Piroplasms are intraerythrocytic parasites that are often transmitted by ixodid ticks, but vertical transmission is an alternative route for some species. In the USA, raccoons (Procyon lotor) are hosts for two known species, a Babesia microti-like sp. and Babesia lotori (in Babesia sensu stricto group). To better understand the natural history of Babesia in raccoons, we tested young raccoons from Minnesota and Colorado for Babesia spp., examined them for ticks, and assessing for splenomegaly as a sign of clinical disease. Raccoons from both states were infected with B. microti-like sp. and Babesia sensu stricto spp. Infections of B. microti-like were common, even in 1-week-old raccoons, suggesting vertical transmission. Babesia sensu stricto infections were more common in older raccoons. Raccoons infected with Babesia sensu stricto had significantly higher spleen:body weight ratios compared with uninfected or B. microti-like sp.-infected raccoons. Ticks were only found on raccoons from Minnesota. The most common and abundant tick was Ixodes texanus but Ixodes scapularis and Dermacentor variabilis were also found on raccoons. We report piroplasm infections and infestations with several tick species in very young raccoons. Young raccoons infected with Babesia sensu stricto spp. had higher spleen:body weight ratios, suggesting a disease risk.

Large-bodied ectoparasites are often observed only in low numbers in the field. How such rarely found parasites persist and maintain viable populations has been an intriguing question inadequately addressed. The simplest hypothesis is the existence of distribution hot spots, and another, but not mutually exclusive, possibility is a form of metapopulation structure where local populations are effectively connected via dispersal. In this study, we conducted an intensive epidemiological survey of a piscicolid leech Taimenobdella amurensis to elucidate spatial population structure and potential dispersal of this rarely found parasite. Four years of potential-host screening (n = 20 664) from 28 tributaries and 10 main stem reaches in a mountain river system of Hokkaido, northern Japan, revealed that occurrences of T. amurensis (n = 1348) were confined to spring-fed tributaries. Since most spring-fed tributaries were small (<1 km in length), it would seem to be unlikely for the ectoparasite to form a persistent local population in each tributary. The main host fish was Dolly Varden charr, which is known to disperse among neighbouring tributaries. These findings suggest that, along with the host, the ectoparasite displays a potential metapopulation structure, in which host-dependent dispersion may overcome local extinction by keeping the local populations connected.

The microaerophilic protozoan parasite Giardia lamblia occurs globally and causes dysentery in humans and animals. Since it is very sensitive to oxygen and reactive oxygen species, G. lamblia disposes over several enzymatic pathways to counter oxidative stress. One of the enzymes involved is thioredoxin reductase (TrxR), a central redox regulator that indirectly reduces peroxiredoxins via thioredoxin, an electron shuttle protein. Interestingly, the components of the TrxR-mediated redox system, including functional thioredoxins, have so far not been described despite their surmised importance for parasite survival. We aimed at filling this gap and attempted to identify functional thioredoxins and other interaction partners of TrxR in G. lamblia. To this end, we conducted database searches and expressed three recombinant candidate thioredoxins in Escherichia coli for ensuing enzyme assays. Further, co-immunoprecipitation experiments were conducted in order to identify further components of the thioredoxin redox network. Finally, the cellular localization of TrxR and peroxiredoxin 1 was determined by immunofluorescence microscopy. Surprisingly, our endeavours did not result in the identification of a functional thioredoxin or other credible interaction partners of TrxR. We, therefore, conclude that there is currently no evidence for a canonical thioredoxin redox network in G. lamblia.

Trypanosoma cruzi is the aetiological agent of Chagas disease. Our group has focused on the study of ribosomal RNA and nucleolar structure in this organism. In this work, we address the cellular location of fibrillarin in epimastigotes. As a conserved and unreported feature in trypanosomatids, fibrillarin in T. cruzi is encoded by two genes that differ by approximately 35% in their deduced amino acid sequences (TcFib 1 and TcFib 2). Chimaeric fluorescent versions of TcFib1 and TcFib2 were individually expressed in T. cruzi cells. Both transfected cultures showed cells with a nucleolar fluorescent signal. We have not found any evident distinction between the structure or expression of Tcfibrillarins to propose a functional difference in cells. With the aid of an anti-TcFib 2 antibody, it was found that the endogenous protein relocates outside of the nucleolus in stationary epimastigotes. This was also the case in metacyclic trypomastigotes observed from aged cultures. The significance of this observation is not known, but a deficiency of fibrillarin nucleolar retention correlates with the observed reduction in the abundance of the pre-ribosomal RNAs species at stationary phase, and suggests that the nucleolar location of this protein depends on physiological processes.

In Democratic People's Republic of Korea, only Plasmodium vivax malaria is prevalent, which is divided into two forms – long incubation form and short form. Among malaria cases reported in a year, long form accounts for 69% and short form 31%. Incubation period of short form ranges from 10 to 29 days (average 17 days) and long from 5·5 to 16 months (average 8–13 months). The most relapses (90%) were reported from May to September – malaria transmission season in the country. Result from preliminary mass chemoprevention in small size of population before transmission season to find appropriate method showed high protective efficacy in two regimens – one regimen given primaquine 0·25 mg base kg−1 day−1 for 14 days (95%) and another 0·5 mg base kg−1 day−1 for 7 days (94%). During the mass chemoprevention with primaquine, some adverse effects were reported but transient. We consider that mass chemoprevention with primaquine before transmission season is of great significance in disturbing the vivax malaria transmission, in which long incubation form is predominant in countries prevailing seasonal malaria.

Northern bobwhite quail (Colinus virginianus), a popular gamebird among hunters, have been declining over recent decades in the Rolling Plains ecoregion. Investigations in the past few years have revealed a high prevalence of eyeworms (Oxyspirura petrowi) and caecal worms (Aulonocephalus pennula) in this ecoregion, prompting a need to better understand their host–parasite interaction and other factors that influence infection. In this study, the efficiency of a mobile laboratory was tested by deploying it to three field sites in the Rolling Plains between July and August of 2017 and collecting cloacal swabs from bobwhites. The DNA was extracted from swabs for quantitative PCR and was run in the mobile and reference laboratory to specifically detect A. pennula and O. petrowi infection. When compared with the Wildlife Toxicology's reference laboratory, the mobile laboratory had a 97 and 99% agreement for A. pennula and O. petrowi, respectively. There were no significant differences in infection levels between field sites. Due to its efficiency, it is proposed that the mobile laboratory would be an effective way to monitor infection levels, in addition to factors that may affect infection such as climate, diapause, and intermediate host populations.

Head lice (Pediculus humanus capitis) infestations are a public health concern. The insecticidal properties of the Australian native plant Kunzea ambigua (commonly known as tick bush) have been documented. In this study, we tested activity of kunzea oil (KO) against head lice through in vitro bioassays. Head lice were exposed to filter paper treated with either KO, as either a 5 or 100% oil, or commercial formulations containing either permethrin or tea tree oil (TTO) for 120 min. Head lice exposure to KO, both as a 5 and 100% solution oil, resulted in 100% mortality within 120 min with a mean survival times of 17·1 and 34·8 min, respectively. There was no significant difference between the mean mortality of head lice exposed to 5% KO (17·1 ± 1·0; 95% CI: 115·2–19·0) and 5% TTO (21·2 ± 1·9; 95% CI: 17·4–25·1). This study revealed, for the first time, that KO holds great potential as an effective alternative to current active ingredients contained within commercial pediculicide formulations.

All organisms encounter pathogens, and birds are especially susceptible to infection by malaria parasites and other haemosporidians. It is important to understand how immune genes, primarily innate immune genes which are the first line of host defense, have evolved across birds, a highly diverse group of tetrapods. Here, we find that innate immune genes are highly conserved across the avian tree of life and that although most show evidence of positive or diversifying selection within specific lineages or clades, the number of sites is often proportionally low in this broader context of putative constraint. Rather, evidence shows a much higher level of negative or purifying selection in these innate immune genes – rather than adaptive immune genes – which is consistent with birds' long coevolutionary history with pathogens and the need to maintain a rapid response to infection. We further explored avian responses to haemosporidians by comparing differential gene expression in wild birds (1) uninfected with haemosporidians, (2) infected with Plasmodium and (3) infected with Haemoproteus (Parahaemoproteus). We found patterns of significant differential expression with some genes unique to infection with each genus and a few shared between ‘treatment’ groups, but none that overlapped with the genes included in the phylogenetic study.

Nematodes in the order Rhabditida, including species of Strongyloides and Pelodera, may be parasites of domestic animals. In this paper, we describe two apparent cases of rhabditid infections, one in a dog and one in a litter of piglets. The dog infection was originally considered likely to be an infection with Strongyloides, based on superficial morphological examination and PCR results without sequencing. However, more careful morphological analysis and inclusion of several molecular analyses, including sequencing, revealed that an infection with Pelodera sp. was more likely, probably Pelodera pseudoteres. Treatment with fenbendazole and selamectin was apparently successful. Similarly, based on both morphological and molecular analyses the apparent piglet infections were considered most likely to be with Rhabditis spp., possibly Rhabditis axei. The detection of larvae of nematodes in the order Rhabditida in fecal samples, particularly from dogs, may easily be considered as being indicative of Strongyloides infection. Given the zoonotic potential of canine Strongyloides, correct diagnosis is important. However, as illustrated by these two cases, careful morphological examination and measurement, supported by full molecular investigations, including sequencing, are essential in order to avoid this misdiagnosis.

We performed a cross-sectional survey in humans to evaluate Lutzomyia longipalpis, i.e. sand fly vector, bite exposure association with Leishmania (Leishmania) infantum chagasi infection in Bujarú municipality, Northern Brazil, an endemic area for visceral leishmaniasis. In recruited individuals, which were stratified by sex and age, we measured L. (L.) i. chagasi parasitic loads with quantitative polymerase chain reaction (qPCR), exposure to sand fly bites with an anti-saliva immunoglobulin G enzyme-linked immunosorbent assay and performed immunological diagnostic tests, in order to evaluate the association between exposure to sand fly bites, and infection. The prevalence increased from 11% when using immunological diagnostic tests to 28% when using qPCR, being around that value for all age classes, but children below 5 years (40%) and people over 60 years (15%). The association between PCR-based L. (L.) i. chagasi prevalence and saliva exposure was convex, reflecting the fact that at both high and low saliva exposure the PCR-based L. (L.) i. chagasi prevalence decreases. This scenario indicates that low sand fly exposure is likely associated with low parasite transmission, while high anti-saliva prevalence, i.e. a large sand fly bite exposure could be associated with anti-Leishmania protective immune mechanisms driven by vector saliva and/or increased parasite exposure.

There is limited evidence of the prevalence of enteric protozoon infections in developed settings. We estimated the prevalence of enteric protozoa and evaluated the outcome of testing algorithms used in hospital settings in Sydney, Australia. This retrospective study assessed microbiological data from four public clinical laboratories. Pooled data from the four hospitals revealed the most common enteric protozoon detected was Blastocystis spp. in an average of 5·4% of cases, followed by Giardia intestinalis (1·1%) and Dientamoeba fragilis (0·8%). Protozoon detection rates between hospitals were significantly different and could be based on multiple factors. The modified iron haematoxylin staining method, consistently detected higher rates of Blastocystis spp., and G. intestinalis in comparison with microscopy of wet preparations, as well as higher rates of G. intestinalis and Cryptosporidium when compared with enzyme immunoassay. The study concludes that there are multiple factors that contribute to the variability in protozoa detection rates in metropolitan hospitals, including widespread variability in the testing protocols for enteric protozoa, individual and population characteristics. A gold standard approach for diagnosis of enteric protozoa is recommended. Molecular diagnostic methods such as polymerase chain reaction would provide consistency across laboratories and yield more reliable estimates of the actual prevalence of enteric protozoa.

Serine protease inhibitors (serpins) play essential physiological roles in a wide range of biological processes. Serpins are researched limited in Taenia solium, although some are considered to participate in host immune responses. Tsserpins were identified as typical serpins due to the primary structure of characteristic features: the serpin motif, serpin signature and reaction centre loop (RCL). RCLs of four serpin genes (TsB6, Ts4848, Ts12383 and Ts570) contained the conserved sequences of inhibitory serpins, which may involve in immune regulation. TsEP45 differed greatly from the patterns of representative serpins, suggesting that TsEP45 may be non-inhibitory. The bioinformatic analyses were supposed that Tsserpins might be a potential antigen for diagnosis. The five recombinant Tsserpin proteins were expressed and identified reacting with Cysticercus cellulosae-positive serum samples. The indirect enzyme-linked immunosorbent assay (iELISAs) based on Tsserpins were developed and validated, one of the five Tsserpins, TsEP45, showed excellent diagnostic results with 93·33% sensitivity and 94·12% specificity, respectively. This performance was in perfect accordance with the results of the bioinformatic analysis. This study provided a comprehensive demonstration of sequences and structural-based analysis of Tsserpins. The iELISAs based on five Tsserpins were developed and compared. TsEP45 was the potential species-specific antigen for developing iELISA to detect porcine cysticercosis.

A total of eight foxhound packs in England and Wales were screened for Echinococcus species using a genus-specific coproantigen ELISA and for Echinococcus granulosus sensu lato and Echinococcus equinus by coproPCR. Main screening (n = 364 hounds) occurred during 2010–2011 wherein a quarter (25.6%) of the foxhound fecal samples tested were Echinococcus coproantigen-positive (93/364). In total, five of eight (62.5%) hunts screened had coproantigen-positive hounds; coproantigen prevalence for individual foxhound packs ranged from 0 to 61.2% and was shown to be >30% in three hunts (in counties of Powys, Wales and Northumberland, England). Foxhound fecal samples from six of the eight tested hunts (four Welsh and two English hunts) were positive by coproPCR for E. granulosus s.l (including one sequence confirmation of E. granulosus sensu stricto) and E. equinus DNA. Analysis of hunt questionnaire data suggested that there was an association between poor foxhound husbandry, especially feeding practices and Echinococcus coproantigen prevalence. Clearer guidelines regarding the risk of canine echinococcosis are required for safe management of foxhound hunts in England and Wales.

The protozoan parasite Trypanosoma evansi is responsible for causing Surra in a variety of mammalian hosts over a wide geographical area. In the absence of an effective vaccine and increasing resistance to current chemotherapeutic agents, peptidases from the S9 prolyl oligopeptidase family have been identified as potential drug and vaccine targets. In order to understand the function of these peptidases during infection, three null mutant clones for prolyl oligopeptidase (Δpop), prolyl oligopeptidase-like (Δpop-like) and oligopeptidase B (Δopb) were generated in T. evansi RoTat 1.2 parasites and used for infection of mice. Mice inoculated with T. evansi Δpop-like mutants were able to survive longer than other groups of mice inoculated with Δpop, Δopb mutants or wild-type parasites. The regression analysis of plasma from mice-infected over time using Δpop-like mutants showed stable levels of interleukin-10 (IL-10) (non-significant slope, P = 0·171) and declining IL-1b levels (negative slope, P = 0·04) when compared with the wild-type control that demonstrated increasing levels of IL-10 and IL-1b (P < 0·01 for both). Further analysis using mouse spleen cells in an in vitro 24 h incubation assay revealed that the percentage of IL-10 producing CD3 positive cells display significantly lower values when incubated with Δpop-like parasites than the wild-type clone (P = 0·002). These results suggest that prolyl oligopeptidase-like peptidase may play a role in immune responses during T. evansi infections by affecting interleukin concentrations in the host.

The Dicyemida and Orthonectida are two groups of tiny, simple, vermiform parasites that have historically been united in a group named the Mesozoa. Both Dicyemida and Orthonectida have just two cell layers and appear to lack any defined tissues. They were initially thought to be evolutionary intermediates between protozoans and metazoans but more recent analyses indicate that they are protostomian metazoans that have undergone secondary simplification from a complex ancestor. Here we describe the first almost complete mitochondrial genome sequence from an orthonectid, Intoshia linei, and describe nine and eight mitochondrial protein-coding genes from Dicyema sp. and Dicyema japonicum, respectively. The 14 247 base pair long I. linei sequence has typical metazoan gene content, but is exceptionally AT-rich, and has a unique gene order. The data we have analysed from the Dicyemida provide very limited support for the suggestion that dicyemid mitochondrial genes are found on discrete mini-circles, as opposed to the large circular mitochondrial genomes that are typical of the Metazoa. The cox1 gene from dicyemid species has a series of conserved, in-frame deletions that is unique to this lineage. Using cox1 genes from across the genus Dicyema, we report the first internal phylogeny of this group.