Rats and mice were infected with either normal metacercariae or metacercariae γ-irradiated at 3 krad. or 4 krad. Flukes were recovered at various times after infection and their teguments examined using a transmission electron microscope. In normal flukes, the secretory granules TO, Tl and T2 were all seen during tegumental development. The teguments of flukes from mice developed faster than the corresponding teguments in rats. TO granules were present from day 0 to day 10 post-infection (p.i.) in mouse flukes and from day 0 to day 14 p.i. in rat flukes. Tl granules first appeared in mouse flukes by day 4 p.i. but not until day 8 p.i. in rat flukes. T2 granules were seen in mouse flukes 2 days p.i. but not before 6 days p.i. in rat flukes. γ-Irradiation at 4 krad prevented normal tegumental development in flukes from both rats and mice. TO granules were present at all times in flukes from either host. Tl granules were produced in mouse flukes but their appearance was delayed until day 6 p.i. No significant production of T2 granules occurred in flukes from either host. Parasite survival was also affected by γ-irradiation and none of the flukes reached maturity. Flukes from rats died between 10 and 21 days p.i and flukes from mice died between 14 and 28 days p.i. γ-Irradiation of metacercariae at 3 krad. had an extremely variable effect on subsequent tegumental development in both rats and mice. Some flukes developed normally, some showed development associated with γ-irradiation at 4 krad, whilst some showed intermediate development.

Lambs which were given 60000 infective larvae ofNematodirus battus progressively threw off adult nematodes from day 20 onwards. Large, hexagonal crystals appeared in the intestine of the adult nematode at about this time and caused blockage of the intestinal-rectal or -cloacal junction. Lambs which were given 1000–2000 infective larvae did not throw off the infection, and adult nematodes from lambs which had been infected for up to 74 days did not contain these crystals. Chemical, histo-chemical and X-ray microanalysis tests on the crystals indicated that they are lipoprotein in composition. The crystals arise within the lumen of the nematode and appear to be associated with the development of immunity to this nematode in lambs.

The family Gnathostomidae contains several genera and a fair number of species of nematodes of rather aberrant type and of uncertain affinities. As pointed out by Baylis and Lane (1920) in their excellent revision of the family, there is little doubt but that it should be included in the superfamily Spiruroidea. The subfamily Gnathostominae is characterised by the possession of a head bulb containing four closed membranous hollow structures, called ballonets by Baylis and Lane, connected posteriorly with four elongate sac-like structures designated cervical sacs. Three genera are recognised in this sub-family as follows: Tanqua, in which the head bulb is provided with transverse cuticular ridges, and Echinocephalus and Gnathostoma in which the head bulb is provided with rows of thorn-like spines. In Echinocephalus the body is smooth and destitute of cuticular spines, whereas in Gnathostoma all or a large part of the body has rows of cuticular spines on the posterior edges of the annulations. The first two genera are parasitic in the intestinal tract of cold-blooded vertebrates, whereas Gnathostoma apparently has its normal habitat in the stomach wall of mammals, as Baylis and Lane have pointed out.

Koga (1922) recorded for the first time the occurrence of metacercariae belonging to the genus Phyllodistomum Braun, 1899, in the freshwater shrimp, Palaemon nipponensis from Japan. Later Yogota (1922), Hirata (1928) and Asada (1928) recorded that shrimps in Japan were infected by larvae of several species of Phyllodistomum.

Only a few immature fragments found. Rostellar hooks 0·011–0·014. A spiny collar present posterior to rostellum. Attributed to this species by reason of its being the only cestode of the family recorded from this host, and by the agreement in size of the rostellar hooks. As the original description is so inadequate it is unfortunate that the present form is immature.

In 1930 Ray published a valuable paper on the genus Selenidium Giard, in which he described sporogony in S. spionis Koll. and S. foliatum Ray. He did not observe schizogony in either of these two, but he confirmed Brasil's account of intracellular schizogony in S. caulleryi Brasil from Protula tubularia Mont, and recorded it for the first time in S. mesnili Brasil from Myxicola infundibulum Mont. After seeing association of gametocytes in both these species he was unable to continue his observations, so I have taken up the work where he left it, choosing S. mesnili rather than S. caulleryi, since it is more easily obtainable. My search for gamete and sporozoite formation has been successful, but I have not been able to make the sporozoites hatch, or in studying sections of Myxicola have I seen sporozoites entering the epithelial cells of the gut.

The aim of the present study was to examine the parasite fauna present in mountain viscacha Lagidium viscacia (Caviomorpha, Chinchillidae) fecal pellets collected from ‘Cueva Peligro’, a cave located in Chubut province, Patagonia, Argentina, throughout the last 1200 years. A total of 84 samples were examined for parasites. Each pellet was whole processed: rehydrated, homogenized, sediment and examined using light microscopy. The samples and eggs of parasites present were described, measured and photographed. Thirty-eight samples tested positive for the nematodes Heteroxynema (Cavioxyura) viscaciae Sutton & Hugot, 1989, Helminthoxys effilatus Schuurmans-Stekhoven, 1951 (Oxyurida: Oxyuridae), Trichuris sp. Roederer, 1761 (Trichinellida: Trichuridae) and one anoplocephalid species (Cestoda: Anoplocephalidae). This is the first time that H. effilatus is reported from ancient times. Significant differences of parasite occurrences through this temporal period were recorded. Parasitic life cycles and their presence along the studied period are so discussed.

Prof. Nuttall has suggested that I should continue his investigations (1913) on variation in size and structure due to nutrition, using other species of Rhipicephalus and species of other genera.

Toxoplasmosis is a serious zoonoses disease and opportunistic, and can be life-threatening. Dexamethasone (DEX) is widely used in the clinic for treatment of inflammatory and autoimmune diseases. However, long-term use of DEX is often easy to lead to acute toxoplasmosis in patients, and the potential molecular mechanism is still not very clear. The aims of this study were to investigate the effect of DEX on proliferation of Toxoplasma and its molecular mechanisms, and to establish the corresponding control measures. All the results showed that dexamethasone could enhance the proliferation of Toxoplasma gondii tachyzoites. After 72 h of DEX treatment, 566 (±7) tachyzoites were found in 100 host cells, while only 86 (±8) tachyzoites were counted from the non-treated control cells (P < 0·01). Gas chromatography (GC) analysis showed changes in level and composition of fatty acids in DEX-treated host cells, and T. gondii. Fish oil was added as a modulator of lipid metabolism in experimental mice. It was found that mice fed with fish oil did not develop the disease after infection with T. gondii, and the structure of fatty acids in plasma changed significantly. The metabolism of fatty acid in the parasites was limited, and the desaturase gene expression was downregulated. These results indicate that the molecular mechanism of dexamethasone to promote the proliferation of T. gondii may be that dexamethasone induces the change of fatty acids composition of tachyzoites and host cells. Therefore, we recommend supplementation of fatty acid in immunosuppressive and immunocompromised patients in order to inhibit toxoplasmosis.

We report 21 thelastomatoid species parasitizing 31 described and 5 undescribed geoscapheine and panesthiine cockroaches, representing all but 1 of the known species of these subfamilies in Australia. The nematodes have 3 distinct patterns of host distribution: dominant, moderate and rare. The 4 dominant species, Cordonicola gibsoni, Leidynemella fusiformis, Travassosinema jaidenae and Aoruroides queenslandensis, are highly prevalent, found in nearly all host species examined, and broadly distributed. The 8 moderate species have lower prevalences but are still widely distributed. Many of these species are more common in one host subfamily than the other. The remaining 9 rare species have highly restricted host and geographical distributions. Six of the 21 species are exclusive to geoscapheines, 5 to panesthiines and 10 are shared. These patterns suggest that most of the reported thelastomatoid species are generalists rather than specialists, that host-specificity within this group is low and that co-evolutionary speciation has had little, if any, impact on structuring the thelastomatoid fauna of Australian burrowing cockroaches. In a broader context, this study provides the first comprehensive examination of the role of coevolutionary speciation and host specificity in regulating the distribution of pinworms in arthropods.

Highlighting the dispersal ecology of parasites is important for understanding epidemiological, demographic and coevolutionary aspects of host–parasite interactions. Yet, critical aspects of the dispersal stage of parasites, such as longevity and the factors influencing it, are poorly known. Here we study the lifespan of the dispersal stage of an ectoparasitic dipteran, Carnus hemapterus, and the impact of gender, body size and food provisioning on longevity. We found that freshly emerged imagoes survive at most less than 4 days. Longevity increased with body size and, since this parasite exhibits sexual size dimorphism, the bigger females lived longer than males. However, controlling for body size suggests that males lived relatively longer than females. Furthermore, a humid environment and food provisioning (flowers) significantly increased individual life spans. We discuss the relative importance of spatial and temporal dispersal in relation to the infectious potential of this parasite.

Predicting the effectiveness of parasite control strategies requires accounting for the responses of individual hosts and the epidemiology of parasite supra- and infra-populations. The first objective was to develop a stochastic model that predicted the parasitological interactions within a group of first season grazing calves challenged by Ostertagia ostertagi, by considering phenotypic variation amongst the calves and variation in parasite infra-population. Model behaviour was assessed using variations in parasite supra-population and calf stocking rate. The model showed the initial pasture infection level to have little impact on parasitological output traits, such as worm burdens and FEC, or overall performance of calves, whereas increasing stocking rate had a disproportionately large effect on both parasitological and performance traits. Model predictions were compared with published data taken from experiments on common control strategies, such as reducing stocking rates, the ‘dose and move’ strategy and strategic treatment with anthelmintic at specific times. Model predictions showed in most cases reasonable agreement with observations, supporting model robustness. The stochastic model developed is flexible, with the potential to predict the consequences of other nematode control strategies, such as targeted selective treatments on groups of grazing calves.

The impact of parasitism on population dynamics is determined in part by the numerical responses of parasites during population fluctuations of their hosts. Vole populations fluctuate in multi-annual cycles allowing such responses to be studied over successive phases of population growth, abundance and decline. We investigate how a helminth community (5 nematode and 7 cestode species) evolved over a full 6-year Water Vole (Arvicola terrestris) population cycle. Brillouin and individual parasite species richness (IPSR) indices were used to measure the numerical response of the parasite community. We report a correlation between levels of parasite intensity and vole population cycle phases. Both indices were consistently higher during pre-decline and decline phases for male and female voles alike. The numerical response of the parasite community suggests that populations may be regulated by parasitism and that studies of this mechanism should allow both for the cyclic or non-cyclic character of the host populations and for the response of the broadest possible set of the local parasite community.

Current systematic review and meta-analysis demonstrate the prevalence reports of filariasis in animals in Iran along with human cases. Studies were screened, relevant papers were selected and the random-effect model was used by forest plot with 95% confidence interval (CI). Of 17 records of human case-reports, particularly from Khuzestan province (5 cases), Dirofilaria repens was the most detected parasite (10 cases) with higher involvement of the right eye (7 cases) than other organs. Eleven animal species were reported to be parasitised by filarioids in Iran. The prevalence of Dirofilaria immitis in canids was 14.69% (95% CI: 10.33–19.67), with highest rates (20.92%; 95% CI: 13.84–29.03) in free-ranging dogs. Male (10.07%; 95% CI: 5.10–16.47) and more than 1-year old (20.77%; 95% CI: 8.66–36.42) dogs were more likely to be found infected. The frequency of other filarioids of zoonotic interest was: Acanthocheilonema reconditum in dogs 2.15% (95% CI: 0.71–4.33), Dipetalonema evansi in camels 10.16% (95% CI: 4.73–17.34), Onchocerca cervicalis in horses 3.63% (95% CI: 1.44–6.75%) and Onchocerca fasciata 16.57% (95% CI: 10.12–24.24%) in camels. Still, our knowledge on parasitic filariae in Iran is limited and more investigation is needed in both human and animal populations.

The organizers of this symposium felt that it could be helpful if the first paper provided a general introduction to the concepts and techniques associated with this rapidly developing area of biology. It is widely but wrongly believed to be a complex and difficult subject. The details of some of the manipulations are sometimes extremely complex, but the general principles are not. Of those responsible for this paper, Andrew Simpson and Tina Walker are active workers in the field, but Roland Terry is not. Following the principle embodied in an old Arabic proverb (Fig. 1), roughly translated as ‘What one fool can understand, another can’, Roland Terry presented the paper.

1. Cysts, formed in a strain of E. invadens growing with a mixed bacterial flora, were sterilized of all but one species of bacterium (organism x), by treatment with chemicals. Strains of E. invadens derived from these cysts were prepared, growing with organism x and either Bact. coli or B. megatherium.

2. A monobacterial strain of E. invadens, growing with Bact. coli alone, was obtained by maintaining a dibacterial strain, growing with organism x and Bact. coli, for 72 days in medium containing gentian violet.

3. A monobacterial strain of E. invadens, growing with Staph. albus, was prepared from cysts, produced in the monobacterial strain of E. invadens + Bact. coli, and sterilized by treatment with chemicals.

4. An axenic strain of E. invadens was prepared by maintaining the monobacterial strain of E. invadens + Staph. albus, in saline-liver medium containing antibiotics. This axenic strain has now been maintained for over 14 months in saline containing untreated, sterile liver, but no antibiotics.

Neutrophil chemotactic activity was detected in the fluid of Toxoplasma gondii cultures by the agarose plate and the Boyden chamber methods. Toxoplasma culture fluid was obtained by incubating the tachyzoites at 37 °C in a 5% CO2 atmosphere for 6 h in Dulbecco's modified Eagle's minimum essential medium containing 10% heat-inactivated foetal calf serum. Soluble extracts from tachyzoites had negligible activity, indicating that the chemotactic factors were metabolites secreted from tachyzoites. The chemotactic activity in Toxoplasma culture fluid depended on the number of tachyzoites and the period of incubation. The substances responsible for neutrophil chemotaxis were two heat-labile peptides with estimated Mr 4·5 and 14 kDa with N-terminal groups free.

Leeches are common in the fountains and pools of Palestine, particularly in the northern parts, known to us familiarly as ‘Galilee,’ and further north in the district of the Lebanon. In the later summer and autumn months they are so plentiful in places that almost every horse and mule passing through these parts has a bleeding mouth. Under such conditions it is not wonderful that human beings from time to time are attacked. The domestic supplies of water are usually protected by the water-carrier's custom of straining it through a piece of fine muslin as he or she fills the pitcher. In some parts of the land the water at the source is kept free from leeches by means of fish; at Deishun, for example, a village in ‘Upper Galilee’ inhabited by Algerian settlers, the large stone tank into which the spring runs is full of a special fish—Capoëta fratercula, a kind of carp—which is there bred for the purpose and which is treasured by the inhabitants with superstitious reverence. Many of the springs in the mountains of Galilee and in the Lebanon are widely known for the multitude of leeches which lurk in their waters, but a thirsty traveller seldom has self-control enough to restrain himself from drinking, and when he does so, particularly at dusk or in the night, he is very likely to suck one in. It is stated in Allbutt and Rolleston's System of Medicine (2nd ed. Vol. II. Part II. p. 959) that the leech “remains in the stomach for a time and then begins to wander.” I have had a long experience of leeches as human parasites but have never seen nor heard of a case like this. The leech in every case I have met has attached itself to the mouth, throat, etc. in the process of swallowing, and I am convinced that once the leech reaches the stomach it is killed. I have never heard of any after symptoms from cases where to my knowledge a leech has been completely swallowed. Many patients can describe the actual moment (during deglutition) when the leech seizes on the throat. One would suppose from the great frequency of leeches in the mouths of horses, etc., that they must sometimes find a temporary resting place there in the human subject; such cases do not however come into the hands of a medical man—the patient or his friends readily removes such an intruder. In the cases, some three dozen or so, which I have had under my own observation the leech has been attached to the epiglottis, the pharynx, the nasal cavities, or—most common of all—the larynx. The frequency of the last situation in my clinical experience is doubtless due to the inability of the fellahin to do anything themselves for the relief of such cases.

In birds, vector-borne parasites invading the bloodstream are important agents of disease, affect fitness and shape population viability, thus being of conservation interest. Here, we molecularly identified protozoan blood parasites in two populations of the threatened Aquatic Warbler Acrocephalus paludicola, a migratory passerine nesting in open marsh. We explored whether prevalence and lineage diversity of the parasites vary by population and whether infection status is explained by landscape metrics of habitat edge and individual traits (body mass, fat score, wing length and sex). Aquatic Warblers were infected by genera Plasmodium, Leucocytozoon and Trypanosoma, with seven, one and four lineages, and 29.9, 0.7 and 12.5% prevalence, respectively. No Haemoproteus infections were detected. Prevalence did not vary between the populations, but lineage diversity was higher in Polesie than in Biebrza for all the lineages pooled and for Plasmodium. Infection by Trypanosoma decreased with patch core area and increased with density of habitat edge. Infection status was not predicted by the individual traits. Our study is the first to show an association between edge-related landscape features and blood parasitism in an open habitat bird. This finding will support informed conservation measures for avian species of the globally shrinking marshland and other treeless habitats.

In this study, the prevalence of piroplasms in dogs was assessed using polymerase chain reaction (PCR) to identify Babesia and Theileria species in 200 dogs from Northern and Central Tunisia between spring and autumn 2014. The overall molecular prevalence for piroplasms was 14·5% ± 0·05 (29/200); PCR detected 2 species, namely Babesia vogeli and Theileria annulata with an overall prevalence of 12·5 ± 0·04 and 2% ± 0·02, respectively. No differences in the molecular prevalences of B. vogeli were revealed for age and sex (P > 0·05). The molecular prevalence of B. vogeli was significantly higher in central Tunisia (26·5% ± 0·01) compared with the North (9·6% ± 0·04) (P < 0·05). More working and companion dogs were infected by B. vogeli (25·8 ± 0·15 and 21·1% ± 0·13, respectively) in comparison with guarding dogs (1·8% ± 0·03) (P < 0·05). Concerning T. annulata, no significant variation was observed for all studied risk factors (P > 0·05). Comparison of the partial sequences of 18S rRNA and Tams 1 genes confirmed the presence of 2 novel B. vogeli and T. annulata genotypes. This is the first molecular detection of T. annulata and genetic characterization of dogs’ piroplasms in Tunisia. Further studies are needed to better assess the epidemiological feature of piroplasms infection in North Africa.