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A model was developed to reproduce the dynamics of the parasitic stages of equine cyathostomins. Based on a detailed review of published literature, a deterministic simulation model was constructed using the escalator boxcar-train approach, which allows for fully-overlapping cohorts of worms and approximately normally distributed variations in age/size classes. Key biological features include a declining establishment of ingested infective stage larvae as horses age. Development rates are constant for all the parasitic stages except the encysted early third stage larvae, for which development rates are variable to reflect the sometimes extended arrestment of this stage. For these, development is slowed in the presence of adult worms in the intestinal lumen, and when ingestion of infective larvae on herbage is high or extended. In the absence of anthelmintic treatments, the life span of adult worms is approximately 12 months, and the presence of an established adult worm burden largely blocks the transition of luminal fourth stage larvae to the adult stage, resulting in mortality of the larvae. This inhibition is removed by effective anthelmintic treatment allowing the rapid replacement of adult worms from the pool of mucosal stages. Within the model, the rate and seasonality at which infective stage larvae are ingested strongly influences the dynamics of the pre-adult stages. While the adult worm burden remains relatively stable within a year, due to the negative feedback they have on developing stages, the numbers and proportions of larval stages relative to the total worm burden increase with the numbers of infective larvae ingested. Further, within the model, the seasonal rise and fall of encysted stages is largely driven by the seasonal pattern of infective larvae on pasture. Because of this, the model reproduces the contrasting seasonal patterns of mucosal larvae, typical of temperate and tropical environments, using only the appropriate seasonality of larvae on pasture. Thus, the model reproduces output typical of different climatic regions and suggests that observed patterns of arrested development may simply reflect the numbers and seasonality of free-living stages on pasture as determined by different management practices and weather patterns.

Ethnopharmacological relevance Jasminum grandiflorum L. is a medicinal plant widely used in the traditional system of Medicine as an anthelmintic in ringworm infections, for treating ulcers, stomatitis, skin diseases, and wounds. Aim of the study The emergence of resistance by different parasites to currently used chemicals has been reported. There are increasing needs for more effective and safer parasiticides. Therefore, the current study was designed to investigate the methanolic extract of the aerial parts of J. grandiflorum subsp. Floribundum (JGTE) to confirm its traditional uses as anthelmintic through a bioassay-guided fractionation and isolation of the active components with anthelmintic activity. Materials and methods The JGTE was partitioned into dichloromethane (DCM-F) and n-butanol (BuOH-F) fractions. The JGTE, fractions, and the isolated compounds were tested in vitro for their anthelmintic activity using two nematodes; one larval stage of cestode and one arthropod. Four major compounds were isolated from the most active fraction (BuOH-F) including two flavonoids and two secoirridoid glycosides, identified as kaempferol-3-O-neohesperoside (1), rutin (2), oleuropein (3), and ligstroside (4). Results Among the isolated compounds from most active fraction (BuOH-F), rutin (2) displayed the highest anthelmintic activity in a dose-dependent activity with IC50 of 41.04 μg/mL against H. muscae adult worm, followed by ligstroside (4) with IC50 of 50.56 μg/mL. Conclusions These findings could advocate the traditional use of J. grandiflorum L. and provide further insight into the anthelmintic activity of flavonoids.

The use of plants for the treatment of diseases in Africa is attracting more attention. This use of plants calls for more researches towards the validation of the healing claims by herbalist and the users of these herbs. Vernonia amygdalina Delile (Asteraceae) is one of the widely used plants in Nigeria by herbalists for the treatment of different diseases. In our previous studies on the methanolic stem-bark extract of this plant, we isolated novel and new compounds after scientifically validating the antidiabetic and anthelmintic effect of the methanolic stem-bark extract. In this present study, we aimed at identifying which of the isolated compounds is or are responsible for the antidiabetic and anthelmintic properties of the methanolic stem-bark extract of the plant. We also evaluated the antioxidation effects of the isolates. The antidiabetic effects of the isolated compounds were carried out in-vivo using streptozotocin-induced diabetes rats, while the anthelmintic effect was done in-vitro with Eisenia foetida, an adult worm. The antioxidation properties were evaluated using 2,2-diphenyl-1-picrylhydrazyl, nitric oxide and hydrogen peroxide radical scavenging protocols. The results obtained showed that out of the five compounds tested, only 6β,10β,14β-Trimethylheptadecan-15α-olyl-15-O-β-D-glucopyranosyl-1,5β-olide showed a significant reduction in the blood glucose in the course of treatment compared to standard metformin, while only glucuronolactone showed anthelmintic effect with total paralysis and death times of 153.7±1.21, 84.9±1.24 and 53.4±0.08, in comparison to 17.3±0.08, 10.5±0.06 and 8.3±0.06 for the standard (albendazole) at 30, 50 and 70 mg, respectively. The isolates also produced different percentages of 2,2-diphenyl-1-picrylhydrazyl, nitric oxide and hydrogen peroxide radicals scavenging abilities. From the results obtained in these studies only 6β,10β,14β-Trimethylheptadecan-15α-olyl-15-O-β-D-glucopyranosyl-1,5β-olide has antidiabetic property out of the five isolated compounds, while only glucuronolactone has anthelmintic property. All the isolated compounds showed mild antioxidation effect. Further researches are needed to identify the mechanism through which the two compounds exerted antidiabetic and anthelmintic effects.

A series of 4-oxycoumarin derivatives was synthesized, characterized and evaluated in vitro and in vivo for antifilarial activity against the human lymphatic filarial parasite, Brugia malayi. A majority of the compounds studied showed potent in vitro activity with low IC50 values in the micro molar (μM) range (0.014-1.73 and 0.0056-0.43) against adult worms and microfilariae, respectively. Compounds 8 and 9 were identified to be the most promising antifilarial candidate molecules exhibiting activity in the nanomolar (nM) range. The IC50 values for compound 8 were 14 nM and 5.6 nM while for compound 9 were 94 nM and 13 nM, respectively, for adult worm and microfilaria. These two compounds also displayed promising adulticidal activity (74.9 ± 4.8% and 69.4 ± 2.8%, respectively) in the primary rodent (jird) screen. This study also serves as a starting point for investigating structure-activity relationship with different amino substituents.

Human schistosomiasis, caused mainly by Schistosoma mansoni, S. japonicum, and S. hematobium, remains a prevalent and serious parasitic disease worldwide. Although it is a debilitating disease, a lack of sensitive methods for the precise diagnosis of active infection cases is important to prevent morbidity. The optimization of new diagnostic approaches may be accomplished by the selection of specific markers. In that manner, markers can be satisfactorily used for detection of different phases of infection, as acute and chronic phases, pre-patent and post-patent phases and after chemotherapy, improving the efficiency of methods. For that purpose, proteomics and glycomics analyses have been performed in schistosomes, in particular S. mansoni, using powerful high-throughput methodologies. These investigations have not only chartered protein, o-glycan and n-glycan profiles across developmental stages within mammalian host, but are also leading to the characterization of features of the surface tegument, the eggshell and excretory-secretory proteomes of schistosomes.

Caenorhabditis elegans is a nematode widely used in biology and genomics as a model organism. We provide an integrated, quantitative reference map for the transcriptome of whole, wild type Bristol N2 strain C. elegans worms. The map has been obtained by meta-analysis of 110 gene expression profiles available in Gene Expression Omnibus (GEO) repository and integrated using the computational biology tool Transcriptome Mapper (TRAM). Following probe assignment to the relative locus and intra- and inter-sample normalization (in particular using the scaled quantile method), a mean, consensus reference value is provided for 45,932 transcripts, along with standard deviation. Expression values are all mapped in the context of genomic coordinates. The map provides easy access to relationships among expression values of different genes in this standard condition, highlights genomic segments with relatively high over-/under-expression and may serve as a reference to test for gene expression variation for both individual genes and the whole transcriptome in specific biological conditions (e.g. mutated strains or differently grown worms). Keywords: C. elegans, Transcriptome map, Gene expression, Adult worms, Meta-analysis

Paragonimus bangkokensis and Paragonimus harinasutai, which are morphologically distinguishable species, often co-infect in the same crab intermediate hosts. Recent molecular phylogenetic analyses revealed that these two species are genetically close to each other and are considered as the sister species. While we have been studying Paragonimus adult worms obtained from the lungs of a cat experimentally infected with Paragonimus metacercariae which were morphologically identified as P. harinasutai collected from central Viet Nam, one out of 6 adult worms has grouped cuticular spines, which is a feature of P. bangkokensis. By molecular analyses, the CO1 sequence of this specimen was identical with that of P. bangkokensis, but the ITS2 and the D2 region of 28S rDNA sequences showed a two peak pattern. Then, PCR products of the ITS2 and the D2 region of 28S rDNA sequences were ligated to TOPO vector and subcloned to determine the heterozygosity. Two types of sequences were obtained from each ITS2 and D2 region of 28S; one was identical with P. harinasutai and the other with P. bangkokensis. Taking all these morphological and molecular data together, we identified this adult worm as a hybrid specimen of P. bangkokensis and P. harinasutai.

The therapeutic effects of praziquantel (PZQ) against a Schistosoma mansoni isolate derived from Nectomys squamipes (isolate R) and a susceptible isolate (BH) were analyzed in Swiss mice by fecal egg counting, adult worm reduction and oogram pattern. Infected mice were orally administrated with 62.5mg/kg (group 1), 125mg/kg (group 2), 250mg/kg (group 3) and 500mg/kg (group 4), each dose divided over 3days (49, 50 and 51days after infection). The data were analyzed using one-way analysis of variance (ANOVA). In regard to isolate R, no fecal eggs were observed with 250mg/Kg and 500mg/kg (p0.05) affected the percentage of mature eggs, regardless of isolate. There was a large increase (p

Cats are considered a susceptible host for Dirofilaria immitis; however, increased host resistance is reflected by relatively low adult worm burdens in natural and experimental infections; the prolonged prepatent period (8 months); the low level and short duration of microfilaremia; and the short life span of adult worms (2–3 years). From April to September 2006, 212 cats and 608 dogs, all exposed for at least one transmission season, were screened for D. immitis infection in a multi-center study in the Po River Valley in northern Italy. Cats were initially evaluated by antibody testing; positive subjects were followed up by antigen testing and echocardiography (and necropsy if death occurred). The prevalence in dogs was 29% by a modified Knott test and antigen testing compared with a prevalence of 4.7% in cats by an antibody test; six of these infections (2.8%) were confirmed by the follow-up evaluations. This field study demonstrated that the prevalence of heartworm infection in cats in this area is within the expected limits of 9–18% of the prevalence in dogs. Antibody testing likely underestimates the real prevalence of D. immitis infection in cats. These results also emphasize the importance of preventive treatment in cats.

The safety of heartworm preventives in heartworm-positive cats has traditionally been evaluated using adult Dirofilaria immitis removed from infected dogs and surgically implanted into the cats. An alternate study model uses infective larvae to establish adult infections in cats. Unfortunately, the number of adult worms resulting from the latter method varies widely from none to more than 30, both unacceptable for studies of natural heartworm infection and for studies evaluating product safety in heartworm-infected cats. We sought to determine infection severity in experimental infections via echocardiography to reduce the chances of enrolling uninfected and heavily infected cats into a study. Eighty adult cats were each inoculated with 60 infective D. immitis larvae and maintained for 8 months to allow for the development of adult worms. Antigen and antibody testing, as well as echocardiographic imaging, were performed to confirm and estimate adult worm burdens. Approximately 8 and 12 months post-infection, echocardiographic examination was performed to confirm and enumerate adult D. immitis populations in the cardiovascular system. Worm burdens were stratified as 0, 1–3, 4–11, and >11 adults, with 0 being considered uninfected and more than 11 considered too heavily infected to be relevant for anthelmintic studies. Cats with clinically relevant infections (1–10 adults) subsequently received multiple treatments with the investigational drug, and worm burdens were confirmed by necropsy 30 days following the final treatment. Worm burden estimated with echocardiography correlated well, but not precisely, with post-mortem counts ( p r 2 = 0.67). Echocardiography under-, over-, and exactly estimated heartworm burden 53%, 27%, and 22% of the time, respectively. Although the correct category (0–4) was determined by echocardiography in only 54% of cats, positive cats were distinguished from negative cats 88% of the time and the heaviest infections (>11) were correctly categorized 95% of the time. Both false negative and false positive results were observed. We conclude that echocardiography is useful for detecting mature experimental heartworm infections, identifying cats that have rejected mature infection, and detecting very heavy heartworm burdens, but it is only moderately accurate in classifying lesser burdens. While echocardiography cannot be relied upon to consistently determine the exact heartworm burden in experimentally infected cats, it is useful in stratifying worm burdens for anthelmintic safety studies.

This study compares the susceptibility to Haemonchus contortus infection in two breeds of sheep endemic to the Canary Islands, the Canaria Hair Breed sheep and the Canaria sheep. Sheep were experimentally infected with 20,000 larvae of H. contortus and animals killed on days 7 and 28 post-infection. No difference between sheep breeds were detected in immature worm counts at days 7 or 28 post-infection. However, in comparison to the Canaria sheep breed, the Canaria Hair Breed sheep showed lower mean faecal egg counts, lower adult worm counts, lower number of eggs in utero and female worm stunting. Overall, these data suggest that the Canaria Hair Breed sheep has a greater resistance to H. contortus infection than Canaria sheep, and that this resistance may act at the level of the adult parasite.

Infections of sheep with the gastrointestinal nematode Teladorsagia circumcincta are characterised by increased concentrations of IgA, eosinophilia and mastocytosis but the interactions between these immune responses are unclear. We investigated the kinetics of the parasite-specific IgA and eosinophil responses in controlled infections in lambs to determine if there were any associations with subsequent worm growth and survival. IgA and eosinophil responses had very similar kinetics and variation in both responses accounted for more of the variation in adult worm length than either trait alone suggesting that IgA and eosinophils interact in regulating the growth of T. circumcincta. Curiously, those animals with higher peak eosinophil responses had longer worms at slaughter emphasising the intriguing complexity of the immune responses to these parasitic infections.

Studies of schistosomiasis japonica in Taiwan indicate that the Formosan strain of Schistosoma japonicum is zoophilic in nature. After the discovery of the adult worm of S. japonicum in 1914, a considerable number of epidemiologic studies and experimental infection studies were conducted. This paper is a review of the history of schistosomiasis japonica in Taiwan from before World War II to 2003.

The cercaria of the schistosome parasite is a short-lived, free-swimming larval stage that is infective for the mammalian, definitive host. This atlas describes the ultrastructure of the cells that comprise the cercaria of Schistosoma mansoni, a leading causative agent of human schistosomiasis. In addition to the cells which make up the various organ systems, such as the nervous, tegumental, osmoregulatory, muscular and primordial digestive systems, also we show the ultrastructure of those cells whose organization or location are not as well defined structurally but are essential nevertheless for the success of the parasite. These latter include the various support cells, and those cells that, upon differentiation into the adult worm, serve reproductive functions. A description is also given of the cells whose sole functions are realized only at the cercarial stage, chiefly involved in the vigorous act of skin penetration. Although we include a detailed review of the ultrastructure of S. mansoni cercariae, much of the information reported has not been previously published. In summary, this paper brings together an ultrastructural description of all the cell types presently known that make up the much studied larval stage of this medically important trematode.

Dirofilariasis is a zoonosis affecting dogs and cats. It was transmitted to man by mosquito bites. Human dirofilariasis is rare. We report a case of 4-year-old girl presented with a subcutaneous palmar nodule of the hand. Surgical excision shows a nodule encircling the forth flexor tendon. The histological examination established the diagnosis by the presence of an adult worm identified as Dirofilaria repens. Surgical excision was curative.

Oue, M., Yamaguchi, H., Sato, K., and Suzuki, M. 2000. Immunohistochemical localization of acid proteinase in Ascaris suum adult worm. Experimental Parasitology 95, 144–147.

Investigations on various aspects of human filariasis using target filarial parasite, Brugia malayi is jeopardised to a great extent due to its prolonged incubation period and poor harvest from the existing experimental animal models. To obviate these difficulties it was contemplated to establish B. malayi infection in immunosuppressed Mastomys coucha . Cortisone, a well known immunosuppressant, was used at 10 mg/kg dose level subcutaneously in two courses each of 5 days duration. The first course was administered 1 week before and the second, a week after infective exposure. Mastomys were exposed either with 100 or 200 infective larvae (L 3 ) each. Untreated age-matched animals were also exposed simultaneously. The minimum prepatent period was observed to be 90.7 days in immunosuppressed animals exposed to 200 L 3 . The course of microfilaraemia in immunosuppressed and control animals was identical upto 180 days of observation period. However, the adult worm recovery from the former group of Mastomys was higher. It is surmised that exposure with B. malayi L 3 in immunosuppressed Mastomys would be of great advantage in getting larger harvests of adult worms of B. malayi .

Lactating adult Romney ewes were infected, 4 weeks post-lambing, with benzimidazole (bz) resistant strains of Ostertagia circumcincta and Trichostrongylus colubriformis. Commencing 4 weeks after the initial infection the ewes were subjected to challenge 3 times weekly with 5000 L3 of bz-susceptible strains of both parasite species. At weekly intervals over the following 6 weeks, groups of ewes were drenched with a bz anthelmintic (oxfendazole) to remove bz-susceptible parasites and slaughtered to determine adult worm burdens of the bz-resistant parasites. The O. circumcincta infection declined exponentially with a mean daily death rate of 10.6% day−1 and no worms were recovered after 4 weeks or more of challenge. The T. colubriformis infection did not decline significantly over the 6 weeks of continuous challenge, indicating that the death rate could not be distinguished from zero. The upper 95% confidence limit for the death rate of T. colubriformis was 4.9%. The implications of these death rates on selection for drug resistance following ewe drenching during the post-partum period are discussed with selection pressure likely to be greater for T. colubriformis than for O. circumcincta.

Studies were conducted on 20 crossbred lambs of 4-5 months old. Ten lambs were Nali x Corriedale cross (Hisardale) and the other 10 were Nali x Lohi cross (Munjal). Seven lambs each of both crossbreeds were infected with 10,000 infective larvae of Haemonchus contortus. Three lambs of each crossbreed served as uninfected controls. Clinicopathological examinations were done before and after infection and all the lambs were necropsied 28 days post-infection. The body weight gain, haemoglobin and packed cell volume were significantly lower in Hisardale lambs and the peripheral eosinophil count was significantly higher in Munjal lambs. Significant hypoalbuminaemia and hypoglobulinaemia, a sharp increase in albumin: globulin ratio; significantly higher faecal egg counts; adult worm counts; abomasal pH, volume, congestion and oedema were observed in Hisardale lambs as compared to Munjal lambs. Clinical signs of haemonchosis were more severe in Hisardale lambs and two of them died. Munjal lambs therefore seem less susceptible than Hisardale lambs to H. contortus infection.

Rejection of adult T. colubriformis was examined in lambs given 2000, 1124, 632 or 200 L3 day-1, 5 days per week for up to 20 weeks. Rejection of adults began at approximately the same time for the first three infection rates, and took about 9 weeks to complete. Approximately 20% of adults were rejected by week 10 of infection at the higher infection rates and it was estimated that rejection commenced at about week 7. This coincided with a decline in establishment of larvae to about 1%. For the low infection rate, there was a delay of about 5 weeks before adult worm rejection commenced and reached equivalent levels to those observed at the higher rates. This delay also coincided with an estimated 5-week delay in larval establishment declining to 1% at the low rate.

Immunology (4th edn)by Richard A. Goldsby, Thomas J. Kindt and Barbara A. Osborne. W.H. Freeman, 2000. £29.99/US$61 (xxv + 670 pages)ISBN 0 7167 3331 5Janis Kuby's book, Immunology, first published in 1992, and as revised editions in 1994 and 1997, has become one of the most widely used immunology textbooks available to undergraduates, and this new and revamped edition is a welcome addition to the literature of the subject. This is a beautifully produced book, with lavish use of colour and clear diagrams, together with links to web sites and CD ROMs, and is an excellent introduction to the science of immunology.Because it is readily available, it is likely to be consulted by parasitologists who will find the caption to the cover very reassuring; ‘Vertebrates are protected by innate and adaptive immunity, two cooperating systems that collaborate to provide an effective defense against a diverse spectrum of pathogens.’ However, the reader must wait until page 425 before the content implied in this statement materializes, and then the actual parasitological content extends to only six pages, two of which are whole-page diagrams. Inevitably, there is not much that can be covered in six pages and what is there is disappointing. The infections covered are malaria, African trypanosomiasis, leishmaniasis and schistosomiasis. Parasitologists might be surprised to learn that ‘In regions where malaria is endemic, the immune response to Plasmodium infection is poor’ and that the development of vaccines appears to be at the x-irradiated sporozoite stage. There is a nice description and diagram of antigenic variation in African trypanosomes, but little else. Schistosomes fare no better, as the account includes the unequivocal statement that ‘…the unexcreted eggs induce cell-mediated delayed-type hypersensitivty reactions resulting in large granulomas…’ and the diagram of the overall immune response is based on what is labelled as the adult worm instead of the schistosomulum, which it obviously should be.In summary, this is an excellent book as far as the concepts of immunology are concerned, but it has very little for parasitologists and it might have been better to omit what is there.

Two flocks of Merino sheep were set-stocked on pastures known to be endemic for Haemonchus contortus. Both flocks included sheep with the three common haemoglobin types (HbAA, HbAB, HbBB). The results of regular monitoring over a two-year period showed a clear relationship between haemoglobin types and susceptibility to haemonchosis. The HbAA sheep experienced fewer deaths, had consistently lower egg counts and exhibited a more frequency and effective self-cure than the HbAB or the HbBB types. Post mortem findings demonstrated that this phenomenon was due to differences in the establishment of adult H contortus and not to suppression of egg laying capacity or an alteration of male to female adult worm ratio.

Antigens were prepared from different stages of worm development and adult worm antigens were fractionated by ion exchange and exclusion chromatography. The antigens, or fractions of them, were assessed for their activity in passive haemagglutination reactions or intradermal tests. The results of the passive haemagglutination reactions indicated that circulating agglutinins were more readily detected when adult stage specific antigens were used. Antigen prepared from worms isolated when the population was declining was less sensitive. Fractions of adult worm antigen did not confer greater sensitivity than the whole worm extract.

Rats were sensitized by subcutaneous implantation of either metacercariae, 4 week-old juveniles, adult worms, or eggs of Fasciola hepatica and then challenged with 30 metacercariae 2 weeks later. Worm burdens were determined 8 weeks after challenge. Apart from adult worms, all implanted stages conferred a significant degree of protection on the recipients. The effectiveness of adult worm implants was not improved by using worms from different sources (sheep and cattle rather than rats) nor by extending the period of sensitization prior to challenge.

Mice immunized with Fasciola hepatica antigens are protected to a challenge exposure with Schistosoma mansoni cercariae. This protection is manifested in a 28–54% reduction in worm burdens of the immunized mice over controls. The protective antigens could be isolated by antibody affinity chromatography and react with an antiserum to S. mansoni. These antigens, when used to immunize mice, result in 50–60% reduction in worm burdens over controls. One protective antigen has been isolated which when used alone or in combination with a B-cell adjuvant such as polyadenylic-polyuridylic acid (poly (AU)) results in 56–81% reduction in worm burdens over controls. The complexity of the F. hepatica adult worm antigens was demonstrated by Laurell crossed immunoelectrophoresis. Crossreactivity with antisera to S. mansoni and S. japonicum and the presence of one common antigen between the two genera have been demonstrated.

Scanning electron microscopy (SEM) of the surface of the adult tapeworm and the freshly evaginated scolex from the cysticercus indicated that in Taenia hydatigena there was a variety of microthrix form. This variety was found between different areas on the same specimen and between the adult and freshly evaginated scolex. In the latter there was a noticeable absence of pointed spikes from most areas. Artifacts attributable to techniques of preparation are also discussed.

Schistosoma mansoni membranes were able to agglutinate mouse erythrocytes. Haemagglutination was mainly inhibited by different mammalian sera, some Salmonella antigens and a soluble factor(s) normally present in the adult worm tegument. The possible role played by this membrane-associated agglutinin in the host-parasite relationship is discussed.

Swine were immunized with partially purified stichosome antigens derived from Trichinella spiralis muscle larvae. In 3 trials, 500 to 600 μg of the solubilized particle component (S3) induced moderate levels of resistance to challenge inoculation; the percent reduction in larvae per gram of muscle ranged from 43 to 55. The effect of immunization with S3 on pig intestinal expulsion of adult worms was determined in one experiment, and the results indicated that S3 immunization was only weakly effective in enhancing gut expulsion. These results suggest that immunization with S3 induces a protective immune response in the pig that may be directed either against the migrating newborn larvae or against adult worm fecundity.

Florida Native lambs, less than 6 months of age, were successfully vaccinated against Haemonchus contortus with a high mol. wt fraction (greater than 30,000 daltons) derived from a somatic extract of H. contortus larvae (SEL) and excretions and secretions (ES) of larvae isolated during in vitro development from the infective 3rd to 4th stage. A 59% reduction in adult worm numbers was obtained in vaccinates compared to naive lambs following challenge. The protection in vaccinated lambs was similar to that seen in lambs exposed to a primary infection of H. contortus larvae which had been cleared with anthelmintic prior to the challenge infection. The unfractionated SEL/ES preparation and a low mol. wt fraction gave no significant protection against challenge infection.

The implantation and development of intravenously injected Trichinella spiralis newborn larvae were examined in different strains of inbred mice by determining muscle larvae burden. This was compared to the numbers of muscle larvae that established after a natural infection during which a quantitative assessment of intestinal newborn larvae production was made. In most inbred strains of mice, newborn larvae do not all successfully implant in muscle. Mice of the DBA/1 strain are the most resistant to successful implantation, and C3H mice are the most permissive. This pattern is evident in the strains studied whether newborn larvae are injected intravenously or are produced by intestinal adults. Thus, after a natural infection, 100% of intestinally produced newborn larvae implanted in C3H mice, whereas in NFR 68% and DBA/1 mice 62% successfully matured in muscle. Immunity to newborn larvae could be demonstrated as early as 10 days after exposure to this stage of the life cycle. This immunity was protective against a complete challenge infection given 9 days after newborn larvae had been injected intravenously. Protection against newborn larvae was identical in male and female mice or in mice from 1 to 9 months of age. We conclude that there are two mechanisms by which mice impair newborn larvae establishment or development in muscle. The first appears to be nonimmunological (non-specific resistance), and the second is immunological. Genetically determined variation in strain-specific expression is apparent with both mechanisms. In strains displaying high intrinsic "resistance" (DBA/1), this process is likely to account for most of the 38% reduction in newborn larvae establishment in a primary infection. However, immunity against newborn larvae develops quickly enough to have a significant effect on migratory larvae in primary infections where adults persist in the intestine (e.g., the B10 congenic mice), or when high adult worm burdens delay adult worm rejection. Muscle larvae burden, therefore, reflects systemic nonspecific resistance to newborn larvae as well as immunological processes that occur in the intestine and systemically.

Febantel at a dose level of 5 mg kg −1 had a lethal efficacy of 54.1% against the adult worm and 69.5% against the migrating larvae of Trichinella spiralis in rats. When administered at 15 mg kg −1 , it demonstrated lethal effects of 94.4, 92.5 and 74.7% against adult, young and encysted larvae, respectively. Infected rats treated with 300 mg kg −1 died. Thiabendazole had efficiencies of 96.4 and 83.3% against intestinal and migrating early muscle phases, respectively, and was only 42% effective against the encysting phase.

Significant reductions in adult worm burdens in lambs less than six months old infected with 5000 third stage Haemonchus contortus larvae were achieved following the combination of a single transfer factor treatment with multiple parenteral treatments of adult parasitic antigen and precipitated immunoglobulin. Specific cellular responses in the abomasa associated with individual treatments were discernible in all the experimental groups and quantitative differences in these responses reflected the varying treatment levels and treatment combinations. The reactions associated with transfer factor were similar to immediate type hypersensitivity responses and their role as possible effector mechanisms in correcting partial immune incompetency in lambs is discussed.

1. 1. Mitochondria in the body wall of various stages in the life cycle of Paragonimus were investigated by means of electron microscopy, and cytochrome components of the adult mitochondria by spectrophotometry at − 196°C. 2. 2. Large numbers of mitochondria were found in the ova of unembryonated eggs, epidermal cells of miracidia, tegument of cercariae, and tegument, subtegumental cells and parenchymal cells of juvenile and adult worms. Mitochondria of the tegument of rediae and metacercariae are comparatively few in number. 3. 3. Well-developed cristae were observed in the mitochondria of epidermal cells of miracidia, tegument of cercariae, and tegument and subtegumental cells of juvenile and adult worms. Mitochondria possess poorly developed short cristae in the ova of unembryonated eggs, tegument of rediae and metacercariae, and parenchymal cells of juvenile and adult worms. 4. 4. Adult mitochondria were found to contain cytochrome b, c 1 c, aa 3 and b-type cytochromes.

The growth and development of Australian strains of E. granulosus were compared in domestic dogs and pure-bred dingoes. The sylvatic strain, which is maintained in a cycle between dingoes and wallabies on the Australian mainland, was found to develop far more rapidly in dingoes than in dogs. Development of this strain in dogs was markedly retarded. However, domestic strains of E. granulosus originating from sheep in Tasmania and the Australian mainland developed at a comparable rate in dingoes and dogs. Dingoes were also found to be more susceptible to infection with the sylvatic strain than dogs, as evidenced by considerable differences in worm burdens. No such differences in susceptibility were seen with the domestic strains. These results not only emphasise the inherent differences between the sylvatic and domestic strains of E. granulosus, but also support previous suggestions that the strains were introduced into Australia independently. The fact that the sylvatic strain appears to be physiologically adapted to the dingo indicates that it was brought into Australia many thousands of years before the original domestic strain.

Shah J. and Ramasamy R. 1982. Surface antigens on cercariae, schistosomula and adult worms of Schistosoma mansoni. International Journal for Parasitology12: 451–461. The surface protein antigens of Schistosoma mansoni were radiolabelled by lactoperoxidase catalysed I125-iodination and analysed by immune-precipitation and polyacrylamide gel electrophoresis. The results showed that regularly labelled surface antigens of mol. wts >150,000, 78,000, 45,000 and 22,000 were present on adult worms. Common surface antigens were observed on the cercariae, schistosomula and adult worms. It is suggested that surface antigens released from living adult worms can sensitise a host to react against the invading schistosomula of a secondary infection. However, the failure to vaccinate mice using material containing adult worm surface antigens suggests that the induction of protective immunity is a complex phenomenon.

Under relatively mild conditions it has been possible to release from 5. mansoni, large amounts of antigens. Immunization experiments performed in rabbits with this phosphate buffered saline extract of adult worms (Saline Extract, SE) in either Complete Freunds Adjuvant or Corynebacterium parvum have resulted in very high levels of protection (76–99%) upon challenge infection of the immunized rabbits. Furthermore, fractionation of SE by gel chromatography, permitted the isolation of a purified fraction (FI) that also induced protection against challenge infection. FI appeared to contain most of the protective antigens of SE. The present data report the evaluation of different parameters related to the immunization, purification and biochemical analysis of SE.

When dogs were immunized with soluble extract of adult Ancylostoma ceylanicum antigen, they were partially resistant to challenge infection in this model of human hookworm infection. Two immunizing doses, each of 1 mg protein suspended in Freund's complete adjuvant, were administered to one group of animals 1 and 3 weeks prior to infection with 5000 larvae. When compared with control dogs given the same infective dose, fecal egg excretion and intestinal adult worm burden in the immunized animals were reduced by 59 and 74%, respectively. Infection had no significant effect on hemoglobin concentrations, mean red cell volumes, total white cell counts, platelet levels, or spontaneous and phytohemagglutinin-induced lymphocyte transformations in both control and immunized animals. Both groups developed an eosinophilia, and lymphocytes from the immunized dogs responded transiently to stimulation with both larval and adult worm antigens. Specific IgM antibodies were transitory in both groups of dogs following infection. IgG antibodies developed significantly 2 weeks after infection in the immunized group; however, they did not appear until 4 weeks after infection in the control group. Both groups developed IgA antibodies 1 week after infection. They were maintained in the control dogs, in contrast to the levels in immunized animals which subsided rapidly 4 weeks after infection. Therefore, when animals are injected with soluble adult worm antigen prior to infection, specific protective immunity is acquired.

Antigenic components which reacted specifically with sera of rats infected with Angiostrongylus cantonensis were prepared from adult worm extract by the use of immunoadsorbent columns. Components common to rat serum were removed from a whole worm extract by passing it through a column of cyanogen bromide-activated Sepharose coupled to rabbit antirat immunoglobulin. Consequently, components common to Ascaris suum were similarly removed using Sepharose linked to immunoglobulin to A. suum . Finally, the sample was applied to a column of Sepharose coupled with immunoglobulin from A. cantonensis infected rats and eluted with glycine-hydrochloric acid buffer. Intradermal skin tests using this preparation gave sensitive and specific reactions.

Heterosexual and homosexual chemoattraction studies were done with 8- to 12-week-old Schistosoma mansoni adults in linear chambers containing Earle's saline, in the absence and presence of both perforated and unperforated dialysis sac chimney barriers. In the absence of barriers attraction was seen in all heterosexual and homosexual combinations. After 90 min of observation at 37 C, organisms maintained at 4 or 37 C for at least 1 hr prior to the assay showed heterosexual attraction similar to those used immediately after perfusion. There was significantly more heterosexual attraction between worms from same than different pairs. In the presence of perforated barriers the greatest attraction was heterosexual, with males moving toward females; heterosexual attraction with females moving toward males was approximately equal to homosexual female attraction, and male homosexual attraction was not seen. In the presence of unperforated barriers the greatest attraction of females toward males occurred during the first 0.5 hr; within 3 to 4 hr females were no longer significantly attracted to males. However, after 0.5 hr males were more significantly attracted to females in unperforated than perforated chimneys. These studies demonstrate that adult schistosomes attract each other in vitro , and that there is a chemical basis for this attraction.

Chemoattraction studies were done with Schistosoma mansoni adults from mice. To test for attraction or repulsion, some worm pairs were separated mechanically and the individuals placed in polycarbonate chambers. Experiments were done at 37 C and chambers contained dialysis tube chimneys. In all cases, heterosexual attraction occurred when one worm, but not two worms, were placed in the chimneys. Unperforated chimneys with specific molecular weight (Mr) exclusions were compared with perforated chimneys to study heterosexual attraction. Attraction was similar in designs using perforated chimneys and those with 50,000 and 12,000 Mr exclusions, but none was seen in chimney designs with 1000 Mr exclusions.

Smyth, J. D., 1971. Development of monozoic forms of Echinococcus granulosus during in vitro culture. International Journal for Parasitology, 1: 121–124. During the course of culturing Echinococcus granulosus from the protoscolex to the adult worm, in vitro, a proportion of organisms in one culture developed sexually mature genitalia without becoming segmented into proglottids, i.e. they were monozoic in form. These monozoic specimens were miniature in size when compared with fully segmented specimens from dogs or from normal cultures; they appeared to contain a full complement of genitalia. This result points to independent control of somatic and sexual differentiation. The implication of this phenomenon in terms of the origin of the Cestoda and of speciation in Echinococcus is discussed.

Studies on heterophile antibody response of rabbits to T. canis infection are reported. Rabbits showed normal heterophile serum antibody titres of 1 5 to 1 10 at the time of infection. Following initial infection with two doses of 1,200 T. canis infective eggs at an interval of two weeks between the doses, little change in the existing herterophile levels was observed. On reinfection with doses of 100,000 and 200,000 ova, a marked rise in heterophile antibody response was observed compared with that in rabbits which received these doses for the first time. In general the complement-fixing anti-Toxocara antibody response to reinfection showed somewhat similar trends to the heterophile antibody response. These heterophile antibodies resemble the classical Forssman type and the corresponding antigen has been shown to be present mainly in the infective eggs and in the intestine of the adult. The cuticle of the adult worm possessed little antigen of this type.

Hockley D. J. and McLaren D. J. 1973. Schistosoma mansoni : changes in the outer membrane of the tegument during development from cercaria to adult worm. International Journal for Parasitology 3: 13–25. The tegumental outer membrane of the cercaria is trilaminate: the adult worm, however, has a seven-layered membrane. Formation of the heptalaminate membrane commences immediately after the cercaria has penetrated the vertebrate host: multilaminate membrane-bounded vacuoles are passed from subtegumental cells into the tegument where they enlarge, join to the outer membrane and open to the exterior. The heptalaminate limiting membrane of the vacuole thus becomes the outer membrane of the tegument. At the same time the original trilaminate tegumental membrane is formed into microvilli which are cast off and thus the cercarial outer membrane is lost. Schistosomula usually have a heptalaminate outer membrane within three hours of penetration. After this time the large vacuoles are replaced by smaller membraneous bodies which presumably contribute to the outer membrane during growth of the schistosomulum. The membraneous bodies are also present in the tegument of the adult worms and there is some evidence that the outer membrane is continually renewed.

Denham D. A. , Ponnudurai T. , Nelson G. S. , Rogers Rosemary and Guy Frances 1972. Studies with Brugia pahangi —II. The effect of repeated infection on parasite levels in cats. International Journal for Parasitology 2: 401–407. 21 cats were given a primary infection of 100–200 infective larvae of Brugia pahangi followed, some time later, by repeated challenge with 50 larvae per time at 10-day intervals. In most cats the microfilarial levels increased considerably but in a minority the levels remained the same as those seen in cats given only one infection. Adult worm recoveries were very much higher than after a single infection but after about 20 challenges there was no further increase in the number of worms establishing an infection. After a long series of challenge infections, the microfilarial counts of some cats suddenly fell and the blood became free of microfilariae.

Summary Ostertagia circumcincta, O. ostertagi and Hyostrongylus rubidus have been cultivated from the infective larva to the adult worm in WAe medium. Other species of gastrointestinal nematodes underwent limited development in this medium. The rate of development of O. circumcincta was slower in vitro than in vivo; adult male worms were first seen after 27 days and adult female worms after 30 days cultivation. They were smaller than worms grown in vivo. O. circumcincta infective larvae were kept either in static water or in water through which air was bubbled continuously; under these conditions other species of nematode larvae are said to undergo a process of maturation which is necessary for optimum development in vitro to take place. There was, however, no apparent effect on the subsequent development in vitro of the treated larvae. Increasing the concentration of O. circumcincta infective larvae in the culture medium resulted in a decrease in the percentage of larvae which developed to the adult stage. O. circumcincta larvae did not undergo any development in a medium in which CEE 50 was lacking. Fewer larvae developed into adult worms in a medium from which any one of the other components was lacking, than in the complete medium.

Protection against challenge with Dictyocaulus viviparus larvae was studied in two groups of calves. The first group was vaccinated orally with an irradiation-attenuated larval vaccine on two occasions, 28 days apart, as recommended by the manufacturer. Each dose contained 1000 larvae. The second group was vaccinated by two subcutaneous injections of vaccine, also 28 days apart. Compared with unvaccinated calves the protection in both groups of vaccinated calves was similar, ie, over 95 per cent reduction in adult worm burdens after an oral challenge of 3000 to 4000 larvae. These results indicate that the passage of irradiated larvae through the intestine and mesenteric lymph nodes is not necessary for the stimulation of a high degree of immunity and opens up the possibility of parenteral vaccination against this and related diseases.

JOYEUX, in 1920, after a survey of most of the evidence, arrived at the conclusion that Hymenolepis nana of man, and H. fraterna of rodents, though apparently indistinguishable in all characters, both of the adult worm and of the egg, are yet two distinct physiological species. More recently, however, two Japanese investigators, Saeki and Uchimura, have denied the validity of the experiments described by Joyeux, and affirm that it is possible to infect mice with H. nana eggs. The original papers of these two Japanese investigators not being easily accessible, and the brief abstracts available providing little or nothing of that detailed information which is so essential in these matters, I have recently been enabled, by the kind hospitality of Dr. A. Bettencourt, to re-examine the subject.