It is now well established that animal parasites elicit vigorous immune responses in their hosts and that the resistance to reinfection thus acquired is mediated through conventional humoral and/or cellular effector mechanisms. It is also recognized, however, that some parasites exhibit extreme longevity in the face of a potentially hostile or lethal environment, and it may be assumed therefore that such organisms possess a repertoire of highly sophisticated and successful evasive strategies. Of all the survival mechanisms thus far proposed, the concept of antigen sharing, or disguise, is probably the most contentious. Arguments have arisen over the nature and origin of the shared determinants and over the validity of their role in ensuring parasite survival within the fully immunocompetent host. This presentation reviews published data concerning the existence of a disguise stratagem amongst medically important parasites and evaluates experiments designed to investigate the functional importance of disguise in immune evasion.

Promastigotes of Leishmania mexicana mutants lacking the multicopy CPB cysteine proteinase genes (ΔCPB) are markedly less able than wild-type parasites to infect macrophages in vitro. ΔCPB promastigotes invade macrophages in large numbers but are unable to survive in the majority of the cells. In contrast, ΔCPB amastigotes invade and survive within macrophages in vitro. This extreme in vitro stage-specific difference was not mimicked in vivo; both promastigotes and amastigotes of ΔCPB produced lesions in BALB/c mice, but in each case the lesions grew considerably more slowly than those caused by wild-type parasites and only small lesions resulted. Inhibition of CPB in situ using cell-permeant peptidyldiazomethylketones had no measurable effect on parasite growth or differentiation axenically in vitro. In contrast, N-benzoyloxycarbonyl-phe-ala-diazomethylketone reduced the infectivity of wild-type parasites to macrophages by 80%. Time-course experiments demonstrated that application of the inhibitor caused effects not seen with ΔCPB, suggesting that CPB may not be the prime target of this inhibitor. The data show that the CPB genes of L. mexicana encode enzymes that have important roles in intracellular survival of the parasite and more generally in its interaction with its mammalian host.

Schistosomiasis is widespread in Uganda along large lakes and rivers with approximately 4 million people infected. Hookworm infections also prevalent throughout the country, while infections with Ascaris lumbricoides and Trichuris trichiura are mainly found in south-western Uganda. A national programme aimed at controlling morbidity due to these infections was launched in 2003. This article describes the perceptions, attitudes, constraints and experiences of those implementing the programme and those receiving the treatment. The study used qualitative data collected largely in two districts but also from 18 other districts implementing the programme. Results showed that mass treatment was perceived to be beneficial because the drugs make people feel better. However, side-effects of praziquantel (PZQ), the smell and size of the tablets and the use of height, not weight, to determine dose were raised as major factors discouraging people from taking the drug. Generally, most of the end-users were appreciative of the programme and were beginning to demand regular treatment. Nevertheless, intensive and sustained health education is still vital for improvement of treatment coverage, especially among the non-compliers. It was repeatedly highlighted that there is a need to stock PZQ in all health facilities in endemic areas. Provision of incentives to drug distributors and to involve as many stakeholders as possible in the planning phase were also raised by respondents. Lessons learned for the development and success of a helminth control programme at a national scale are discussed.

The dominant repetitive deoxyribonucleic acid (DNA) sequence in the genome of a clone of Trypanosoma (Nannomonas) simiae has been identified and cloned as a recombinant plasmid. The recombinant plasmid was used in hybridization analyses of DNA samples obtained from various trypanosome species and subspecies. The results indicated that the T. simiae repetitive DNA sequence hybridized with DNA derived only from T. simiae; it did not hybridize with DNA derived from clones or stocks of T. congolense, or from any other trypanosome species examined. A preliminary characterization of the cloned DNA sequence and its use in the identification of T. simiae of similar genotypes are presented.

The complete Taenia asiatica mitochondrial genome was amplified by long extension polymerase chain reaction (long PCR) to yield overlapping fragments that were then completely sequenced. The whole mitochondrial genome was 13703 bp long and contained 12 protein-encoding, 2 ribosomal RNA (small and large subunits), 22 transfer RNA genes and a short non-coding region. Thus, its gene contents are like those typically found in metazoan animal mitochondrial genomes (apart from the absence of atp8). All the genes were transcribed from the same strand. The 3′ end 34 bp region of nad4L overlapped with the 5′ end portion of nad4. The tRNA genes were 61–69 bp long, and the secondary structures of 18 tRNAs had typical clover-leaf shapes with paired DHU arms. However, trnC, trnS1, trnS2 and trnR had unpaired DHU arms that were 7–12 bp in length. The tRNAs that transferred serine lacked a DHU arm, as is also observed in a number of parasitic platyhelminths and metazoans. However, the trematode trnRs have paired DHU arms. The T. asiatica mtDNA non-coding region was like that in other cestodes since it was composed of a short non-coding region of 72 nucleotides and a long non-coding region of 176 nucleotides separated by a trnL1/, trnS2/, trnL2/, trnR/, nad5 gene cluster. The sequences of the cox1 genes between T. asiatica and T. saginata differ by 4·6%, while the T. asiatica cob gene differs by 4·1% and 12·9% from the cob genes of T. saginata and T. solium, respectively. In conclusion, the T. asiatica mitocondrial genome should provide a resource for comparative mitochondrial genomics and systematic studies of parasitic cestodes.

LYMFASIM is a simulation model for lymphatic filariasis transmission and control. We quantified its parameters to simulate Wuchereria bancrofti transmission by Anopheles mosquitoes in African villages, using a wide variety of reported data. The developed model captures the general epidemiological patterns, but also the differences between communities. It was calibrated to represent the relationship between mosquito biting rate and the prevalence of microfilariae (mf) in the human population, the age-pattern in mf prevalence, and the relation between mf prevalence and geometric mean mf intensity. Explorative simulations suggest that the impact of mass treatment depends strongly on the mosquito biting rate and on the assumed coverage, compliance and efficacy. Our sensitivity analysis showed that some biological parameters strongly influence the predicted equilibrium pre-treatment mf prevalence (e.g. the lifespan of adult worms and mf). Other parameters primarily affect the post-treatment trends (e.g. severity of density dependence in the mosquito uptake of infection from the human blood, between-person variability in exposure to mosquito bites). The longitudinal data, which are being collected for evaluation of ongoing elimination programmes, can help to further validate the model. The model can help to assess when ongoing elimination activities in African populations can be stopped and to design surveillance schemes. It can be a valuable tool for decision making in the Global Programme to Eliminate Lymphatic Filariasis.

A series of line drawings of the unsporulated and sporulated oocysts of the species of Eimeria found in cattle and sheep in Britain has been compiled.

The incidence of the different species in faecal samples from animals, of which only a minority were known to be suffering from enteritis or diarrhoea, has been recorded. Samples from sheep frequently contained five or six different species among which those that are believed to be pathogenic (E. arloingi, E. crandallis, E. ninaekohlyakimovae) were the most common.

The samples from cattle most frequently contained two or three species. E. bovis and E. zuerni, which are associated with acute disease, were the most common.

Infection and inflammation in the gastrointestinal (GI) tract induces a number of changes in the GI physiology of the host. Experimental infections with parasites represent valuable models to study the structural and physiological changes in the GI tract. This review addresses research on the interface between the immune system and GI physiology, dealing specifically with 2 major components of intestinal physiology, namely mucin production and muscle function in relation to host defence, primarily based on studies using the mouse-Trichinella spiralis system. These studies demonstrate that the infection-induced T helper 2 type immune response is critical in generating the alterations of infection-induced mucin production and muscle function, and that this immune-mediated alteration in gut physiology is associated with host defence mechanisms. In addition, by manipulating the host immune response, it is possible to modulate the accompanying physiological changes, which may have clinical relevance. In addition to enhancing our understanding of immunological control of GI physiological changes in the context of host defence against enteric infections, the data acquired using the mouse-T. spiralis model provide a basis for understanding the pathophysiology of a wide range of GI disorders associated with altered gut physiology.

Oögyrodactylus farlowellae gen. et sp.nov., an oviparous monogenean, is described from the skin and fins of Farlowella amazonum, a South American loricarid catfish. The Oögyrodactylidae fam.nov., containing O. farlowellae and Phanerothecium caballeroi Kritsky and Thatcher, 1977, is placed with the Gyrodactylidae in the Gyrodactylidea. Although oviparous, the Oögyrodactylids are closely related to the viviparous gyrodactylids. Both families share a combination of characters, including haptor morphology, articulated marginal hooks and spike sensilla, which is not seen in other monogeneans. O. farlowellae is similar to a hypothetical ancestor of the gyrodactylids and shows that the family arose from monopisthocotylean rather than polyopisthocotylean stock. There is a close resemblance between the reproductive system of the immature Oögyrodactylus and that of the mature Gyrodactylus, suggesting that progenesis, involving the precocious maturation of oocytes, may have been important in the evolution of the viviparous genera. O. farlowellae retains eggs individually in the ootype until embryonation is comparatively advanced. After oviposition the eggs adhere to the substrate and hatch to give a crawling, unciliated larva. These are adaptations to a host which inhabits fast-flowing streams, where the eggs and infective larvae are exposed to a constant, uni-directional water current. The life-cycle (egg to adult) is completed in 11–13 days at 27 °C.

The present report is an account of observations made in Bagdad during the year 1910 (March to November) on the Oriental Sore as it occurs in this part of the world. Though the sore of Bagdad may not differ very markedly from that of other places, it is so common here that all stages and types of the sore may easily be studied, and such points as the early age of infection, immunity, and duration of the disease are very clearly exemplified. Accordingly, a more or less complete account of this disease of Bagdad, known locally as the Date boil or Arabic “Uchut,” will be given, though descriptions of the sore as it occurs in several parts of the world have been published by other observers. During the investigations various side issues arose, and as these suggest certain interesting points, three sections have been added dealing with (1) the life history of Lankesteria culicis (Ross) a gregarine of Stegomyia fasciata, (2) Haemogregarina canis and its development both in the dog and the tick Rhipicephalus sanguineus, and (3) Her-petomonas muscae domesticae, and other flagellates of the house-fly.

Between 20% and 60% of the population of most countries are infected with the protozoan Toxoplasma gondii. Subjects with clinically asymptomatic life-long latent toxoplasmosis differ from those who are Toxoplasma free in several behavioural parameters. Case-control studies cannot decide whether these differences already existed before infection or whether they were induced by the presence of Toxoplasma in the brain of infected hosts. Here we searched for such morphological differences between Toxoplasma-infected and Toxoplasma-free subjects that could be induced by the parasite (body weight, body height, body mass index, waist-hip ratio), or could rather correlate with their natural resistance to parasitic infection (fluctuating asymmetry, 2D[ratio ]4D ratio). We found Toxoplasma-infected men to be taller and Toxoplasma-infected men and women to have lower 2D[ratio ]4D ratios previously reported to be associated with higher pre-natal testosterone levels. The 2D[ratio ]4D ratio negatively correlated with the level of specific anti-Toxoplasma antibodies in Toxoplasma-free subjects. These results suggest that some of the observed differences between infected and non-infected subjects may have existed before infection and could be caused by the lower natural resistance to Toxoplasma infection in subjects with higher pre-natal testosterone levels.

Platelets take an active part in immunological processes as well as in haemostasis, especially in the host-parasite relationship. Our aim is to assess the growth of Plasmodium falciparum, cultured in human erythrocytes in the presence of fresh washed human platelets, since thrombocytopaenia is frequently observed during malarial infections. Our results show that platelets induce a dose-related growth inhibition of P. falciparum. Both proliferation and maturation of intraerythrocytic stages of the parasite are inhibited. This growth inhibition is triggered by the parasite itself as neither specific antibodies nor any other components are needed to activate platelets. Activated platelets are directly toxic since complement is not involved. Furthermore, inhibition is not mediated by erythrocyte lysis or by toxic oxygen metabolites. Platelets induce an inhibition of P.falciparum growth, at least in vitro, although the importance of their role played in vivo in malarial immunity has yet to be evaluated.

Although the relationship between intestinal parasitism, the ingestion and use of energy, and host survival is expected, little work has been done to outline the effect of such organisms upon their host's nutritional requirements in an ecological context. This study is the first to demonstrate that an intestinal helminth previously reported to be of little or no histopathological consequence, Plagiorhynchus cylindraceus, has a significant detrimental impact upon the flow of food energy through a definitive host, the European starling, Sturnus vulgaris. Within both male and female adult European starlings reductions in standard metabolic rates occurred as the result of initial infection, indicating that the host's basal metabolism/thermal regulatory abilities were altered. Moreover, initially infected male starlings, but not females, had an increased consumption and excretion of energy and maintained lower average daily body weights versus controls when temperature stressed. These results appear to be due to either a parasite-mediated alteration in host activity and/or to the disruption of host-digestive abilities. Additionally, these data indicate that, overall, male and female S. vulgaris respond differently to infection and that intestinal helminths normally thought to be of little or no pathological consequence to the host are factors that should be addressed in future studies regarding animal energetics, ecology, and behaviour.

Studies of topical treatments for leishmaniasis were systematically reviewed, to evaluate the therapeutic efficacy, safety and any adverse effects of these treatments. The papers identified in the databases PubMed and Web of Knowledge involved eight studies with a total of 1744 patients. The majority of trials was from Iran (4/8), covered a period of 8 years (2003–2011), and included patients 4–85 years of age. The most frequent Leishmania species in the studies were L. tropica (4/8) and L. major (2/8). The treatments administered were thermotherapy, paromomycin and combinations, CO2 laser, 5-aminolevulinic acid hydrochloride (10%) plus visible red light (633 nm) and cryotherapy. Six articles reported cure rates over 80·0%. Six studies reported on failure rates, three of them reporting rates lower than 10%. Four studies did not report relapses or recurrences, while the other studies reported low rates (1·8–6·3%). The most common adverse effects of the topical treatments were redness/erythema, pain, pruritus burning, oedema, vesicles and hyper- or hypopigmentation. The results provide strong evidence that the treatments topical evaluated showed high cure rates, safety and effectiveness, with low side-effects, relapse and recurrence rates, except for cryotherapy, which showed a moderate cure rate.

The essential biological features of snail infection by miracidia are incorporated into a simple model which describes the rate of change with respect to time of the number of miracidial infections/host. The model is based on the assumption that the net rate of infection is directly proportional to the density of both miracidia and hosts. Empirical evidence is provided to support this assumption. The basic framework of the model is expanded to take into account demographic stochasticity in infection and is used to predict the percentage of snails that become infected after exposure to a known number of miracidia for a set period of time. The influence of miracidial mortalities and age-dependent infectivity are examined and theoretical predictions are compared with a range of experimental results.

Underlying heterogeneity in the distribution of the number of infections/snail is shown to generate an artifactual decrease in infection rates as exposure density rises, if rate estimation procedures are based on an assumption of randomness. Empirical evidence is presented to illustrate the generation of over-dispersion in the number of miracidial infections/snail under tightly controlled laboratory conditions, using supposedly homogeneous snail populations.

Biological causes for underlying patterns of heterogeneity are discussed in relation to snail susceptibility to infection and ‘attractiveness’ to infective stages.

The ‘Muguga cocktail’ live vaccine comprises three Theileria parva stocks (Muguga, Kiambu 5 and the buffalo-derived Serengeti-transformed) and has been used extensively in Eastern, Central and Southern Africa with an infection and treatment protocol to protect cattle against East Coast fever. We report the characterization of the three component vaccine stocks using a panel of polymorphic micro-satellite and mini-satellite markers and the development of a stock-derived PCR method that distinguishes two of the vaccine stocks. These markers, with the use of a recently developed Reverse Line Blot assay, have enabled us to address four important questions in relation to vaccination. First, how closely related are the vaccine stocks, secondly do all three stocks persist post-vaccination and induce a carrier state, thirdly is there evidence for the transmission of the vaccine stocks and fourthly does vaccination prevent infection with local genotypes? The results show that Muguga and Serengeti-transformed stocks are highly related but very distinct from Kiambu 5 that persists in vaccinated cattle establishing a carrier state. No evidence was obtained for the transmission of vaccine stocks to co-grazed animals, although these animals were infected with up to 8 different T. parva genotypes showing there was a significant level of tick challenge. Some of the vaccinated animals become infected with a subset of local genotypes providing evidence for limited vaccine ‘breakthrough’.

The cuticle of adults of Nippostrongylus brasiliensis has been described using histological, histochemical and ultrastructural techniques.

The cuticle has the following layers: an outer triple-layered membrane; a single cortical layer; a fluid-filled layer which is traversed by numerous collagen fibrils; struts which support the fourteen longitudinal ridges of the cuticle and which are suspended by collagen fibrils in the fluid-filled layer; two fibre layers, each layer apparently containing three layers of fibres; and a basement lamella.

The fluid-filled layer contains haemoglobin and esterase.

The muscles of the body wall are attached to either the basement lamella or to the fibre layers of the cuticle.

The mitochondria of the hypodermis are of normal appearance.

The longitudinal ridges of the cuticle appear to abrade the microvilli of the intestinal cells of the host.

Possible functions of the cuticle are discussed.

I wish to thank Dr P. Tate, in whose department this work was done, for helpful suggestions and criticism at all stages of this work, and Mr A. Page for technical assistance. I also wish to thank Professor Boyd for permission to use the electron microscope in the Department of Anatomy.

There are two ways in which trematodes can be used in the control of other trematodes which transmit diseases of medical or veterinary importance. Either they can interfere with the reproductive capacity of the host species of snails, or they can exert an antagonistic effect against the larval stages of the target trematode species inside the snail. Often the two effects act together.

There are six essential criteria for the selection of a suitable species of snail for control: (1) complete and permanent sterilizing effect; (2) clear dominance over target trematodes; (3) strong infectivity to molluscs of all ages; (4) high egg productivity in the definitive host; (5) lack of pathogenicity towards man and domestic animals; (6) ease and low cost of maintenance of the life-cycle.

Various field trials are discussed and it is considered that trematode species producing rediae are usually dominant over those producing only sporocysts (such as the schistosomes). Most species used in control trials to date have belonged to the family Echinostomatidae as they have rediae, and eggs that can be produced in large numbers in a laboratory host such as the rat.

The mathematical basis and feasibility of control schemes are discussed and it is concluded that much more information is necessary before their potential can be evaluated.

In a recent paper (Nicoll, 1914) an account was given of the Trematode parasites occurring in the fishes of the English Channel, and at the same time an attempt was made to compare the records found in that locality with those in other British areas.

Juvenile hormone and its analogues inhibited growth of Panagrellus redivivus and of the free-living stages of Haemonchus contortus. Substances extracted from nematodes had similar actions and also showed the activity of juvenile hormone in insects. Partly purified material from 1 g of freezedried juveniles of H. contortus contained about 200 Tenebrio units.