The calcium-dependent protein kinases (CDPKs) are unique enzymes found only in plants, green algae, ciliates and apicomplexan parasites. In this study, a novel CDPK gene of Eimeria tenella, designed EtCDPK3, was cloned using rapid amplification of cDNA ends (RACE) based on the expressed sequence tag (EST). The entire cDNA of EtCDPK3 contained 1637 nucleotides encoding 433 amino acids and the deduced EtCDPK3 protein had canonical characteristic domains identified in other CDPKs, including a well-conserved amino-terminal kinase domain and a carboxy-terminal calmodulin-like structure with 4 EF-hand motifs for calcium binding. The expression profiles of the EtCDPK3 gene in different development stages were investigated by real-time quantitative PCR. Messenger RNA levels from the EtCDPK3 gene were higher in sporozoites than in other stages (unsporulated oocysts, sporulated oocysts and merozoites). Western blot analysis showed that rabbit antiserum against recombinant EtCDPK3 could recognize a native 49 kDa protein band of parasite. Indirect immunofluorescent antibody labelling revealed dispersed localization of EtCDPK3 during the first schizogony and intense specific staining. EtCDPK3 was located at the apical end of the sporozoites after early infection of DF-1 cells and the protein was highly expressed. Inhibition of EtCDPK3 function using specific antibodies reduced the ability of E. tenella to invade host cells. These results suggested that EtCDPK3 may be involved in invasion and survival of the parasite intracellular stages of E. tenella. Because this kinase family is absent from hosts, it represents a valid target that could be exploited for chemotherapy against Eimeria spp.

Decades of intensive anthelmintic treatment has caused equine large strongyles to become quite rare, while the cyathostomins have developed resistance to several drug classes. The larval culture has been associated with low to moderate negative predictive values for detecting Strongylus vulgaris infection. It is unknown whether detection of other large strongyle species can be statistically associated with presence of S. vulgaris. This remains a statistical challenge because of the rare occurrence of large strongyle species. This study used a modified Poisson regression to analyse a dataset for associations between S. vulgaris infection and simultaneous occurrence of Strongylus edentatus and Triodontophorus spp. In 663 horses on 42 Danish farms, the individual prevalences of S. vulgaris, S. edentatus and Triodontophorus spp. were 12%, 3% and 12%, respectively. Both S. edentatus and Triodontophorus spp. were significantly associated with S. vulgaris infection with relative risks above 1. Further, S. edentatus was associated with use of selective therapy on the farms, as well as negatively associated with anthelmintic treatment carried out within 6 months prior to the study. The findings illustrate that occurrence of S. vulgaris in larval cultures can be interpreted as indicative of other large strongyles being likely to be present.

Identification of high-risk regions of schistosomiasis is important for rational resource allocation and effective control strategies. We conducted the first study to apply the newly developed method of adaptive kernel density estimation (KDE)-based spatial relative risk function (sRRF) to detect the high-risk regions of schistosomiasis in the Guichi region of China and compared it with the fixed KDE-based sRRF. We found that the adaptive KDE-based sRRF had a better ability to depict the heterogeneity of risk regions, but was more sensitive to altering the user-defined smoothing parameters. Specifically, the impact of bandwidths on the estimated risk value and risk significance (P value) was higher for the adaptive KDE-based sRRF, but lower on the estimated risk variation standard error (s.e.) compared with the fixed KDE-based sRRF. Based on this application the adaptive and fixed KDE-based sRRF have their respective advantages and disadvantages and the joint application of the two approaches can warrant the best possible identification of high-risk subregions of diseases.

The main aim of this study is to overview the past and present situations of human taeniases and cysticercosis in Indonesia and including future perspectives. Through joint projects from 1996, we have confirmed the occurrence of Taenia saginata (beef tapeworm) in Bali, of Taenia solium (pork tapeworm) mainly in Papua and sporadically in Bali, and of Taenia asiatica in North Sumatra. These taeniases were caused through eating uncooked pork and pig viscera for T. solium and T. asiatica, respectively, and beef for T. saginata. The distribution of these tapeworms in Indonesia is basically highly restricted by the traditional cultural and religious backgrounds in each island. T. saginata is relatively common in Bali although people consume pork ‘lawar’ more than beef ‘lawar’. Taeniases due to T. saginata or T. asiatica and T. solium and cysticercosis due to T. solium have also been sporadically reported in some other islands. Among these species, T. solium is exceptional since humans can be infected not only by larval stages (cysticerci) in pork but also by eggs released from human tapeworm carriers. Cysticercosis has been confirmed in Indonesia in humans, pigs and even dogs.

Mucosal mast cells (MMC) play a crucial role in the expulsion of Strongyloides ratti adults from the small intestine of mice. We reported the large intestinal parasitism of S. ratti in rats, and there has been no report on MMC in the large intestine of the natural host. We studied kinetics of MMC, together with eosinophils, in the upper and lower small intestines, caecum and colon of infected rats. Two distinct phases of mastocytosis were revealed: one in the upper small intestine triggered by stimulation of ‘ordinary’ adults, and the other in the colon stimulated by ‘immune-resistant’ adults that started parasitizing the colon around 19 days post-infection. In all 4 intestinal sites, the MMC peaks were observed 5–7 days after the number of adult worms became the maximum and the height of MMC peaks appeared to be dependent on the number of parasitic adults, suggesting an important role played by worms themselves in the MMC buildup.

The pathogens Plasmodium juxtanucleare and chicken anaemia virus (CAV) are easily transmitted and potentially harmful to chickens. In this study, we established an experimental model to investigate the effects of avian malaria caused by P. juxtanucleare in white leghorn specific-pathogen-free (SPF) chicks previously immunosuppressed with CAV. Parasitaemia, haematological variables and clinical and pathological parameters were determined in four different experimental groups: chicks coinfected by CAV and P. juxtanucleare strain (Coinfected group), chicks exclusively infected by CAV (CAV group) or P. juxtanucleare (Malaria group) and uninfected chicks (Control group). Our data demonstrated that P. juxtanucleare parasitaemia was significantly higher in the Coinfected group. Furthermore, haematological parameters, including the RBC, haematocrit and haemoglobin concentration were significantly reduced in coinfected chicks. In agreement with the changes observed in haematological features, the mortality among coinfected chicks was higher compared with animals with single infections. Clinical analysis indicated moderate changes related to different organs size (bursa of Fabricius, heart and liver) in coinfected birds. The experimental coinfection of SPF chickens with P. juxtanucleare and CAV may represent a research tool for the study of avian malaria after CAV immunosuppression, enabling measurement of the impacts caused by different pathogens during malarial infection.

Understanding disease transmission is important to species management and human health. Host body condition, nutrition and disease susceptibility interact in a complex manner, and while the individual effects of these variables are well known, our understanding of how they interact and translate to population dynamics is limited. Our objective was to determine whether host relative body condition influences epidemic dynamics, and how this relationship is affected by food availability. Poecilia reticulata (guppies) of roughly similar size were selected and assembled randomly into populations of 10 guppies assigned to 3 different food availability treatments, and the relative condition index (Kn) of each fish was calculated. We infected 1 individual per group (‘source’ fish) with Gyrodactyus turnbulli and counted parasites on each fish every other day for 10 days. Epidemic parameters for each population were analysed using generalized linear models. High host Kn—particularly that of the ‘source’ fish—exerted a positive effect on incidence, peak parasite burden, and the degree of parasite aggregation. Low food availability increased the strength of the associations with peak burden and aggregation. Our findings suggest that host Kn and food availability interact to influence epidemic dynamics, and that the condition of the individual that brings the parasite into the host population has a profound impact on the spread of infection.

Members of the ATP-binding cassette (ABC) transporter family (P-glycoproteins, Half-transporters and Multidrug Resistant Proteins) potentially play a role in the development of anthelmintic resistance. The aim of this study was to investigate the possible involvement of ABC transporters in anthelmintic resistance in the bovine parasite, Cooperia oncophora. Partial sequences of 15 members of the ABC transporter protein family were identified, by mining a transcriptome dataset combined with a degenerate PCR approach. Reverse transcriptase PCR showed that most of the ABC transporters identified were constitutively transcribed throughout the life cycle of C. oncophora. Constitutive differences in gene transcript levels between a susceptible and resistant isolate were only observed for Con-haf-9 and Con-mrp-1 in eggs of the resistant isolate, while no differences were observed in L3 or the adult life stage. Analysis of resistant adult worms, collected from calves 14 days after treatment with either ivermectin or moxidectin, showed a significant 3- to 5-fold increase in the transcript levels of Con-pgp-11 compared to non-exposed worms. Interestingly, a 4-fold transcriptional up-regulation of Con-pgp-11 was also observed in L3 of the resistant isolate, after in vitro exposure to different concentrations of ivermectin, whereas this effect was not observed in exposed L3 of the susceptible isolate. The results suggest that the worms of this particular resistant isolate have acquired the ability to up-regulate Con-pgp-11 upon exposure to macrocyclic lactones. Further work is needed to understand the genetic basis underpinning this process and the functional role of PGP-11.

We counted the numbers of pupae of two ectoparasitic flies (Protocalliphora sp. and Ornithomyia sp.) in the nests of a passerine bird, the pied flycatcher (Ficedula hypoleuca) to find out if their prevalence or intensity are affected by long-term environmental pollution by a copper smelter and whether such an interaction would have impacts on birds' breeding success. Fecal metal concentrations of F. hypoleuca nestlings were used to explore direct association between metal levels and parasite prevalence, but we also included other explanatory factors in our analysis, such as timing of breeding, brood size, ambient temperature, habitat quality and host population density. We found that environmental pollution decreased the prevalence of Protocalliphora via changed habitat quality but did not affect the prevalence of Ornithomyia. The prevalence of neither ectoparasite was, however, directly related to ambient metal levels. Both ectoparasites showed higher prevalence when ambient temperature during the nestling period was high, emphasizing the potential of climate change to modify host–parasite relationships. The prevalence of Ornithomyia was further highest in dense F. hypoleuca populations and late broods. Nestling survival decreased with increasing infestation intensity of Ornithomyia while no association was found for Protocalliphora. Despite relatively low numbers and overall weak effect of parasites on survival, the possible delayed and/or sublethal effects of these ectoparasites call for further studies. Our results suggest that pollution-related effects on avian ectoparasite numbers are species-specific and reflect habitat changes rather than direct toxic effect of heavy metals.

The effect of insect vectors on avian exposure to infection by pathogens remains poorly studied. Here, we used an insect repellent treatment to reduce the number of blood-sucking flying insects in blue tit Cyanistes caeruleus nests and examined its effect on nestling health status measured as body mass, nestling phytohaemagglutinin (PHA) response and blood parasite prevalence. We found that (i) the insect repellent treatment significantly reduced the number of blood-sucking flying insects in nests and (ii) the number of blood-sucking flying insects had a significant effect on the prevalence of the blood parasite Trypanosoma independently of the treatment. In addition, we found support for an adverse effect of parasite infections on nestling PHA response. Nestlings infected by Trypanosoma mounted a weaker response against PHA than non-parasitized ones. In addition, the number of blowflies in the nest was negatively associated with nestling PHA response. Overall, we found support for the hypothesis that blood-sucking flying insects attacking nestlings increase their exposure to parasite infections. Our results further substantiate the adverse effect of parasites on nestling condition.

The name Paragonimus westermani (Kerbert, 1878) is commonly applied to members of a species complex that includes the well-known Asian lung fluke of medical and veterinary importance. Unambiguous molecular and morphological evidence showing the presence of a member of the complex in India has recently been published. In the present study we report the occurrence of 2 more members of the P. westermani complex in northeastern (NE) India. Surveys of the freshwater crabs Maydelliatelphusa lugubris in NE India revealed 2 morphologically distinct types of lung fluke metacercariae. Phylogenetic analyses, using DNA sequences from ITS2, 28S and cox1 gene regions indicate that these lung metacercariae belong to P. westermani complex. Type 1 metacercariae have a more basal position within the complex whereas type 2 metacercariae are closely related to the relatively derived forms of P. westermani from NE Asia (Japan, Korea, China) and Vietnam. A third type of metacercaria (type 3), detected in another crab host, Sartoriana spinigera in Assam, was phylogenetically close to P. siamensis, also a member of the P. westermani group. Molecular evidence has demonstrated the existence of 3 genotypes of lung flukes within the Paragonimus westermani complex in NE India. Two of these were previously unknown.

Parasitic helminths are ubiquitous in most host, including human, populations. Helminths often alter the likelihood of infection and disease progression of coinfecting microparasitic pathogens (viruses, bacteria, protozoa), and there is great interest in incorporating deworming into control programmes for many major diseases (e.g. HIV, tuberculosis, malaria). However, such calls are controversial; studies show the consequences of deworming for the severity and spread of pathogens to be highly variable. Hence, the benefits of deworming, although clear for reducing the morbidity due to helminth infection per se, are unclear regarding the outcome of coinfections and comorbidities. I develop a theoretical framework to explore how helminth coinfection with other pathogens affects host mortality and pathogen spread and evolution under different interspecific parasite interactions. In all cases the outcomes of coinfection are highly context-dependent, depending on the mechanism of helminth-pathogen interaction and the quantitative level of helminth infection, with the effects of deworming potentially switching from beneficial to detrimental depending on helminth burden. Such context-dependency may explain some of the variation in the benefits of deworming seen between studies, and highlights the need for obtaining a quantitative understanding of parasite interactions across realistic helminth infection ranges. However, despite this complexity, this framework reveals predictable patterns in the effects of helminths that may aid the development of more effective, integrated management strategies to combat pathogens in this coinfected world.

The migration of infective nematode larvae into the tissues of their hosts has been proposed as a mechanism of reducing larval mortality and increase parasite lifetime reproductive success. Given that individual hosts differ in the level of exposure, strength of immune response and physiological conditions we may expect the number of larvae in tissue to vary both between and within hosts. We used 2 gastrointestinal nematode species common in the European rabbit (Oryctolagus cuniculus) and examined how the number of larvae in the tissue changed with the immune response, parasite intensity-dependent constraints in the lumen and seasonal weather factors, in rabbits of different age, sex and breeding status. For both nematode species, larvae from the gastrointestinal tissue exhibited strong seasonal and host age-related patterns with fewer larvae recovered in summer compared to winter and more in adults than in juveniles. The number of larvae of the 2 nematodes was positively associated with intensity of parasite infection in the lumen and antibody responses while it was negatively related with air temperature and rainfall. Host sex, reproductive status and co-infection with the second parasite species contributed to increase variability between hosts. We concluded that heterogeneities in host conditions are a significant cause of variability of larval abundance in the gastrointestinal tissues. These findings can have important consequences for the dynamics of nematode infections and how parasite's life-history strategies adjust to host changes.

DEAD Box RNA helicases are essential enzymes that are involved in RNA metabolic processes such as transcription, pre-mRNA splicing, translation initiation and RNA decay. We have previously over-expressed and biochemically characterized an immunodominant cDNA clone encoding DEAD box RNA helicase (BmL3-Helicase) isolated by immunoscreening of the larval stage cDNA library of Brugia malayi. In the current study, the 3D structure was determined and the immunoprophylactic efficacy of BmL3-Helicase was investigated by immunizing Mastomys coucha with the recombinant protein and subsequently challenging with B. malayi infective larvae. The immunization had an adverse outcome on the establishment of challenged larvae resulting in a 67·4% reduction in adult parasite recovery, a 86·7% decrease in the microfilarial density and profound sterility of the recovered female worms. The immune response thus generated was investigated by measuring the levels of specific antibodies including IgG subclasses, reactive oxygen species and cytokines.

The taxonomy of Echinococcus has long been controversial. Based mainly on differences in morphology and host-parasite specificity characteristics, 16 species and 13 subspecies were originally described. Subsequently, most of these taxa were regarded as synonyms for Echinococcus granulosus and only 4 valid species were recognised: E. granulosus; E. multilocularis; E. oligarthrus and E. vogeli. But, over the past 50 years, laboratory and field observations have revealed considerable phenotypic variability between isolates of Echinococcus, particularly those of E. granulosus, which include differences in: morphology in both larval and adult stages, development in vitro and in vivo, host infectivity and specificity, chemical composition, metabolism, proteins and enzymes, pathogenicity and antigenicity. The application of molecular tools has revealed differences in nucleic acid sequences that reflect this phenotypic variation and the genetic and phenotypic characteristics complement the previous observations made by the descriptive parasitologists many years ago. The fact that some of these variants or strains are poorly or not infective to humans has resulted in a reappraisal of the public health significance of Echinococcus in areas where such variants occur. A revised taxonomy for species in the Echinococcus genus has been proposed that is generally accepted, and is based on the new molecular data and the biological and epidemiological characteristics of host-adapted species and strains.

The co-occurrence of different pathogen species and their simultaneous infection of hosts are common, and may affect host health outcomes. Co-infecting pathogens may interact synergistically (harming the host more) or antagonistically (harming the host less) compared with single infections. Here we have tested associations of infections and their co-infections with variation in growth rate using a subset of 455 animals of the Infectious Diseases of East Africa Livestock (IDEAL) cohort study surviving to one year. Data on live body weight, infections with helminth parasites and haemoparasites were collected every 5 weeks during the first year of life. Growth of zebu cattle during the first year of life was best described by a linear growth function. A large variation in daily weight gain with a range of 0·03–0·34 kg, and a mean of 0·135 kg (0·124, 0·146; 95% CI) was observed. After controlling for other significant covariates in mixed effects statistical models, the results revealed synergistic interactions (lower growth rates) with Theileria parva and Anaplasma marginale co-infections, and antagonistic interactions (relatively higher growth rates) with T. parva and Theileria mutans co-infections, compared with infections with T. parva only. Additionally, helminth infections can have a strong negative effect on the growth rates but this is burden-dependent, accounting for up to 30% decrease in growth rate in heavily infected animals. These findings present evidence of pathogen–pathogen interactions affecting host growth, and we discuss possible mechanisms that may explain observed directions of interactions as well as possible modifications to disease control strategies when co-infections are present.

In 2009, a haplotype closely related to European strains of Echinococcus multilocularis was detected in a dog from the Quesnel region of British Columbia, Canada. We now report the establishment of this same haplotype in 7 coyotes (Canis latrans) trapped within 40 km of Quesnel, BC. In addition, 3 coyotes and 1 red fox (Vulpes vulpes) harboured adult cestodes morphologically compatible with that of E. multilocularis (overall prevalence 33% in 33 carnivores). None of 156 potential intermediate hosts, including 131 representatives of two highly suitable rodent species, Peromyscus maniculatus and Microtus pennsylvanicus, trapped from a region 120–210 km south of Quesnel were infected. This report confirms the establishment and local transmission of a European-type strain of E. multilocularis (the causative agent of human alveolar hydatid disease), in wildlife in a forested region of North America where this cestode had not been previously detected, with significance for public and animal health.

Eimeria maxima has been used as a model apicomplexan parasite to study sexual stage development and oocyst wall formation. A complete understanding of the wall's biochemical and biophysical properties is of great interest in research on all apicomplexan parasites. Purified gametocytes, zygotes and oocysts were analysed by three-dimensional confocal microscopy, and wide-field fluorescent microscopy was used to investigate the appearance and spatial organization of the 2 types of wall-forming bodies (WFBs). In addition, a variety of staining procedures and immunoassays were used to assess the biosynthesis, metabolic activity, intactness and molecular composition of the WFBs in situ. WFBs were extracted from gametocytes/zygotes and their composition was assessed by microscopy and SDS-PAGE analysis. It was concluded that isolated gametocytes are intact and metabolically active. Additionally, it was observed that the Type 1 WFBs are aligned at the periphery of the parasite and fuse together producing neutral lipid rich patches that appear to be inserted into the space between 2 parasite-specific membranes. Finally, it was shown that the WFBs extracted from purified gametocytes had the same shape, size and staining properties as those observed in situ, and contained the major glycoprotein antigens known to be present in these organelles.

This paper deals largely with the dynamics and changes in the helminth parasite communities of fish along the trophic gradient of lakes. The use of parasitological community data as a bioindicator of environmental health underlines the need to study parasite communities at comparable localities with known pollution levels. The comparison of the conditions in different habitats might be helpful to differentiate between normal fluctuations in ambient conditions and pollution-mediated effects. Therefore, the present study was designed to examine the community structure of parasites in snow trout (Schizothorax niger Heckel) inhabiting 3 lakes of contrasting trophic status in Kashmir. The idea of selecting the lakes, namely Anchar (strongly hypereutrophic), Dal (eutrophic) and Manasbal (mesotrophic) for this study was intentional as they depict different trophic gradients and exhibit the desirable pattern which was a prerequisite for this study. The findings presented in this article suggest an apparent lake-wise gradient in community structure, as the increase in trematode and cestode infections in Anchar was markedly greater, to levels clearly distinguishable from those in the other two water bodies. We conclude that human-induced eutrophication of lakes modifies the parasite community at component level and community-level studies on parasites may provide information on health status of lakes.