Cryptosporidium is increasingly recognized as one of the major causes of moderate to severe diarrhoea in developing countries. With treatment options limited, control relies on knowledge of the biology and transmission of the members of the genus responsible for disease. Currently, 26 species are recognized as valid on the basis of morphological, biological and molecular data. Of the nearly 20 Cryptosporidium species and genotypes that have been reported in humans, Cryptosporidium hominis and Cryptosporidium parvum are responsible for the majority of infections. Livestock, particularly cattle, are one of the most important reservoirs of zoonotic infections. Domesticated and wild animals can each be infected with several Cryptosporidium species or genotypes that have only a narrow host range and therefore have no major public health significance. Recent advances in next-generation sequencing techniques will significantly improve our understanding of the taxonomy and transmission of Cryptosporidium species, and the investigation of outbreaks and monitoring of emerging and virulent subtypes. Important research gaps remain including a lack of subtyping tools for many Cryptosporidium species of public and veterinary health importance, and poor understanding of the genetic determinants of host specificity of Cryptosporidium species and impact of climate change on the transmission of Cryptosporidium.

Monepantel (MOP), a new anthelmintic drug from a group of amino-acetonitrile derivatives, has been intensively studied during last years. Many authors examined this new drug from different perspectives, e.g. efficacy against different species and stages of parasites, mode of action, metabolism, pharmacokinetics, toxicity, resistance, ecotoxicity, etc. MOP is an anthelmintic for livestock (currently only sheep and goats), with molecular mode of action which is different to all other anthelmintics. MOP has a broad-spectrum of activity against gastrointestinal nematodes of sheep, including adults and L4 larvae of the most important species. The key feature of MOP is its full effectiveness against strains of nematodes resistant to benzimidazoles, levamisole, macrocyclic lactones and closantel. After oral administration, MOP is quickly absorbed into the bloodstream and quickly metabolized to MOP sulfone that has a similar efficacy as the parent molecule. Several other MOP metabolites formed in ovine hepatocytes were described. MOP and its metabolites are considered to be non-toxic to environment and its components, such as soil microflora, aquatic organisms, dung organisms, vegetation, etc. The aim of the presented review was not to collect all reported data but to bring an overview of various approaches in the study of MOP and to evaluate their principal results.

Toxoplasmosis is a worldwide zoonosis. However, data from Portugal are limited and a considerable part of the literature is in Portuguese. Currently, the rate of congenital infection in Portugal is unknown, and almost nothing is known of sequelae of congenital toxoplasmosis. There is no recent general population-based serological survey of Toxoplasma gondii in humans in Portugal. In addition, there is little information on genetic characteristics of T. gondii in animals and humans. In the present paper, we review prevalence, clinical spectrum and epidemiology of T. gondii in humans and animals in Portugal. This knowledge should be useful to biologists, public health workers, physicians and veterinarians.

Myxosporeans are among the most common parasites of marine fish. Their economic importance is mainly as pathogens of both wild and farmed fish, but they have also been used as biological tags in population studies of their fish hosts. Here we review the literature and show the distribution of different families of Myxosporea infecting marine fishes in the world's oceans – the North Atlantic, South Atlantic, North Pacific, South Pacific and Indian. We also analyse their distribution in different orders of marine fishes. New families, genera and species of marine Myxosporea are continually being described and many more await description. Some regions, in particular the North Atlantic, have been more thoroughly investigated than others, so the analyses we present may not reflect the true distributions and we acknowledge that these may change considerably as other regions are investigated more fully. The distribution of myxosporean families in different taxonomic groups of marine fishes can indicate phylogenetic relationships between parasite and host and suggest the origins of different myxosporean taxa. We present some examples, while recognizing that new molecular information on phylogenetic relationships within the Myxozoa will lead to major changes in classification.

To investigate larval development of Acanthocheilonema reconditum in the cat flea Ctenocephalides felis, fleas were fed through an artificial feeding system with dog blood containing different concentrations of microfilariae (i.e. low, group L = 250; medium, group M = 500; high, group H = 1500 microfilariae per mL) or no microfilariae (group C). Fleas were sampled at 12 different time-points throughout the study period (D1–D28) and A. reconditum was detected by dissection, PCR and histology. Of 2105 fleas fed with infected dog blood, 891 (38·7%) died during the study before being sampled whilst the remaining (n = 1214) were examined for A. reconditum. Upon dissection, first-stage larvae (L1) were identified after 2 days post infection (D2), second-stage (L2) at D13 and infective third-stage larvae (L3) at D15. Eighteen (30%) of 60 pools of fleas molecularly examined tested positive. Histologically, L2 were detected at D13 in the sub-cuticle region embedded in the back muscle of one female flea. This study provides original data on larval development of A. reconditum in C. felis and reports on the usefulness of the artificial feeding system.

Apicomplexan parasites cause devastating diseases in humans and livestock. Previously we demonstrated that antibodies targeting transmissible forms of the apicomplexan parasite, Eimeria, are effective at reducing parasite shedding thus preventing the transmission of the disease. However, the mechanisms responsible have not been fully defined. Moreover, there is no direct evidence that the parasite-specific IgG antibodies can reach the parasite developing in the enterocytes of the infected chicken host. This study summarizes our efforts using host immunity, parasite proteomics and 3D microscopy to provide a step forward in our understanding of how this immune response works. Eimeria maxima is an important pathogen of poultry and used as a surrogate for a number of human pathogens including Toxoplasma and Plasmodium. Our studies demonstrate that immunization with the purified wall forming bodies (WFBs) results in a production of parasite-specific IgG antibodies, which have the ability to reach in situ gametocytes in the intestinal lumen and permeate the enterocyte/parasite membranes in order to bind to the cytoplasmic Type 1 and Type 2 WFBs. This raises the intriguing possibility that via this process antibodies block the development of Eimeria maxima in vivo.

Strongyloides venezuelensis is a parasitic nematode that infects rodents. Although Strongyloides species described to date are known to exhibit parthenogenetic reproduction in the parasitic stage of their life cycle and sexual reproduction in the free-living stage, we did not observe any free-living males in S. venezuelensis in our strain, suggesting that the nematode is likely to depend on parthenogenetic reproduction. We confirmed by cytological analysis that S. venezuelensis produces eggs by parthenogenesis during the parasitic stage of its life cycle. Phylogenetic analysis using nearly the full length of 18S and D3 region of 28S ribosomal RNA gene suggested that S. venezuelensis is distantly related to another rodent parasite, namely Strongyloides ratti, but more closely related to a ruminant parasite, Strongyloides papillosus. Karyotype analysis revealed S. venezuelensis reproduces with mitotic parthenogenesis, and has the same number of chromosomes as S. papillosus (2n = 4), but differs from S. ratti (2n = 6) in this regard. These results, taken together, suggest that S. venezuelensis evolved its parasitism for rodents independently from S. ratti and, therefore, is likely to have a different reproductive strategy.

Serine protease inhibitors (serpin) play essential roles in many organisms. Mammalian serpins regulate the blood coagulation, fibrinolysis, inflammation and complement activation pathways. In parasitic helminths, serpins are less well characterized, but may also be involved in evasion of the host immune response. In this study, a Schistosoma japonicum serpin (SjB10), containing a 1212 bp open reading frame (ORF), was cloned, expressed and functionally characterized. Sequence analysis, comparative modelling and structural-based alignment revealed that SjB10 contains the essential structural motifs and consensus secondary structures of inhibitory serpins. Transcriptional profiling demonstrated that SjB10 is expressed in adult males, schistosomula and eggs but particularly in the cercariae, suggesting a possible role in cercarial penetration of mammalian host skin. Recombinant SjB10 (rSjB10) inhibited pancreatic elastase (PE) in a dose-dependent manner. rSjB10 was recognized strongly by experimentally infected rat sera indicating that native SjB10 is released into host tissue and induces an immune response. By immunochemistry, SjB10 localized in the S. japonicum adult foregut and extra-embryonic layer of the egg. This study provides a comprehensive demonstration of sequence and structural-based analysis of a functional S. japonicum serpin. Furthermore, our findings suggest that SjB10 may be associated with important functional roles in S. japonicum particularly in host-parasite interactions.

The aim of this study was to assess the effect of sulfamethoxazole/trimethoprim (ST) supplemented with diphenyl diselenide and sodium selenite in experimental toxoplasmosis, on oxidant/antioxidant biomarkers and cytokine levels. Eighty-four BALB/c mice were divided in seven groups: group A (negative control), and groups B to G (infected). Blood and liver samples were collected on days 4 and 20 post infection (p.i.). Levels of thiobarbituric acid (TBA) reactive substances and advanced oxidation protein products (AOPP) were assessed in liver samples. Both biomarkers were significantly increased in infected groups on day 4 p.i., while they were reduced on day 20 p.i., compared with group A. Glutathione reductase (GR) activity significantly (P<0·01) increased on day 4 p.i., in group G, compared with group A. INF-γ was significantly increased (P<0·001) in both periods, day 4 (groups B, C, F and G) and 20 p.i. (groups C, F and G). IL-10 significantly reduced (P<0·001) on day 4 p.i. in group B; however, in the same period, it was increased (P<0·001) in groups C and G, compared with group A. On day 20 p.i., IL-10 increased (P<0·001) in groups F and G. Therefore, our results highlighted that these forms of selenium, associated with the chemotherapy, were able to reduce lipid peroxidation and protein oxidation, providing a beneficial immunological balance between the production of pro- and anti-inflammatory cytokines.

Antibodies (Ab) recognizing G-protein coupled receptors, such as β 1 and β 2 adrenergic (anti-β 1-AR and anti-β 2-AR, respectively) and muscarinic cholinergic receptors (anti-M2-CR) may contribute to cardiac damage, however their role in chronic chagasic cardiomyopathy is still controversial. We describe that Trypanosoma cruzi-infected C3H/He mice show increased P and QRS wave duration, and PR and QTc intervals, while the most significant ECG alterations in C57BL/6 are prolonged P wave and PR interval. Echocardiogram analyses show right ventricle dilation in infected animals of both mouse lineages. Analyses of heart rate variability (HRV) in chronically infected C3H/He mice show no alteration of the evaluated parameters, while C57BL/6 infected mice display significantly lower values of HRV components, suggesting autonomic dysfunction. The time-course analysis of anti-β 1-AR, anti-β 2-AR and anti-M2-CR Ab titres in C3H/He infected mice indicate that anti-β 1-AR Ab are detected only in the chronic phase, while anti-β 2-AR and anti-M2-CR are observed in the acute phase, diminish at 60 dpi and increase again in the chronic phase. Chronically infected C57BL/6 mice presented a significant increase in only anti-M2-CR Ab titres. Furthermore, anti-β 1-AR, anti-β 2-AR and anti-M2-CR, exhibit significantly higher prevalence in chronically T. cruzi-infected C3H/He mice when compared with C57BL/6. These observations suggest that T. cruzi infection leads to host-specific cardiac electric alterations.