This study reports that inhibition of Leishmania Topo-I with the minor groove-binding ligands (MGBLs) Hoechst 33342 (Ho342) blocks parasite growth in culture by mechanisms involving DNA breakage. While Ho342 inhibited the replication of several species of Leishmania in a dose- and time-dependent manner, Ho258 was not effective. Cytofluorometric analysis suggested that superior effectiveness of Ho342 over Ho258 was attributed to Leishmania parasites being more permeable toward Ho342. This observation was supported by the ability of both Ho342 and Ho258 to block the relaxation of supercoiled pBR322 DNA by Leishmania Topo-I. The Ho342 specificity toward L. donovani Topo-I was reinforced by the observation that increased Topo-I gene expression and Topo-I activity in Leishmania was paralleled by augmented resistance for this compound. Furthermore, the capacity of NaCl treatment to reverse MGBL-mediated DNA break suggests that Ho342 targetted Topo-I. Moreover, we observed that Ho342-inducible arrest of Leishmania growth was accompanied by G1 arrest and induction of cell death that closely resembles apoptosis. Taken together, our results suggest that MGBL compounds show promise as Topo-I inhibitors against Leishmania infection.

Pelodera strongyloides larvae were found in the conjunctival sacs of Apodemus sylvaticus and Clethrionomys glareolus and in hair follicles of A. sylvaticus. Those in the eyes were 3rd-stage larvae while most of those in the dermis were early 4th stages. There was no evidence of pathology and sections of the skin showed that the nematodes were well-tolerated by the mice. Nematodes emerged from the skin of freshly killed mice and moulted once to the adult stage in 1–2 days at 15 °C. The stimulus to resume development appeared to be a reduction in temperature rather than presence of bacterial food or reduction in osmotic pressure. Countless generations ensued on nutrient agar provided the nematodes were periodically sub-cultured onto fresh agar. Nematodes from the eyes died in culture. Dauerlarvae of P. strongyloides were produced in exhausted cultures. They resumed development on fresh agar but not in distilled water. About half could be induced to exsheath by a temperature similar to that of mouse skin. A. sylvaticus probably accumulates nematode larvae in the dermis during its life and the nematodes resume development when the host dies.

Gyrodactylus salaris is a serious pest of wild pre-smolt Atlantic salmon (Salmo salar) in Norway. The closely related G. thymalli, originally described from grayling (Thymallus thymallus), is assumed harmless to both grayling and salmon. The 2 species are difficult to distinguish using traditional, morphometric methods or molecular approaches. The aim of this study was to explore whether there is a consistent pattern of morphometrical variation between G. salaris and G. thymalli and to analyse the morphometric variation in the context of ‘diagnostic realism’ (in natural populations). Specimens from the type-material for the 2 species are also included. In total, 27 point-to-point measurements from the opisthaptoral hard parts were used and analysed by digital image processing and uni- and multivariate morphometry. All populations most closely resembled its respective type material, as expected from host species, with the exception of G. thymalli from the Norwegian river Trysilelva. We, therefore, did not find clear support in the morphometrical variation among G. salaris and G. thymalli for an a priori species delineation based on host. The present study also indicates an urgent need for more detailed knowledge on the influence of environmental factors on the phenotype of gyrodactylid populations.

In the Final Report of the League of Nations International Commission on Sleeping Sickness (1928) certain tentative conclusions were expressed about the behaviour of T. gambiense, recently isolated from man, in the blood of monkeys and of certain domestic ruminants. These conclusions, which were intended primarily to serve as a basis for further researches, were set forth in the Summary of Part I of that Report, and read as follows:

Normal human serum (HS) contains trypanolytic activity and agglutinins to Trypanosoma equiperdum, while such activities are not found in sera from a range of animals susceptible to infection. HS given to T. equiperdum-infected mice caused a rapid decrease in the number of circulating trypanosomes and protection from lethal infection. Trypanolytic activity of human serum was found to be associated, after DEAE chromatography and Sephadex G-200 gel filtration, with the fraction containing 19S antibodies. Immunofluorescence assays confirmed a binding of human IgM and C1q complement component onto the surface of T. equiperdum. Anti-T. equiperdum activity of HS was specifically directed to T. equiperdum surface components and not to some mouse serum components adsorbed on parasites during the growth in the host, because HS adsorbed in vivo in CD-1 mice retained full protective and agglutinating properties. Trypanocidal activity appears in human serum about the 7th month after birth and persists until late in life. On the contrary, human purified high-density lipoprotein had no significant in vitro or in vivo trypanocidal activity. In conclusion, strong natural anti-T. equiperdum activity in human serum was mainly mediated by natural antibodies of the IgM class. The presence of natural IgM active against T. equiperdum in HS could represent one of the natural mechanisms of resistance of refractory hosts against trypanosome infections. This phenomenon provides further evidence that host specificity of trypanosomes may be partly conditioned by the presence of natural antibodies.

Using a combination of morphological, life-cycle and molecular data, we describe a new apicomplexan parasite Eimeria telekii n.sp. from a striped grass mouse Lemniscomys striatus captured in Kenya. Oocysts are oval to spherical or ellipsoidal, 20·4×15·7 (15·5–25·0×12·0–20·0)μm with a colourless, smooth and bilayered wall. Sporocysts are ellipsoidal, 11·2×7·8 (10·0–12·0×7·0–9·0)μm with a small Stieda body and granular sporocyst residuum and contain 2 elongated, banana-shaped sporozoites with a single refractile body. Life-cycle, pathogenicity and host specificity of this parasite were studied in laboratory-bred Lemniscomys barbarus and BALB/c mice. Two asexual stages and the sexual phase took place within the enterocytes of the caecum and colon of L. barbarus but not in inoculated BALB/c mice. An infectious dose of 5000 oocysts caused severe clinical illness and mortality in 2/2 (100%) L. barbarus. Phylogenetic analysis of the small subunit rRNA gene of E. telekii and members of the genera Eimeria, Cyclospora and Isospora placed E. telekii within the eimerian rodent clade.The nucleotide sequence was deposited in the GenBankTM under the accession number AF246717.

1. The effects of the following acids were studied: hydrochloric, nitric, sulphuric, formic, acetic, propionic, butyric, isovaleric, glycollic, lactic, oxalic, malonic, succinic, malic, tartaric, and citric.

2. The general effects of immersion in acid media include an increased stickiness of the cuticle in certain solutions, and the development of lateral bulges in the cuticle at the anterior region of the body, not necessarily in the same solutions. Movement gradually decreases, and death eventually occurs, often followed by swelling.

3. The survival times in various solutions were noted. Preliminary experiments showed that the logarithm of the survival time was approximately proportional to the logarithm of the normality of the acid. Later results showed great variability, and it was necessary to restrict the work to a single normality of each acid.

4. The toxicities of 0·206 N solutions of the sixteen acids were measured. These results showed that the mineral acids had markedly greater effects than the organic acids, and the importance of the former was further illustrated by using mixtures of HCl containing varying amounts of organic acids. The differences between the mineral acids may be explained by the lyotropic effects of the anions.

5. Equal normalities of organic acids were made up in a solution of HCl sufficiently strong to render the organic acids almost entirely undissociated. The relative toxicities of the mixtures were essentially the same as those of the dissociated acids.

6. The differences between the acids are thus partly due to the pH differences, and partly due to the dissimilar effects of the undissociated acids. The latter are believed to be due to a variety of causes, including molecular size, polarity of the molecule, and other factors as yet undecided.

Apyrases (ATP-diphosphohydrolase) comprise a ubiquitous class of glycosylated nucleotidases that hydrolyse extracellular ATP and ADP to orthophosphate and AMP. One class of newly-described, Ca2+-dependent, salivary apyrases known to counteract blood-clotting, has been identified in haematophagous arthropods. Herein, we have identified a gene (Oos-apy-1) encoding a protein that structurally conforms to the Ca2+-activated apyrase from the bed bug, Cimex lectularius, by immunologically screening an Ostertagia L4 cDNA expression library. The expressed protein (rOos-APY-1) was biochemically functional in the presence of Ca2+ only, with greatest activity on ATP, ADP, UTP and UDP. Host antibodies to the fusion protein appeared as early as 14 days post-infection (p.i.) and increased through 30 days p.i. Immunohistochemical and Western blot analyses demonstrated that the native Oos-APY-1 protein is present in the glandular bulb of the oesophagus and is confined to the L4. A putative signal sequence at the N-terminus and near 100% identity with a Teladorsagia circumcincta L4 secreted protein is consistent with the native protein being secreted at the cellular level. Predicated upon substrate specificity, the native protein may be used by the parasite to control the levels of host extracellular nucleotides released by locally-damaged tissues in an effort to modulate immune intervention and inflammation.

Mono-metacercarial infections of Echinostoma revolutum in the domestic chick yielded 14- or 15-day-old worms that produced viable eggs, indicating that this species can self-fertilize under conditions which preclude cross-fertilization. In multiple infection studies, chicks were fed either 5 or 10 cysts and each infected chick contained 2–7 worms at necropsy 14 or 15 days later. Worms from multiple infections were mainly paired or clustered and they tended to locate more posteriorly in the intestine than single worms. Length measurements of single and multiple worms were similar. Both the number of eggs and the percentage of hatched eggs were considerably greater in multiple than in single infections.

The numbers of mature worms which developed in young rats after their mothers were injected with 4000 L3 late in lactation were 1% (Nippostrongylus brasiliensis) and 24% (Strongyloides ratti) of the dose administered. The low value for N. brasiliensis validates the conclusion that milk is a real and important vehicle for infection in S. ratti since possible errors from skin invasion of the young would have been common to both species.

The level of mature S. ratti infection in lactating mothers in this experiment was negligible, 97–99% of the adult worms appearing in the offspring.

These results may indicate that the milk route is possible with N. brasiliensis even though it is quantitatively insignificant.

In the course of a Mosquito Survey carried out in the neighbourhood of Birmingham on July 31 and August 1, 1928, a large number of female mosquitoes of the two species Aëdes (Aëdes) cinereus and Aëdes (Ochlerotatus) annulipes were collected and subsequently examined.

1. Sheep myiasis was investigated in certain districts in Ayrshire, Arran and Argyllshire.

2. Larvae from cases of myiasis were collected and bred out in flyproof apparatus.

3. The fly season was found to last approximately from May till September, reaching its height in July and August.

4. The western districts were found to be the most heavily affected.

5. The flies were found to be partial to low-lying, sheltered ground, especially where much bracken was present.

6. The methods of carcass burial were found to be primitive and inadequate. In most of the farms dipping was carried out without sufficient attention to cleanliness and adequate time of immersion.

7. The hibernation of various species of blow-fly was studied. They were found to pass the winter as prepupae, pupation never occurring normally till April or May.

8. Several species of carrion-feeding blow-fly besides Lucilia sericata were found to be causing secondary myiasis, occasionally and in small numbers, in certain districts, mainly in the west. The species involved were: Lucilia caesar, L. illustris, Protophormia terraenovae, Calliphora erythrocephala, C. vomitoria and Muscina pabulorum. Four of these species Lucilia illustris, Protophormia terraenovae, Calliphora vomitoria and Muscina pabulorum have not previously been recorded from sheep. Records of cases in which these flies occurred are given.

Experiments were carried out to investigate the effect of variations in humidity and osmotic pressure upon the development and hatching of the eggs of Nematodirus battus. It was found that no development or hatching took place unless there was free water available, though humidity effects could enhance the subsequent response of the eggs in water. Larvae were found to be very resistant to prolonged exposure to low humidity. The concentration of the hatching medium showed little effect upon development of eggs, though the rate of larval emergence was reduced as the concentration of the culture medium increased. The relevance of this information is discussed in the context of other requirements of the egg stages during their hatching phase and how this may affect the behaviour of this nematode under field conditions.

The gross- and histopathology of natural and experimental Schistosoma curassoni infections in sheep were studied. The data obtained showed that S. curassoni infection in sheep causes only slight clinico-pathological manifestations with preferential involvement of the liver, the lower intestine and the urinary bladder. A variable spectrum of host reaction to the eggs within an individual animal was observed, reflecting the duration of presence of eggs in the organs. In the liver, egg granulomas were most numerous in the perilobular regions, while in the intestine, lesions were most pronounced in the mucosa of the rectum. The presence of eggs in 10% of the urinary bladders examined indicated some bladder involvement.

1. With unfed 1st instars the relation between mean length of life and saturation deficit at constant temperatures between 7 and 15° C. at relative humidities between 7 and 90% is hyperbolic. The relationship becomes more linear at higher temperatures.

At constant saturation deficits insects live longer at 15° C. than at lower temperatures. Longevity also decreases with rise of temperature above approximately 15° C.

2. In general, the longevity curves, except for those at temperatures below 15° C., bear a very similar relation to saturation deficit and to each other as the reciprocal curves for rate of water-loss at the different temperatures.

The influence of climatic factors on longevity at constant temperatures is discussed at length and it is concluded that over much of the temperature and humidity range survival time is limited by water-loss. At the higher humidities it is thought that either food, or perhaps an excessive accumulation of water within the insect, limits survival and causes a departure from the hyperbolic relation of longevity to saturation deficit.

3. The effects on longevity of a single meal are discussed. The principal effect of a blood meal is to increase the time of survival. But the factors which limit survival at different humidities appear to be the same as with unfed bugs, except at high humidities below about 15° C.

4.Mellanby's data on the rate of water-loss from fasting adult bed-bugs is analysed. It is found that the rate of water-loss is directly proportional to saturation deficit at constant temperatures between 8 and 37° C. and between 0 and 90% r.h. Although the rate may always be directly proportional to saturation deficit, the expression is not always constant.

Rate = K + b (saturation deficit), where K varies with temperature and b remains constant.

5. Longevity in relation to host blood is discussed. Rabbit blood appears to be slightly less favourable to survival than human blood.

6. If bugs are allowed to feed to repletion, longevity is not correlated with the size of the meal, nor with the weight of the unfed insect.

Virgin females live longer than mated ones, but no effects of mating on survival were noticed with males. Mated males tend to outlive mated females except at very low temperatures: virgin females live longer than unmated males.

7. The results of other workers and the possible causes of some discrepancies are discussed.

8. The maximum survival times of bugs are listed. Adults and 5th instars live longer than other stages. In a house which has remained empty for a long time it is probable that 5th instars and adults, particularly unmated female adults, would predominate in the population.

The longest observed survival was between 562 and 572 days.

The distribution–co-occurrence and exchange of adult cestode species in two fish communities (the Bothnian Bay and Lake Yli-Kitka both in Finland) was studied. Coexistence of two or more mature cestode species in the same fish host population was zero for all fish species studied (33) except pike in the Bothnian Bay and whitefish in the lake. It was found that 60% of the fish species studied in the Bothnian Bay and 80% of the fish species studied from Lake Yli-Kitka harboured only 1 mature cestode species. Exchange of adult cestode species between the different fish species in these two fish communities was found to be as rare as coexistence. The infra-community structure of adult cestodes in freshwater fish thus turned out to be markedly different from what is known to be the situation in birds. The evolutionary explanation behind the differences is discussed.

Four species of the genus Capillaria—C. anatis, C. bursata, C. caudinflata and C. obsignata—are described from the domestic fowl. C. bursata constitutes a new species record for Britain. Taxonomic problems concerning these species in particular, and of Capillaria species in general, are discussed in the light of experience gained from the present study.

This work was carried out during the tenure of a British Egg Marketing Board research studentship and is part of a thesis accepted by the University of London for the Ph.D. degree. My thanks are due to the director of the Houghton Poultry Research Station for granting facilities for work and to the staff for their help and encouragement. Mr R. A. Avery kindly supplied me with material collected from the Wildfowl Trust, Slimbridge.

Broadly oval, 5·8 × 3·9 mm., slightly broader at the posterior third; rounded in front, the posterior border more flattened. Integument mammillate and with dorsal depressions and discs, and ventral grooves strongly recalling O. coriaceus (see Fig. 1). Numerous short white hairs scattered over the integument, and notably a ring of close-set clavate hairs round the base of each trochanter. Eyes absent. The half-gorged ♂ measures 6 × 4 mm.

Pentastomids comprise a highly specialized taxon of arthropod-like parasites that probably became adapted to the lungs of amphibians and reptiles early in their long evolutionary history. Few other macroparasites exploit this particular niche. Pentastomids are often large, long-lived and yet they cause little observable pathology in lungs, despite being haematophagous. The lungs of all tetrapods are lined with pulmonary surfactant, a remarkable biological material consisting of a complex mixture of phospholipids, neutral lipids and proteins that has the unique ability to disperse over the air-liquid lining of the lung. In the lower tetrapods it acts as an anti-glue preventing adhesion of respiratory surfaces when lungs collapse during swallowing prey or upon expiration. In mammals, pulmonary surfactant also plays a critical role regulating the activity of alveolar macrophages, the predominant phagocytes of the lower airways and alveoli. This review outlines the evidence suggesting that lung-dwelling pentastomids, and also nymphs encysted in the tissues of mammalian intermediate hosts, evade immune surveillance and reduce inflammation by coating the chitinous cuticle with a their own stage-specific surfactant. The lipid composition of surfactant derived from lung instars of the pentastomid Porocephalus crotali cultured in vitro is very similar to that recovered from the lung of its snake host. Pentastomid surfactant, visualised as lamellate droplets within sub-parietal cells, is delivered to the cuticle via chitin-lined efferent ducts that erupt at a surface density of < 400 mm-2. The fidelity of the system, which ensures that every part of the cuticle surface is membrane-coated, testifies to its strategic importance. Two other extensive glands discharge membrane-associated (hydrophobic ?) proteins onto the hooks and head; some have been purified and partly characterized but their role in minimising inflammatory responses is, as yet, undetermined.

Human cysticercosis, caused by accidental ingestion of eggs of Taenia solium, is one of the most pathogenic helminthiases and is listed among the 17 WHO Neglected Tropical Diseases. Controlling the life-cycle of T. solium between humans and pigs is essential for eradication of cysticercosis. One difficulty for the accurate detection and identification of T. solium species is the possible co-existence of two other human Taenia tapeworms (T. saginata and T. asiatica, which do not cause cysticercosis in humans). Several key issues for taeniasis/cysticercosis (T/C) evidence-based epidemiology and control are reviewed: (1) advances in immunological and molecular tools for screening of human and animals hosts and identification of Taenia species, with a focus on real-time detection of taeniasis carriers and infected animals in field community screenings, and (2) spatial ecological approaches that have been used to detect geospatial patterns of case distributions and to monitor pig activity and behaviour. Most recent eco-epidemiological studies undertaken in Sichuan province, China, are introduced and reviewed.