The essential oil (EO) of Thymus capitatus, seven fractions (F1–F7) obtained from silica gel chromatography, and several pure EO components were evaluated with respect to in vitro activities against Echinococcus multilocularis metacestodes and germinal layer (GL) cells. Attempts to evaluate physical damage in metacestodes by phosphoglucose isomerase (PGI) assay failed because EO and F1–F7 interfered with the PGI-activity measurements. A metacestode viability assay based on Alamar Blue, as well as transmission electron microscopy, demonstrated that exposure to EO, F2 and F4 impaired metacestode viability. F2 and F4 exhibited higher toxicity against metacestodes than against mammalian cells, whereas EO was as toxic to mammalian cells as to the parasite. However, none of these fractions exhibited notable activity against isolated E. multilocularis GL cells. Analysis by gas chromatography-mass spectrometry showed that carvacrol was the major component of the EO (82.4%), as well as of the fractions F3 (94.4%), F4 (98.1%) and F5 (90.7%). Other major components of EO were β-caryophyllene, limonene, thymol and eugenol. However, exposure of metacestodes to these components was ineffective. Thus, fractions F2 and F4 of T. capitatus EO contain potent anti-echinococcal compounds, but the activities of these two fractions are most likely based on synergistic effects between several major and minor constituents.

This description is based upon a study of six identical monogenetic trematodes which were collected from the gills of the tunny by Mr F. S. Russell, F.R.S., and which were presented to the writer for identification. They had been fixed already in a flexed but otherwise excellent condition in Bouin's fluid on cleanly cut pieces of gill tissue to which they were adherent. Two of the specimens were cut into serial sections while still in situ on the gills, and the remaining specimens were detached carefully from the gills and examined whole. Gill tissue of the fish in the vicinity of the parasite was seen to be modified and such observations as could be made on the effect of the parasite on the tissues of the host have been recorded.

Vitamin K (as menaphthone sodium bisulphite) added to a deficient diet reduced mortality due to Eimeria tenella or E. necatrix, had a slight effect on haematocrit, but had no obvious effect on weight gain or faecal blood; 0·1 ppm gave a maximal response. The effect of vitamin K on mortality was not absolute; the magnitude of the effect depended on the size of the challenge dose of oocysts. Likewise, the response of an infection to anticoccidial drugs, particularly monensin, depended on the severity of challenge. The effect of adding vitamin K in the presence of drug was to effectively reduce the coccidial challenge; no other interaction of vitamin K and drug has been found. No effects with vitamin K deficiency or supplementation were seen in cases of infections with E. acervulina, E. brunetti or E. maxima. The use of a deficient diet for experimental work is therefore quite justified – particularly as it results in a 4-fold saving of oocysts for inoculation purposes in the case of the haemorrhagic species.

The use of a selective schedule of tests to identify a viable population of isolated adult Onchocerca volvulus (Nematoda: Filarioidea) has been investigated in a large worm population. The study was initiated to develop methodology appropriate to test new candidate macrofilaricides for their in vitro activity against O. volvulus. After removal from the host the viability of isolated intact parasites was estimated by assessing the motility indices of male worms, and the colorimetric quantification of the reduction of the bioreducible tetrazolium reagent XTT and lactate output by female worms. Additionally the motility of whole females and the movement of inner organs of female worms were scored quantitatively. These response parameters were used to sort the adult worms into viability groups at the start of the in vitro culture. The adult worms were then observed for 6 days and viability was assessed regularly during the culture period. At the end of the culture period, the reduction of the water-insoluble tetrazolium reagent MTT was used to determine the formazan formed by the entire male and female worms. The response parameters used at the start of the culture proved to be highly predictive for detecting viable and non-viable adult worms. In the group of worms selected as ‘viable’ around 70% kept their motility and metabolic activity at a high level until the end of the culture compared to the initial level. In contrast, none of the female worms and only 13% of the male worms categorized as ‘poorly viable’ demonstrated a motility index or metabolic level at the end of the culture period that was comparable to that of the worms in the ‘viable’ groups. For female worms the lactate output correlated significantly with weight whereas no correlation was seen between MTT reduction and weight.

A strain of Plasmodium gallinaceum has been treated for 16 months with chloroquine, under conditions which previously have produced strains resistant to proguanil, sulphonamides and pamaquin, but no change in reaction to the drug has occurred.

Hirstiella spp. are common ectoparasites of captive green iguanas (Iguana iguana). Suggested treatments are empirical and some of them are of low efficacy and potentially toxic. The objective of this open-label study was to investigate the short-term efficacy and safety of a single application of 0·25% fipronil solution for the treatment of hirstiellosis. The skin of 50 green iguanas was thoroughly examined with the aid of bright light and magnifying lenses. A total of 21 iguanas were found to be infested, harbouring 1–24 mites (median: 5). All 35 mites collected from 17 iguanas were identified as Hirstiella sp. Both infested and non-infested lizards, sharing the same enclosure, were carefully wiped with 0·25% fipronil solution. The safety and the efficacy of the treatment were evaluated after 2 days in 47/50 (94%) and 7 days in 29/50 (58%) iguanas. Compared with pre-treatment levels, the parasitic load did not changed significantly on the second day but was significantly lower on day 7 (P = 0·006). No adverse reactions were noticed. Based on these results a single whole-body application of 0·25% fipronil solution can be considered a safe and effective treatment for the reduction of parasitic burden in captive green iguanas infested by Hirstiella sp. mites.

Salivary molecules, as glycine-rich proteins (GRPs), are essential to tick attachment and feeding on the host and are suggested to be involved in the host's immune system evasion, therefore representing natural candidates in the search for protective vaccine antigens. This work shows the molecular characterization of a GRP from Rhipicephalus microplus (RmGRP). The cDNA and putative amino acid sequences were analysed, as well as the transcription level in tick tissues/developmental stages, showing the highest levels of gene expression in 1-day-old larvae and salivary glands of fully engorged females. RmGRP gene silencing resulted in a lower hatching rate of larvae from treated females. In addition, recombinant RmGRP (rRmGRP) was recognized by sera from naturally and experimentally infested bovines, displaying considerable differences among the individuals tested. rRmGRP was recognized by anti-saliva and anti-salivary glands sera, while anti-rRmGRP serum recognized RmGRP in saliva and salivary glands, indicating its secretion into the host. The data collected indicate that RmGRP may present roles other than in the tick–host relationship, especially in embryo development. In addition, the high expression in adult females, antigenicity and presence of shared characteristics with other tick protective GRPs turns RmGRP a potential candidate to compose an anti-tick vaccine cocktail.

The morphology and biology of the various stages of the life-cycle of Trypanosoma evotomys has been studied in laboratory bred vertebrate and invertebrate hosts. The morphology of T. evotomys in the blood of the bank-vole, Clethrionomys glareolus, is typical of that of a trypanosome of the subgenus Herpetosoma, but the shape and size of the trypanosome in C. glareolus is more variable during the reproductive phase of the infection than in the adult phase. The duration of the infection of T. evotomys in C. glareolus varies from 22 to 31 days in experimental infections and the incubation period of the infection initiated by metatrypanosomes is 5–6 days. The peak of the parasitaemia varied from 15000 to 55000 parasites per mm3 of blood. The reproductive stages of T. evotomys are found in the spleen and lymphoid tissue (appendix) of the bank-vole, and reproduction is by equal, binary or multiple fission in the amastigote stage. T. evotomys was not transmissible to M. agrestis, mice or rats. Cyclical development of T. evotomys took place in the flea, Nosopsyllus fasciatus, and metatrypanosomes developed in the intestine of the flea. No intracellular forms of T. evotomys were found in the mid-gut of the flea.

The encouragement, help and advice of Dr P. Tate is gratefully acknowledged. Financial support was received from the Agricultural Research Council to whom thanks are also due.

Host and Record. A single female was found attached close to the left pelvic fin of a Histiophorus brevirostris Playfair caught off the south-west coast of Ceylon in January, 1932. One of the egg-strings was missing.

The infective larvae of S. ratti were non-feeding and none of a wide variety of possible substrates had any effect on the respiratory rate of intact worms. Sodium succinate increased the oxygen uptake of larval homogenates.

The cytochrome chain inhibitors, sodium cyanide, sodium azide and urethane all reversibly inhibited the respiration of the infective larvae. The inhibition caused by carbon monoxide was photo-reversible and 2,4-dinitrophenol inhibited respiration rather than stimulated it. Methylene blue increased the oxygen uptake of homogenates, but had no effect on the intact larva. Iodoacetamide and sodium arsenite irreversibly inhibited respiration, whilst sodium fluoride, sodium pyrophosphate and sodium malonate were without effect on the intact larvae.

This work was carried out during the tenure of a Medical Research Council Scholarship.

Anguillicola crassus is the most invasive species of its genus and it is a successful colonizer of different eel species worldwide. It is so far the only species of the genus Anguillicola whose life cycle has been studied completely. To analyse whether differences in life cycle may explain differences in invasiveness, we infected European eels with Anguillicola novaezelandiae under laboratory conditions. Anguillicola novaezelandiae shows a synchronized development in the European eel. Eggs with second-stage larvae appeared 120 days after infection. No density-dependent effect in parasite development could be found for A. novaezelandiae. The present study shows that the life cycle of A. novaezelandiae differs on final host level compared with A. crassus in ways which result in a less successful invasion of new host species.

Taenia solium, a causative agent of taeniasis and cysticercosis, has evolved a repertoire of lipid uptake mechanisms. Proteome analysis of T. solium excretory-secretory products (TsESP) identified 10 kDa proteins displaying significant sequence identity with cestode hydrophobic-ligand-binding-proteins (HLBPs). Two distinct 362- and 352-bp-long cDNAs encoding 264- and 258-bp-long open reading frames (87 and 85 amino acid polypeptides) were isolated by mining the T. solium expressed sequence tags and a cDNA library screening (TsHLBP1 and TsHLBP2; 94% sequence identity). They clustered into the same clade with those found in Moniezia expansa and Hymenolepis diminuta. Genomic structure analysis revealed that these genes might have originated from a common ancestor. Both the crude TsESP and bacterially expressed recombinant proteins exhibited binding activity toward 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS), which was competitively inhibited by oleic acid. The proteins also bound to cis-parinaric acid (cPnA) and 16-(9-anthroyloxy) palmitic acid (16-AP), but showed no binding activity against 11-[(5-dimethylaminonaphthalene-1-sulfonyl) amino] undecanoic acid (DAUDA) and dansyl-DL-α-aminocaprylic acid (DACA). Unsaturated fatty acids (FAs) showed greater affinity than saturated FAs. The proteins were specifically expressed in adult worms throughout the strobila. The TsHLBPs might be involved in uptake and/or sequestration of hydrophobic molecules provided by their hosts, thus contributing to host-parasite interface interrelationships.

Comparing parasitic infection among individuals of wildlife populations can provide insight into factors that influence wildlife disease ecology. Strongylids are parasitic worms that infect the intestinal tract of vertebrates, and infection with strongylids can be approximated by counting strongylid eggs in dung samples. Here we tested for correlations between strongylid egg counts and 18 different individual characteristics, environmental and social factors in individually known wild African elephants. We counted more eggs in the dung samples of younger elephants and females relative to mature elephants and males. We also found that elephants spending more time outside reserves shed more strongylid eggs than elephants that were more often within reserves. Elephants that were less socially integrated, as measured by how much aggression they received from other elephants, shed fewer strongylid eggs; relatedly, socially isolated orphan elephants that had left their family shed fewer strongylid eggs than elephants that remained with their family. Our results suggest that landscapes altered by livestock grazing and social disruption caused by humans may impact parasitic infection in wildlife.

Although the gross and microscopic pathology in rats infected with Angiostrongylus cantonensis has been well described, corresponding changes detected using diagnostic imaging modalities have not been reported. This work describes the cardiopulmonary changes in mature Wistar rats chronically infected with moderate burdens of A. cantonensis using radiology, computed tomography (CT), CT angiography, echocardiography, necropsy and histological examinations. Haematology and coagulation studies were also performed. Thoracic radiography, CT and CT angiography showed moderately severe alveolar pulmonary patterns mainly affecting caudal portions of the caudal lung lobes and associated dilatation of the caudal lobar pulmonary arteries. Presumptive worm profiles could be detected using echocardiography, with worms seen in the right ventricular outflow tract or straddling either the pulmonary and/or the tricuspid valves. Extensive, multifocal, coalescing dark areas and multiple pale foci affecting the caudal lung lobes were observed at necropsy. Histologically, these were composed of numerous large, confluent granulomas and fibrotic nodules. Adult worms were found predominantly in the mid- to distal pulmonary arteries. An inflammatory leukogram, hyperproteinaemia and hyperfibrinogenaemia were found in most rats. These findings provide a comparative model for A. cantonensis in its accidental hosts, such as humans and dogs. In addition, the pathological and imaging changes are comparable to those seen in dogs infected with Angiostrongylus vasorum, suggesting rats infected with A. cantonensis could be a model for dogs with A. vasorum infection.

The distribution of anionic residues on the surface of erythrocytes infected with Plasmodium falciparum was studied using cationized ferritin (CF) and transmission electron microscopy. CF staining of uninfected erythrocytes or erythrocytes infected with a knobless variant resulted in a dense and uniform distribution of ferritin particles; however, when red cells infected with a knob-inducing variant were exposed to CF, aggregates of ferritin particles were observed in the region of membrane elevation. Lectin binding to the erythrocyte surface was visualized by transmission electron microscopy using ferritin-conjugated lectins and lectin-fetuin-gold. No differences were observed in the lectin-binding patterns of malaria-infected or uninfected erythrocytes using WGA (wheat-germ agglutinin), RCA (ricin), and Limax flavus lectin. In distinct contrast to the uniform distribution of ferritin particles seen with these lectins was the appearance of clusters of ferritin-ConA over the knobby regions. Localized aggregates of ConA were not seen in knob-free areas or on the surface of red cells infected with a knobless variant. No significant differences were found in the agglutination reactions of normal and infected cells with the Cancer antennarius lectin specific for O-acylated sialic acids.

Biochemical studies on the phosphatase systems of Gastrothylax crumenifer have been made. The maximum activity of the phosphatase enzyme was found to be at 5 pH. The action of magnesium and fluoride ions on the acid phosphatase activity shows that both act as inhibitors. The day-to-day variation in the phosphatase activity of the samples, as measured by block differences, was found to be significant at different pH levels. The heat denatured extract showed low and fairly constant acid phosphatase activity.

This study was conducted to identify surface antigens of the microfilarial sheath of Litomosoides carinii which are accessible to antibodies. Rabbit antisera were raised against the soluble and insoluble fractions of purified sheaths by extracting them with a buffer containing 2-mercaptoethanol and sodium dodecylsulphate. These sera and rabbit hyperimmune sera directed against homogenates of total microfilariae, mature (i.e. microfilariae liberating) female parasites and excretory–secretory products of adult females were able to agglutinate live and formaldehyde-fixed microfilariae. When the antisera directed against sheath constituents were administered to patently infected Mastomys coucha, the microfilaraemia of these animals was rapidly reduced and remained low for a period of 2–3 weeks. Antibodies specifically binding to the microfilarial surface were immunoaffinity-purified on formaldehyde-fixed microfilariae. The antibodies react with sheath antigens of 40 and 120 kDa molecular mass which are produced by the epithelium of the distal uterus of the mature female, secreted and attached to the surface of the sheaths. A 120 kDa antigen recognized by anti-sheath surface antibodies was also detected in the excretory–secretory products of in Vitro-cultured immature female L. carinii from day 30 post-infection onwards. In the excretory–secretory products of mature adult female parasites recovered on day 130 post-infection, this 120 kDa molecule was absent. However, material reacting with the antibody was detected in the stacking gel of SDS-polyacrylamide gels. This finding may indicate that the basic units forming the 120 kDa antigen of immature adults or microfilarial sheath surface antigens occur in a highly polymerized form in the excretory–secretory products of mature female parasites.

Early this year (1932) we examined eight American raccoons (Procyon s. Notocyon lotor) whose faeces, according to Darling, contained Coccidia of our species.

1. An outline of the life history of Cephus pygmaeus Linnaeus is given.

2. The parasites of Cephus are listed and are discussed briefly in relation to the particular parasite Collyria calcitrator Gravenhorst.

3. It is shown that if the host larvae collected from wheat-stubble in autumn are used for the investigation of the extent of parasitism by Collyria, allowance must be made for the fact that the parasite Pleurotropis benefica Gahan is intrinsically inferior to Collyria, and that its cocoons must represent hosts left unparasitized by Collyria.

4. In summer the adults of Collyria emerge, on the whole, earlier than those of the host Cephus. This suggests that at the beginning of the season of oviposition there will be a scarcity of hosts in comparison with the numbers of parasites wishing to oviposit. The relative activity of host and parasite during the egg-laying period is worked out on hypotheses of the average length of life of the individuals, and is shown diagrammatically.

5. The Cephus larvae travel down the stem and hibernate at the base. When the wheat is cut, a proportion of the larvae and their parasites are removed with the straw. The way in which this may prevent the stubble material from giving a true indication of the degree of parasitism in the population as a whole is discussed.

6. On the basis that 3910 hosts receive 3600 parasites, various hypothetical distributions are worked out arithmetically in order to find which type of discrimination between healthy and parasitized hosts gives an arrangement of parasites most in agreement with what has been found for Collyria in Cephus. The most satisfactory result is that obtained when it is assumed that the probability of an already parasitized host being re-attacked varies with the proportion of parasitized hosts. It is also shown that a shortage of hosts at a time of parasite activity may cause a high degree of superparasitism, thus giving a false impression of the parasite's power of discrimination.

7. Suggestions for further field work are given.

The newly formed egg-shell from eggs in the proximal part of the uterus of Paraplerurus sauridae is colourless and transparent, whereas the shell from eggs in the distal uterus is golden yellow in colour. Histochemical tests reveal the presence of phenol, protein and phenolase in the freshly formed egg-shell. The egg-shell from eggs in the distal uterus shows the property of sclerotin. Histochemical reactions, chromatography and spectrum analysis reveal the presence of a dityrosyl linkage in the egg-shell. The nature of the protein component in the egg-shell is discussed.