Observations on the movement of fluids in the vicinity of the mouthparts of actively feeding female Dermacentor andersoni were made with the aid of trans-illuminated live-hamster pouch host-tissue. Following tick attachment and the invasion of ‘attaching cement’ into the outer skin layers, there appeared a progressive release of host blood as the tick settled into a feeding pattern. Short periods of sucking, each followed by an immediate ejaculation of saliva, became lengthened as feeding progressed, as did the resting intervals between sucking. Other movements brought about by the tick included a ‘toying’ of the tissue fluid, a rapid vibration of the same, and a distinct regurgitation of host-blood material. A sudden haemorrhage usually appeared at the feeding site about 2½ h after attachment of partially fed ticks.

Speculations are made concerning the part played by the release of tick saliva and tick water loss, its probable relationship to host paralysis, and its apparent role in tick nourishment.

The parasitic mite, Varroa destructor, is the most important threat for apiculture in most bee-keeping areas of the world. The mite is carried to the bee brood cell, where it reproduces, by a nurse bee; therefore the selection of the bee stage by the parasite could influence its reproductive success. This study investigates the role of the cuticular hydrocarbons of the European honeybee (Apis mellifera) in host-selection by the mite. Preliminary laboratory bioassays confirmed the preference of the varroa mite for nurse bees over pollen foragers. GC-MS analysis of nurse and pollen bees revealed differences in the cuticular hydrocarbons of the two stages; in particular, it appeared that pollen bees have more (Z)-8-heptadecene than nurse bees. Laboratory experiments showed that treatment of nurse bees with 100 ng of the pure compound makes them repellent to the varroa mite. These results suggest that the mite can exploit the differences in the cuticular composition of its host for a refined selection that allows it to reach a brood cell and start reproduction. The biological activity of the alkene encourages further investigations for the development of novel control techniques based on this compound.

Benzimidazole (BZ) resistance is widespread and appears to be readily selected in a variety of nematode parasites of animals. There have been reports of a lack of efficacy of BZ anthelmintics against soil transmitted nematode parasites of humans. However, resistance to BZs in nematodes of humans has not been confirmed. It is difficult to perform tests to confirm anthelmintic resistance in humans for a variety of technical and ethical reasons. The use of anthelmintic drugs for the control of helminth parasites in people is increasing massively as a result of numerous programmes to control gastrointestinal nematode parasites in children, the Global Program for the Elimination of Lymphatic Filariasis and other programmes. Many of these programmes are dependent on BZ anthelmintics and this will increase the pressure for resistance development to BZ anthelmintics in nematode parasites of people. We need to perform monitoring for anthelmintic resistance in these programmes and we need new tools to make that monitoring sensitive, inexpensive and practical. There is a real need for DNA-based markers for BZ resistance in nematode parasites of humans. We have a reasonable understanding of the molecular mechanisms and genetics of BZ resistance in some nematode parasites of animals and similar mechanisms are likely to prevail in nematodes of humans. Based on the likelihood that similar single nucleotide polymorphisms (SNPs) will be involved in BZ resistance in human, as in animal nematode parasites, rapid SNP assays have been developed for possible BZ resistance development in Wuchereria bancrofti.

Malarial gametocytes circulate in the peripheral blood of the vertebrate host as developmentally arrested intra-erythrocytic cells, which only resume development into gametes when ingested into the bloodmeal of the female mosquito vector. The ensuing development encompasses sexual reproduction and mediates parasite transmission to the insect. In vitro the induction of gametogenesis requires a drop in temperature and either a pH increase from physiological blood pH (ca pH 7·4) to about pH 8·0, or the presence of a gametocyte-activating factor recently identified as xanthurenic acid (XA). However, it is unclear whether either the pH increase or XA act as natural triggers in the mosquito bloodmeal. We here use pH-sensitive microelectrodes to determine bloodmeal pH in intact mosquitoes. Measurements taken in the first 30 min after ingestion, when malarial gametogenesis is induced in vivo, revealed small pH increases from 7·40 (mouse blood) to 7·52 in Aedes aegypti and to 7·58 in Anophěles stephensi. However, bloodmeal pH was clearly suboptimal if compared to values required to induce gametogenesis in vitro. Xanthurenic acid is shown to extend the pH-range of exflagellation in vitro in a dose-dependent manner to values that we have observed in the bloodmeal, suggesting that in vivo malarial gametogenesis could be further regulated by both these factors.

The environmental route of transmission is important for many protozoan and helminth parasites, with water, soil and food being particularly significant. Both the potential for producing large numbers of transmissive stages and their environmental robustness (with the ability to survive in moist microclimates for prolonged periods of time) pose persistent threats to public and veterinary health. Increased demands made on natural resources increase the likelihood of encountering environments and produce contaminated with parasites. In the last 30 years, endemic and epidemic waterborne and foodborne outbreaks in developed countries have led to a reappraisal of conventional isolation and detection methods. While these methods have proved invaluable in our understanding of environmental transmission routes for helminths, they have been less effective for the parasitic protozoa. Robust, efficient detection, viability and typing methods are required to assess risk and to further epidemiological understanding. Greater awareness of parasite contamination of our environment and its impact on health has precipitated the development of better detection methods. Currently, nowhere is this more apparent than with Cryptosporidium, with a broad range of immunological, microscopical and molecular methods available. The upsurge in molecular techniques, particularly the polymerase chain reaction, for determining occurrence and viability have brought with them the added benefits of increased sensitivity and specificity, yet many methods still have to be shown to address these issues consistently in the field. Rapid commercialization of reagents and standardization of methods provide consistency. The advances identified in non-destructive and destructive methods for the protozoa have application for helminths and emerging pathogens and should determine the importance of the matrices involved in the environmental transmission of parasites, further safeguarding public and veterinary health.

Growing evidence demonstrates that bacterial species diversity is substantial, and many of these species are pathogenic in some contexts or hosts. At the same time, laboratories and museums have collected valuable animal tissue and ectoparasite samples that may contain substantial novel information on bacterial prevalence and diversity. However, the identification of bacterial species is challenging, partly due to the difficulty in culturing many microbes and the reliance on molecular data. Although the genomics revolution will surely add to our knowledge of bacterial systematics, these approaches are not accessible to all researchers and rely predominantly on cultured isolates. Thus, there is a need for comprehensive molecular analyses capable of accurately genotyping bacteria from animal tissues or ectoparasites using common methods that will facilitate large-scale comparisons of species diversity and prevalence. To illustrate the challenges of genotyping bacteria, we focus on the genus Bartonella, vector-borne bacteria common in mammals. We highlight the value and limitations of commonly used techniques for genotyping bartonellae and make recommendations for researchers interested in studying the diversity of these bacteria in various samples. Our recommendations could be applicable to many bacterial taxa (with some modifications) and could lead to a more complete understanding of bacterial species diversity.

Ecdysteroids (moulting hormones), juvenoids and neuropeptides in ticks are reviewed but, by far, the emphasis is on the former since this class of hormones has been the subject of most investigations. In immature stages of ticks, ecdysteroids have been shown to regulate moulting and to terminate larval diapause. Although there is a paucity of information on the molecular action of ecdysteroids in ticks, their action appears to be via a heterodimeric ecdysone/ultraspiracle receptor, as in insects. The role of ecdysteroids in sperm maturation in adult males is considered. In females, ecdysteroids function in the regulation of salivary glands, of production of sex pheromones and of oogenesis and oviposition. There is evidence for ecdysteroid production in the integument and pathways of hormone inactivation are similar to those in insects. Ecdysteroids also function in embryogenesis. Although evidence for the occurrence and functioning of juvenile hormones in ticks has been contradictory, in recent thorough work it has not been possible to detect known juvenile hormones in ticks, nor to demonstrate effects of extracts on insects. Factors (neuropeptides) from the synganglion affect physiological processes and limited immunocytochemical studies are reviewed. Sigificantly, a G-protein-coupled receptor has been cloned, expressed, and specifically responds to myokinins.

Plasmodium ookinetes are elongate, motile and invasive while inside the mosquito gut but promptly metamorphose into spherical immobile oocysts upon coming in contact with the basement membrane surrounding the midgut. There they begin a prolonged growth period characterized by massive DNA synthesis for the production of sporozoites. Living Plasmodium gallinaceum ookinetes attached avidly to the murine extracellular matrix proteins, laminin and collagen type IV. In ELISA-type assays, the main ookinete surface protein, Pgs28 was implicated as a mediator of parasite attachment to these basement membrane constituents. Laminin and collagen IV adhered to ookinete and oocyst lysates spotted onto nitrocellulose membranes. Receptor–ligand blot assays demonstrated that Pgs28 and an oocyst-specific antigen recognized by the mAb 10D6 interact with murine collagen IV and laminin. 10D6 antigen was also recognized by monospecific antiserum against the human epidermal growth factor receptor. Mosquito-derived laminin was incorporated into oocyst capsules of P. gallinaceum growing in Aedes aegypti. We hypothesize that contact with the mosquito basement membrane triggers the transformation of ookinetes into oocysts. Coalescence of basement membrane proteins onto the capsules masks developing oocysts from the mosquito's immune system and facilitates their prolonged extracellular development in the mosquito body cavity.

European eels (Anguilla anguilla) from 2 sampling sites on the Rhine river (near Karlsruhe and near Worms) were investigated with respect to their parasite communities. Nine different metazoan species were found to live in and on the eels. The highest number of species was recorded from the intestine, which contained up to 6 different helminths. Among these, acanthocephalans were the most prevalent worms with the eel-specific parasite Paratenuisentis ambiguus as the dominant species of the intestinal component communities at both sites. Comparing the intestinal parasites from eels caught near Karlsruhe with those from Worms, the acanthocephalans showed a significantly lower abundance at Worms. A significantly lower mean number of intestinal helminth species as well as a significantly lower Brillouin's Index was found at Worms compared with Karlsruhe. This difference could be related to the abundance of the respective intermediate crustacean hosts. At the sampling site Worms the amphipod Corophium curvispinum was the dominant crustacean. Additionally, only the isopod Jaera istri and the amphipod Dikerogammarus villosus were found. All these crustacean species have only recently colonized the Rhine river system via the Main-Danube canal, built in the early 1990s. They are not known to act as intermediate hosts for any of the acanthocephalans found in the eels. The site near Karlsruhe exhibited a higher crustacean diversity, including Asellus aquaticus and different species of the genus Gammarus, which are all known intermediate hosts for the acanthocephalans found. Therefore, changes of eel parasite diversity can be correlated with the appearance of invading crustacean species (neozoans).

Aelurostrongylus abstrusus (Strongylida, Angiostrongylidae) and Troglostrongylus brevior (Strongylida, Crenosomatidae) are regarded as important lungworm species of domestic felids, with the latter considered an emerging threat in the Mediterranean region. The present study aimed to assess their concurrent development in the mollusc Helix aspersa (Pulmonata, Helicidae). Thirty snails were infested with 100 first-stage larvae (L1) of A. abstrusus and T. brevior, isolated from a naturally infested kitten. Larval development was checked by digesting five specimens at 2, 6 and 11 days post infestation. Larvae retrieved were morphologically described and their identification was confirmed by specific PCR and sequencing. All H. aspersa snails were positive for A. abstrusus and T. brevior, whose larval stages were simultaneously detected at each time point. In addition, snails were exposed to outdoor conditions and examined after overwintering, testing positive up to 120 days post infestation. Data herein presented suggest that A. abstrusus and T. brevior develop in H. aspersa snails and may eventually co-infest cats. Data on the morphology of both parasitic species in H. aspersa provide additional information on their development and identification, to better understand the population dynamics of these lungworms in receptive snails and paratenic hosts.

The genetic structure of Anisakis physeteris from the Mediterranean Sea has been analysed electrophoretically at 22 enzyme loci. The samples studied, although differing in the life-stage (larvae and adults), and in the host (the fishes Micromesistius poutassou and Trachurus trachurus, and the sperm whale Physeter macrocephalus) were genetically homogeneous. Of these loci 11 (Ldh, Sod, Np, Adk-2, Pgm-1, Est-1, Est-2, Acph-1, Acph-2, Lap-2 and Ca) were found to be monomorphic, while the other 11 (Sdh, Mdh, ldh, 6-Pgdh, G3pdh, Got, Adk-1, Pgm-2, Lap-1, Mpi and Gpi) showed from 2 to 7 alleles. The following values of genetic variability were estimated: He = 0·ll, P = 0·50, A = 1·95. Distinct alleles were found between A. physeteris and the A. simplex complex at 19 out of the 22 loci studied, and only few rare alleles were shared at the remaining 3 loci. The genetic divergence between A. physeteris and A. simplex A and B is therefore very high, the values of Nei’s index D being 7·384 and 6·443 respectively (I = 0·001 and 0·002). The assignation of A. physeteris and the A. simplex complex to two distinct subgenera, Skrjabinisakis and Anisakis, as proposed by Mosgovoy on a morphological basis, appears to be fully justified according to our genetic data.

Purified eosinophil and neutrophil cationic proteins isolated from the lysosomal secretion granules of human leucocytes have been tested for cytotoxic capacity against lung-stage schistosomula of Schistosoma mansoni in vitro. Eosinophil cationic protein (ECP) caused paralysis but not death at high concentration; this effect was reversible and involved no gross pathological manifestations. Eosinophil protein X (EPX) and neutrophil cationic protein (NCP) were highly toxic at concentrations of 10−5 mol/1, and induced paralysis at sublethal concentrations. These two proteins exerted their cidal effect principally against the subtegumental musculature and internal tissues of the parasite rather than against the surface syncytium and tegumental outer membrane. ECP and NCP were shown to bind to lung worms at paralysing concentrations, but this binding occurred independently of the charge of the parasite surface. Of several control proteins tested, only protamine was capable of destroying lung-stage parasites; the manifestations of damage were different, however, from those induced by the granulocyte-derived proteins. Parallel assays demonstrated that EPX also possessed cytotoxic capacity against newly transformed schistosomula, but it was less efficient than ECP in this respect. The data are discussed in relation to potential post-skin mechanisms of challenge attrition in the immunized host.

The ultrastructural morphology of selected microfilariae from four genera is described and compared. 1. The sheath is composed of a thick layer of material not limited by membranes. 2. The cuticle is composed of a trilaminate membrane, a dense cortical layer and an inner fibrous layer. The outer leaflet of the trilaminate membrane is covered with a dense surface layer. 3. The hypodermis is formed of four components, and the outer membrane of each component is castellated. 4. Muscle cells are located in the four quadrants of the worm; each cell is divided into a contractile and a non-contractile region. Anterior muscle cells are probably involved in the movement of the hook. 5. A buccal capsule is situated at the anterior tip of the microfilaria; it is connected to the pharyngeal thead. The thread is already surrounded by the future oesophageal cells. It is not yet known whether these structures are functional in the microfilaria. 6. Three kinds of sensory organelle have been identified; they all contain modified cilia. The hook is associated with one of the amphids. 7. The excretory vesicle opens through a pore in the cuticle and is surrounded at its base by an elongate cell. The apparatus may possibly have an excretory, secretory or osmoregulatory function. 8. The inner body is composed of dense, granular material; it is already surrounded by the future intestinal cells. The inner body is thought to represent some kind of reserve material. 9. Apart from its size the G1 cell shows no unusual characteristics. 10. The anal vesicle opens through a pore in the cuticle and is surrounded at its base by the three R cells. The anal apparatus may be instrumental in the removal of waste materials, or it may be involved in some secretory activity.

The ecology of Leishmania of man is concerned with the circulation of the parasite in nature from one mammal to another by the bite of phlebotomine sandflies. The natural vertebrate hosts are anthropocentrieally referred to as reservoir hosts although in sorac foci of human leishmaniasis (anthroponotic cutaneous leishmaniasis and Indian kala-azar) man himself is thought to be the reservoir.

Sheep in which abomasal fundic pouches had been made were infected with Ostertagia circumcincta (150000 larvae in one sheep, 100000 in three sheep). Subsequently studies were made on pouch secretion, food intake, plasma pepsinogens and abomasal pouch secretory responses when the sheep first ate. A functional abomasal lesion was apparent within 4 days of infection judged by the changes in plasma pepsinogen levels and the sodium concentrations of abomasal contents. Whereas the secretory activity of the abomasal fundic pouches (never exposed to parasites) was maintained or increased, the pH and sodium concentration of contents taken from the infected part of the abomasum were indicative of either a failure to secrete or of a permeability reabsorptive lesion. Ultrastructural studies demonstrated that parietal cells of the pouches had the appearance of cells subjected to strong secretory stimuli, but those of infected abomasa were similar to cells of gastric mucosa subjected to agents suppressing secretion. Factors which might operate, on the one hand, to stimulate secretion from separated fundic abomasal pouches, and on the other to inhibit or modify the secretory activity of the fundic mucosa of the infected abomasa, are discussed.

The pharyngeal component of the enteric nervous system of the parasitic nematode, Ascaris suum exhibits immunoreactivity for serotonin (5-hydroxytryptamine or 5-HT) and for FMRFamide-like peptides. This paper describes the application of an in vitro pharmacological approach to investigate the functional role of 5-HT and FMRFamide-like peptides. The pharyngeal pumping behaviour of Ascaris suum was monitored using a modified pressure transducer system which measures pharyngeal pressure changes and therefore pumping. The pharynx did not contract spontaneously; however, 5-HT (10-1000 μM) stimulated pumping at a frequency of 0·5 Hz. FMRFamide had no apparent effect on pharyngeal pumping. The native nematode FMRFamide-related peptide (FaRP), KSAYMRFamide inhibited the pumping elicited by 5-HT. The duration of inhibition was dose-dependent (0·1-1000 nM) with a threshold of 0·1 nM. In 4 preparations, the inhibition of the pharyngeal muscle was preceded by an initial excitation and increase in the amplitude of pharyngeal pressure changes. The pharynx is involved in various nematode processes, including feeding, regulation of hydrostatic pressure and excretion. The role of 5-HT and KSAYMRFamide in the pharyngeal function of nematodes is discussed.

Here we examined whether the recent dramatic decline in malaria transmission in Sri Lanka led to a major bottleneck in the local Plasmodium vivax population, with a substantial decrease in the effective population size. To this end, we typed 14 highly polymorphic microsatellite markers in 185 P. vivax patient isolates collected from 13 districts in Sri Lanka over a period of 5 years (2003–2007). Overall, we found a high degree of polymorphism, with 184 unique haplotypes (12–46 alleles per locus) and average genetic diversity (expected heterozygosity) of 0·8744. Almost 69% (n = 127) isolates had multiple-clone infections (MCI). Significant spatial and temporal differentiation (FST = 0·04–0·25; P⩽0·0009) between populations was observed. The effective population size was relatively high but showed a decline from 2003–4 to 2006–7 periods (estimated as 45 661 to 22 896 or 10 513 to 7057, depending on the underlying model used). We used three approaches – namely, mode-shift in allele frequency distribution, detection of heterozygote excess and the M-ratio statistics – to test for evidence of a recent population bottleneck but only the low values of M-ratio statistics (ranging between 0·15–0·33, mean 0·26) were suggestive of such a bottleneck. The persistence of high genetic diversity and high proportion of MCI, with little change in effective population size, despite the collapse in demographic population size of P. vivax in Sri Lanka indicates the importance of maintaining stringent control and surveillance measures to prevent resurgence.

Here we examine 3157 foxes from 6 districts of the Slovak Republic in order to determine for the first time the distribution, prevalence and identity of Mesocestodes spp. endemic to this part of central Europe. During the period 2001–2006, an average of 41·9% of foxes were found to harbour Mesocestoides infections. Among the samples we confirmed the widespread and common occurrence of M. litteratus (Batsch, 1786), and report the presence, for the first time, of M. lineatus (Goeze, 1782) in the Slovak Republic, where it has a more restricted geographical range and low prevalence (7%). Using a combination of 12S rDNA, CO1 and ND1 mitochondrial gene sequences together with analysis of 13 morphometric characters, we show that the two species are genetically distinct and can be differentiated by discrete breaks in the ranges of the male and female reproductive characters, but not by the more commonly examined characters of the scolex and strobila. Estimates of interspecific divergence within Mesocestoides ranged from 9 to 18%, whereas intraspecific variation was less than 2%, and phylogenetic analyses of the data showed that despite overlapping geographical ranges, the two commonly reported European species are not closely related, with M. litteratus more closely allied to North American isolates of Mesocestoides than to M. lineatus. We confirm that morphological analysis of reproductive organs can be used to reliably discriminate between these often sympatric species obtained from red foxes.

Here we describe the purification and characterization of a vitellin (VT) degrading cysteine endopeptidase (VTDCE) from eggs of the hard tick Boophilus microplus. A homogeneous enzyme preparation was obtained by chromatographic fractionation on ion-exchange and gel filtration columns and an autolysis step. This step consisted of incubation of a semipurified enzyme (after the first ion-exchange chromatography) at pH 4·0 that dissociated the enzyme from VT, to which VTDCE is naturally tightly associated. The enzyme purity was confirmed by capillary and native gel electrophoresis, and SDS–PAGE suggested the enzyme is a dimer of 17 and 22 kDa. VTDCE was active upon several synthetic substrates, with a preference for a hydrophobic or a basic residue in P1, and a hydrophobic residue in P2. VTDCE also hydrolysed haemoglobin, albumin, gelatin and vitellin. VTDCE is inactive in the absence of DTT and was totally inhibited by E-64, indicating it is a cysteine endopeptidase. Our results suggest that VTDCE is a major enzyme involved in yolk processing during B. microplus embryogenesis.

Macroparasites potentially play a significant but often ignored role in the ecology and dynamics of wild ruminant populations. In the Arctic, parasites may impact on host populations by exacerbating the effects of seasonal and limited forage availability on the condition, fecundity and survival of individuals. We studied the effects of abomasal nematode parasites and warble flies, Hypoderma tarandi, on condition and pregnancy of caribou Rangifer tarandus in the Dolphin-Union herd, Nunavut, Canada. By the end of winter, female caribou over 2 years old showed a significant decrease in body weight with increasing nematode burden, and a decrease in back fat depth with increasing warble abundance. These effects were exaggerated in the non-pregnant fraction of the population. High warble larvae burdens were also associated with significantly reduced probability of being pregnant. Our research demonstrates a negative relationship between parasites and caribou condition that may have consequences for their fitness. Additionally, we discuss the possibility that muskox Ovibos moschatus share some parasite species with the caribou and could lead to elevated burdens in the sympatric host. Parasites may have been a contributory factor in a previous winter range-shift of the caribou herd and this may reflect a form of apparent competition between the two ungulate species.