific identification has been difficult due to a paucity of detailed morphological and biological information provided in the original description of some species. However, the introduction of DNA analysis has dramatically improved diagnosis. For morphological characterization, this paper proposes a new set of schematics including additional measurements to give a more thorough description of spore morphology, and provides evidence for uniqueness of 4 new species: Kudoa gunterae n. sp. (from 10 pomacentrid species and 1 apogonid species), K. kenti n. sp. (from 4 pomacentrid species), K. paraquadricornis n. sp. (from 4 carangid species), and K. whippsi n. sp. (from 8 pomacentrid species and 1 apogonid species). Subtle morphological differences found between closely related species were reflected in their genetics, with increased resolution provided by the large subunit, compared with that of the small subunit, of the ribosomal DNA gene region. This article proposes comprehensive requirements for species descriptions within the Kudoidae that incorporate biology, morphology, and genetic sequence.

Relationships between ascariasis and lactose digestion and between ascariasis and food transit time from mouth to caecum were investigated in young children from Chiriqui Province, Republic of Panama. The breath hydrogen method was used in both studies. Ascaris-infected children showed a significantly poorer degree of lactose digestion following a test oral load than uninfected children. Recovery of the capacity of the children to digest lactose was still not fully complete for at least 3 weeks following anthelmintic treatment. On average, the mouth-to-caecum transit time was similar in infected and uninfected children, but among the Ascaris-infected children the transit time tended to be shorter in relation to the intensity of infection. Evidence from a cross-sectional survey indicated that ascariasis was significantly associated with reduced plasma vitamin A and carotenoid concentrations. This relationship remained after controlling for a range of socio-economic variables. Ascaris-infected children were frequently found to have lower haematocrits and blood haemoglobin concentrations than uninfected children, but these relationships could not be attributed to ascariasis alone.

The surface lipophosphoglycans (LPG) of Leishmania promastigotes express stage- and species-specific polymorphisms that are defined by variations in the type and number of phosphorylated oligosaccharide repeats. We have studied how these polymorphic structures control the development of transmissible infections in the sandfly vector as well as the species-specificity of vectorial competence. Procyclic promastigotes displayed an inherent capacity to bind to midgut epithelial cells of a competent vector. This capacity was lost during their transformation to metacyclic promastigotes, permitting the selective release and anterior migration of infective-stage parasites for subsequent transmission by bite. Midgut attachment and release were found to be controlled by developmental modifications in terminally exposed saccharides on LPG, which, depending on the species of Leishmania, involved either substitution or capping of terminal side-chain sugars, loss of terminal side-chain sugars, substitution or loss of neutral capping sugars. The stage-specific terminal sugars involved in midgut adhesion are, in some cases, also species-specific, and the extent to which these differences affect midgut attachment, forcefully predicted vectorial competence.

We review the literature on parameter values relevant to the epidemiology of strongyle nematode infections of domestic sheep. Information is subdivided by parasite genus, country of origin and climate type. While field observations have been made in a large number of countries, the bulk of studies under controlled conditions have been conducted in Australia, New Zealand and the UK. For these countries, experiments and parameters are interpreted in terms of a previously published model of nematode dynamics, and are used to calculate the basic reproduction number. Average values range from less than 6 for Haemonchus contortus in New Zealand and a winter rainfall region of Australia, to more than 16 for Ostertagia circumcincta in New Zealand and the UK. Additional considerations of the effects of climate and the annual replacement of host stock show that for conditions favourable for parasite transmission this is a robust indicator of parasite epidemiology. When climate variation and annual replacement are added to the model, it is shown to reasonably describe the qualitative behaviour of an experimental data set, indicating it to be a useful tool for further investigation of some of the underlying assumptions of sheep–nematode dynamics.

An enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to Encephalitozoon cuniculi in man, using spores derived from tissue culture as antigen. Negligible cross-reactions were found with other microsporidia of vertebrate or of invertebrate origin and there was no cross-reaction with Toxoplasma gondii, using ELISA, immunoperoxidase or immunofluorescence staining. A high prevalence of antibodies to E. cuniculi was found in patients suffering from schistosomiasis, malaria and neurological and psychiatric disorders, but not in healthy individuals.

Immunocytochemical techniques used in conjunction with confocal scanning laser microscopy (CSLM) and electron microscopy have been used to demonstrate, for the first time, the distribution of the parasitic platyhelminth neuropeptide, neuropeptide F (NPF) in the cestode, Moniezia expansa. Antisera were raised to intact NPF(1–39) and to the C-terminal decapeptide of NPF(30–39). These antisera were characterized and validated for use in both immunocytochemistry and radioimmunoassay (RIA). NPF immunoreactivity (IR) was detected using both antisera throughout all of the major components of the central and peripheral nervous systems of the worm. The pattern of NPF-IR was found to mirror the IR obtained using a C-terminally directed pancreatic polypeptide (PP) antiserum and FMRFamide antisera; blocking studies using these antisera revealed that FMRFamide and PP antisera cross-react with NPF(M. expansa). RIA of acid-alcohol extracts of the worm measured 114 ng/g using the C-terminal NPF antiserum and 56 ng/g using the whole-molecule-directed antiserum. While the C-terminally-directed NPF antiserum cross-reacts with NPF-related peptides from other invertebrates, the whole-molecule-directed NPF antiserum is specific for NPF(M. expansa). The C-terminal NPF antiserum has potential for use in the identification and purification of NPF analogues from other platyhelminth parasites.

Avian trypanosomes are widespread parasites of birds, the transmission of which remains mostly unclear, with various blood-sucking insects mentioned as possible vectors. A search for vectors of trypanosomes of sparrowhawk (Accipiter nisus), buzzard (Buteo buteo), lesser-spotted eagle (Aquila pomarina) and kestrel (Falco tinnunculus) was performed in Czech and Slovak Republics. Black flies (Eusimulium spp.), hippoboscid flies (Ornithomyia avicularia), mosquitoes (Culex pipiens pipiens) and biting midges (Culicoides spp.), trapped while attempting to feed on raptor nestlings, were found to contain trypanosomatids in their intestine. Trypanosomes from the raptors and blood-sucking insects were isolated, and their 18S rRNA sequences were used for species identification and for the inference of intra- and interspecific relationships. Together with the trypanosome isolated from a black fly, the bird trypanosomes formed a well-supported Trypanosoma avium cladeThe GenBank accession numbers of the determined sequences are: AF416559 (Trypanosoma ‘avium’ APO1), AF416560 (Herpetomonas sp. CER1), AF416561 (Trypanosoma sp. CUL1), AF416562 (Trypanosoma sp. OA6), AF416563 (Trypanosoma ‘avium’ SIM3).. The isolates derived from hippoboscid flies and mosquitoes are most likely also avian trypanosomes infecting birds other than the studied raptors. Analysis of the kinetoplast, that has features characteristic for the avian trypanosomes (minicircle size; dimensions of the kinetoplast disc), provided further evidence for the identification of vectors. It is suggested that all trypanosomes isolated from raptors included in this study belong to the T. avium complex and are transmitted by the ornithophilic simuliids such as Eusimulium securiforme.

The studies presented in this paper describe the effects of control exerted by the immunological response of the host (sheep) on the developmental stages and fecundity of the parasite Nematodirus spathiger. Thirty Merino lambs, maintained worm-free, were randomly divided among three treatment groups each containing ten animals. The group 1 lambs were each given a single dose of 50,000 infective larvae, the group 2 animals were given a single dose of 130,000 infective larvae, and the group 3 animals were given twenty-five consecutive daily doses of 2000 infective larvae. Group fecundity was estimated by performing worm egg counts on daily faecal samples and development of the parasite burden was followed by carrying out differential worm counts on animals slaughtered at crucial stages during the infections. Total fecundity was greatest in group 1 and least in group 3 with group 2 intermediate. An inverse relationship between total fecundity and percentage retardation of development (percentage of 4th-stage larvae in the total worm burden) was demonstrated between the three treatment groups.

The results of the studies also show that control of the parasitic infection is mediated about threshold levels of immunological responsiveness and is expressed by (1) elimination at the infective (L3) stage, (2) retardation of development at the L4 stage, (3) reduction in egg production of the adult female, (4) elimination of adult worms, and (5) discrimination against the female in both the degree of retardation in the L4 stage and the extent of elimination in the adult stage.

Great variation in response was observed between individuals within treatment groups. The source of variation is attributed to differences in degree of antigenic disparity of the parasite with individual members of the heterozygous host population in which antigenic characters are not uniformly segregated.

The concept of ‘fitness’ of the parasitic species was introduced into the discussion to provide a rational interpretation of the results.

We are indebted to Dr S. S. Y. Young, Division of Animal Genetics, C.S.I.R.O., for advice and assistance with the statistical analyses, which were performed by Mrs M. Tonkin, and to Dr D. F. Stewart for his constructive criticism of the manuscript. Careful technical assistance was given by Mr E. Teleki and Misses Helen Giller and Berenice Merchant.

Eimerian oocysts were found in 98% of 422 faeces samples from goats in SE England. It was found that 74% of the samples contained thousands or tens of thousands of oocysts/g. Kids less than 1 year old had higher oocyst counts than yearling or adult goats. Nine species of Eimeria were identified, and 65% of the samples contained 3–5 species. The most prevalent species were E. arloingi (94%), E. hirci (69%), E. christenseni (64%) and E. caprina (55%). E. ninakohlyakimovae (48%), E. alijevi (42%) and E. apsheronica (23%) were common, and E. joichijevi (8%) and E. caprovina (4%) were comparatively rare. Developmental stages of E. caprina destroyed the crypt epithelium in the mucosa of the large intestine, causing severe haemorrhagic enteritis similar to that produced by E. ninakohlyakimovae. The literature on Eimeria species in sheep and goats is reviewed and, on the grounds of priority, E. bakuensis is the correct name for E. ovina in sheep.

Studies of invertebrate–parasite interactions frequently report that infection reduces host fecundity. The extent of the reduction is likely to be determined by a wide range of host and parasite factors. We conducted a laboratory experiment to evaluate the role of parasite genetics and infection genetic diversity on the fecundity of mosquitoes carrying malaria parasites. The malaria vector Anopheles stephensi was infected with either of 2 different genotypes of the rodent malaria parasite Plasmodium chabaudi, or by a mixture of both. Mixed genotype infections reduced mosquito fecundity by 20%, significantly more than either of the 2 single genotype infections. Mixed genotype infections were associated with high gametocyte densities and anaemia in mice, both of which were correlated with reduced bloodmeal size in mosquitoes. Bloodmeal size was the most important predictor of mosquito fecundity; the presence and number of parasites had no direct effect. Parasite density influenced the propensity of mosquitoes to feed on infected mice, with a higher percentage of mosquitoes taking a meal as asexual parasite and gametocyte density increased. Thus mosquitoes may preferentially feed on hosts who will most impair their fecundity.

The question of whether the known immunosuppressive effects of Babesia microti may disrupt the development of acquired resistance to its tick vector, Ixodes trianguliceps, in natural rodent hosts (Clethrionomys glareolus), and thus enhance thedisease transmission potential, is addressed experimentally. The results show for the first time that natural hosts can acquire resistance to ticks; that this acquired resistance is manifested chiefly by a strongly density-dependent reduction in the percentage of attached larvae that engorge; that the density dependence is quantitatively similar whether the host receives occasional large tick challenges or frequent low infestations; but that infection with B. microti does not disrupt this pattern of acquired resistance. Of two important natural host species, Apodemus sylvaticus can support repeated infestations of I. trianguliceps, but is a poor host to B. microti, while C. glareolus develops acquired resistance to the tickvector, but supports much higher-level, longer-lasting B. microti infections.

In areas where malaria is endemic, helminthic infections, caused by intestinal or filarial parasites, commonly coexist with malaria in the same individual. This study investigates the course of Plasmodium berghei malaria infection in CBA/J mice inoculated with irradiated attenuated 3rd-stage larvae (L3) of Brugia pahangi. Peripheral eosinophil counts, serum IgE levels and cytokine production revealed that the filarial antigen induced T-helper type 2 (Th2) cell predominance in these mice, which protected them against the development of cerebral malaria. These mice significantly prolonged their survival, compared with the control mice after P. berghei infection. All of the mice not inoculated with irradiated L3 died within 12 days with acute neurological manifestations unrelated to the level of parasitaemia after infection of P. berghei. Conversely, most of the inoculated mice lived more than 3 weeks following infection with P. berghei, dying in the fourth week of severe anaemia and overwhelming parasitaemia. This suggests that Th2-dominant responses lead to the downregulation of susceptibility to murine cerebral malaria.

Laboratory studies on a group of 20 patients from the Rio Negro Valley, Colombia selected for detailed study showed that 14 gave antibody reactions on immunoassay consistent with Trypanosoma cruzi or T. rangeli infections. Four were diagnosed as having T. rangeli infection, 4 had mixed infections and 6 were infected with T. cruzi alone. Immunoprecipitation analysis showed that sera from T. crwzi-infected patients recognized a similar range of trypomastigote-derived polypeptides as sera from patients in Brazil, and all of the Colombian sera reacted with the 160 kiloDalton (kDa) polypeptide associated with active infection. Although sera from patients with T. rangeli infection alone gave a positive immunofluorescence or ELISA reaction with T. rangeli, they failed to bind to parasite polypeptides by either immunoprecipitation or Western blotting. Intriguingly, sera from patients with mixed infections consistently gave a stronger, but qualitatively similar, binding reaction in immunoprecipitation and Western blotting compared to sera from patients infected with T. cruzi alone.

A holotrichous ciliate found repeatedly in very large numbers in the body cavity of larval midges (Chironomus plumosus) from Paris and Berlin areas is described as a new species of the genus Tetrahymena, named T. chironomi sp.nov. It appears to represent a true example of facultative parasitism, since parasites released from the host survive in laboratory cultures, and free-living ciliates believed identical have been isolated from fresh-water sources in nature. Over a 3-month period more than 2000 larvae, principally fourth-instar stages, were examined; about 9 % of these were found to be infected with ciliates.

T. chironomi is the thirteenth species to be added to the growing holotrich hymenostome genus Tetrahymena. It is taxonomically distinguishable from other members of the genus on the basis of a combination of characteristics related to its morphology and bionomics. It is one of the smallest species, has 24–27 ciliary meridians and a relatively large, spherical micronucleus, does not exhibit dimorphism or cystic stages in its life cycle, and does not possess a caudal cilium.