The epidemiology and genetic variability of 2 parasitic nematodes Heligmosomoides polygyrus and Syphacia stroma of Apodemus spp. were investigated. Both are parasites of the same host, exhibit a direct life-cycle and are dioecious. However, H. polygyrus has a diploid and S. stroma a haplodiploid mode of reproduction. Haplodiploidy may lead to a more female biased sex ratio and reduced genetic variability. Levels of genetic diversity were analysed using both isoenzyme electrophoresis and RAPDs (random amplified polymorphic DNA). Both parasites showed a female biased sex ratio with a stronger bias for the haplodiploid parasite. Results showed significantly fewer genetic polymorphisms as measured by RAPDs for the haplodiploid parasite S. stroma in comparison with H. polygyrus. Despite the observed female biased sex ratio this could not be explained by a significant amount of inbreeding. Heterozygote deficiency for individual allozyme loci – which could indicate inbreeding – was not found in either parasite species. Other features of the particular life-history of these species are likely to have an impact on the sex ratio and genetic variability too.

Cunliffe (1921) has shown that the various stages of Ornithodoros moubata may be distinguished by slight differences in the shape of the spiracles. Nuttall, Cooper and Robinson (1908) have described in detail the structure of the spiracles of another tick, Haemaphysalis punctata. Otherwise the spiracles of ticks have received little attention except from systematists, and though Nuttall and his collaborators described a closing mechanism in Haemaphysalis, no study of its function was made. In this paper I propose to describe the structure of the spiracle of Ornithodoros moubata, and show how its function may be investigated by experiments.

Study of the mode of action of the anti-parasitic ‘hydrogenophore’, closantel, revealed that mitochondria isolated from livers of untreated rats, 13 weeks after infection with Fasciola hepatica metacercariae, were uncoupled. This uncoupling of mitochondria might be induced by a product(s) excreted by the liver fluke. The lipid extractable product(s) binds to albumin and has a molecular weight between 500 and 1000 Daltons. A second unexpected finding indicates that closantel affects the motility of Schistosoma mansoni in vitro by interferin with mitochondrial ATP synthesis. The results obtained are suggestive of a role for aerobic metabolism in the generation of energy required for motility.

Trout acclimated to 20 °C could not be infected with Cryptobia salmositica. Those acclimated to 5 °C had longer pre-patent periods and considerably lower parasitaemias than those at 10 °C. Forty days after infection, the parasitaemias in fish at 10 °C fluctuated, while this was not observed in those at 5 °C. In vitro incubation of Cryptobia in plasma from 20 °C fish did not affect the motility nor the infectivity of the parasite. Fish infected at 15 °C (low parasitaemias and 2 weeks after inoculation) lost their infections when the ambient temperature was raised to 20 °C. However, in fish with more acute infections (4 weeks after inoculation), the parasitaemias were only substantially reduced when the ambient temperature was raised to 20 °C. Trypanosoma danilewskyi were detected in goldfish acclimated to 10, 20 and 30 °C. However, the parasitaemias in goldfish at 10 and 30 °C were consistently much lower than those at 20 °C.

1. Some account of the occurrence of “Hepaticola” hepatica in various hosts is given, and it is recorded from the wood-mouse (Apodemus sylvaticus) in England.

2. Some additions and corrections are made to the morphological des scription of “H.” hepatica, which is shown to possess characters (presence of “bacillary bands,” presence of a spicule in the male) the supposed absence of which had led to the erection of the genus Hepaticola as distinct from Capillaria.

3. The status of the genera Hepaticola, Eucoleus, Thominx, Calodium and Liniscus is discussed, and the conclusion is reached that these should all be suppressed as synonyms of Capillaria, which is redefined.

Glycans at the surface of adult Schistosoma mansoni were investigated with gold-labelled lectins. The fragile complex of the glycans with the outer membranes could be preserved for electron microscopy by avoiding extensive pre-fixation with aldehydes and by introducing osmium-ferrocyanide as a membrane fixative. Male and female worms were entirely covered with glycans that intensely bound lectins from Erythrina cristagalli and Datura stramonium, suggesting that galactose(β1–4)N-acetylglucosamine residues occur in high numbers in the surface glycans. Similar staining was obtained with lectins from Triticum vulgaris, Glycine max and Ricinus communis agglutinin I, which react with N-acetylglucosamine or terminal galactose residues and bind non-selectively with high affinity to N-acetyllactosamine. Fucose, N-acetylgalactose and sialic acid were not detected with lectins and sialidase treatment. The tegument contained an abundance of glycans with the same lectin reactivities as the surface-expressed molecules, indicating that the worms synthesize and replenish their surface glycans and do not merely adsorb host substances. Glycomimesis is discussed as a mechanism of immune evasion in view of N-acetyllactosamine being a common and weakly immunogenic component in glycans of vertebrate hosts. S. mansoni might disguise themselves with the glycans against attack by immune effectors.

Some callus tissues induced by 2,4–D and derived from plants resistant to plant-parasitic nematodes lost their resistance to the nematodes. Red clover callus supported a large population of A. ritzemabosi, whereas red clover seedlings did not. Six races of D. dipsaci were cultured on lucerne and red clover callus tissues and reproduced rapidly, although races usually multiplied more on callus from susceptible than from resistant plants. A. ritzemabosi, normally only a foliage parasite, reproduced equally well in stem and root callus. H. rostochiensis did not reproduce in callus culture.

Nematodes multiplied most in callus that grew fastest; both reproduction of A. ritzemabosi and the growth of callus were greatest with 0.125 mg/1 of 2,4–D. Reproduction was inhibited by 5.0 mg/100 ml of 2,4–D. 2,4–D influenced nematode reproduction indirectly by making callus, which provides a better environment for nematode feeding and reproduction.

Nematode extracts added to an agar medium caused callus formation on red clover seedlings and nematodes feeding on these tissues reproduced faster than on normal seedlings. Hence, the substances secreted by a nematode into a plant may act on the tissues in a manner similar to 2,4–D. The host–parasite relationship is probably partially controlled by the host's plant-growth substances and the effect on them of the nematode's secretions.

We thank Mr C. T. Drakes for assistance, and Mr K. Smith of Imperial Chemical Industries for advice with the initial callus culture.

1. Perispiracular glands are present in the larvae of Anopheles and Culex.

2. These glands secrete an oily substance which is responsible for the hydrofuge properties of the spiracular region of mosquito larvae.

3. The differential wetting of the spiracular region and the action of oil on mosquito larvae depend on the presence of this oily secretion.

Meerkats are one of the most endearing of South African's wildlife celebrities and one of the most highly studied social mammals. However, although parasites are widely recognized as important regulatory factors in animal population, basic knowledge on meerkats’ parasites is lacking. Here 100 fresh fecal samples of wild meerkats were examined for the presence of endoparasitic infection. Endoparasitic taxa identified by the presence of eggs or oocysts included Toxocara suricattae, Oxynema suricattae, Pseudandrya suricattae, Cystoisospora sp. and Eimeria sp. Non-specific diagnoses were made for parasites in the Order Strongylida, Order Spirurida and coccidian based on the morphology and size of the eggs and oocysts. The prevalence of infection with T. suricattae and the strongylate species increased with age, while prevalence of coccidia and intensity of infection by the strongylate species increased with decreasing group size, suggesting that stress associated with living in smaller group may increase susceptibility to parasitism. Moreover, parasite communities were more similar between individuals from the same group than between individuals from different groups, suggesting an important role of the environment in parasite infestation. We did not detect any differences between males and females. This study represents the first detailed report of gastrointestinal parasites in wild meerkats, and is a key starting point for future studies on the effect of endoparasite load in the life history of this species.

Parasites are known to have direct negative effects on host fitness; however, the indirect effects of parasitism on host fitness sans infection are less well understood. Hosts undergo behavioural and physiological changes when in proximity to parasites. Yet, there is little experimental evidence showing that these changes lead to long-term decreases in host fitness. We aimed to determine if parasite exposure affects host fitness independent of contact, because current approaches to parasite ecology may underestimate the effect of parasites on host populations. We assayed the longevity and reproductive output of Drosophila nigrospiracula exposed or not exposed to ectoparasitic Macrocheles subbadius. In order to preclude contact and infection, mites and flies were permanently separated with a mesh screen. Exposed flies had shorter lives and lower fecundity relative to unexposed flies. Recent work in parasite ecology has argued that parasite–host systems show similar processes as predator–prey systems. Our findings mirror the non-consumptive effects observed in predator–prey systems, in which prey species suffer reduced fitness even if they never come into direct contact with predators. Our results support the perspective that there are analogous effects in parasite–host systems, and suggest new directions for research in both parasite ecology and the ecology of fear.

The development of the vitellaria of Fasciola hepatica within the liver of its rat host was studied by means of whole-mount stained preparations and transmission electron microscopy, together with light and electron immunocytochemistry using an antibody to vitelline protein B, an eggshell precursor protein synthesized by F. hepatica. No vitelline cells could be identified in flukes recovered from the liver parenchyma, by any of the methods used. In contrast, follicles were present in flukes at the earliest time of recovery from the bile duct, namely, 5 weeks 3 days post-infection. The vitellaria in these flukes formed a row of small follicles on either side of the body. Development of the follicles was rapid: by 6 weeks 3 days, the vitellaria resembled those in the adult fluke and eggs were present in the uterus. Immunolabelling was confined to the shell protein globules in the vitelline cells, confirming the packaging of the eggshell protein within the shell globule clusters.

The prevailing hypothesis concerning the pathogenesis of toxoplasmic hydrocephalus alleges that (a) parasites invade and destroy the ependymal lining of the lateral ventricles, followed by (b) the sloughing of masses of degenerating ependymal and inflammatory cells leading to obstruction of the ventricular foramina and aqueduct of Sylvius, thereby initiating the hydrocephalus. Our observations in chronically infected mice indicate otherwise. Parasite invasion of the ependyma was not detected; the intraventricular masses of cellular ‘debris’ contained neither ependymal nor inflammatory cells; and obstruction of the ventricular foramina and/or aqueduct was not seen. As an alternative hypothesis, we suggest the development of hydrocephalus in the infected mice was consequent to severe leptomeningeal inflammation blocking the subarachnoid space and impeding the resorption of cerebrospinal fluid by the arachnoid villi. Narrowing of the aqueduct of Sylvius, when present, was adjudged the result, not the cause of the hydrocephalus, due to compression of the midbrain by the enlarging lateral ventricles.

Leishmaniasis is a widely spread and zoonotic disease with serious problems as low effectiveness of drugs, emergence of parasite resistance and severe adverse reactions. In recent years, considerable attention has been given to secondary metabolites produced by Photorhabdus luminescens, an entomopathogenic bacterium. Here, we assessed the leishmanicidal activity of P. luminescens culture fluids. Initially, promastigotes of Leishmania amazonensis were incubated with cell free conditioned medium of P. luminescens and parasite survival was monitored. Different pre-treatments of the conditioned medium revealed that the leishmanicidal activity is due to a secreted peptide smaller than 3 kDa. The Photorhabdus-derived leishmanicidal toxin (PLT) was enriched from conditioned medium and its effect on mitochondrial membrane potential of promastigotes, was determined. Moreover, the biological activity of PLT against amastigotes was evaluated. PLT inhibited the parasite growth and showed significant leishmanicidal activity against promastigote and amastigotes of L. amazonensis. PLT also caused mitochondrial dysfunction in parasites, but low toxicity to mammalian cell and human erythrocytes. Moreover, the anti-amastigote activity was independent of nitric oxide production. In summary, our results highlight that P. luminescens secretes Leishmania-toxic peptide(s) that are promising novel drugs for therapy against leishmaniasis.

Research on emerging infectious diseases calls for a work on collections of pathogens (including hosts or vectors from which the pathogens were isolated), related to human and animal health, to wildlife or on the environmental material. In this respect, the adoption of a One Health perspective is determined by the need for a common approach to consider the collection, storage and use of pathogens coming from human or non-human sources, and particularly when the same pathogen is taken from different environments. In response to this development, our purpose is to delineate a flexible regulation framework concerning collections of pathogens from various origins or hosts and their associated data in order to facilitate scientific work and research partnerships. The legal and ethical cutting-edge research on Biomedical Big Data is particularly stimulating when it comes to address challenges related to collections or biobanks of pathogens such as prior informed consent and accessibility, Material Transfer Agreement or benefit sharing.

Pneumocystis organisms are airborne-transmitted fungal parasites that infect the lungs of numerous mammalian species with strong host specificity. In this study, we investigated the genetic diversity and host specificity of Pneumocystis organisms infecting Southeast Asian murid rodents through PCR amplification of two mitochondrial genes and tested the co-phylogeny hypothesis among these fungi and their rodent hosts. Pneumocystis DNA was detected in 215 of 445 wild rodents belonging to 18 Southeast Asian murid species. Three of the Pneumocystis lineages retrieved in our phylogenetic trees correspond to known Pneumocystis species, but some of the remaining lineages may correspond to new undescribed species. Most of these Pneumocystis species infect several rodent species or genera and some sequence types are shared among several host species and genera. These results indicated a weaker host specificity of Pneumocystis species infecting rodents than previously thought. Our co-phylogenetic analyses revealed a complex evolutionary history among Pneumocystis and their rodent hosts. Even if a significant global signal of co-speciation has been detected, co-speciation alone is not sufficient to explain the observed co-phylogenetic pattern and several host switches are inferred. These findings conflict with the traditional view of a prolonged process of co-evolution and co-speciation of Pneumocystis and their hosts.

Montgomery (1917) showed that Nairobi sheep disease, a tick-borne gastro-enteritis of sheep and goats in East Africa, was caused by a filtrable virus transmitted most commonly by the brown tick, Rhipicephalus appendiculatus. The transmission of the disease by this tick was confirmed by Daubney & Hudson (1931, 1934), who demonstrated also that ticks infected in any instar usually transmitted the disease when fed in the succeeding stage on susceptible sheep; and that the virus ingested by a female fed on an infected sheep passed through the eggs to the larvae of the next generation.

Although results from field surveys have linked parasites to oxidative stress in their fish hosts, direct evidence involving experimentally infected hosts is lacking. We evaluated the effects of experimental infections with larval trematodes on induction of oxidative stress in fathead minnows, Pimephales promelas. Juvenile fish were exposed in the laboratory to the larvae (cercariae) of 2 species of trematode: Ornithodiplostomum sp. that develops in the liver, and O. ptychocheilus that develops in the brain. For Ornithodiplostomum sp., lipid peroxidation concentration in liver tissue increased 5 days after exposure and remained higher than controls until the end of the experiment at 28 days. For O. ptychocheilus, liver lipid peroxidation concentration was higher than controls at 5 days, but not thereafter. Sustained elevation in lipid peroxidation concentration for the liver trematode may be explained by direct tissue damage caused by developing larvae in the liver, or by an immune response. These experimental results support those from field studies, indicating that the lipid peroxidation assay may be an effective biomonitor for parasite-induced oxidative stress in fish, and that the nature of the oxidative stress response is species and/or tissue specific.

Since the construction of the Diama Dam (1985), the epidemiology of schistosomiasis along the Senegal River Basin (SRB) has been extremely dynamic with outbreaks of both intestinal and urogenital schistosomiasis. In the early 2000s, technicians reported cases of suspected urogenital schistosomiasis in adults from the local hospital in Richard-Toll, Lower SRB. The genetic analysis of schistosome miracidia isolated from 11 patients in 2012 from two neighbourhoods (Campement and Gaya) of Richard-Toll confirmed infection with Schistosoma haematobium but also S. haematobium/S. bovis hybrids. Thirty-seven per cent of the miracidia were S. bovis/S. haematobium hybrids and 63% were pure S. haematobium. The data are discussed in relation to the ongoing dynamic epidemiology of the schistosomes in Senegal and the need to treat non-target individuals.

In laboratory experiments, we investigated how media with varying ratio of peat:sand and two levels of compaction influence dispersal success of entomopathogenic nematode (EPN) species with different foraging strategies: Steinernema carpocapsae (ambusher), Heterorhabditis downesi (cruiser) and Steinernema feltiae (intermediate). Success was measured by the numbers of nematodes moving through a 4 cm column and invading a wax moth larva. We found that both compaction and increasing peat content generally decreased EPN infective juvenile (IJ) success for all three species. Of the three species, H. downesi was the least affected by peat content, and S. carpocapsae was the most adversely influenced by compaction. In addition, sex ratios of the invading IJs of the two Steinernema species were differentially influenced by peat content, and in the case of S. feltiae, sex ratio was also affected by compaction. This indicates that dispersal of male and female IJs is differentially affected by soil parameters and that this differentiation is species-specific. In conclusion, our study shows that organic matter: sand ratio and soil compaction have a marked influence on EPN foraging behaviour with implications for harnessing them as biological pest control agents.