At one of the meetings of the Royal Society of Tropical Medicine and Hygiene, I made a very short communication on the three blood-sucking midges (Jobling, 1929). My particular reference was to Culicoides vexans, which is the most troublesome and commonestspecies in spring, in the northern and the north-western suburbs of London. At that time I had been studying the life history of this midge, including the morphology of its eggs, larvae and the pupa, but this work was not completed.

Babesia sp. BQ1 (Lintan) is a Babesia isolated from sheep infested with Haemaphysalis qinghaiensis in China, and is closely related to B. motasi based on the 18S rRNA gene sequence. In the present study, an ELISA was developed with merozoite antigens of Babesia sp. BQ1 (Lintan) (BQMA) purified from in vitro culture. When the positive threshold was chosen as 30% of the antibodies rate, evaluated with 198 negative sera, the specificity was 95·5%. Except for Babesia sp. Tianzhu, there was no cross-reaction between BQMA and positive sera from Babesia sp. BQ1 (Ningxian)-, Babesia sp. Hebei-, Babesia sp. Xinjiang-, Theileria luwenshuni-, T. uilenbergi-, or Anaplasma ovis-infected sheep, which are the dominant haemoparasites of small ruminants in China. Specific antibodies against Babesia sp. BQ1 (Lintan) were produced 1 or 2 weeks post-infection and a high level of antibodies persisted for more than 8 months in experimentally infected sheep. This ELISA was tested on 974 sera collected from field-grazing sheep in 3 counties of Gansu province, northwestern China to evaluate the seroprevalence of Babesia sp. BQ1 (Lintan) infection and the average positive rate was 66·84%. The feasibility of increasing the specificity of this BQMA-based ELISA, by using some BQMA antigens for serodiagnosis is discussed.

The value of precipitin and intradermal tests as a means of diagnosing trichinosis in man and swine is discussed. The precipitin test appears to be reliable in detecting established trichinosis in swine, and with the conditions under which the observations were made, is highly specific. Established trichinosis in man has been invariably detected by the precipitin test, but its diagnostic value is greatly diminished by the fact that it is also positive with serum from individuals who have recently received quinine treatment for malaria. Certain other drugs appear to affect this reaction in a similar manner. The intradermal test appears to be specific for trichinosis in man and swine when high dilutions of the test antigen are used. The reaction is positive in the early stages of the disease and is of the immediate type in both of these hosts. A survey of swine has shown that the precipitin and intradermal tests are more accurate than muscle examination.

The transmission mechanisms of microsporidia between generations of Operophtera brumata, a geometrid moth with an univoltine life-cycle, have been investigated. The parasites, Orthosoma operophterae, Pleistophora operophterae and Nosema wistmansi were present in moths collected from Wistman's Wood on Dartmoor. An infection rate of 100% was found in eggs laid by moderately or heavily infected female moths. Thus, 100% infection was found in eggs laid by 78 out of 90 infected females. Lower prevalences were found in eggs laid by the remaining 12 and these moths were subsequently shown to have very light infections. Male moths do not pass on this infection to progeny. The development of O. operophterae was followed during embryonation. The microsporidia do not invade the cells of the developing larva but are restricted to the yolk, where spores accumulate in abundance after earlier merogonies. When the larva is mature and ready to hatch, spores are ingested with the remains of the yolk, as the larva eats its way through the egg-shell. Spores are then found in the meconium in the lumen of the gut. These spores are infective and, once the gut of the larva has become functional, are responsible for infecting the tissues of the larvae which harbour them, as well as healthy larvae reared with them. Spores of O. operophterae held in the natural environment for 7 months from winter until mid-summer still retained infectivity and those contaminating the environment from the bodies of one generation must contribute to transmission between generations.

Human and animal nanophyetiasis is caused by intestinal flukes belonging to the genus Nanophyetus distributed on both North American and Eurasian coasts of Northern Pacific. In spite of the wide geographical distribution and medical and veterinary importance of these flukes, the intra-generic taxonomy of Nanophyetus spp. remains unresolved. The two most widely distributed nominal species, Nanophyetus salmincola and Nanophyetus schikhobalowi, both parasitizing humans and carnivorous mammals, were described from North America and eastern Eurasia, respectively. However, due to their high morphological similarity their interrelationships remained unclear and taxonomic status unstable. In this study, we explored genetic diversity of Nanophyetus spp. from the Southern Russian Far East in comparison with that of samples from North America based on the sequence variation of the nuclear ribosomal gene family (18S, internal transcribed spacers, ITS1-5·8S-ITS2 and 28S). High levels of genetic divergence in each rDNA region (nucleotide substitutions, indels, alterations in the secondary structures of the ITS1 and ITS2 transcripts) as well as results of phylogenetic analysis provided strong support for the status of N. salmincola and N. schikhobalowi as independent species.

C57B1/6 male mice with chronic trichinellosis, and age-matched uninfected control mice, were inoculated with B16 melanoma cells. Tumour development was inhibited in the infected animals. In the infected tumour-bearing mice, the tumour induction intervals were longer and the tumour size was subsequently smaller than in the control mice. Moreover, when the number of tumour cells in the inoculum was less than that required to produce 100% tumour incidence in the uninfected mice (<1 × 104 cells), significantly more of the mice with an infection of 2 months duration remained tumour-free. These results were significant at the P<0·05 level.

Fructosamine concentrations reflect protein status and because infection with Teladorsagia circumcincta can induce a relative protein deficiency, we examined the usefulness of fructosamine concentrations as markers of the intensity of infection in naturally infected lambs. Fructosamine concentration was a heritable trait and variation in fructosamine concerntrations was associated with differences in body weight, and a variety of parasitological variables; animals with increased fructosamine concentrations grew more quickly, had increased faecal egg counts in one of the three study years, had decreased pepsinogen concentrations and decreased IgA activity against 4th-stage larvae of T. circumcincta. Fructosamine concentrations were also associated with variation in the subsequent acquisition of nematodes and in the length of adult female T. circumcincta; lambs with increased fructosamine concentrations had fewer nematodes but the mean length of adult female T. circumcincta was longer. Therefore fructosamine concentrations are potentially useful indicators of the severity of nematode infection and may predict magnitude of subsequent infection.

Components of the intricate ked-sheep pattern, of significance in dissemination of the ked, are defined. It was found that the dissemination potential (percentage of population on the fleece surface) on one sheep was constantly greater than on a second. Bright sunshine caused an increase in the dissemination potential, particularly on the first sheep. It was concluded that the stimulating factor was a rise in the fleece temperature in regions directly exposed to the rays of the sun.

The factor or factors causing differences in dissemination potential arose from similar degrees of temperature change being superimposed on inherently different fleeces. The sexes behaved similarly on both sheep.

Keds were able to transfer readily between the two sheep. However, when they were concentrated on the sheep with a high dissemination potential, the population of the two-sheep system declined rapidly; when they were placed on the sheep with a low dissemination potential, the population of the two-sheep system increased. Approximately half of the keds leaving the sheep with a high dissemination potential did not reach a second host. It thus acted as a disinfecting agent.

Bird and host predation were discounted as factors in causing ked population change.

Onchocerca volvulus proteins labelled with 125I were immunoprecipitated with onchocerciasis and lymphatic filariasis human serum pools in order to differentiate between cross-reacting and non-cross-reacting antigens. Analysis of the immunoprecipitates by two-dimensional gel electrophoresis revealed that all high molecular weight (Mr) O. volvulus antigens cross-reacted with the lymphatic filariasis serum pools. We observed, however, that at least 8 0. volvulus antigens were specifically immunoprecipitated only by the onchocerciasis serum pools, with Mr ranging from 20000 up to 43000 Daltons. These results suggest that the lower MrO. volvulus antigens are more species specific than the other antigens. The significance of these findings for the immunodiagnosis of onchocerciasis is discussed.

1. A parasitic spiral organism averaging 4 to 8μ long, with regular, closely set spirals about 0·75μ broad, has been found in the stomach in eight cats, none of which showed any obvious signs of gastric disturbance. The organisms occurred in the lumina of ducts and glands throughout the stomach, and also within the oxyntic cells. They were not seen in any part of the intestines except the very beginning of the duodenum, or in any other organ.

2. They are extremely active, and are readily stained by aniline dyes.

3. The mode of passage from one animal to another is not known, but food and faeces may be eliminated as possible sources of infection.

Blatticola monandros Zervos lives in the hind gut of the endemic New Zealand cockroach Parellipsidion pachycercum Johns. A field survey showed that infection prevalence was high (54 %) in small nymphs and increased further with cockroach size to a maximum (92 %) in penultimate nymphs. Variance to mean ratios and the Chi-square test for goodness of fit of a Poisson distribution provide strong evidence that the distribution of the nematode was not clumped (over-dispersed) or Poisson (random) but under-dispersed in most host size classes. The modal infrapopulation type consisted of 1 adult male and 1 adult female. Other infrapopulations were transitional to this type. Monogamous infrapopulations increased in prevalence with increased host size. Juvenile males were uncommon and probably develop faster into adults than juvenile females. Infrapopulations with 2 juvenile males were very rare and no cockroach contained 2 adult males, although some contained 2 adult females. Seasonal variations in prevalence and infrapopulation structure were slight over a 3 year period, except during one unusually dry summer. During the drought, prevalence of monogamous infrapopulations and of transitional infrapopulations were lowest, while prevalence of single-worm and single-sex infrapopulations were greatest. It is evident that competition between females reduces fecundity. When only 1 adult female nematode is present in an adult cockroach, more eggs are produced than the total produced if 2 adult females are present. Eggs were produced cyclically with short periods of high egg production interspersed with several days of very low or no egg production. Most eggs produced on any one day were attached to the outer surface of only 1 of the up-to-6 faecal pellets produced by the host/day. Mechanisms which may regulate infrapopulations and control reproductive competition and cyclical egg production are discussed. It is suggested that B. monandros regulates its own infrapopulation.

The number of adult Strongyloides ratti which developed in the guts of lactating rats after subcutaneous injection of 4000 L3 on day 18–20 post partum was taken to be a measure of the relative importance of alternative larval routes. When injection was carried out at different times before and after weaning, larvae were diverted from a route bypassing the gut in nursing mothers to one leading to the gut (‘migration reversal’) in mothers without young in a period of less than 10 h. Migration reversal was mostly completed in lactating females injected at the time of weaning when compared with nulliparous controls. A stimulus-sensitive period shortly after injection, predicted from these dynamics, was demonstrated. Worms injected into lactating females 10 h after removal from their pups showed complete migration reversal. In similarly treated rats, given 1 h suckling 3 h after injection, migration reversal was practically abolished. These inter-relationships, in conjunction with earlier findings, are used to deduce the possible humoral mechanisms involved and to develop a working hypothesis to account for larval orientation based on features of the mammalian pulmonary microvasculature.

The ultrastructure of the normal caecum of chickens and of chickens infected with Trichomonas gallinarum has been investigated. In infected caeca some villi and crypts of LieberkÜhn appear normal whereas others show marked changes in structure of the epithelial cells. The most obvious changes are loss of microvilli and glycocalyx and an increase in number of vesicles which stain metachromatically with Azur II. T. gallinarum has been detected between epithelial cells and in the lamina propria. Bacteria often, but not always, accompanied the protozoa in the tissues.

1. Choricotyle chrysophryi van Beneden & Hesse has been recorded for the first time since its original discovery in 1863, and from a new host Pagellus centrodontus (De la Roche).

2. The history of C. chrysophryi and of allied species has been reviewed, resulting in the substitution of the generic name Choricotyle van Beneden & Hesse, 1863 for Diclidophora Goto, 1894 and the family name Choricotylidae nov. for Diclidophoridae Fuhrmann, 1928.

3. The anatomy of Choricotyle chrysophryi has been investigated by means of serial sections, revealing specialized features in the presence of a terminal languette and of a ‘ring-organ’.

In the current study, phage-exposed mimotopes as targets against tegumentary leishmaniasis (TL) were selected by means of bio-panning cycles employing sera of TL patients and healthy subjects, besides the immune stimulation of peripheral blood mononuclear cells (PBMCs) collected from untreated and treated TL patients and healthy subjects. The clones were evaluated regarding their specific interferon-γ (IFN-γ) and interleukin-4 (IL-4) production in the in vitro cultures, and selectivity and specificity values were calculated, and those presenting the best results were selected for the in vivo experiments. Two clones, namely A4 and A8, were identified and used in immunization protocols from BALB/c mice to protect against Leishmania amazonensis infection. Results showed a polarized Th1 response generated after vaccination, being based on significantly higher levels of IFN-γ, IL-2, IL-12, tumour necrosis factor-α (TNF-α) and granulocyte-macrophage colony-stimulating factor (GM-CSF); which were associated with lower production of specific IL-4, IL-10 and immunoglobulin G1 (IgG1) antibodies. Vaccinated mice presented significant reductions in the parasite load in the infected tissue and distinct organs, when compared with controls. In conclusion, we presented a strategy to identify new mimotopes able to induce Th1 response in PBMCs from TL patients and healthy subjects, and that were successfully used to protect against L. amazonensis infection.

Epidemics in English crayfish, Astacus pallipes, were found to be due to micro-sporidia and yeasts similar to, if not identical with, those causing diseases in another Crustacean, namely, Gammarus pulex, in many parts of England.

In spite of the vast distribution and considerable impact on human and animal health of Ascaris suum and A. lumbricoides, little is known of the sexual biology and reproductive capacity of these intestinal nematodes. By oral transfer of adult female worms to previously parasite-naive pigs we show that in the absence of males the egg production ceases after 2–3 weeks. Such females readily resume egg production a few days after oral transfer of male worms. These observations throw light on an important aspect of Ascaris biology, but also pave the way for possible experimental interbreeding between the human and pig Ascaris species.

A 230000 molecular weight Plasmodium yoelii protective antigen was characterized. Two monoclonal antibodies against P. yoelii immunoprecipitated the 230000 mol. wt protein and a number of lower molecular weight polypeptides. These polypeptides were shown by peptide mapping and specific antibody binding to be fragments of the large protein. Iodination experiments suggested that the lower molecular weight species may be present on the surface of the merozoite. The protein was found not to be glycosylated. By serology, related antigens were shown to be associated with blood-stage schizonts of P. vinckei subspp., P. chabaudi subspp. and P. falciparum.

Ticks are blood-feeding arthropods widely distributed in the world and vectors of several diseases. As haematophagy demands evasion strategies and repeatedly infested hosts develop protective immune responses, we investigated the mechanisms of the Rhipicephalus (Boophilus) microplus saliva anti-haemostatic activity and the possible relationship between the acquired natural anti-tick host resistance and anti-haemostatic action. For this purpose, we studied the effects of R. microplus saliva on different pathways of haemostasis and tested whether repeated infested bovine sera (RIBS) are able to abolish salivary anti-haemostatic activities. R. microplus saliva (i) displays inhibitory activity upon collagen-induced platelet aggregation; (ii) inhibits the induction of endothelial pro-coagulant state; and (iii) reduces thrombogenesis in vivo. RIBS were shown to be able to partially block the delay of coagulation and the anti-thrombotic effect of saliva, and to totally abolish the modulation of endothelium activation. Conversely, RIBS has no effect on the inhibition of platelet aggregation. These results show, for the first time, the neutralization ability of sera from acquired resistance hosts against tick anti-haemostatics. Moreover, this is the first report of a haematophagous parasite able to modulate endothelial cell pro-coagulant state, and addresses the presence of anti-platelet and anti-thrombotic activity in R. microplus saliva.