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Immunoglobulin E (IgE) is thought to have evolved to protect mammalian hosts against parasitic infections or toxins and plays a central role in the pathogenesis, diagnosis, and therapy of IgE-mediated allergy. Despite the prominence of IgE responses in most parasitic infections, and in stark contrast to its use in the diagnosis of allergy, this isotype is almost completely unexploited for parasite diagnosis. Here, we discuss the perceived or real limitations of IgE-based diagnosis in parasitology and suggest that the recent creation of a new generation of very sensitive cellular IgE-based reporters may represent a powerful new diagnostic platform, but needs to be based on a very careful choice of diagnostic allergens.

Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of the three infections overlap, but brain inflammation and the course of the disease differ, depending on the amoeba that is responsible. Understanding the differences between these amoebae can result in the development of strategies to prevent and treat these infections. Recently, numerous scientific advancements have been made in the understanding of pathogenicity mechanisms in general, and the basic biology, epidemiology, and the human immune response towards these amoebae in particular. In this review, we combine this knowledge and aim to identify which factors can explain the differences between the lethal brain infections caused by N. fowleri, B. mandrillaris, and Acanthamoeba spp.

Toxoplasmosis caused by the protozoan parasite Toxoplasma (T.) gondii, occurs worldwide. Infections range from asymptomatic to life-threatening disease. T. gondii infection is acquired either via bradyzoites in meat or via oocysts in the environment, but the relative importance of these routes and the different sources remains unclear. This study examined possible risk factors for toxoplasmosis in the Netherlands. A case-control study was conducted including persons with a recent infection and individuals with a negative test result for IgM and IgG to T. gondii between July 2016 and April 2021. Forty-eight cases and 50 controls completed the questionnaire. Food history and environmental exposures were compared using logistic regression. Consumption of different meat types was found to be related to recent infection. In the multivariable model, adjusted for age, gender and pregnancy, consumption of meat of large game animals (adjusted odds ratio (aOR) 8.2, 95% confidence interval 1.6-41.9) and sometimes (aOR 4.1, 1.1-15.3) or never (aOR 15.9, 2.2-115.5) washing hands before preparing food remained. These results emphasize the value of the advice to be careful with consumption of raw and undercooked meat. Good hand hygiene also could be promoted in the prevention of T. gondii infection.

In this clinical pearl an ectopic human Dioctophyma renale infection in the abdominal cavity is reported for the first time. The patient presented with a gastric perforation and the release of an adult Dioctophyma renale through an abdominal drain and three co-infections (Plasmodium malariae, Strongyloides stercoralis and Mansonella perstans).

Examination of viability of trypomastigotes before and after single-dose pentamidine treatment demonstrated that single-dose pentamidine substantially affected motility of trypomastigotes, a proxy of drug efficacy. This suggests that single-dose pentamidine may be of added value to bridge time until suramin will be available for treatment of human East Africa trypanosomiasis.

Background In falciparum malaria the total parasite biomass can be estimated by blood levels of histidine-rich protein 2 (PfHRP2), a Plasmodium falciparum-specific protein, which has been widely studied in malaria-endemic regions. This study investigates the usefulness of PfHRP2 as marker for disease severity in imported falciparum malaria. Methods A retrospective cohort analysis was done in 145 patients with imported falciparum malaria. Associations between PfHRP2, malaria disease severity and classic parameters of disease severity were examined by statistical analyses. Patients with different travel purposes were examined in two groups: visiting friends and relatives (VFRs) and other travel purposes (mainly tourists). Results High PfHRP2 levels were clearly associated with disease severity. VFRs status showed to be an independent determinant protecting against severe malaria. At similar PfHRP2 levels VFRs patients had significantly lower levels of peripheral blood parasitemia compared to other patients. Conclusion Our study confirms the association between PfHRP2 and disease severity in patients with imported falciparum malaria, but for proper interpretation of PfHRP2 levels as disease severity marker in travellers, the possible presence of pre-existing acquired anti-malarial immunity should be taken into account as the correlation between PfHRP2 levels and disease severity differed significantly between VFRs patients and patients with other travel purposes.

Primary amoebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoeba Naegleria fowleri. The amoeba migrates along the olfactory nerve to the brain, resulting in seizures, coma, and, eventually, death. Previous research has shown that Naegleria gruberi, a close relative of N. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several already-approved inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine., Primary amoebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoeba Naegleria fowleri. The amoeba migrates along the olfactory nerve to the brain, resulting in seizures, coma, and, eventually, death. Previous research has shown that Naegleria gruberi, a close relative of N. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several already-approved inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine. Our data demonstrate that etomoxir, orlistat, perhexiline, thioridazine, and valproic acid inhibited growth of N. gruberi. We then tested these compounds on N. fowleri and found etomoxir, perhexiline, and thioridazine to be effective growth inhibitors. Hence, not only are lipids the preferred food source for N. gruberi, but also oxidation of fatty acids seems to be essential for growth of N. fowleri. Inhibition of fatty acid oxidation could result in new treatment options, as thioridazine inhibits N. fowleri growth in concentrations that can be reached at the site of infection. It could also potentiate currently used therapy, as checkerboard assays revealed synergy between miltefosine and etomoxir. Animal testing should be performed to confirm the added value of these inhibitors. Although the development of new drugs and randomized controlled trials for this rare disease are nearly impossible, inhibition of fatty acid oxidation seems a promising strategy as we showed effectivity of several drugs that are or have been in use and that thus could be repurposed to treat PAM in the future.

Background Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale and A. ceylanicum), Strongyloides stercoralis and Schistosoma in human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. Methods and principal findings A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris, Trichuris, N. americanus, Ancylostoma, Strongyloides and Schistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. Conclusions/Significance We showed the technical feasibility of an international EQAS for the NAAT of STHs, Strongyloides and Schistosoma. In addition, we documented that there are clear benefits for participating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs., Author summary Tests that detect parasite DNA in human stool are increasingly being used for the diagnosis of infections with intestinal worms, including schistosomiasis. To ensure the quality in diagnostic testing of these parasitic worms, it is important that laboratories evaluate the diagnostic performance of their DNA-based tests. This can best be achieved by participating in an external quality assessment scheme (EQAS). An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. Currently, such an EQAS for parasitic worms is lacking. We therefore piloted an international EQAS for the diagnosis of parasitic worms involving 15 laboratories in Africa, Asia, Australia, Europe, and North America. Although most laboratories performed well, we could clearly identify those laboratories that may need to improve their test protocol. We found that laboratories were using many different test protocols, and further research should aim to verify whether this has an impact on the performance of the diagnostic outcomes.

Toll-like receptor 2 (TLR2) is an important pattern recognition receptor on the surface of host immune cells that binds a variety of ligands that are released by microorganisms as well as by damaged or dying host cells. According to the current concept, TLR2/1 and TLR2/6 heterodimers are activated by tri- or di-acylated ligands, respectively. However, also mono-acyl phospholipid containing lipid fractions derived from parasites, were reported to be able to activate TLR2. In order to provide conclusive evidence for the TLR2 activating capacity of mono-acyl phospholipids derived from pathogens, we developed a biosynthetic method to enzymatically convert commercially available phospholipids into several mono-acyl-phospholipid variants that were examined for their TLR2 activating capacity. These investigations demonstrated that 1-(11Z-eicosenoyl)-glycero-3-phosphoserine 20:1 (20:1 lyso-PS) is a true agonist of the TLR2/6 heterodimer and that its polar headgroup as well as the length of the acyl chain are crucial for TLR2 activation. In silico modelling further confirmed 20:1 mono-acyl PS as a ligand for TLR2/6 heterodimer, as this predicted that multiple hydrogen bonds are formed between the polar headgroup of 20:1 mono-acyl PS and amino acid residues of both TLR2 and TLR6. Future studies can now be performed to further assess the functions of 20:1 lyso-PS as an immunological mediator, because this enzymatic method enables its preparation in larger quantities than is possible by isolation from the parasite that naturally produces this compound, Schistosoma mansoni, the source of the original discovery (Van der Kleij et al., 2002).

For some diseases, successful vaccines have been developed using a nonpathogenic counterpart of the causative microorganism of choice. The nonpathogenicity of the rodent Plasmodium berghei (Pb) parasite in humans prompted us to evaluate its potential as a platform for vaccination against human infection by Plasmodium falciparum (Pf), a causative agent of malaria. We hypothesized that the genetic insertion of a leading protein target for clinical development of a malaria vaccine, Pf circumsporozoite protein (CSP), in its natural pre-erythrocytic environment, would enhance Pb's capacity to induce protective immunity against Pf infection. Hence, we recently generated a transgenic Pb sporozoite immunization platform expressing PfCSP (PbVac), and we now report the clinical evaluation of its biological activity against controlled human malaria infection (CHMI). This first-in-human trial shows that PbVac is safe and well tolerated, when administered by a total of ~300 PbVac-infected mosquitoes per volunteer. Although protective efficacy evaluated by CHMI showed no sterile protection at the tested dose, significant delays in patency (2.2 days, P = 0.03) and decreased parasite density were observed after immunization, corresponding to an estimated 95% reduction in Pf liver parasite burden (confidence interval, 56 to 99%; P = 0.010). PbVac elicits dose-dependent cross-species cellular immune responses and functional PfCSP-dependent antibody responses that efficiently block Pf sporozoite invasion of liver cells in vitro. This study demonstrates that PbVac immunization elicits a marked biological effect, inhibiting a subsequent infection by the human Pf parasite, and establishes the clinical validation of a new paradigm in malaria vaccination.

Nontraumatic myelopathy causes severe morbidity and is not uncommon in Africa. Clinically, patients often present with paraplegia, and extrinsic cord compression and transverse myelitis are most common causes. Data on exact pathogenesis are scanty because of limitations in diagnostic methods. In Queen Elizabeth Central Hospital, Blantyre, Malawi, we recorded consecutive patients presenting with nontraumatic paraplegia for maximally 6 months between January and July 2010 and from March to December 2011. The diagnostic workup included imaging and examining blood, stool, urine, sputum, and cerebrospinal fluid (CSF) samples for infection. After discharge, additional diagnostic tests, including screening for virus infections, borreliosis, syphilis, and schistosomiasis, were carried out in the Netherlands. The clinical diagnosis was, thus, revised in retrospect with a more accurate final differential diagnosis. Of 58 patients included, the mean age was 41 years (range, 12-83 years) and the median time between onset and presentation was 18 days (range, 0-121 days), and of 55 patients tested, 23 (42%) were HIV positive. Spinal tuberculosis (n = 24, 41%), tumors (n = 16, 28%), and transverse myelitis (n = 6, 10%) were most common; in six cases (10%), no diagnosis could be made. The additional tests yielded evidence for CSF infection with Schistosoma, Treponema pallidum, Epstein-Barr virus (EBV), HHV-6, HIV, as well as a novel cyclovirus. The diagnosis of the cause of paraplegia is complex and requires access to an magnetic resonance imaging (MRI) scan and other diagnostic (molecular) tools to demonstrate infection. The major challenge is to confirm the role of detected pathogens in the pathophysiology and to design an effective and affordable diagnostic approach.

Background Liver injury is a known feature of severe malaria, but is only incidentally investigated in uncomplicated disease. In such cases, drug-induced hepatotoxicity is often thought to be the primary cause of the observed liver injury, and this can be a major concern in antimalaria drug development. We investigated liver function test (LFT) abnormalities in patients with imported uncomplicated malaria, and in Controlled Human Malaria Infection (CHMI) studies. Methods Clinical and laboratory data from 484 imported malaria cases and 254 CHMI participants were obtained from the Rotterdam Malaria Cohort database, and the Radboud University Medical Center database (between 2001 and 2017), respectively. Routine clinical LFTs, clinical profiles, parasite densities, hematological, and inflammation parameters were assessed in 217 patients with imported falciparum malaria upon admission, and from longitudinal data of 187 CHMI participants. Findings Upon admission, the proportion of patients with imported uncomplicated malaria and elevated liver enzymes was 128/186 (69%). In CHMI, 97/187 (52%) participants showed LFT abnormalities, including mild (64%, >1.0 ≤ 2.5× upper limit of normal (ULN)), moderate (20%, >2.5 ≤ 5.0xULN) or severe (16%, >5.0xULN). LFT abnormalities were primarily ALT/AST elevations and to a lesser extent γGT and ALP. LFT abnormalities peaked shortly after initiation of treatment, regardless of drug regimen, and returned to normal within three to six weeks. Positive associations were found with parasite burden and inflammatory parameters, including cumulative inflammatory cytokine responses and oxidative stress markers (r = 0·65, p = 0·008, and r = −0·63, p = 0·001, respectively). Interpretation This study shows that reversible liver injury is a common feature of uncomplicated falciparum malaria, most likely caused by an enduring pro-inflammatory response post treatment. The recognition of this phenomenon is of clinical relevance for individual patient care as well as clinical development of (new) antimalarial drugs. Fund PATH Malaria Vaccine Initiative (MVI)

For some diseases, successful vaccines have been developed using a nonpathogenic counterpart of the causative microorganism of choice. The nonpathogenicity of the rodent

Primary Amoebic Meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoebaNaegleria fowleri. The disease mostly affects healthy children and young adults after contaminated water enters the nose, generally during recreational water activities. The amoeba migrate along the olfactory nerve to the brain, resulting in seizures, coma and eventually death. Previous research has shown thatNaegleria gruberi, a close relative ofN. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine. Our data demonstrate that etomoxir, orlistat, perhexiline, thioridazine and valproic acid inhibited growth ofN. gruberi. Furthermore, additive effects were seen when drugs were combined. Both thioridazine and valproic acid inhibit in vitro growth ofN. gruberiin concentrations that can be obtained at the site of infection, which is doubtful with the currently used drugs amphotericin B and miltefosine. Both thioridazine and valproic acid have already been used for other diseases. As the development of new drugs and randomized controlled trials for this rare disease is nearly impossible, repurposing drugs is the most promising way to obtain additional drugs to combat PAM. Thioridazine and valproic acid are available drugs without major side-effects and can, therefore, be used as new complementary options in PAM therapy.

Ciliates are highly complex unicellular eukaryotes. Most of them live in aerobic environments and possess mitochondria. However, in several orders of ciliates, anaerobic species evolved that contain “hydrogenosomes”, organelles that produce hydrogen and ATP. These hydrogenosomes of ciliates have not been studied in the same detail as those of trichomonads and chytrid fungi. Therefore, generalizations on the characteristics of hydrogenosomes of ciliates are somewhat premature, especially since phylogenetic studies suggest that hydrogenosomes have arisen independently several times in ciliates. In this chapter, the hydrogenosomes of the anaerobic, heterotrichous ciliate Nyctotherus ovalis from the hindgut of cockroaches will mainly be described as these are the ones that are, at the moment, the most thoroughly studied. Thus far, this is the only hydrogenosome known to possess a genome and this genome is clearly of mitochondrial origin. In fact, the hydrogenosome of N. ovalis unites typical mitochondrial features such as a genome and an electron-transport chain with the most characteristic hydrogenosomal property, the production of hydrogen. The hydrogenosomal metabolism of N. ovalis will be compared with that of two other ciliates that have been studied in less detail, i.e. the holotrichous rumen ciliate Dasytricha, and the free-living plagiopylid ciliate Trimyema. All studies combined indicate that it is likely that the various types of hydrogenosomes in ciliates evolved by modifications of aerobic mitochondria when the different ciliates adapted to anaerobic or micro aerobic environments. Furthermore, it is clear that the hydrogenosomes of anaerobic ciliates are different from those of chytrid fungi and from the well-studied ones in trichomonads.

We present a unique case of disseminated Leishmaniasis in an HIV patient. Two different Leishmania species were identified by genomic sequencing in both bone marrow and skin. The Leishmania infection could be suppressed but not cured, despite a high dose of amphotericin B of nearly 65 g over more than 6 years.

Background After a controlled human malaria infection (CHMI), presentation of clinical signs and symptoms and host responses is heterogeneous. Transforming growth factor-beta (TGF-β) is the first serum cytokine that changes in malaria-naive volunteers after CHMI. We studied a possible relation between TGF-β changes, pro-inflammatory cytokines, activation of haemostasis and endothelial cells and clinical symptoms. Methods A panel of cytokines including TGF-β, and markers of activation of haemostasis and endothelial cells were measured in blood samples of 15 volunteers at baseline before CHMI and during CHMI at day of treatment. The change of the parameters on the day of treatment was examined for a significant alteration during infection. Results Nine of 15 volunteers showed a significant decrease in TGF-β compared to baseline, with concomitant increased concentrations of D-dimer (p = 0.012), Von Willebrand factor (p = 0.017), IL-6 (p = 0.012) and IFN-γ (0.028) and a significantly decreased platelet count (p = 0.011). In contrast, 6 of 15 volunteers showed sustained or increased TGF-β concentrations without change in the aforementioned parameters. The sustained responders presented with less moderate and severe clinical symptoms than the negative responders (p = 0.036) and had a higher baseline lymphocyte count (p = 0.026). TGF-β concentrations did not correlate with the parasitaemia on day of treatment. Conclusion Early decreases of serum TGF-β might function a marker for a pro-inflammatory host response and downstream clinical symptoms and pathology during CHMI.

To the Editor: Cutaneous leishmaniasis (CL) is a protozoan disease transmitted by sand flies that usually runs a relatively mild course. Classic CL starts as a red papule at the place of the insect bite; it gradually enlarges into a painless nodule or plaque-like lesion, which eventually becomes encrusted. When the crust falls off, a typical ulcer with raised and indurated border becomes apparent. CL can cause considerable illness and may leave disfiguring and disabling scars after healing. The interplay between Leishmania species and host immune response is complex, and, as a result, disease manifestations may vary substantially among species as well as among infected persons (1,2). An estimated 0.7–1.2 million new CL cases occur annually in tropical and subtropical regions of the world. CL is currently endemic in >98 countries worldwide; Afghanistan, Algeria, Colombia, Brazil, Iran, Syria, Ethiopia, North Sudan, Costa Rica, and Peru together account for up to 75% of global estimated CL incidence (3).

Introduction. Chagas disease is caused by infection with the protozoan Trypanosoma cruzi. It is endemic to the American continent due to the distribution of its insect vectors. The disease is occasionally imported to other continents by travel of infected individuals. It is rarely diagnosed in the Netherlands and exact numbers of infected individuals are unknown. Clinical manifestations can start with an acute phase of 4–8 weeks with non-specific, mild symptoms and febrile illness. In the chronic phase, it can lead to fatal cardiac and gastro-intestinal complications. Case presentation. We describe a case of a 40-year-old man with end-stage cardiomyopathy due to Chagas disease. He lived in Surinam for more than 20 years and had an unremarkable medical history until he was hospitalized due to pneumonia and congestive heart failure. Despite antibiotic treatment and optimizing cardiac medication, his disease progressed to end-stage heart failure for which cardiac transplantation was the only remaining treatment. A left ventricular assist device (LVAD) was implanted as a bridge to transplantation. Tissue analysis after LVAD surgery revealed ongoing myocarditis caused by Chagas disease. Based on a literature review, a scheme for follow up and treatment after transplantation was postulated. Conclusion. Chagas disease should be taken into account in patients from endemic countries who have corresponding clinical signs. Heart transplantation in patients with Chagas cardiomyopathy is accompanied by specific challenges due to the required immunosuppressive therapy and the thereby increased risk of reactivation of a latent T. cruzi infection.

Background: Real-time PCR methods are increasingly used in routine patient care settings not only to determine the presence or absence of pathogens in patient materials, but also to obtain semiquantitative results to estimate the pathogen load. However, it is so far unknown how well these methods are harmonized among different laboratories. Methods: Sets of stool samples were distributed three to four times per year to ca. 25–40 participating laboratories within the European Union as part of an external quality assessment scheme (EQAS) for the detection of gastrointestinal protozoa. This paper presents the results obtained over a 3-year period for Entamoeba histolytica, Entamoeba dispar, Giardia lamblia, Cryptosporidium species and Dientamoeba fragilis. Results: Although both false-positive and false-negative results were reported, the overall sensitivity and specificity were high. The substantial differences in the quantitative output of the real-time PCR assays could be traced back to differences in DNA isolation procedures between different laboratories. Conclusions: Participation in an EQAS proved to be important as it provides information on how the real-time PCR methods used by the participant compares to the generally reported results and indicates how procedures could be improved. Semiquantitative results of real-time PCR methods are not exchangeable between laboratories as long as the diagnostic procedures are not harmonized. Intralaboratory comparison of semiquantitative real-time PCR results seems only possible by the use of calibration curves derived from well-validated standards in clinical material and not by spiking solutions with purified DNA.

The hydrophobic molecules of the metabolome - also named the lipidome - constitute a major part of the entire metabolome. Novel technologies show the existence of a staggering number of individual lipid species, the biological functions of which are, with the exception of only a few lipid species, unknown. Much can be learned from pathogens that have evolved to take advantage of the complexity of the lipidome to escape the immune system of the host organism and to allow their survival and replication. Different types of pathogens target different lipids as shown in interaction maps, allowing visualization of differences between different types of pathogens. Bacterial and viral pathogens target predominantly structural and signaling lipids to alter the cellular phenotype of the host cell. Fungal and parasitic pathogens have complex lipidomes themselves and target predominantly the release of polyunsaturated fatty acids from the host cell lipidome, resulting in the generation of eicosanoids by either the host cell or the pathogen. Thus, whereas viruses and bacteria induce predominantly alterations in lipid metabolites at the host cell level, eukaryotic pathogens focus on interference with lipid metabolites affecting systemic inflammatory reactions that are part of the immune system. A better understanding of the interplay between host-pathogen interactions will not only help elucidate the fundamental role of lipid species in cellular physiology, but will also aid in the generation of novel therapeutic drugs.

In the presence of oxygen, Euglena gracilis mitochondria function much like mammalian mitochondria. Under anaerobiosis, E. gracilis mitochondria perform a malonyl-CoA independent synthesis of fatty acids leading to accumulation of wax esters, which serve as the sink for electrons stemming from glycolytic ATP synthesis and pyruvate oxidation. Some components (enzymes and cofactors) of Euglena's anaerobic energy metabolism are found among the anaerobic mitochondria of invertebrates, others are found among hydrogenosomes, the H

In the presence of oxygen, Euglena gracilis mitochondria function much like mammalian mitochondria. Under anaerobiosis, E. gracilis mitochondria perform a malonyl-CoA independent synthesis of fatty acids leading to accumulation of wax esters, which serve as the sink for electrons stemming from glycolytic ATP synthesis and pyruvate oxidation. Some components (enzymes and cofactors) of Euglena’s anaerobic energy metabolism are found among the anaerobic mitochondria of invertebrates, others are found among hydrogenosomes, the H2-producing anaerobic mitochondria of protists.

Contains fulltext : 177607.pdf (Publisher’s version ) (Closed access) Malaria sporozoites must first undergo intrahepatic development before a pathogenic blood-stage infection is established. The success of infection depends on host and parasite factors. In healthy human volunteers undergoing controlled human malaria infection (CHMI), we directly compared three clinical Plasmodium falciparum isolates for their ability to infect primary human hepatocytes in vitro and to drive the production of blood-stage parasites in vivo. Our data show a correlation between the efficiency of strain-specific sporozoite invasion of human hepatocytes and the dynamics of patent parasitemia in study subjects, highlighting intrinsic differences in infectivity among P. falciparum isolates from distinct geographical locales. The observed heterogeneity in infectivity among strains underscores the value of assessing the protective efficacy of candidate malaria vaccines against heterologous strains in the CHMI model.

Background Treatment of blood samples from hemorrhagic fever virus (HFV)-infected patients with 0.1% detergents has been recommended for virus inactivation and subsequent safe laboratory testing. However, data on virus inactivation by this procedure are lacking. Here we show the effect of this procedure on diagnostic test results and infectious Ebola virus (EBOV) titers. Methods Serum and whole-blood samples were treated with 0.1% or 1% sodium dodecyl sulfate (SDS) or 0.1% Triton X-100 and assayed for clinical chemistry and malaria antigen detection. Infectious EBOV titers were determined in SDS-treated plasma and whole blood from EBOV-infected nonhuman primates (NHPs). Infectious titers of EBOV or herpes simplex virus type 1 (HSV-1) in detergents-treated cell culture medium containing various serum concentrations were determined. Results Laboratory test results were not affected by 0.1% detergent treatment of blood samples, in contrast with 1% SDS treatment. However, 0.1% detergent treatment did not inactivate EBOV in blood samples from infected NHPs. Experiments with cell culture medium showed that virus inactivation by detergents is annulled at physiological serum concentrations. Conclusions Treatment of blood samples with 0.1% SDS or Triton X-100 does not inactivate EBOV. Inactivation protocols for HFV should be validated with serum and whole blood.

Background Levels of both angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) correlate with malaria disease severity and are proposed as biomarkers and possible therapeutic targets. To establish their role in malaria, a systematic review was performed of the literature on Ang-1 and Ang-2 with regard to their potential as biomarkers in malaria and discuss their possible place in adjuvant treatment regimens. Methods Ten electronic databases were systematically searched to identify studies investigating Ang-1 and Ang-2 in human and murine malaria in both clinical and experimental settings. Information about the predictive value of Ang-1 and Ang-2 for disease severity and their regulatory changes in interventional studies were extracted. Results Some 579 studies were screened; 26 were included for analysis. In all five studies that determined Ang-1 levels and in all 11 studies that determined Ang-2 in different disease severity states in falciparum malaria, a decline in Ang-1 and an increase of Ang-2 levels was associated with increasing disease severity. All nine studies that determined angiopoietin levels in Plasmodium falciparum patients to study their ability as biomarkers could distinguish between multiple disease severity states; the more the disease severity states differed, the better they could be distinguished. Five studies differentiating malaria survivors from non-survivors with Ang-2 as marker found an AUROC in a range of 0.71–0.83, which performed as well or better than lactate. Prophylactic administration of FTY720, rosiglitazone or inhalation of nitric oxide (NO) during malaria disease in mice resulted in an increase in Ang-1, a decrease in Ang-2 and an increased survival. For rosiglitazone, a decrease in Ang-2/Ang-1 ratio was observed after post-infection treatment in mice and humans with malaria, but for inhalation of NO, an effect on Ang-1 and survival was only observed in mice. Conclusion Both Ang-1 and Ang-2 levels correlate with and can distinguish between malaria disease severity states within the group of malaria-infected patients. However, distinct comparisons of disease severity states were made in distinct studies and not all distinctions made had clinical relevance. Changes in levels of Ang-1 and Ang-2 might also reflect treatment effectiveness and are promising therapeutic targets as part of multi-targeted therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1624-8) contains supplementary material, which is available to authorized users.

To the Editor: Balamuthia mandrillaris is a free-living ameba that has a worldwide distribution in soil and was first reported in 1990 (1). Approximately 200 B. mandrillaris meningoencephalitis cases have been described, mostly from warm climate areas in South America. Its prevalence in the United States is estimated to be 1 case/year (2). However, B. mandrillaris meningoencephalitis has not been reported in Africa, and only 4 cases have been reported in Europe (3–6). Transmission occurs through the respiratory tract or the skin or by organ transplant, and the incubation period varies from weeks to months after primary infection (7). After an indolent, subacute phase with aspecific symptoms, the amebae invade the central nervous system, and illness rapidly progresses, leading almost invariably to death (7). Because B. mandrillaris is difficult to detect in soil, its specific geographic distribution around the world is unknown and is estimated on the basis of where illnesses have been reported (7). This report addresses fatal B. mandrillaris meningoencephalitis in a woman from the Netherlands who had visited The Gambia. In December 2013, a previously healthy 61-year-old white woman in the Netherlands sought care for fever, headaches, and muscle pains she had experienced for 1 week. That year, she had traveled 4 times to The Gambia, the last visit being 1 month before her hospitalization (Technical Appendix Table 1). After she returned from her visit in September 2013, fatigue, diarrhea, fever, and pustular skin lesions on her back and lower extremities developed. A wound swab culture showed Staphylococcus aureus, for which she was treated successfully with oral clarithromycin and topical fucidin ointment. On admission in December, her physical and neurologic examination results were unremarkable. Malaria was excluded; because of persisting headaches, a cerebral computed tomography scan without contrast was performed but showed no abnormalities. In the following days, high fevers, altered mental status, and nuchal rigidity without focal neurologic deficits developed. Cerebrospinal fluid (CSF) examination showed mononuclear pleocytosis, highly elevated protein levels, and low glucose levels (Technical Appendix Table 2). Serial cerebral computed tomography and magnetic resonance imaging scans showed development of an asymmetric hydrocephalus and diffuse leptomeningeal and subependymal contrast enhancement, especially around the brainstem, without signs of intracerebral mass lesions (Technical Appendix Figure). Presumed diagnosis was tuberculous meningitis, and she was treated with tuberculostatic drugs (isoniazid, rifampin, pyrazinamide, and ethambutol) combined with intravenous acyclovir, ceftriaxone, and co-trimoxazole for other infectious causes of meningoencephalitis. Despite external lumbar and ventricular (both lateral ventricles and fourth ventricle) CSF drainage, her neurologic condition deteriorated. Multiple cranial nerve palsies developed, and she became comatose and died 11 days after admission. Informed consent for postmortem examination was obtained, and macroscopic pathologic examination showed uncal and cerebellar herniation caused by increased intracranial pressure. Microscopic brain tissue examination showed signs of acute granulomatous inflammation, multiple hemorrhagic infarctions, and angiitis in the presence of numerous amebic trophozoites and cysts (Figure), which showed granulomatous hemorrhagic necrotic amebic meningoencephalitis. Real-time PCR and subsequent sequencing on brain biopsy and CSF specimens showed B. mandrillaris to be the causative ameba (8,9). Figure Postmortem pathologic findings for woman in the Netherlands who died of Balamuthia mandrillaris meningoencephalitis after returning from travel to The Gambia. A) Macroscopic coronal central section scan showing hemorrhagic necrotizing lesions of the subependymal, ... The infection could have been acquired in The Gambia or the Netherlands because the patient had intensive soil contact in The Gambia, where she frequently cultivated land, and in the Netherlands, where she worked in glass horticulture. She may have been infected through the skin after contact with contaminated soil, but her skin lesions were atypical for B. mandrillaris, and postmortem examinations failed to identify B. mandrillaris except in the central nervous system. The lack of reported B. mandrillaris cases from Africa might indicate a low number of postmortem examinations and little access to advanced diagnostics, rather than a low environmental prevalence of B. mandrillaris. The few reported cases in Europe might be related to lack of awareness and to clinical signs and symptoms that mimic tuberculous meningitis: a lymphocytic pleocytosis with an elevated protein level and a low glucose level in CSF, together with a hydrocephalus and subependymal and leptomeningeal contrast enhancement on magnetic resonance imaging (10). Also, B. mandrillaris meningoencephalitis imaging findings are often nonspecific, including cerebral edema, hydrocephalus, multiple space-occupying and ring-enhancing lesions, leptomeningeal enhancement, or formation of mycotic aneurysms (2). Furthermore, amebic trophozoites are seldom detected in CSF by microscopy (2,3). Consequently, B. mandrillaris meningoencephalitis could be underdiagnosed, especially where this infection has no or only sporadic reports. B. mandrillaris should be considered in refractory or unexplained cases of meningoencephalitis, even outside the Americas and in immunocompetent patients. Detecting B. mandrillaris by PCR in CSF seems most likely to enable early diagnosis and timely treatment. However, appropriate therapy is not well defined; success has been sparsely reported with the simultaneous use of azoles, flucytosine, pentamidine, sulfazidine, macrolide antimicrobial drugs, phenothiazines, and miltefosine (2,7,10). Technical Appendix. Timeline of relevant events, laboratory investigations during hospitalization, and imaging results for Dutch traveler who died of Balamuthia mandrillaris meningoencephalitis after returning from The Gambia. Click here to view.(248K, pdf)

Until now, two studies investigated whether the long-term survival after heart transplantation is affected by the Toxoplasma serostatus of the recipient and the donor (1, 2). These studies, however, yielded conflicting results as to the recipient serostatus. Arora et al. reported that a Toxoplasma seropositive status in heart transplant recipients was associated with an increased risk of all-cause mortality as well as risk of death by cardiac allograft vasculopathy and Doesch et al. reported that a Toxoplasma seronegative status was associated with an increased mortality risk (1, 2). In both studies, no association of donor serostatus and mortality was found. Toxoplasma gondii is an obligate intracellular protozoan parasite with a worldwide distribution that can invade and replicate in almost all nucleated cells of warm-blooded mammals. After the primary acute infection, the parasite remains in the body in a quiescent state by the formation of tissue cysts in predominantly muscle and brain tissue. Therefore, toxoplasmosis is a lifelong infection and the prevalence of human T. gondii infections thus increases with age. Its prevalence is reported to be more than 50% in many parts of the world (3). In immunocompetent individuals, the infection is usually asymptomatic, although cases of severe disease due to unusual T. gondii genotypes from South and Central America have been reported (4). In immunocompromised patients, however, toxoplasmosis can be a severe disease (3). Solid-organ transplant recipients are immunocompromised due to the required high dose of immunosuppressive medication. Heart transplant recipients are known to be at risk for toxoplasmosis, especially when recipients are seronegative (and thus naive for T. gondii) and receive a heart transplant, containing tissue cysts, from a T. gondii–infected donor (5). In these cases, prophylactic treatment is indicated to prevent toxoplasmic myocarditis and fatal disseminated toxoplasmosis (5, 6). Also, antibiotic drugs, administered prophylactically to Toxoplasma mismatched recipients, could have a direct or indirect immunomodulatory effect and could negatively influence patient outcome by their side effects (7). Cardiac allograft vasculopathy, a process in which chronic inflammation and immune activation play an important role, is a major cause of death after heart transplantation (8, 9). A T. gondii infection might influence the host immunologic status and thereby affect the risk for cardiac allograft vasculopathy. Therefore, the effects of a T. gondii infection on the survival after heart transplantation have been subject of study. Because of the earlier conflicting results of studies, which involved rather small numbers of patients and a limited follow-up duration, we performed a study on our whole population of heart transplant recipients to evaluate the effects of a T. gondii infection in the recipient and/or the donor on survival after heart transplantation.

Blastocystis is a protozoan parasite of controversial clinical significance that is often detected in stools of patients with gastrointestinal complaints. Patients infected with Blastocystis and persistent, unexplained gastrointestinal complaints are often treated with the intention to eradicate Blastocystis. However, there is no consensus on the most effective drug. We performed a retrospective follow-up study with a large cohort of patients in which the natural disease course and efficacy of treatment with either paromomycin, clioquinol, or metronidazole were evaluated. With an eradication rate of 77 %, treatment with paromomycin appeared significantly more effective than treatment with clioquinol (38 %), metronidazole (38 %), or no treatment (22 %). This study showed that (1) Blastocystis was frequently observed in the stools of our patient group (34 %), (2) spontaneous clearance of Blastocystis infections occurred only in a small proportion of patients (22 %), and therefore (3) drug treatment is required for more efficient eradication of Blastocystis. Paromomycin exhibited superior performance in comparison to both metronidazole and clioquinol.

Malaria sporozoites must first undergo intrahepatic development before a pathogenic blood-stage infection is established. The success of infection depends on host and parasite factors. In healthy human volunteers undergoing controlled human malaria infection (CHMI), we directly compared three clinical

Background Acute kidney injury (AKI) is a frequently encountered complication of imported Plasmodium falciparum infection. Markers of structural kidney damage have been found to detect AKI earlier than serum creatinine-based prediction models but have not yet been evaluated in imported malaria. This pilot study aims to explore the predictive performance of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) for AKI in travellers with imported P. falciparum infection. Methods Thirty-nine patients with imported falciparum malaria from the Rotterdam Malaria Cohort with available serum and urine samples at presentation were included. Ten of these patients met the criteria for severe malaria. The predictive performance of NGAL and KIM-1 as markers for AKI was compared with that of serum creatinine. Results Six of the 39 patients (15 %) developed AKI. Serum and urine NGAL and urine KIM-1 were all found to have large areas under the receiver operating characteristics curves (AUROC) for predicting AKI. Urine NGAL was found to have an excellent performance with positive predictive value (PPV) of 1.00 (95 % CI 0.54–1.00), a negative predictive value (NPV) of 1.00 (95 % CI 0.89–1.00) and an AUROC of 1.00 (95 % CI 1.00–1.00). Conclusion A good diagnostic performance of NGAL and KIM-1 for AKI was found. Particularly, urine NGAL was found to have an excellent predictive performance. Larger studies are needed to demonstrate whether these biomarkers are superior to serum creatinine as predictors for AKI in P. falciparum malaria. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1516-y) contains supplementary material, which is available to authorized users.

The schistosome eggshell is a hardened and tanned structure made from cross-linked proteins. It is synthesized within the female worm from many different kinds of proteins and glycoproteins. Once the egg is released in the circulation, the outer surface of the eggshell is exposed and hence a direct site of interaction between the parasite and the host. The major eggshell protein is p14, but about one third of the eggshell is made from common cellular proteins, some of which are known to be immunogenic. This has many consequences for parasite-host interactions. However, so far, the eggshell has gained little attention from researchers. We will discuss the structure of the eggshell and its role in granuloma formation, host factor binding and egg excretion. (c) 2011 Elsevier Inc. All rights reserved.