The host recognition and invasion process of Myxobolus cerebralis actinospores (triactinomyxon, TAM) was studied on a genetic level. A small-scale in vitro assay was developed to activate a large number of TAMs simultaneously, and to monitor the host invasion in the absence of live fish. The transcriptomes of non-activated and in vitro-activated TAMs were compared by suppressive subtractive hybridization (SSH) to identify parasite genes involved in the host invasion process. Differential screening and a subsequent BLAST search revealed 15 of 452 SSH-library clones expressed differently in activated TAMs. None of the 15 transcripts obtained has previously been identified from M. cerebralis. Quantitative real-time PCR was used to examine the relative expression profile of 8 selected transcripts upon TAM activation and after penetration of the host. Four of these were found to be up-regulated in activated TAMs, while expression was relatively low in non-activated TAMs and in infected fish tissue, indicating that they are relevant genes during host recognition or subsequent host invasion of M. cerebralis TAMs.

Histomonas meleagridis is a protozoan parasite of various galliform birds causing a type of enterohepatitis termed histomonosis or ‘blackhead disease’. Due to the ban of chemotherapeutic substances and an increase in free-range poultry production, histomonosis is currently a re-emerging disease. So far limited molecular knowledge is available. In the present work, mRNAs coding for antigenic proteins of H. meleagridis were identified. For this purpose, a cDNA expression library was constructed from a mono-eukaryotic culture of H. meleagridis. The library was screened with polyclonal rabbit serum raised against purified H. meleagridis trophozoites. Polyclonal rabbit serum specifically recognized the same major H. meleagridis antigens as chicken and turkey sera originating from animal trials, but displayed a significantly lower bacteria-dependent background signal. After 2 rounds of screening, a total of 95 positive clones were sequenced. Bioinformatics analyses were performed on nucleotide and deduced amino acid sequences, identifying 37 unique clones. Based on the homology to other protozoan parasites, mostly Trichomonas vaginalis, the clones were grouped according to functional aspects: structural proteins, possible surface proteins, oxygen reducing proteins, ribosomal proteins, protein kinases and various other intracellular proteins.

Species belonging to the genera Cryptosporidium are recognized as waterborne pathogens. Solar water disinfection (SODIS) is a simple method that involves the use of solar radiation to destroy pathogenic microorganisms that cause waterborne diseases. A notable increase in water temperature and the existence of a large number of empty or partially excysted (i.e. unviable) oocysts have been observed in previous SODIS studies with water experimentally contaminated with Cryptosporidium parvum oocysts under field conditions. The aim of the present study was to evaluate the effect of the temperatures that can be reached during exposure of water samples to natural sunlight (37–50°C), on the excystation of C. parvum in the absence of other stimuli. In samples exposed to 40–48°C, a gradual increase in the percentage of excystation was observed as the time of exposure increased and a maximum of 53·81% of excystation was obtained on exposure of the water to a temperature of 46°C for 12 h (versus 8·80% initial isolate). Under such conditions, the oocyst infectivity evaluated in a neonatal murine model decreased statistically with respect to the initial isolate (19·38% versus 100%). The results demonstrate the important effect of the temperature on the excystation of C. parvum and therefore on its viability and infectivity.

Nested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a ‘Nestedness’ programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33–66% of analysed ectoparasite assemblages, and 25–75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness.

An unknown Trypanosoma species was isolated from an axenic culture of intact skin from a domestic dog captured in Rio de Janeiro, Brazil, which was co-infected with Leishmania (Viannia) braziliensis. Giemsa-stained smears of cultures grown in different media revealed the presence of epimastigotes, trypomastigotes, spheromastigotes, transitional stages, and dividing forms (epimastigotes or spheromastigotes). The highest frequency of trypomastigotes was observed in RPMI (15·2%) and DMEM (9·2%) media containing 5% FCS, with a mean length of these forms of 43·0 and 36·0 μm, respectively. Molecular analysis by sequential application of PCR assays indicated that this trypanosome differs from Trypanosoma cruzi and T. rangeli when specific primers were applied. On the other hand, a PCR strategy targeted to the D7 domain of 24sα rDNA, using primers D75/D76, amplified products of about 250 bp in that isolate (stock A-27), different from the amplification products obtained with T. cruzi and T. rangeli. This organism differs from T. cruzi mainly by the size of its trypomastigote forms and kinetoplasts and the absence of infectivity for macrophages and triatomine bugs. It is also morphologically distinct from salivarian trypanosomes reported in Brazil. Isoenzyme analysis at 8 loci demonstrated a very peculiar banding pattern clearly distinct from those of T. rangeli and T. cruzi. We conclude that this isolate is a new Trypanosoma species. The name T. caninum is suggested.

The polymerase chain reaction was used to detect trypanosomes in samples collected from cattle, wild animals and tsetse flies in KwaZulu-Natal Province, South Africa. A total of 673 samples from cattle and 266 from tsetse flies in the study area located near the Hluhluwe-Umfolozi Game Reserve were analysed. Both Trypanosoma congolense and T. vivax were found as single or mixed infections in cattle and tsetse flies. Moreover, the T. congolense in the infections were found to comprise 2 genotypic groups: the Savannah-type and the Kilifi-type, which were present either as single or mixed infections in cattle and in tsetse flies.

In this paper, we aimed to explore the effects of the calpain inhibitor III (MDL28170) and to detect calpain-like molecules (CALPs) in epimastigote forms of Trypanosoma cruzi isolate Dm28c. MDL28170 at 70 μM promoted a powerful reduction in the growth rate after 48 h. The IC50 value was calculated to be 31·7 μM. This inhibitor promoted an increase in the cellular volume, but not cell lysis, resulting in a trypanostatic effect. T. cruzi CALPs presented a strong cross-reactivity with anti-Drosophila melanogaster calpain and anti-cytoskeleton-associated protein from Trypanosoma brucei antibodies, and labelling was found mainly intracellularly. Furthermore, an 80 kDa reactive protein was detected by Western blotting assays. No significant cross-reactivity was found with anti-human brain calpain antibody. The expression of CALPs was decreased in cells kept for long periods in axenic cultures in comparison to a strain recently isolated from mice, as well as in MDL28170-treated cells, the latter being paralleled by an increased expression of cruzipain. Different levels of CALPs expression were also detected in distinct phylogenetic lineages, like Y strain (lineage TCI), Dm28c (TCII) and INPA6147 strain (Z3 zymodeme). These results may contribute for the investigation of the functions of CALPs in trypanosomatids.

Although there is an increasing understanding of the role of parasites in their host dynamics, accurate, quantitative estimates of parasite caused morbidity in wild animals are rare. Here, we examine the possible impact of 2 tick species (Ixodes ricinus, I. hexagonus) on the condition of the European hedgehog (Erinaceus europaeus). For this, we tested for correlations between blood parameters of 36 adult hedgehogs from an experimental population enclosed in a natural habitat and their tick infestation over a period of 8 months (March–October 2007). We found correlations between the tick infestation and the concentration of red blood cells, haemoglobin, haematocrit, MCH, MCHC, thrombocytes, lymphocytes and neutrophils. These results indicate that ticks can induce anaemia in the hedgehog. The peripheral blood characteristics and the erythrocyte indices characterize this anaemia as haemorrhagic and regenerative. During the course of our study the hedgehogs of our population showed below normal mortality but morbidity was found to be high resulting from the blood loss caused by the feeding activity of the ticks.

The sheep scab mite, Psoroptes ovis, induces an intensely pruritic exudative dermatitis which is responsible for restlessness, loss of appetite and weight loss. Within the first 24 h of infection, there is a rapid inflammatory influx of eosinophils and apoptosis of the keratinocytes at the site of infection. The former cell type is capable of a sustained respiratory burst, toxic products of which may directly damage the mite and also contribute to lesion formation. Analysis of a P. ovis expressed sequence tag (EST) database identified a number of antioxidant enzyme-encoding sequences, including peroxiredoxin (thioredoxin peroxidase EC 1.11.1.15), all of which may help the mite endure the potentially toxic skin environment. A full length sequence encoding Po-TPx, a protein of 206 amino acids which showed high homology to a peroxiredoxin from the salivary gland of the tick Ixodes scapularis, was amplified from P. ovis cDNA. Recombinant Po-TPx was expressed in bacteria and antiserum to this protein was used to localize native Po-TPx in mite sections. Peroxiredoxin was localized, amongst other sites, to a subpharyngeal region in mite sections. The recombinant protein was recognized by sera from sheep infested with the mite suggesting that it may be secreted or excreted by the mite and interact with the host immune response.

In Australia, macropodids are common intermediate hosts for the cestode Echinococcus granulosus, and sylvatic transmission is maintained via wild dogs. The parasite causes mortality in a number of macropodid species and the sylvatic cycle provides a source of infection to domestic livestock and humans. We determined the efficacy of the hydatid vaccine, EG95 in the tammar wallaby, Macropus eugenii, challenging either 1 or 9 months post-vaccination. EG95 provides similar protection to that seen in sheep (96–100%). Control tammars were significantly more likely to become infected (odds ratio 29·44; CI 4·13, 209·97; P=0·001) and to develop more cysts (count ratio 26·69; CI 5·83, 122·19; P<0·001). The vaccination may be beneficial if administered pre-release in captive breeding programmes for endangered macropodids. Further work to develop oral delivery methods may enable vaccine administration of wild animals and thereby a reduction in sylvatic transmission.