Single infections of Trichinella spiralis of 48 h duration did not produce a significant degree of immunity in mice.

Single or triple light infections of 7 h duration which, it is suggested, were composed entirely of fourth-stage larvae, did not produce significant immunity.

Single infections of 3 or 4 days duration did produce immunity. It is suggested that the fourth-stage intestinal larvae and the fourth moult are not the most important sources of immunizing antigen in a T. spiralis infection.

I would like to express my gratitude to H.M. Treasury and to the Agricultural Research Council for financial support during the time that this work was being conducted. I would also like to thank Professor W. I. B. Beveridge, within whose department this work was conducted, for the facilities provided. The helpful advice of my colleagues R. M. Connan and R. S. Phillips was of great value during the time that this manuscript was being prepared for publication.

During the early stages of the primary Plasmodium chabaudi chabaudi AS parasitaemia in CBA/Ca mice this parasite invaded normocytes, but as the parasitaemia developed increasing numbers of parasites were seen within reticulocytes. During and just after peak parasitaemia, as further parasite replication was controlled, the ‘crisis’ phase ensued, mice became increasingly anaemic and reticulocyte numbers were markedly increased. As the parasitaemia was resolved during crisis in excess of 25% of parasites had invaded reticulocytes. In phenylhydrazine-pretreated mice with artificially high reticulocyte levels and infected with P. c. chabaudi AS, normocyte/reticulocyte invasion occurred with equal frequency. No reduction in the infectivity of parasite populations developing in reticulocytes was observed.

A method for phenetic analysis of karyotype data has been developed for Leishmania populations. Measurement of size difference between chromosomes recognized by a given DNA probe in different isolates led to the formulation of a Chromosome Size Difference Index (CSDI). The method was applied to phenetic analysis of 4 sets of chromosomes – each set being recognized by a different probe – in 37 L. (Viannia) peruviana isolates sampled along a North–South transect through the Peruvian Andes and, in 11 L. (V.) braziliensis isolates from the Amazonian forest (Peru, Bolivia and Brazil). Karyotype variability was better accounted for by CSDI than by a method based on disjunctive encoding of karyotype data. CSDI evidenced the nature of relationships between L. braziliensis and L. peruviana and it provided a coherent picture of geographical and genomic differentiation among parasite populations. The latter did cluster according to their geographical origin. L. braziliensis was found karyotypically more homogeneous than L. peruviana. Within L. peruviana, Northern populations were closer to L. braziliensis than to Southern L. peruviana populations. The validity of karyotypic populations, or karyodemes, was sustained.

The causal prophylactic activity of the novel hydroxynaphthoquinone, S66C80, was assessed against the exo-erythrocytic (EE) stages of Plasmodium berghei cultured in the human hepatoma cell line, HepG2. 566C80 was found to be highly active as an inhibitor of EE development and was more active than the established causal prophylactic pyrimethamine. A 566C80 concentration of 1·85 × 10−9 M, added 3 h after sporozoite invasion, reduced the numbers of EE forms visible at 48 h by 50%, while the equivalent concentration of pyrimethamine was 1·95 × 10−8 M.

Vertically transmitted symbionts can be maintained in a host population only if they do not reduce host fitness, unless they compensate by manipulation of their host's reproduction or have alternative mode of transmission. In Leptopilina boulardi, a parasitoid of Drosophila larvae, some females are infected by viral particles showing both maternal and horizontal transmission. Horizontal transmission occurs when larvae from infected and uninfected individuals of L. boulardi compete in the same host. This situation is facilitated by the increasing tendency to accept already parasitized hosts that viral infection induces in L. boulardi females. Estimation of the adaptive significance of this behavioural modification requires measuring the effect of viral presence on other parasitoid physiological features. Here, we show that viral infection in females imposes no cost on adult survival, a low cost on developmental rate and tibia length, and leads to a strong reduction of locomotor activity. Surprisingly, infected females show higher egg load which could be accounted for by a redirection of energy allocation to egg production. The high intensity of superparasitism in infected females induced a dramatic decrease in pre-imaginal survival of the parasitoid's offspring, representing a potential indirect cost of infection. Low overall pathogeny induced by viral particles appears to be well suited to both transmission modes, both of them requiring females ability to locate and (super)parasitize hosts.

In the last decade, mobile technology offered new opportunities and challenges in animal health surveillance. It began with the use of basic mobile phones and short message service (SMS) for disease reporting, and the development of smartphones and other mobile tools has expanded the possibilities for data collection. These tools assist in the collection of data as well as geo-referenced mapping of diseases, and mapping, visualization and identification of vectors such as ticks. In this article we share our findings about new technologies in the domain of animal health surveillance, based on several projects using a wide range of mobile tools, each with their specific applicability and limitations. For each of the tools used, a comprehensive overview is given about its applicability, limitations, technical requirements, cost and also the perception of the users.The evaluation of the tools clearly shows the importance of selecting the appropriate tool depending on the envisaged data to be collected. Accessibility, visualization and cost related to data collection differ significantly among the tools tested. This paper can thus be seen as a practical guide to the currently available tools.

Four synthetic peptides which comprise the immunodominant linear epitopes of the EG95 recombinant protein, were investigated for their ability to induce host-protective immunity against Echinococcus granulosus in sheep. Sheep were immunized with either free peptide or peptide conjugated to diphtheria toxoid and challenge infected with E. granulosus eggs. All of the peptides elicited specific antibody, but these did not kill the parasite in in vitro culture assays, nor did the peptides induce protection against challenge infection. In contrast, anti-EG95 antibodies affinity purified against each of the 4 peptides were lethal to the parasite in in vitro culture. These affinity-purified antibodies were shown to contain specific antibody to both peptide and EG95. In in vitro inhibition assays, the peptides did not diminish anti-EG95 antibody binding to EG95 or parasite lysis in oncosphere killing assays. These results suggest that the fine specificities of antibodies raised against the recombinant protein are different to those raised against the peptide immunogens and that the majority of the antibody induced by vaccination with EG95 is raised against conformational determinants.

To identify the genes encoding novel immunodominant antigens of Theileria parva a λgt11 library of piroplasm genomic DNA was immunoscreened with bovine recovery serum and a gene encoding a 150 kDa antigen (p150) was identified. The predicted polypeptide contains an N-terminal secretory signal sequence and a proline-rich region of repeated amino acid motifs. The repeat region is polymorphic between stocks of T. parva in both copy number and sequence, and analysis of the repeat region from 10 stocks of T. parva revealed 5 p150 variants. A monoclonal antibody (mAb) against the T. parva polymorphic immunodominant molecule (PIM) cross-reacted with the recombinant p150. The p150 has sequence homology with a PIM peptide sequence containing the anti-PIM mAb epitope. Immunoelectron microscopy demonstrated that the p150 antigen, like PIM, is located in the microspheres of the sporozoites and is exocytosed following sporozoite invasion of the host lymphocyte. By immunoelectron microscopy p150 was subsequently transiently detectable on the sporozoite surface and in the lymphocyte cytosol. Immunoblotting showed that p150 is also expressed by the schizont stage, but at much lower levels compared to the sporozoite. These results suggest a major role for p150 in the early events of host–sporozoite interaction.

Prevalence and abundance of Cryptosporidium spp. and Giardia spp. infections were studied over the 8-year period in 3 species of rodents in N.E. Poland (bank vole Myodes glareolus-1523; yellow-necked mouse Apodemus flavicollis- 638; common vole Microtus arvalis- 419). Prevalence was 53·8, 28·1 and 62·3% respectively for Cryptosporidium spp. and 58·3, 24·4 and 74·2% respectively for Giardia spp. Prevalence and abundance of infection varied markedly across 8 years of the study with 1998 and 2002 being years of higher prevalence and abundance, following changes in the densities of host species. The distribution of intestinal protozoa in forest rodents did not vary in the 3 isolated sites during the 4-year study. In the case of Cryptosporidium, fewer older animals carried infection and infections of the oldest bank and common voles were relatively milder. In the case of Giardia in yellow-necked mice, infections were more common in older age classes (2 and 3). The two species showed significant co-occurrence and in animals carrying both species there was a strong significant positive correlation between abundance of infection with each. These data are discussed in relation to the parasite genotypes identified in this region and in respect of the role of various ecological factors in shaping of intestinal protozoa communities.

One of the ways of human parasitic infection is the accidental ingestion of vegetables contaminated with parasites, which represents a major human health hazard. This non-exhaustive review aims to evaluate studies carried out on five types of vegetables (lettuce, parsley, coriander, carrot and radish) since 2000, particularly the methods used for recovery, concentration, detection and identification of protozoan parasites such as Toxoplasma gondii, Giardia duodenalis and Cryptosporidium spp., and the results of each work. Various studies have determined the presence of pathogenic parasites in fresh vegetables with different rates; this variation in rate depends particularly on the detection method used which is related to each parasite and each vegetable type. The variation in parasitic prevalence in food could be due to different factors such as the geographical location, the size of analysed samples and the methods used for parasite detection.

Fallisia effusa gen.nov., sp.nov. (Haemosporidiidea: Garniidae) is described in the teiid lizard, Neusticurus bicarinatus, from Pará State, north Brazil. Schizogony and gametogony both take place within thrombocytes and white cells of the peripheral blood. There is no development in the red blood cells, by which character the organism is differentiated from Garnia, the other known genus within the family. Another species, Fallisia modesta gen.nov., sp.nov., is described in the iguanid lizard, Tropidurus torquatus hispidus, also from Pará, Brazil. It is distinguished from F. effusa by its development principally in the lymphocytes, as opposed to the thrombocytes. There are other, striking morphological differences between the two species. It is recommended that great care is needed in the interpretation of so-called ‘exo-erythrocytic stages’ of saurian plasmodia, which may well really belong to members of the Garniidae, in mixed infections.

Infective-stage larvae of three different isolates of Toxocara canis were intrinsically ([35S]methionine) labelled in culture, to determine the presence of similarities or differences in the somatic and ES antigens expressed between larvae derived from different hosts and different geographical regions. Two other closely related ascaridids, Toxascaris leonina which infects cats and dogs, and Toxocara vitulorum (Neoascaris vitulorum) which infects cattle, were also compared to T. canis larvae by this method. Overall comparisons were made by 1- and 2-dimensional electrophoresis, while immunological cross-reactivities between the different species were analysed by radio-immunoprecipitation. Our results show that extensive physicochemical characteristics are shared between T. canis isolates, both from different hosts and different geographical locations. A substantial overlap was revealed when T. canis and T. vitulorum antigens were compared, whereas Toxascaris was found to produce a distinct antigen profile: this result was independent of whether methionine- or Iodogen-labelled products were being considered. Antigen recognition by polyclonal antibodies raised to all three species and to the cat ascaridid Toxocara cati, revealed considerable cross-reactivities. The cross-reactions were especially prominent between the Toxocara species, a fact further substantiated when reactivity of T. canis ES-specific monoclonal antibodies were tested against T. leonina and T. vitulorum antigens. The ES antigens of T. leonina were not recognized by the T. canis monoclonals, whereas the majority of these antibodies precipitated antigens of T. vitulorum. One which did not react with T. vitulorum was monoclonal antibody Tcn 2, indicating its species-specific reactivity and therefore its potential for the specific diagnosis of human toxocariasis.

Microfilariae of Onchocerca lienalis were obtained from the umbilical skin of naturally infected cattle and were injected into mice. Maximum numbers of microfilariae were recovered from the skin and ears of mice when using the subcutaneous route of inoculation. Microfilariae were distributed throughout the pinna of the ear but were concentrated towards the tip where histological sections showed them to be in the dermis and adipose tissue. Using the number of parasites recovered from the ears as an index of the intensity of infection it was found that inbred CBA/H T6T6 mice were one of the most susceptible of 11 strains of mice examined. No difference in susceptibility was found between male and female CBA mice of the same age, but marked differences were demonstrated between male CBA mice of different ages. After infection with 5000 microfilariae the recovery of parasites from the ears increased rapidly to a peak at day 35 when 10% of the inoculum was recovered, and thereafter declined up to day 242. Over a range of inoculation doses examined it was found that there was a direct, linear relationship between the number of microfilariae recovered from the ears and the number in the inoculated dose. CBA mice showed marked resistance to reinfection with microfilariae. Six days after challenge with a secondary infection recoveries of microfilariae from the ears were only 26% of the level in challenge controls and fell to 3% of the level of controls by day 35. It is concluded that the model of O. lienalis microfilariae in CBA mice shows considerable promise as a tool for research into immunological responses to skin-dwelling microfilariae, which are the principal cause of pathology in onchocerciasis.

The reproductive kinetics of Protopolystoma xenopodis primary and secondary infections in Xenopus laevis were monitored in a 3-year study. Thirty-five naïve, lab-raised, full-sib X. laevis from 1 spawning were each exposed to 30 P. xenopodis eggs. The course of infections at 20 °C was monitored by screening isolated hosts for parasite egg production. Ninety-four percent of toads supported the development of gravid parasites. Infections became patent 9–19 weeks p.i., lasted 3–30 months and produced estimated totals of 1–7152 eggs/host. Variation in primary infection characters was discontinuous: a subgrouping of hosts (16%) was characterized by extended infection duration and low reproductive rate. In order to test the effect of long-term infection history on a subsequent challenge, each host was re-exposed to P. xenopodis infective stages (30 eggs/host) 6 months after the loss of its original infection. Establishment of patent infection was significantly lower (15%), and pre-patent period (12–28 weeks) longer, than in primary infections of the same hosts, and than in concurrently exposed naïve controls (contemporary full-sibs of the primary/secondary infection group, maintained in parallel; n = 28). There was no relationship between primary infection characteristics and secondary infection outcome. Overall reproductive output per initial infective stage for the primary exposure exceeded that for the secondary exposure by a ratio of 15[ratio ]1. Results suggest that primary infection with P. xenopodis can elicit strong, long-term protective immunity against re-infection in X. laevis.

A procedure is described for the isolation of sub-cellular fractions from bloodstream forms of Trypanosoma brucei. The method leaves intact most of the nuclei, mitochondria and microbodies. All the fractions have been chemically characterized and tested for 10 enzymatic markers. About 5% of total cell protein was isolated as a microsomal fraction containing mostly plasma membranes and endoplasmic reticulum vesicles. Plasma membranes were purified by high-speed centrifugation on magnesium-containing Dextran, and on linear sucrose-density gradients. The yield of membranes was approximately 0·3% of the total cell protein. The purified material had a sucrose density of 1·14 g/cm3 and consisted of smooth vesicles. Specific activity of the membrane markers Na+, K+, ouabain-sensitive ATPase and adenylate cyclase were 26-and 20-fold higher, respectively, than in total cells. Neither DNA nor RNA was detected. The sum of the cholesterol and phospholipid content was 0·99 mg/mg protein. The cholesterol/phospholipid molar ratio was 1 : 2.

The use of human diploid cell lines of finite life for the in vitro production of Trypanosoma cruzi is described. Both MRC5 and WI38 cells release trypomastigotes with less than 5% amastigotes. This could form the basis for biochemical and immunological studies, which were previously limited by the problems of separating parasites from blood. By selecting the in vitro passage number of the parasite it is possible to select for either the broad or the slender forms of trypomastigotes, allowing comparative studies of these forms within a single strain of the parasite. It is also possible to isolate amastigotes by disrupting the cells before trypomastigotes appear, and separating them from cell debris with Metrizamide. It is shown that by incorporating [3H]uridine in the cell-culture medium, labelled trypomastigotes are obtained. The release of this label (putative RNA) provides a relatively simple isotopic assay for parasite death. Examples of this assay for testing drug toxicity and in immunological lysis are presented.

Forty Theileria schizont-infected lymphocyte culture isolates from Zimbabwe were characterized using a panel of antischizont monoclonal antibodies (MAbs) and 4 Theileria parva DNA probes containing cloned extrachromosomal element, Tpr repetitive, ribosomal and telomeric sequences. The Theileria isolates were assigned as T. parva or T. taurotragi on the basis of reactivities with MAbs and restriction fragment length polymorphisms (RFLPs) detected using the extra chromosomal element probe. Cattle-derived T. parva isolates were relatively homogeneous on the basis of reactivities with MAbs and RFLPs detected using Tpr repetitive and ribosomal DNA probes. In contrast to previous results from Kenya, most of the cattle-derived isolates from Zimbabwe exhibited very similar Tpr restriction fragment patterns, although the Tpr genotypes of buffalo-derived isolates were heterogeneous. This suggests that selection for a particular Tpr genotype may be occurring in cattle. Many isolates with similar Tpr genotypes were differentiated by RFLPs detected using the telomeric DNA probe. The T. parva Boleni immunizing stock was distinguished from all other isolates by telomeric RFLPs. The T. parva Boleni Tpr repetitive DNA probe cross-hybridized with T. taurotragi DNA and detected RFLPs between different T. taurotragi isolates.

Periodicity of occurrence in the final host has been observed in only a few of the known Acanthocephala of fish (Van Cleave, 1916; Steinstrasser, 1936; Komarova, 1950; Shulman & Shulman-Albova, 1953). The periodicity appears to be due to the simultaneous operation of a complex of physiological, developmental and ecological factors.

In the present investigation a detailed study has been made of both the occurrence and the developmental cycle of Echinorhynchus truttae in its hosts in a small trout stream, Afon Terrig, in North Wales. An attempt has also been made to ascertain to what extent some of the various and varying ecological and physiological factors influenced the incidence, degree of parasitization and the development of the worm in nature.

Samples of the intermediate host, Gammarus pulex pulex L., and the final host the brown trout, Salmo trutta L., were taken monthly at three points or stations where the stream was readily accessible. Station I was at Rhydtalog as far upstream as practicable. Station III was at the opposite end of the stream near Caegwydd and station II was about mid-way between the other two sampling points. To ensure that each host sample was examined in as fresh a condition as possible, autopsy of the intermediate host was completed before the definitive host was taken.

Within the first week of each month from November 1961 to January 1963, shrimps were taken from over a stretch of about 30 m at each station.

Three distinct muscle types have been identified within the metacestode of Grillotia erinaceus. These consist of peripheral somatic myofibres plus two muscle systems directly involved in parasite attachment to the host, i.e. the tentacular bulb and its antagonistic retractor muscle. In common with other cestodes the somatic muscle consists of smooth-type fibres running longitudinally and obliquely to the main body axis. The retractor muscle consists of myofibres with centrally displaced nuclei. Upon contraction these latter fibres become spirally orientated causing the muscle to coil and lateral membranes to become elevated as spikes. Definitive nerve processes have not been identified within somatic or retractor muscle. Individual tentacular bulbs form the proximal terminus for a closed hydraulic system. Each bulb consists of overlapping, contrarotating myofibres which display obvious striations; the striations appear in alternate fibres to be in transverse and oblique planes. Adjacent myofibres are separated by approximately 0·5 μm, possess abundant mitochondria and have shallow t-tubules plus associated vesicles of sarcoplasmic reticulum at each Z line. Thick myofilaments are surrounded by 13, shared, thin myofilaments. Close neuronal control for the bulb muscle is suggested by the presence of obvious motor end-plates which contain both lucent and dense neurovesicles.

1. A survey of 227 rooks (Corvus frugilegus frugilegus L.) and seventy jackdaws (C. monedula spermologus Vieill.) was conducted in Hertfordshire. The birds were examined by means of cultures of their peripheral blood, or (in the case of eleven rooks and one jackdaw only) bone-marrow, on N.N.N. medium. Twenty-seven rooks (11·9%) and six jackdaws (8·6%) were found to be infected.

Some of the rooks were examined at a time of year when the trypanosomes are not present in the peripheral circulation; other rooks were examined in the first year of their life before adults of Ornithomyia avicularia (the vector of this parasite) were present. Ignoring birds of these two groups, twenty-six out of seventy-eight (33·3 %) adult rooks were found to be infected. This value probably approximates to the natural infection rate among adult rooks (and perhaps jackdaws).

2. The trypanosome in question is a large spindle-shaped form, measuring an average of 48·2µ in length (excluding flagellum) and 5·5µ in width. There is a tapering aflagellar region extending 14·1µ (on the average) beyond the kineto-plast. This trypanosome is assigned to the species T. avium Danilewsky, 1885.