The genus Entamoeba comprises mostly gut parasites and commensals of invertebrate and vertebrate animals including humans. Herein, we report a new species of Entamoeba isolated from the gut of Asian swamp eels (Monopterus albus) in northern Thailand. Morphologically, the trophozoite is elongated and has a single prominent pseudopodium with no clear uroid. The trophozoite is actively motile, 30–50 µm in length and 9–13 µm in width. Observed cysts were uninucleate, ranging in size from 10 to 17.5 µm in diameter. Chromatin forms a fine, even lining along the inner nuclear membrane. Fine radial spokes join the karyosome to peripheral chromatin. Size, host and nucleus morphology set our organism apart from other members of the genus reported from fish. The SSU rRNA gene sequences of the new isolates are the first molecular data of an Entamoeba species from fish. Phylogenetic analysis places the new organism as sister to Entamoeba invadens. Based on the distinct morphology and SSU rRNA gene sequence we describe it as a new species, Entamoeba chiangraiensis.

The effects of malaria infection on RBC sialic acids and sialoglycoproteins were studied with asexual blood-stage infections of Plasmodium knowlesi in rhesus monkeys. Glycoprotein radio-isotope labelling methods were used to compare the sialoglycoproteins of normal RBC and P. knowlesi schizont-infected RBC (SI-RBC). Tritiation of glycoproteins from SI-RBC with the standard sialidase + galactose oxidase/NaB3H4 method or standard periodate/NaB3H4 method was significantly decreased when compared to normal RBC. However, tritium uptake into glycoproteins was normal when SI-RBC were treated with 5-fold higher concentrations of both enzymes in the first labelling method, or with a 5-fold increase in the molar ratio of periodate to sialic acid in the second method. The mobility of tritiated host cell glycoproteins on SDS–polyacrylamide gels was identical for SI-RBC and normal RBC. New bands, possibly glycoproteins, of 230, 160, 90, 52, and 30 kDa were detected after labelling SI-RBC by the modified periodate/NaB3H4 method. Sialic acid analysis of normal rhesus monkey RBC (62μg/1010 RBC) revealed that 46% of the total sialic acid was N-glycolylneuraminic acid, 33% was N-acetyl-9-O-acetylneuraminic acid, and the remainder N-acetylneuraminic acid. SI-RBC collected either directly from infected monkeys or after in vitro culture of ring-infected RBC in horse serum, had increased total sialic acid (126 or 115μg/1010 RBC, respectively). The sialic acid content of infected RBC must increase during parasite development since RBC infected with ring-stage P. knowlesi had the same content as normal RBC. There was no significant difference in the ratio of the three sialic acids of SI-RBC and normal RBC. In contrast, the uninfected RBC from infected blood of different monkeys showed marked variation in sialic acid composition and generally had a lower sialic acid content than normal RBC.

Naive CBA/Ca mice and CBA/Ca mice vaccinated 4 weeks previously with radiation-attenuated cercariae of Schistosoma mansoni were subjected to 550 rad of whole body (gamma) irradiation and then challenged 3 days laterwith normal cercariae. The perfusion recovery data showed that this procedure reduced theprimary worm burden in naive mice by 22% and the challenge worm burden in vaccinated mice by 82%. Irradiation also ablated the peripheral blood leucocytes of both mouse groups by 90%–100% at the time of challenge. Histological data revealed that such treatment caused a dramatic change in number, size and leucocyte composition of cutaneous inflammatory skin reactions that characterize challenged vaccinated mice and are known to entrap invading larvae; cutaneous eosinophils were preferentially abolished by this treatment. Polyvaccine mouse serum that conferred protection passively upon naive recipient mice, failed to protect naive/irradiated mice when administered by the same protocol. Distraction of macrophages by treatment of mice with silica did not affect the establishment of a primary worm burden and reduced the protection exhibited by vaccinated mice by only 16%. These data indicate that radio-sensitive cells are important to both innate and specific acquired resistance in this mouse model and that macrophages contribute only marginally to the expression of vaccine immunity.

The Trematode parasites of man have been so frequently listed and, for the most part, so fully described in various text-books and treatises on parasitology, pathology and tropical medicine that it might seem superfluous to enumerate them again. My object in doing so is to provide a basis for comparison with the parasites of the Primates, our knowledge of which is still extremely fragmentary, and with the parasites of Mammals in general. It is hoped that the works which are cited will prove to be the most useful or the most authoritative original references available.

In April 1953, several specimens of the common commercial mullet, Mugil cephalus L., heavily infested with cysts in the body cavity, were received. In May, June and July 1953, several specimens of the estuarine catfish, Netuma australis (Gunther) (Family Ariidae), similarly infected, came to hand. All specimens were taken from the lower reaches of the Brisbane River, Brisbane.

Parasite–host interactions mediated by cell surface proteins have been implicated as a critical step in infections caused by the microsporidian Nosema bombycis. Such cell surface proteins are considered as promising diagnostic markers and targets for drug development. However, little research has specifically addressed surface proteome identification in microsporidia due to technical barriers. Here, a combined strategy was developed to separate and identify the surface proteins of N. bombycis. Briefly, following (1) biotinylation of the spore surface, (2) extraction of total proteins with an optimized method and (3) streptavidin affinity purification of biotinylated proteins, 22 proteins were identified based on LC-MS/MS analysis. Among them, 5 proteins were confirmed to be localized on the surface of N. bombycis. A total of 8 proteins were identified as hypothetical extracellular proteins, whereas 7 other hypothetical proteins had no available function annotation. Furthermore, a protein with a molecular weight of 18·5 kDa was localized on the spore surface by western blotting and immunofluorescence analysis, even though it was predicted to be a nuclear protein by bioinformatics. Collectively, our work provides an effective strategy for isolating microsporidian surface protein components for both drug target identification and further diagnostic research on microsporidian disease control.

Host range and parasite specificity determine key epidemiological, ecological and evolutionary aspects of host–parasite interactions. Parasites are usually classified as generalists or specialists based on the number of hosts they feed on. Yet, the requirements of the various stages of a parasite may influence the suitability of a given host species. Here, we investigate the generalist nature of three common ectoparasites (the dipteran Carnus hemapterus and two species of louse flies, Pseudolynchia canariensis and Ornithophila metallica), exploiting two avian host species (the European roller Coracias garrulus and the Rock pigeon Columba livia), that frequently occupy the same breeding sites. We explore the prevalence and abundance of both the infective and the puparial stages of the ectoparasites in both host species. Strong preferences of Pseudolynchia canariensis for pigeons and of Carnus hemapterus for rollers were found. Moderate prevalence of Ornithophila metallica was found in rollers but this louse fly avoided pigeons. In some cases, the infestation patterns observed for imagoes and puparia were consistent whereas in other cases host preferences inferred from imagoes differed from the ones suggested by puparia. We propose that the adult stages of these ectoparasites are more specialist than reported and that the requirements of non-infective stages can restrict the effective host range of some parasites.

In vitro tests were performed to evaluate the ability of 6 isolates of the nematophagous fungus Pochonia chlamydosporia to infect immature and mature Toxocara canis eggs on cellulose dialysis membrane. There was a direct relationship between the number of eggs colonized and the increase in the days of interaction, as well as between the number of eggs colonized and the increase in the concentration of chlamydospores (P<0·05). Immature eggs were more susceptible to infection than mature eggs. The isolate Pc-04 was the most efficient egg parasite until the 7th day, and showed no difference in capacity to infect mature and immature eggs in comparison to Pc-07 at 14 and 21 days of interaction, respectively. Isolate Pc-04 was the most infective on the two evolutionary phases of the eggs at most concentrations, but its ability to infect immature eggs did not differ from that presented by the isolates Pc-07 and Pc-10 at the inoculum level of 5000 chlamydospores. Colonization of infective larvae inside or outside the egg was observed in treatments with the isolates Pc-03, Pc-04, Pc-07 and Pc-10. The isolate Pc-04 of P. chlamydosporia has great biological capacity to destroy immature and mature T. canis eggs in laboratory conditions.

Humans are infected by 2 genetic assemblages (A and B) of Giardia duodenalis, a protozoan parasite that causes gastro-intestinal disease. Sub-assemblages AI, AII, BIII and BIV are commonly identified in human cases. Detection requires amplification of G. duodenalis loci. Subsequent DNA sequencing or restriction fragment length polymorphism (RFLP) identifies sub-assemblages but is expensive (DNA sequencing) or insensitive (RFLP). This study investigated a fluorescence-based detection method, using terminal-restriction fragment length polymorphism (T-RFLP) of the glutamate dehydrogenase gene to characterize human infections. Clinical samples (n=73), positive for Giardia were collected in New South Wales, Australia, and were used to evaluate T-RFLP detection. The accuracy and sensitivity of T-RFLP detection was established by comparison to DNA sequencing and RFLP. Sub-assemblage assignment by T-RFLP identified BIV as the common subtype in N.S.W cases, whilst AI, AII and BIII were also detected. When compared to DNA sequencing and RFLP, analysis by T-RFLP was a reliable and reproducible method. Automated fluorescent detection enabled accurate sizing of restriction fragments and provided a sensitive alternative to RFLP. Discrimination of sub-assemblages by T-RFLP was comparable to DNA sequencing, but was efficient and inexpensive. The protocol described here provides a rapid and sensitive diagnostic tool for routine sample screenings in epidemiological research.

An amoeba was found in the faeces of ten out of fourteen English goats from three different localities.

The amoeba, of which a detailed description is given, is morphologically identical with Entamoeba debliecki of the pig and is therefore included in the same species.

A statistical analysis shows that the caprine strains of E. debliecki comprise two races distinguishable from one another by the size of their cysts but identical in all other features.

The caprine amoeba appears to be non-pathogenic.

In view of their bearing upon the systematic position of the parasite of the goat, a critical review is given of the data concerning the various amoebae previously recorded from the pig, goat and some other ruminants.

Protection against infection with Trichinella spiralis is conferred upon mice by the passive transfer to them of a specific immune serum from rabbits. A smaller percentage of mice treated with the immune serum die, and fewer larvae invade the muscles of the treated mice than among control animals. The action of the antibody of the immune serum appears to be directed specifically against the ingested larvae which are maturing to adult worms in the intestine of the infected animals. The results obtained thus far indicate that an immune serum would have little therapeutic value in the later stages of the disease.

Sarcocystis spp. are intracellular coccidian parasites which infect domestic and wild animals and birds, resulting in considerable economic losses in production animals, and public health concerns worldwide. Sarcocystis spp. have an indirect life cycle where wild and/or domestic canine species primarily serve as definitive hosts and several domestic and wild animals (such as camels) act as intermediate hosts. In Northern Africa, the Middle East, Central Asia and China, camel meat is preferred due to cultural and religious traditions as well as its lower cholesterol/fat content than other red meat. However, camel meat quality could be downgraded by the presence of sarcocysts. To date, two Sarcocystis spp. have been reported from camels, including Sarcocystis ippeni (forms microscopic sarcocysts) and Sarcocystis cameli (forms both macroscopic and microscopic sarcocysts). Sarcocystosis is usually asymptomatic, though significant pathogenic effects have also been reported in camels. Despite the high occurrence of sarcocystosis in camels, little is known about various aspects of the disease in these animals. This paper provides a comprehensive review of the existing knowledge on the taxonomy, pathogenesis, epidemiology and diagnosis of Sarcocystis spp. infecting camels and it also highlights areas for further research that could enhance our understanding about sarcocystosis in camels.

We investigated the segregation of an intracellular microsporidian parasite during host cell division. A time-course experiment was carried out to examine the distribution of parasites relative to host chromosomal DNA via light and electron microscopy. Fluorescent light microscopy and EM studies showed that the parasite lay in the perinuclear zone of the host cell during interphase and segregated to daughter cells at mitosis. At metaphase, the parasite was frequently closely associated with host microtubules and mitochondria. Electron-dense bridges were observed between the parasites and the host microtubules and also between host mitochondria and microtubules. The study suggests that both the parasite and the host cell organelles segregate in association with spindle microtubules.

Photoleter anterouterus Fischthal & Nasir, 1974, from Pelecanus occidentalis Linnaeus and Pelecanus erythrorhynchos Gmelin from Florida, USA and the ventrogenital complexes of Photoleter gastrophilus (Kossack, 1910) from Delphinus delphis Linnaeus from Queensland, Australia and of Phocitrema fusiforme Goto & Ozaki, 1930 from Alopex lagopus (Linnaeus) and Phoca vitulina Linnaeus from Alaska are redescribed. The genus Photoleter Odhner, 1914 is emended and compared with Phocitrema Goto & Ozaki, 1930 and both genera are compared with members of, and as a result transferred from the family Opisthorchiidae Looss, 1899 to, the subfamily Centrocestinae Looss, 1899, family Heterophyidae Odhner, 1914.

Trypanosomatid protozoa include heteroxenic species some of them pathogenic for men, animals and plants. Parasite membrane contains ecto-enzymes whose active sites face the external medium rather than the cytoplasm. Herpetomonas sp. displayed a Mg2+-dependent ecto-ATPase activity, a Mg-independent ecto-ADPase and an ecto-phosphatase activity. Both, the ecto-ADPase and phosphatase activities were insensitive to CrATP (chromium(III) adenosine 5′-triphosphate complex). Ecto-ATPase activity was reversibly inhibited. At 2 mm ATP the apparent Ki was 4·7±1·0 μm but a fraction of about 40–50% was insensitive to CrATP. Remarkably, at low substrate concentration (0·2 mm) more than 90% of the ecto-ATPase was inhibited with Ki=0·33±0·10 μm. These parameter dependences are interpreted as the presence of 2 ecto-ATPases activities, one of them with high ATP apparent affinity and sensitivity to CrATP. DIDS (4,4 diisothiocyanatostilbene 2,2′ disulfonic acid), suramin and ADP were also effective as inhibitors. Only ADP presented no additive inhibition with CrATP. The pattern of partial inhibition by CrATP was also observed for the ecto-ATPase activities of Leishmania amazonensis, Trypanosoma cruzi and Trypanosoma rangeli. CrATP emerges as a new inhibitor of ecto-ATPases and as a tool for a better understanding of properties and role of ecto-ATPases in the biology of parasites.

A new method of computing the infectivity index of microfilariae (mf) for the mosquito population is proposed using the estimated mf density distribution in the human population. The observed density distribution is considered a compound of the Poisson and the gamma distributions. The former distribution describes the probability of a specimen containing a specified number of mf and the latter describes the density distribution of mf in the host population. The mf infectivity index is the probability that a blood meal will include at least 1 mf, conditional on the population-density distribution of mf as specified by the gamma distribution. Actual data indicate that this population-density-based infectivity index can be considerably different from the conventional index based on the survey-density distribution. The level of the carrier rate of mf in a survey is greatly influenced, apart from the sample variation, by the average volume of blood taken from each person. The rate computed on the estimated population-density distribution of mf is convertible to any base amount of blood.

Since I published (1925) a description of this interesting new species of a Caryophyllaeid, Woodland (1926) has suggested that the bodies which I described as post-ovarian vitellaria (1925, p. 233, fig. 2, p.ov.vit.) are in reality ovarian follicles, and that, therefore, the worm is a Lytocestus and not Caryophyllaeus. Southwell in his papers (1928 and 1930) has embodied my original description of this worm and has concluded the description by referring to Woodland's remark regarding the post-ovarian vitellaria, without definitely assigning the species to the genus Lytocestus. With additional material at my disposal, it was possible to re-examine its anatomy, and I have found that the bodies described and figured by me as post-ovarian vitellaria are in reality ovarian follicles. I also take this opportunity of publishing a more complete and, I hope, a more accurate description of its general anatomy.

Isoenzyme analysis was used to characterize 6 species of trypanosomes of the subgenus Herpetosoma using 13 different enzyme systems. The species studied were Trypanosoma lewisi, T. musculi, T. grosi, T. microti, T. evotomys and T. nabiasi which cannot be distinguished on morphological grounds. Extracts for thin-layer starch-gel electrophoresis were prepared from cultures of insect forms in either Schneider's Drosophila or Grace's insect tissue culture media with foetal calf serum or a nutrient agar medium. Extracts of T. lewisi and T. musculi bloodstream forms were also run for comparison. All parasites gave distinct patterns which enabled them to be differentiated on one or more enzyme systems. Two types of computer analysis were used to group the parasites; using these techniques the murine parasites T. lewisi, T. musculi and T. grosi fell into one broad group, and T. microti and T. evotomys of microtine rodents formed another. These findings are in accord with earlier observations on the behavioural characteristics of these parasites in their mammalian host and their vector (fleas). The clear differences observed provide the basis for the application of other biochemical and immunological techniques for differentiation within this subgenus of trypanosomes.

The haplosporidian described is found in the Malpighian tubules of the beetle Gonocephalum arenarium in the Cape Peninsula, South Africa.

With the exception of the germination, which must take place in the digestive tract, the life cycle is completed within the Malpighian tubules. Studied over a period of several years, it has been found that the incidence of infection averages about 5 %.

Six Malpighian tubules connect with the gut, and in an infected insect all six are almost always parasitized to the same degree and by the same forms of the parasite.

A DNA probe PCsv4 and a subclone thereof PCsv4.1, hybridize specifically to rodent malaria DNA. DNA purified from a small volume (10 μ1) of infected mouse blood was used to determine the composition of the parasite population present. The hybridization signal following PCsv4 probing of slot-blotted DNA correlated directly with parasitaemia. The hybridization pattern and Intensity, resulting from probing restriction enzyme digested and Southern-blotted genomic DNA, determined the identity of the infecting parasite line(s), and provided a semi-quantitative measure of parasite burden. Fifteen parasite lines representative of all four Plasmodium species infecting rodents can be differentiated in this way.