Red fox (Vulpes vulpes) is the most abundant wild canid species in Austria, and it is a well-known carrier of many pathogens of medical and veterinary concern. The main aim of the present study was to investigate the occurrence and diversity of protozoan, bacterial and filarial parasites transmitted by blood-feeding arthropods in a red fox population in western Austria. Blood (n = 351) and spleen (n = 506) samples from foxes were examined by PCR and sequencing and the following pathogens were identified: Babesia canis, Babesia cf. microti (syn. Theileria annae), Hepatozoon canis, Anaplasma phagocytophilum, Candidatus Neoehrlichia sp. and Bartonella rochalimae. Blood was shown to be more suitable for detection of Babesia cf. microti, whilst the spleen tissue was better for detection of H. canis than blood. Moreover, extremely low genetic variability of H. canis and its relatively low prevalence rate observed in this study may suggest that the parasite has only recently been introduced in the sampled area. Furthermore, the data presented here demonstrates, for the first time, the possible vertical transmission of H. canis from an infected vixen to the offspring, and this could explain the very high prevalence in areas considered free of its main tick vector(s).

This paper describes a mathematical model which allows us to compare the data collected from short-term cross-sectional surveys with the population dynamics of host and parasite populations over longer periods of time. The model extends an earlier framework for two parasite species in one host, to one for an arbitrary number of parasite species. We show that the conditions necessary for the coexistence of two parasite species extend to expressions for the coexistence of three or more parasite species. Furthermore, the model suggests that those species which form the ‘core’ of the parasite community are those whose high fecundity and transmission efficiency permit them to colonize hosts readily. In contrast, those species which are classified as ‘satellite’ species of the community are either species with low fecundity, or low transmission efficiencies. This work confirms earlier studies that suggest that increasing degrees of aggregation are crucial in allowing several species of parasites to coexist in the same species of hosts.

The properties of the model are compared with patterns observed in data collected for helminth parasites of Anolis lizards, wood mice and eels. This combined theoretical and empirical approach confirms the importance of the life history strategies of the parasite in determining the abundance of each species in the community. It suggests that studies of parasite community structure have to pay more attention to the strategies pursued by each individual species before interactions between species are considered.

Representative samples of Ugandan Schistosoma mansoni from Lake Albert and Lake Victoria were examined using DNA barcoding, sequence analysis of two partially overlapping regions – ASMIT (396 bp) & MORGAN (617 bp) – of the mitochondrial cytochrome oxidase subunit I (cox1). The Victorian sample exhibited greater nucleotide diversity, 1·4% vs. 1·0%, and a significant population partition appeared as barcodes did not cross-over between lakes. With one exception, Lake Albert populations were more mixed by sampled location, while those from Lake Victoria appeared more secluded. Using statistical parsimony, barcode ASMIT 1 was putatively ancestral to all others and analysis of MORGAN cox1 confirmed population diversity. All samples fell into two of five well-resolved lineages; sub-lineages therein broadly partitioning by lake. It seems that barcode ASMIT 1 (and close variants) was likely widely dispersed throughout the Nilotic environment but later diversified in situ, and in parallel, within Lake Albert and Lake Victoria. The genetic uniformity of Ugandan S. mansoni can no longer be assumed, which might better explain known epidemiological heterogeneities. While it appears plausible that locally evolved heritable traits could spread through most of the Lake Albert populations, it seems unlikely they could quickly homogenise into Lake Victoria or amongst populations therein.

The effect of bait-delivered anthelmintic to reduce the prevalence of Echinococcus multilocularis in wild red foxes was evaluated in Koshimizu, in the eastern part of Hokkaido, Japan. The study area (200 km2) was divided into baited and non-baited sections. The anthelmintic baits were distributed around fox den sites in the baited section every month for 13 months. After 1 year of the anthelmintic bait distribution, the prevalence of E. multilocularis in foxes, evaluated either by the parasite egg examination (from 27.1 to 5.6%) or coproantigen ELISA (from 59.6 to 29.7%), decreased in the baited section contrasting to that in the non-baited section (parasite egg: from 18.8 to 24.2%; ELISA: from 41.9 to 45.8%). The prevalence of E. multilocularis in grey red-backed vole Clethrionomys rufocanus, caught around fox dens, born after bait distribution also decreased and was significantly lower than that in non-baited section. However, within the study periods, the coproantigen-positive rate in fox faeces sporadically increased, while egg-positive rate constantly decreased. Since coproantigen ELISA can detect pre-patent infection, this observation indicates that reinfection pressure in the baited section was still high even after the 13 months of anthelmintic bait distribution. Therefore, the bait distribution longer than our study period is required for the efficient control of E. multilocularis in wild red fox population.

Manuls or Pallas' cats (Felis manul, syn. Otocolobus manul) are endangered wild cats from Central Asia kept and bred in many zoos. Despite good breeding success young cats frequently die from acute toxoplasmosis. From 1998 to 2002, a breeding pair in the Schönbrunn Zoo in Vienna, Austria, gave birth to 24 kittens; 58% of kittens died between the 2nd and the 14th week of life, mostly due to acute toxoplasmosis. The epidemiology of toxoplasmosis in Pallas' cats was examined and a control strategy to protect the kittens from fatal toxoplasmosis was developed. One 12-week-old kitten from a litter of 6 born in 2001 died of generalized toxoplasmosis. This kitten had shed T. gondii oocysts that were bioassayed in mice. Toxoplasma gondii was isolated in tissue culture inoculated with tissues of these mice. The surviving animals were immediately treated with clindamycin for 16 weeks; they acquired a natural infection and seroconverted by the end of this time without clinical signs.

Immune serum accelerated the expulsion of Trichuris muris when transferred into normal mice on days 0 and 3 after infection, but had no effect when the recipient mice had been immunosuppressed by sublethal irradiation or by cortisone treatment. Delaying serum transfer until days 7 and 8 in normal mice failed to accelerate expulsion, although immune mesenteric lymph node cells (MLNC) accelerated expulsion whether transferred early or late in infection.

Expulsion from NIH mice, normally complete by 12 days, was prevented by sublethal irradiation given as late as 9 days after infection, but could be restored by subsequent transfer of immune MLNC or, to a lesser degree, non-immune MLNC. Immune MLNC were unable to restore worm expulsion in mice irradiated before infection.

These results are interpreted as showing that the immune expulsion of T. muris from mice during a primary infection requires the sequential activities of antibody-mediated and lymphoid cell-mediated components.

Knowledge about how parasites choose their hosts is scarce and incomplete. Recent work has primarily focused on host health (i.e. immunocompetence) whereas ecological factors have been largely neglected. Here we investigate whether the immunocompetence, the nutritional condition or body size of nestling European bee-eaters Merops apiaster are used as parameters for habitat choice of the haematophagous fly Carnus hemapterus. We found that (i) flies consistently and non-randomly preferred larger nestlings, even after controlling for differences in habitat availability (host surface), (ii) in the presence of similar-sized hosts, parasites' choice for an individual was less likely than if hosts differed in size, (iii) the more the hosts differed in size, the more the parasites aggregated on the larger nestling and (iv) parasites changed their preference according to size criteria regardless of the identity of the larger host. Neither immunocompetence nor host body condition could account for parasites' preference. Our results do not support the prediction of the Tasty Chick Hypothesis, namely that the poor immunocompetence ability of junior chicks makes them more attractive to parasites. We conclude that basic ecological factors (e.g. body size) can be essential for parasites when choosing a host.

The objective of the present study was to evaluate the anticoccidial effect of different concentrations of the herbal complex of 4 plants (leaves of Azadirachta indica and Nicotiana tabacum, flowers of Calotropis procera and seeds of Trachyspermum ammi) in broiler chickens in comparison with amprolium anticoccidial. Three concentrations (2 g, 4 g and 6 g) of herbal complex were given to the experimental groups once a day and amprolium (at the dose rate of 125 ppm) was given orally in drinking water from the 14th to the 21st days of age. One group was kept as infected, non-medicated control and one as non-infected, non-medicated control. All groups were inoculated orally with 75 000 sporulated oocysts on the 14th day of age except the non-infected, non-medicated control. Among herbal complex medicated groups, the maximum anticoccidial effect was seen in the group medicated with 6 g herbal complex followed by 4 g and 2 g herbal complex medicated groups. Treatment with 6 g of the herbal complex significantly reduced the negative performance and pathogenic effects associated with Eimeria tenella challenge at a level that was comparable with amprolium when using a largely susceptible recent field isolate. In summary, concentration-dependent anticoccidial activity of the studied herbal complex suggests its use as an alternative anticoccidial agent to chemotherapeutic drugs for Eimeria tenella control.

1. Heat is an important factor in stimulating bed bugs to obtain food. Light and atmospheric humidity do not influence the reactions to heat to any great extent, but the state of nutrition and moulting do interfere with them.

2. The bug detects heat very slowly. At a room temperature of 23° C., from a distance of 4 cm., about 1½ min. were required before a bug reacted to the heat of the hand. At a lower temperature a longer period was required.

3. At ordinary room temperature a differential temperature of about 2° C. was necessary to cause a reaction to heat.

4. Bed bugs, although attracted to heat, will be repelled when the temperature is too high. Bugs were repelled by objects at 43° C. at a distance of about 3 cm.

5. Bed bugs have a sense of smell, but only react when very close to the odoriferous substance.

6. The odours of blood, muscle, subcutaneous tissue and clean, washed skin seemed to have no influence upon the bug; the odour of bile repels them; while liver at first attracted and then repelled them.

7. The odour of perspiration, depending upon its state of decomposition, sometimes repels and at others attracts bed bugs. Of the substances tested the odours of sebum and cerumen had the greatest attracting power.

8. The bed bug apparently discriminates between foods by taste.

9. Negative reactions to water counterbalance positive reactions to heat and odour.

10. The tendency to be in contact with an object, rather than the negative reaction to light, underlies the gregarious habit of the bed bugs as well as their search for places of retreat.

An account is given of the life cycle and morphology of T. grayi in the crocodile (Crocodilus niloticus) and in the tsetse-fly (Glossina palpalis). The immunological relations of this trypanosome to its hosts and its affinities to other species are also dealt with.

T. grayi belongs to the group of trypanosomes developing in the posteriorstation of the invertebrate host and transmitted by the contaminative method (“lewisi group”).

T. grayi occurs in very small numbers in the crocodile and is concentrated chiefly in the peripheral circulation of the skin (about 200 parasites per 1 c.c. of blood). It is one of the largest trypanosomes, the blood forms measuring up to 91μ

When fed on an infected crocodile the tsetse-fiy takes up not more than about six trypanosomes. These commence their development in the mid-gut, giving rise to crithidial and trypanosome forms, and later extend to the hind-gut where their evolution is completed and the infective metacyclic trypanosomes are produced. These, when voided with the faeces, serve to infect the crocodile per os.

Since the incubation period of T. grayi in the crocodile is about four days, this is the time required for the small metacyclic trypanosomes to develop into the large blood forms.

The distribution of T. grayi in the gut of the fly in the course of its development is determined by the presence of the peritrophic membrane and involves three successive waves of migration in opposite directions: (1) From the intraperitrophic space backwards, into the colon, thence (2) forwards into the extraperitrophic space up to and including the mid-gut; and finally (3) they again migrate backwards, to the hind-gut. (Diagrams of the life cycle and distribution of T. grayi in Glossina are given in Text-figs. 2 and 3.)

Evidence is produced to show that the so-called “cysts” of T. grayi described by previour authors are really artifacts.

Apparently the majority of crocodiles in Victoria Nyanza harbour T. grayi. The trypanosome has no harmful efleet upon the crocodile and it was proved that the infection can persist for more than two years.

The crocodile appears to possess a natural partial or tolerance immunity against T. grayi, which does not protect it from invasion by the parasite, but maintains its numbers at a constantly low level.

The infection rate in the experimental tsetse-ffies is very high (average 61 per cent.) in the early days of infection, but later f ails to an average of 17·3 per cent. The majority of the flies, originally fully susceptible to infection, appear to acquire an immunity after the fifth day.

The average degree of infection in “wild” flies is 11·2 per cent. This compares closely with that in the experimental flies. Hence it is inferred that the majority of these flies had fed in nature on infected crocodiles.

T. grayi is closely allied to trypanosomes of the “lewisi group” and to some of the trypanosomes of land reptiles and amphibia. On the strength of the clifterence existing between these two groups of trypanosomes, some modification in the accepted classification of these species is introduced.

A name, T. theodori sp.n., is proposed for the goat trypanosome described by Theodor (1928).

Giardia lamblia, a protozoan parasite, infects a wide variety of vertebrates, including humans. Studies indicate that this anaerobic protist possesses a limited ability to synthesize lipid molecules de novo and depends on supplies from its environment for growth and differentiation. It has been suggested that most lipids and fatty acids are taken up by endocytic and non-endocytic pathways and are used by Giardia for energy production and membrane/organelle biosynthesis. The purpose of this article is to provide an update on recent progress in the field of lipid research of this parasite and the validation of lipid metabolic pathways through recent genomic information. Based on current cellular, biochemical and genomic data, a comprehensive pathway has been proposed to facilitate our understanding of lipid and fatty acid metabolism/syntheses in this waterborne pathogen. We envision that the current review will be helpful in identifying targets from the pathways that could be used to design novel therapies to control giardiasis and related diseases.

Chagas' disease, caused by the protozoan Trypanosoma cruzi, represents a serious health problem in Latin America, and the available chemotherapy, which is based on 2 nitro-derivatives, is not satisfactory. In folk medicine, natural products including naphthoquinones have been employed for the treatment of different parasitic diseases. In the pursuit of alternative drugs for Chagas' disease, we investigated the mechanism of action of the triazolic naphthoquinone (TN; 2,2-dimethyl-3-(4-phenyl-1H-1,2,3-triazol-1-yl)-2,3-dihydronaphtho[1,2-b]furan-4,5-dione), which is the most active compound against T. cruzi trypomastigotes among a series of naphthofuranquinones. TN was active against the 3 parasite forms producing a dose-dependent inhibitory effect. In epimastigotes, TN induced reservosome disruption, flagellar blebbing, Golgi disorganization, the presence of cytosolic concentric membrane structures and abnormal multiflagellar parasites. The treatment also led to the appearance of well-developed endoplasmic reticulum profiles surrounding organelles that associated with an increase in monodansylcadaverine labelling, suggesting autophagy as part of the TN mechanism of action. Interestingly, no ultrastructural damage was detected in the mitochondria of naphthoquinone-treated epimastigotes. Flow cytometric analysis demonstrated an impairment of mitosis, an increase in ROS production and the maintenance of mitochondrial membrane potential. TN could be a good starting point in the investigation of a chemotherapeutic approach for the treatment of Chagas' disease.

Similarities in the immunobiology of different parasitic worm infections indicate that co-evolution of humans and helminths has shaped a common anti-helminth immune response. However, recent in vitro and immuno-epidemiological studies highlight fundamental differences and plasticity within host-helminth interactions. The ‘trade-off’ between immunity and immunopathology inherent in host immune responses occurs on a background of genetic polymorphism, variable exposure patterns and infection history. For the parasite, variation in life-cycle and antigen expression can influence the effector responses directed against them. This is particularly apparent when comparing gastrointestinal and tissue-dwelling helminths. Furthermore, insights into the impact of anti-helminthic treatment and co-infection on acquired immunity suggest that immune heterogeneity arises not from hosts and parasites in isolation, but also from the environment in which immune responses develop. Large-scale differences observed in the epidemiology of human helminthiases are a product of complex host-parasite-environment interactions which, given potential for exposure to parasite antigens in utero, can arise even before a parasite interacts with its human host. This review summarizes key differences identified in human acquired immune responses to nematode and trematode infections of public health importance and explores the factors contributing to these variations.

The lack of an adequate model for Leishmania (Viannia) braziliensis infection is a limiting factor for studying American tegumentary leishmaniasis (ATL). The golden hamster (Mesocricetus auratus) is a promising model because besides being highly susceptible to dermotropic Leishmania infection, the lesions are very similar to cutaneous leishmaniasis (CL) in humans. However, different Leishmania isolates or species and/or protocols have resulted in different outcomes, whereas no study has evaluated the reproducibility of L. braziliensis infection in this model. The natural history of L. braziliensis infection in 34 hamsters was evaluated by using a single parasite isolate in 8 independent experiments under similar experimental conditions. Clinical, histological and immunological analyses were performed. The hamsters presented skin ulcers similar to those observed in ATL. The intra-experiment lesion increment tended to show an intermediary variance. Histological analysis of infected skins showed granulomatous reaction, scarce amastigotes, and Schaumann's bodies. Blood lymphocytes proliferated in response to leishmanial antigens. The severity of the infection was positively correlated to spleen weight, and the titres of anti-Leishmania IgG antibodies. Our findings indicate that the hamster is an appropriate model for immunopathogenesis studies of CL caused by L. braziliensis, supporting its use in clinical, vaccine and chemotherapy experimental protocols.

Many marine fisheries in South American Atlantic coasts (SAAC) are threatened by overfishing and under serious risk of collapsing. The SAAC comprises a diversity of environments, possesses a complex oceanography and harbours a vast biodiversity that provide an enormous potential for using parasites as biological tags for fish stock delineation, a prerequisite for the implementation of control and management plans. Here, their use in the SAAC is reviewed. Main evidence is derived from northern Argentine waters, where fish parasite assemblages are dominated by larval helminth species that share a low specificity, long persistence and trophic transmission, parasitizing almost indiscriminately all available fish species. The advantages and constraints of such a combination of characteristics are analysed and recommendations are given for future research. Shifting the focus from fish/parasite populations to communities allows expanding the concept of biological tags from local to regional scales, providing essential information to delineate ecosystem boundaries for host communities. This new concept arose as a powerful tool to help the implementation of ecosystem-based approaches to fisheries management, the new paradigm for fisheries science. Holistic approaches, including parasites as biological tags for stock delineation will render valuable information to help insure fisheries and marine ecosystems against further depletion and collapse.

Echinococcus granulosus and Echinococcus multilocularis are cestode parasites, of which the metacestode (larval) stages cause the diseases cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. Albendazole and mebendazole are presently used for chemotherapeutical treatment. However, these benzimidazoles do not appear to be parasiticidal in vivo against AE. In addition, failures in drug treatments as well as the occurrence of side-effects have been reported. New drugs are needed to cure AE and CE, which are considered to be neglected diseases. Strategies currently being implemented to identify novel chemotherapeutical treatment options include (i) conventional primary in vitro testing of broad-spectrum anti-infective drugs, either in parallel with, or followed by, animal experimentation; (ii) studies of drugs which interfere with the proliferation of cancer cells and of Echinococcus metacestodes; (iii) exploitation of the similarities between the parasite and mammalian signalling machineries, with a special focus on targeting specific signalling receptors; (iv) in silico approaches, employing the current Echinococcus genomic database information to search for suitable targets for compounds with known modes of action. In the present article, we review the efforts toward obtaining better anti-parasitic compounds which have been undertaken to improve chemotherapeutical treatment of echinococcosis, and summarize the achievements in the field of host-parasite interactions which may also lead to new immuno-therapeutical options.

The gene for the 32 kDa surface protein (p32) of Theileria sergenti was cloned into λgt11 and its nucleotide sequence was determined. The gene encodes a protein of 283 amino acids as deduced from its nucleotide sequence with a 22 residue N-terminal signal peptide. Using this cDNA as a probe we have isolated another two clones from a cDNA library with a CDM8 vector system derived from the same parasite stock. Comparison with three cDNA clones revealed differential polyadenylation and differences in sequences of non-coding regions. Within the coding regions, there were nucleotide transitions which affected the Pst I-restriction site, and one of the transitions was also accompanied by an amino acid substitution (Ala to Gly). Southern blot analysis showed hybridization pattern changes among the parasites isolated from individual calves at different times after infection. From these results, we conclude that at least 3 genetically different parasite populations may coexist, and that transition to predominant parasite populations might occur during persistent infections in a host, possibly to evade the host immune responses.

The adult of P. crucibulum is redescribed to form a basis for comparison with the cercaria and metacercaria. Particular emphasis is given to the structure and function of the rhynchus, digestive system and reproductive system. Some features, notably prepharyngeal glands and spematophores, have not previously been recorded in this species.

The sporocyst and cercaria which were found in Mytilus edulis are described for the first time. Out of 6907 mussels examined from Borth Rocks, Cardigan Bay, 0·26% were infected with P. crucibulum and 0·06 % with P. squamatus. The cercaria of the latter is redescribed on a comparative basis with that of P. crucibulum, to avoid confusion. The two cercariae are clearly distinguished by three features – flame-cell formula, shape of the excretory vesicle, and structure of the tail stem (this being bilobed in P. crucibulum and trilobed in P. squamatus). The significance of the two types of tail in securing attachment to the second intermediate host is discussed.

Metacercariae of P. crucibulum were obtained experimentally in ‘O’ group specimens of Scophthalmus maximus. Three other species of fish, namely Limanda limanda, Onus mustelus and Gobius minutus were also successfully infected. The metacercariae did not develop in the following fish: S. rhombus, Pleuronectes platessa, Cottus bubalis and Blennius pholis. Possible mechanisms which might account for host specificity within Pleuronectidae and Scophthalmus are suggested.

The development of the metacercaria in the connective tissues and musculature of S. maximus was followed over a period of 10 months. Within 1 month of infection the hyaline cyst of parasitic origin breaks down, enabling the parasite to feed directly on the host tissues. This feature is thought to account for the advanced development of the metacercaria, which 1 month after infection could clearly be identified with the adult on the basis of comparative morphology, and at 2 months resembles the adult in every respect except the development of the vitellaria. Egg production only occurs within the intestine of Conger conger, the definitive host.

The localization and distribution of neuropeptides in the central nervous system of the pig roundworm, Ascaris suum, have been determined by an indirect immunofluorescence technique in conjunction with confocal microscopy. Antisera to 25 vertebrate peptides and two invertebrate peptides were used to screen the worm for immunoreactivity (IR). Immuno-staining was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), neuropeptide Y (NPY), gastrin, cholecystokinin (CCK), substance P (SP), atrial natriuretic peptide (ANP), salmon gonadotropin-releasing hormone (SGnRH), mammalian gonadotropin-releasing hormone (MGnRH), chromogranin A (CGA) and FMRFamide. The most extensive patterns of IR occurred with antisera to PYY, FMRFamide and gastrin. IR was evident in nerve cells and fibres in the ganglia associated with the anterior nerve ring and in the main nerve cords and their commissures; IR to FMRFamide also occurred in the posterior nerve ring. Immunostaining for the other peptides was confined to the nerve cords, with the number of immunoreactive nerve fibres varying from peptide to peptide.

Epidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes for Ascaris lumbricoides and Trichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.