The 70 kDa heat-shock protein (Hsp70) sequences are considered one of the most conserved proteins in all domains of life from Archaea to eukaryotes. Hammondia heydorni, H. hammondi, Toxoplasma gondii, Neospora hughesi and N. caninum (Hammondia-like organisms) are closely related tissue cyst-forming coccidians that belong to the subfamily Toxoplasmatinae. The phylogenetic reconstruction using cytoplasmic Hsp70 coding genes of Hammondia-like organisms revealed the genetic sequences of T. gondii, Neospora spp. and H. heydorni to possess similar levels of evolutionary distance. In addition, at least 2 distinct genetic groups could be recognized among the H. heydorni isolates. Such results are in agreement with those obtained with internal transcribed spacer-1 rDNA (ITS-1) sequences. In order to compare the nucleotide diversity among different taxonomic levels within Apicomplexa, Hsp70 coding sequences of the following apicomplexan organisms were included in this study: Cryptosporidium, Theileria, Babesia, Plasmodium and Cyclospora. Such analysis revealed the Hammondia-like organism to be the lowest divergent group when compared to other groups within the phylum Apicomplexa. In conclusion, the Hsp70 coding sequences proved to be a valuable genetic marker for phylogenetic reconstruction and may constitute a good candidate to be used with other genes for species phylogeny within this group of organisms.

Recent schistosomiasis control efforts in sub-Saharan Africa have focused nearly exclusively on treatment of humans with praziquantel. However, the extent to which wild mammals act as reservoirs for Schistosoma mansoni and therefore as sources of renewed transmission following control efforts is poorly understood. With the objective to study the role of small mammals as reservoir hosts, 480 animals belonging to 9 rodent and 1 insectivore species were examined for infection with schistosomes in Kisumu, in the Lake Victoria Basin, Kenya. Animals were collected from 2 sites: near the lakeshore and from Nyabera Marsh draining into the lake. A total of 6·0% of the animals captured, including 5 murid rodent species and 1 species of shrew (Crocidura olivieri) were infected with schistosomes. Four schistosome species were recovered and identified using cox1 DNA barcoding: S. mansoni, S. bovis, S. rodhaini and S. kisumuensis, the latter of which was recently described from Nyabera Marsh. Schistosoma mansoni and S. rodhaini were found infecting the same host individual (Lophuromys flavopunctatus), suggesting that this host species could be responsible for the production of hybrid schistosomes found in the area. Although the prevalence of S. mansoni infection in these reservoir populations was low (1·5%), given their potentially vast population size, their impact on transmission needs further study. Reservoir hosts could perpetuate snail infections and favour renewed transmission to humans once control programmes have ceased.

The prophylactic efficacy of autoclaved Leishmania donovani (ALD) and autoclaved L. major (ALM) – a heterologous vaccine developed against cutaneous leishmaniasis (used as a reference vaccine), along with BCG – was evaluated against L. donovani in hamsters (Mesocricetus auratus). Animals were immunized with triple doses (21 days apart) of either ALD or ALM (1·0 mg) with or without BCG (0·1 mg) and challenged 21 days later with 1×106L. donovani amastigotes intracardially. Animals immunized with ALM+BCG and ALD+BCG yielded 94·3% and 86·1% parasite inhibition respectively in comparison to the BCG only and unvaccinated controls. Fifty and 33·3% of the vaccinated animals (ALM+BCG and ALD+BCG respectively) were completely devoid of parasites when tested on day 45 post-challenge (p.c.) and survived till the experiment was terminated. The mean survival of ALM+BCG and ALD+BCG groups (animals harbouring parasites) was longest (168 and 139 days respectively). No significant increase in anti-leishmanial antibody level (ELISA) was noticed in ALD+BCG and ALM+BCG groups whereas it increased progressively in the rest of the experimental groups. The lymphoproliferative responses to PHA and Con A, of the 2 vaccinated groups were comparable to that of normal controls on day 45 p.c. The study suggests that ALD along with BCG can offer substantial protection against visceral leishmaniasis in hamsters.

Treatment of liver fibrosis associated with Schistosoma japonicum ova-induced granulomas remains a challenging proposition. Paeoniflorin (PAE, C23H28O11) has anti-inflammatory, anti-allergic, and immunoregulatory effects and it is commonly used in Chinese Herbal prescriptions to treat hepatic disorders. The present study was carried out to investigate the effects of PAE on hepatic fibrosis of mice infected with S. japonicum and to explore its possible mechanism. Upon pathological examination of PAE-treated mice, the size of egg granuloma, fibrosis scores, the concentration of IL-13 and hydroxyproline in liver were significantly reduced compared with the model mice. In the primary culture of hepatic stellate cells (HSCs), PAE inhibited IL-13-induced collagen synthesis. These results suggested that PAE might alleviate the hepatic granulomas and fibrosis caused by S. japonicum and the inhibitory effect of PAE on hepatic fibrosis might be associated with its ability to decrease the level of IL-13 and to interfere with the IL-13 signalling molecule in HSCs.

The resistance of captive reared red grouse to Trichostrongylus tenuis was measured as the proportion of ingested infective 3rd-stage larvae which failed to develop to adult worms. Individual grouse showed wide, repeatable variations in resistance. Seasonal variations may also have occurred. Red grouse acquired little or no effective immunity to reinfection after challenge with a single dose of infective larvae. In trickle-dosed grouse, however, adult worms weakly inhibited the establishment of incoming larvae in an intensity-dependent fashion. Despite this, the proportion of larvae established in trickle infections was similar to that in single-dose challenges.

The atmosphere plays a key role in plant disease, but only recently has it become understood that atmospheric pollutants can influence the response of plants to attack by pests and pathogens. This paper reviews the evidence for this phenomenon, considering impacts of sulphur dioxide, nitrogen dioxide and ozone, mainly on fungal pathogens and aphid pests. Field observations in polluted areas have indicated changes in abundance of pests and pathogens and in some cases a causal link has been demonstrated in controlled experiments. A major study is described in which consistent marked positive impacts of SO2 and NO2 have been shown on a range of British agricultural aphid pests, using four different approaches: fumigations, nitration studies, exposure along air pollution gradients and a nation-wide field survey. Ozone, in contrast, produces a more complex range of responses. These effects are apparently mediated via chemical changes in the plant. Fungal pathogens show both positive and negative responses to air pollutants. A study is described in which these opposite responses in two different fungal species were observed in a field SO2–fumigation system and confirmed in controlled laboratory fumigations. Models are presented to describe the complex pathways by which air pollutants could influence host plant performance via impacts on pests and pathogens.

When eggs of the monogenean parasite Entobdella hippoglossi, from the skin of the halibut (Hippoglossus hippoglossus), are incubated at 7 °C in alternating 12 h periods of dim blue light (intensity about 3 nW/cm2) and darkness, free-swimming larvae are recovered mostly at the end of the first 2 h of the period of darkness. Larvae do not emerge in significant numbers when the eggs are mechanically disturbed during the light or dark periods, or when the eggs are placed in shadow for periods of 5–25 min during the illumination period. The treatment of fully developed eggs with washings from halibut or from sole or with halibut skin mucus failed to produce hatching.

The free-swimming life of the larvae at 7 °C is in excess of 24 h and within 4 h of hatching at 4 °C some larvae are able to attach themselves to halibut skin and shed their ciliated epidermal cells.

The relationship between the hatching pattern of the eggs of the parasite and the behaviour of the halibut is discussed.

The behaviour of Heterodera schachtii second-stage juveniles in response to mustard (Sinapis alba) rooxudates was observed and analysed under aseptic conditions in a standardized bioassay. Aggregation of juveniles on an agarose layer occurred within less than 30 min in the area where root exudates had been applied and persisted for several hours. Analysis of time-lapse video recordings showed that the aggregation did not result from a directed orientation of the juvenile towards the root exudate. This was supported by an orientation assay using single juveniles. Aggregated juveniles showed pre-infection exploratory behaviour, including stylet thrusting and head-end bending, while staying at rest for several minutes.

Daily 1 mg doses of a cortisone derivative, betamethasone, caused an increase in oocyst production and extended the patent period of E. mivati infections in partially immunized chickens. The more prolonged the course of cortisone injections, the greater the effect, although this was substantial when only a single dose was given, especially if this was at or near to the time of oocyst inoculation. E. mivati infections in susceptible chickens were similarly affected but not to such a great extent.

The possible means whereby cortisone treatment reduces acquired immunity to E. mivati infection are discussed.

Thanks are due to Mrs P. Hesketh and to other members of the parasitology department for technical assistance, also to the senior poultry attendant for care of the animals. Mr C. C. Wannop examined several of the birds post mortem.

Five new species of Eimeria are described, viz. E. ablephari from Ablepharus boutonii (Scincidae), E. egerniae from Egernia whitii (Scincidae), E. gehyrae from Gehyra variegata (Gekkonidae), E. lampropholidus from Lampropholis guichenoti and E. leiolopismatis from Leiolopisma challengeri. The characters of these species and the other coccidia from lizards are tabulated and a host check-list is given. Gall bladder parasitism is discussed as is the significance of complete sporogony occurring within the host's body. Some ideas concerning the possible events occurring in the evolution of the Haemosporina are presented.

I wish to thank Miss J. Arnold of the Zoology Department, University of Western Australia, for her identification of many of the lizards and Miss S. Curtis for her drawings. Finally I wish to thank Dr H. M. D. Hoyte, Department of Parasitology, University of Queensland, for his interest and helpful criticism of the manuscript.

The effect of oxyclozanide (2,2′-dihydroxy-3,3′,5,5′,6-pentachlorobenzanilide) on Hymenolepis microstoma in the bile duct of mice, and H. diminuta in the small intestine of mice and rats was measured. Oxyclozanide at doses as low as 4mg/kg removed 13-day-old H. diminuta and caused no obvious harmful effect to the rat host up to the maximum level (256 mg/kg) tested. Worms were displaced and degenerating within 1 h. Results in mice were more difficult to assess because of the immune response, but similar total amounts of oxyclozanide caused destrobilation and loss of 7-day-old H. diminuta. Oxyclozanide was less effective against 21-day-old H. microstoma attached in the bile duct. Approximately half the strobila was lost following dosing at 5 mg/kg and progressively greater amounts as the dose level was increased. At 50 mg/kg worm loss commenced but even at 150 mg/kg 25 % of worms survived. The time taken to regrow to the original adult size varied but was complete within 7–9 days at levels up to 25 mg/kg. Double dosing at 5-day intervals did not enhance the effect of a single dose. The apparent existence of a sensitivity gradient down the strobila in H. microstoma is discussed.

Entomopathogenic nematodes of the genus Heterorhabditis are morphologically conservative, consequently the majority of isolates remain unassigned at the species level. When a Heterorhabditis infective juvenile infects an insect host, it develops into a protandrous hermaphrodite female. These first-generation females give rise to a second generation which contains both males and females. Because of this complex life-cycle and also because of uncertainty as to whether second-generation females are amphimictic, cross-breeding studies to facilitate species determination have not been carried out previously. We demonstrate here that second-generation Heterorhabditis females are amphimictic. Because of this finding, we have been able to develop a successful cross-breeding technique for the purposes of species determination in Heterorhabditis. Interstrain crosses using second-generation males and females from the appropriate strains have been successfully set up in Xenorhabdus luminescens-treated G. mellonella cadavers and also on agar plates. Using the techniques described here we confirm that H. bacteriophora (Brecon strain), H. megidis and H. zealandica are distinct biological species, we note that the H. bacteriophora group contains at least 2 species and we provide evidence for the existence of a new Irish species of Heterorhabditis.

An account is given of experiments on the aphistransmission of the composite virus disease of tobacco known as rosette. It is shown that the component viruses—the vein-distorting and mottle viruses—persist for long periods in the body of the aphis, and that as many as twenty consecutive tobacco plants can be infected in 24 hr. serial transfers without the insect having recourse to a fresh source of virus.

The aphis Myzus persicae is the most efficient vector, the aphis M. convolvuli being less effective. The aphides M. circumflexus and Macrosiphum gei failed to transmit the virus.

It is shown that the mottle virus can only be transmitted by the aphis when it is accompanied in the plant by the other component of the rosette disease, the vein-distorting virus. The latter virus is easily transmitted by the aphis, either alone or in combination with the mottle virus.

The writer's best thanks are due to Miss Margaret Short for her assistance with the large numbers of aphis-transmissions, and to Dr Douglas Lea and Dr Roy Markham for suggestions in the course of the work.

The shaping of a child's immune system starts in utero, with possible long-term consequences in later life. This review highlights the studies conducted on the development of the immune system in early childhood up to school-age, discussing the impact that environmental factors may have. Emphasis has been put on studies conducted in geographical regions where exposure to micro-organisms and parasites are particularly high, and the effect that maternal exposures to these may have on an infant's immune responses to third-party antigens. In this respect we discuss the effect on responses to vaccines, co-infections and on the development of allergic disorders. In addition, studies of the impact that such environmental factors may have on slightly older (school) children are highlighted emphasizing the need for large studies in low to middle income countries, that are sufficiently powered and have longitudinal follow-up components to understand the immunological footprint of a child and the consequences throughout life.

On parasitization with larval Brugia pahangi the infected flight muscle fibres of ‘resistant’ Anopheles labranchiae atroparvus undergo the following ultrastructural changes. The fibres become almost totally devoid of glycogen, their sarcoplasmic reticulum becomes elongate and closely associated with muscle fibrils. These fibrils degenerate and vesicles appear both within the degenerate fibril and within elements of the sarcoplasmic reticulum. Vesicles accumulate around the worm and degenerate to a uniform mass which eventually becomes melanized from its inner edge (next to the parasite) outwards.

The infected flight muscle fibres of both ‘resistant’ Aedes aegypti and ‘susceptible’ Aedes togoi are almost totally devoid of glycogen granules, but show no other ultrastructural change from the uninfected state.

We examined the effects of Haemoproteus infection on the survival and pathology caused in the biting midges. Forty-six females of Culicoides impunctatus were exposed experimentally by allowing them to feed on a naturally infected red-backed shrike infected with Haemoproteus lanii (lineage hRB1, gametocytaemia 5·2%). Seventeen females were fed on an uninfected bird (controls). Dead insects were collected, counted and used for dissection, histological examination and polymerase chain reaction-based testing. Parasites were present in all experimentally infected biting midges, but absent from control insects. Survivorship differed significantly between the control and infected groups. Twelve hours post-exposure (PE), 45 (98%) experimentally infected midges were dead, but all control midges remained alive, and many of them survived until 7 day PE. The migrating ookinetes of H. lanii overfilled midgut, markedly damaged the midgut wall, entered the haemocoel and overfilled the abdomen and thorax of exposed biting midges. Massive infection by migrating ookinetes led to damage of abdomen and thorax of biting midges. The parasites often present in large clumps in the haemocoel in abdomen and thorax, leading to the interruption of the haemolymph circulation. These are the main reasons for rapid death of biting midges after feeding on high-intensity infections of Haemoproteus parasites.

Trypanosoma (Megatrypanum) theileri from cattle and trypanosomes of other artiodactyls form a clade of closely related species in analyses using ribosomal sequences. Analysis of polymorphic sequences of a larger number of trypanosomes from broader geographical origins is required to evaluate the clustering of isolates as suggested by previous studies. Here, we determined the sequences of the spliced leader (SL) genes of 21 isolates from cattle and 2 from water buffalo from distant regions of Brazil. Analysis of SL gene repeats revealed that the 5S rRNA gene is inserted within the intergenic region. Phylogeographical patterns inferred using SL sequences showed at least 5 major genotypes of T. theileri distributed in 2 strongly divergent lineages. Lineage TthI comprises genotypes IA and IB from buffalo and cattle, respectively, from the Southeast and Central regions, whereas genotype IC is restricted to cattle from the Southern region. Lineage TthII includes cattle genotypes IIA, which is restricted to the North and Northeast, and IIB, found in the Centre, West, North and Northeast. PCR-RFLP of SL genes revealed valuable markers for genotyping T. theileri. The results of this study emphasize the genetic complexity and corroborate the geographical structuring of T. theileri genotypes found in cattle.

The Global Program for the Elimination of Lymphatic Filariasis (GPELF) intends to achieve its aims through yearly mass treatments with albendazole (ABZ) combined with ivermectin (IVM) or diethylcarbamazine (DEC). The use of ABZ and IVM separately to combat parasites of veterinary importance has, on many occasions, resulted in widespread drug resistance. In order to help predict the spread of potential ABZ resistance alleles through a population of Wuchereria bancrofti, we have developed a mathematical model that incorporates population genetics into EPIFIL, a model which examines the transmission dynamics of the parasite. Our model considers the effect of the combined treatments on the frequency of a recessive allele, which confers ABZ resistance. The model predicts that after 10 yearly treatments with ALB and DEC, 85% coverage and an initial resistance allele frequency of 5%, the frequency of the resistance genotype will increase from 0·25 to 12·7%. If non-random mating is assumed, the initial genotype frequency will be 2·34% and will increase to 62·7%. ABZ and IVM combination treatment may lead to weaker selection for this genotype. Treatment coverage, initial allele frequencies and number of treatments also affect the rate of selection.

Leishmania produce several types of mucin-like glycoproteins called proteophosphoglycans (PPGs) some of which are secreted while others are found on the surface of promastigotes and amastigotes. These proteins are thought to be important in the transmission, invasion and subsequent intracellular survival of parasites. The structure and function of PPGs are species and stage-specific in the case of L. major and L. mexicana, but no such information has hitherto been available for L. donovani. This study presents, for the first time, an initial characterization (localization) of PPG in sodium stibogluconate (SSG)-resistant and sensitive clinical isolates of L. donovani from Bihar (India) by confocal microscopy, flow cytometry and Western blotting using antibodies to L. major PPG. Confocal microscopy analysis revealed that both promastigotes and amastigotes possess PPG on their cell membrane and flagellar pocket membrane but its expression was variable in different isolates. The quantitative analysis by FACS and Western blotting showed that the expression and intensity of PPG bands was higher in SSG-resistant isolates. This study suggests the possibilities of involvement of PPG in drug-resistant mechanisms and of using PPG abundance as a marker for identifying drug-resistant clinical isolates in Indian kala azar.

Studies of population genetic structure of parasites can be used to infer which parasite genes are under selection. Here, the population structure of 4 genes associated with drug resistance of Plasmodium falciparum (the chloroquine resistance transporter, pfcrt, dihydrofolate reductase, dhfr, dihydropteroate synthase, dhps, and multi-drug resistance, pfmdr-1) were examined in parasite populations in 3 villages in eastern Sudan and in an urban area of Khartoum, the capital. In order to differentiate the effects of drug selection from neutral influences on population structure, parasites were also genotyped for 3 putatively neutral microsatellite loci (polyα, TA81 and pfg377), and for 2 antigenic loci that are either under balancing selection or neutral, merozoite surface protein 1 and 2, (MSP-1 and MSP-2). Cross-sectional surveys were carried out during the peak transmission (wet) season and in the ensuing dry season. No significant variation in frequencies of MSP-1 and MSP-2 alleles was seen among villages in the eastern region and between the villages and Khartoum, nor between the wet and dry season. However, the drug resistance genes, pfmdr-1, pfcrt and dhfr and to a lesser extent the microsatellite loci showed high FST values when comparing villages with Khartoum, indicating strong geographical differentiation at these loci. Moreover, variation in frequencies of the drug resistance genes, pfmdr-1, pfcrt and dhfr, was observed between the wet and dry season. These differences most probably reflect the variation in drug pressure between each region, and in drug usage between the wet and dry season in a given region.