Juerg Utzinger

Integration of Water, Sanitation, and Hygiene for the Prevention and Control of Neglected Tropical Diseases: A Rationale for Inter-Sectoral Collaboration

Improvements of water, sanitation, and hygiene (WASH) infrastructure and appropriate health-seeking behavior are necessary for achieving sustained control, elimination, or eradication of many neglected tropical diseases (NTDs). Indeed, the global strategies to fight NTDs include provision of WASH, but few programs have specific WASH targets and approaches. Collaboration between disease control programs and stakeholders in WASH is a critical next step. A group of stakeholders from the NTD control, child health, and WASH sectors convened in late 2012 to discuss opportunities for, and barriers to, collaboration. The group agreed on a common vision, namely “Disease-free communities that have adequate and equitable access to water and sanitation, and that practice good hygiene.” Four key areas of collaboration were identified, including (i) advocacy, policy, and communication; (ii) capacity building and training; (iii) mapping, data collection, and monitoring; and (iv) research. We discuss strategic opportunities and ways forward for enhanced collaboration between the WASH and the NTD sectors.

Metabolic alterations in the hamster co-infected with Schistosoma japonicum and Necator americanus

Co-infection with hookworm and schistosomes is a common phenomenon in sub-Saharan Africa, as well as in parts of South America and southeast Asia. As a first step towards understanding the metabolic response of a hookworm-schistosome co-infection in humans, we investigated the metabolic consequences of co-infection in an animal model, using a nuclear magnetic resonance (NMR)-based metabolic profiling technique, combined with multivariate statistical analysis. Urine and serum samples were obtained from hamsters experimentally infected with 250 Necator americanus infective L(3) and 100 Schistosoma japonicum cercariae simultaneously. In the co-infection model, similar worm burdens were observed as reported for single infection models, whereas metabolic profiles of co-infection represented a combination of the altered metabolite profiles induced by single infections with these two parasites. Consistent differences in metabolic profiles between the co-infected and non-infected control hamsters were observed from 4 weeks p.i. onwards. The predominant metabolic alterations in co-infected hamsters consisted of depletion of amino acids, tricarboxylic acid cycle intermediates (e.g. citrate and succinate) and glucose. Moreover, alterations of a series of gut microbial-related metabolites, such as decreased levels of hippurate, 3-hydroxyphenylpropionic acid, 4-hydroxyphenylpropionic acid and trimethylamine-N-oxide, and increased concentrations of 4-cresol glucuronide and phenylacetylglycine were associated with co-infection. Our results provide a first step towards understanding the metabolic response of an animal host to multiple parasitic infections.

Metabolic profiling of a Schistosoma mansoni infection in mouse tissues using magic angle spinning-nuclear magnetic resonance spectroscopy.

In order to enhance our understanding of physiological and pathological consequences of a patent Schistosoma mansoni infection in the mouse, we examined the metabolic responses of different tissue samples recovered from the host animal using a metabolic profiling strategy. Ten female NMRI mice were infected with approximately 80 S. mansoni cercariae each, and 10 uninfected age- and sex-matched animals served as controls. At day 74 post infection (p.i.), mice were killed and jejunum, ileum, colon, liver, spleen and kidney samples were removed. We employed (1)H magic angle spinning-nuclear magnetic resonance spectroscopy to generate tissue-specific metabolic profiles. The spectral data were analyzed using multivariate modelling methods including an orthogonal signal corrected-projection to latent structure analysis and hierarchical principal component analysis to assess the differences and/or similarities in metabolic responses between infected and non-infected control mice. Most tissues obtained from S. mansoni-infected mice were characterized by high levels of amino acids, such as leucine, isoleucine, lysine, glutamine and asparagine. High levels of membrane phospholipid metabolites, including glycerophosphoryl choline and phosphoryl choline were found in the ileum, colon, liver and spleen of infected mice. Additionally, low levels of energy-related metabolites, including lipids, glucose and glycogen were observed in ileum, spleen and liver samples of infected mice. Energy-related metabolites in the jejunum, liver and renal medulla were found to be positively correlated with S. mansoni worm burden upon dissection. These findings show that a patent S. mansoni infection causes clear disruption of metabolism in a range of tissues at a molecular level, which can be interpreted in relation to the previously reported signature in a biofluid (i.e. urine), giving further evidence of the global effect of the infection.

Integrated Cytokine and Metabolic Analysis of Pathological Responses to Parasite Exposure in Rodents

Parasitic infections cause a myriad of responses in their mammalian hosts, on immune as well as on metabolic level. A multiplex panel of cytokines and metabolites derived from four parasite-rodent models, namely, Plasmodium berghei−mouse, Trypanosoma brucei brucei−mouse, Schistosoma mansoni−mouse, and Fasciola hepatica−rat were statistically coanalyzed. 1H NMR spectroscopy and multivariate statistical analysis were used to characterize the urine and plasma metabolite profiles in infected and noninfected animals. Each parasite generated a unique metabolic signature in the host. Plasma cytokine concentrations were obtained using the ‘Meso Scale Discovery’ multi cytokine assay platform. Multivariate data integration methods were subsequently used to elucidate the component of the metabolic signature which is associated with inflammation and to determine specific metabolic correlates with parasite-induced changes in plasma cytokine levels. For example, the relative levels of acetyl glycoproteins extracted from the plasma metabolite profile in the P. berghei-infected mice were statistically correlated with IFN-γ, whereas the same cytokine was anticorrelated with glucose levels. Both the metabolic and the cytokine data showed a similar spatial distribution in principal component analysis scores plots constructed for the combined murine data, with samples from all infected animals clustering according to the parasite species and whereby the protozoan infections (P. berghei and T. b. brucei) grouped separately from the helminth infection (S. mansoni). For S. mansoni, the main infection-responsive cytokines were IL-4 and IL-5, which covaried with lactate, choline, and d-3-hydroxybutyrate. This study demonstrates that the inherently differential immune response to single- and multicellular parasites not only manifests in the cytokine expression, but also consequently imprints on the metabolic signature, and calls for in-depth analysis to further explore direct links between immune features and biochemical pathways.

Panorganismal Metabolic Response Modeling of an Experimental Echinostoma caproni Infection in the Mouse

Metabolic profiling of host tissues and biofluids during parasitic infections can reveal new biomarker information and aid the elucidation of mechanisms of disease. The multicompartmental metabolic effects of an experimental Echinostoma caproni infection have been characterized in 12 outbred female mice infected orally with 30 E. caproni metacercariae each, using a further 12 uninfected animals as a control group. Mice were killed 36 days postinfection and brain, intestine (colon, ileum, jejeunum), kidney, liver, and spleen were removed. Metabolic profiles of tissue samples were measured using high-resolution magic angle spinning 1H NMR spectroscopy and biofluids measured by applying conventional 1H NMR spectroscopy. Spectral data were analyzed via principal component analysis, partial least-squares-derived methods and hierarchical projection analyses. Infection-induced metabolic changes in the tissues were correlated with altered metabolite concentrations in the biofluids (urine, plasma, fecal water) using hierarchical modeling and correlation analyses. Metabolic descriptors of infection were identified in liver, renal cortex, intestinal tissues but not in spleen, brain or renal medulla. The main physiological change observed in the mouse was malabsorption in the small intestine, which was evidenced by decreased levels of various amino acids in the ileum, for example, alanine, taurine, glutamine, and branched chain amino acids. Furthermore, altered gut microbial activity or composition was reflected by increased levels of trimethylamine in the colon. Our modeling approach facilitated in-depth appraisal of the covariation of the metabolic profiles of different biological matrices and found that urine and plasma most closely reflected changes in ileal compartments. In conclusion, an E. caproni infection not only results in direct localized (ileum and jejenum) effects, but also causes remote metabolic changes (colon and several peripheral organs), and therefore describes the panorganismal metabolic response of the infection.

Differences in microscopic diagnosis of helminths and intestinal protozoa among diagnostic centres

Sub-specialized tropical medicine laboratories are essential for the accurate diagnosis of many tropical infections that may not be correctly diagnosed in conventional laboratories. However, processing and examination of ‘identical’ biofluid specimens such as blood, stool and urine at different laboratories often results in considerable diagnostic discrepancies. For example, interlaboratory differences have been documented in the microscopic examination of malaria slides [1], and discrepancies have been observed when comparing different rapid tests for malaria diagnosis [2]. The aim of this study was to compare the results obtained at sub-specialized tropical medicine laboratories for the microscopic diagnosis of helminths and intestinal protozoa in faecal samples obtained from a rural community in an endemic area of sub-Saharan Africa. The study compared two European tropical disease diagnostic centres with each other and one of the two European centres with a West African centre. Our study was designed as a cross-sectional communitybased survey and was carried out in May 2002 in the village of Zouatta II, western Cote d’Ivoire. This village is endemic for Schistosoma mansoni, soil-transmitted helminths (Ascaris lumbricoides, hookworms and Trichuris trichiura) and intestinal protozoa [3]. Polyparasitism is extremely common [3, 4]. Details of the study area, as well as field and laboratory procedures, have been presented elsewhere [3]. In brief, approval of the study was obtained from the institutional review boards of the Centre Suisse de Recherches Scientifiques (Abidjan, Cote d’Ivoire) and the Swiss Tropical Institute (Basel, Switzerland). The study received ethical clearance from the Ministry of Public Health in Cote d’Ivoire and permission was also granted to us by local village authorities. Three consecutive morning stool specimens were collected over a 3-day period from 561 randomly selected community members aged 5 days to 91 years. Specimens were transferred to a laboratory in the nearby district town and processed the same day. From each specimen, a 42 mg Kato–Katz thick smear was prepared according to a standard procedure [5]. The slides were allowed to clear for 30–45 min prior to examination under a light microscope by experienced laboratory technicians. Specimens were analysed for S. mansoni and soil-transmitted helminths, with the numbers of eggs counted and recorded for each species separately. Individuals who tested positive for S. mansoni and/or soil-transmitted helminths were treated with a single oral dose of 40 mg/kg praziquantel and/or 400 mg albendazole, respectively. In addition, 1–2 g of each stool specimen was conserved in a sodium acetateacetic acid-formalin (SAF) solution on the same day of collection for future processing 6–12 months later at the other diagnostic centres. I. I. Bogoch Faculty of Medicine, University of Toronto, Toronto, M5S 1A8, Canada e-mail: ibogoch@hotmail.com

Systems Metabolic Effects of a Necator americanus Infection in Syrian Hamster

Hookworms (Ancylostoma duodenale and Necator americanus) are blood-feeding intestinal nematodes that infect approximately 700 million people worldwide. To further our understanding of the systems metabolic response of the mammalian host to hookworm infection, we employed a metabolic profiling strategy involving the combination of (1)H NMR spectroscopic analysis of urine and serum and multivariate data analysis techniques to investigate the biochemical consequences of a N. americanus infection in the hamster. The infection was characterized by altered energy metabolism, consistent with hookworm-induced anemia. Additionally, disturbance of gut microbiotal activity was associated with a N. americanus infection, manifested in the alterations of microbial-mammalian cometabolites, including phenylacetylglycine, p-cresol glucuronide, 4-hydroxy-3-methyl-phenylpropionic acid, hippurate, 4-hydroxyphenylactate, and dimethylamine. The correlation between worm burden and metabolite concentrations also reflected a changed energy metabolism and gut microbial state. Furthermore, elevated levels of urinary 2-aminoadipate was a characteristic feature of the infection, which may be associated with the documented neurological consequences of hookworm infection.

Systems parasitology: effects of Fasciola hepatica on the neurochemical profile in the rat brain.

We characterize the integrated response of a rat host to the liver fluke Fasciola hepatica using a combination of 1H nuclear magnetic resonance spectroscopic profiles (liver, kidney, intestine, brain, spleen, plasma, urine, feces) and multiplex cytokine markers of systemic inflammation. Multivariate mathematical models were built to describe the main features of the infection at the systems level. In addition to the expected modulation of hepatic choline and energy metabolism, we found significant perturbations of the nucleotide balance in the brain, together with increased plasma IL‐13, suggesting a shift toward modulation of immune reactions to minimize inflammatory damage, which may favor the co‐existence of the parasite in the host. Subsequent analysis of brain extracts from other trematode infection models (i.e. Schistosoma mansoni, and Echinostoma caproni) did not elicit a change in neural nucleotide levels, indicating that the neural effects of F. hepatica infection are specific. We propose that the topographically extended response to invasion of the host as characterized by the modulated global metabolic phenotype is stratified across several bio‐organizational levels and reflects the direct manipulation of host–nucleotide balance.

Chemometric analysis of biofluids from mice experimentally infected with Schistosoma mansoni

BackgroundThe urinary metabolic fingerprint of a patent Schistosoma mansoni infection in the mouse has been characterized using spectroscopic methods. However, the temporal dynamics of metabolic alterations have not been studied at the systems level. Here, we investigated the systems metabolic changes in the mouse upon S. mansoni infection by modeling the sequence of metabolic events in urine, plasma and faecal water.MethodsTen female NMRI mice, aged 5 weeks, were infected with 80 S. mansoni cercariae each. Ten age- and sex-matched mice remained uninfected and served as a control group. Urine, plasma and faecal samples were collected 1 day before, and on eight time points until day 73 post-infection. Biofluid samples were subjected to 1H nuclear magnetic resonance (NMR) spectroscopy and multivariate statistical analyses.ResultsDifferences between S. mansoni-infected and uninfected control mice were found from day 41 onwards. One of the key metabolic signatures in urine and faecal extracts was an alteration in several gut bacteria-related metabolites, whereas the plasma reflected S. mansoni infection by changes in metabolites related to energy homeostasis, such as relatively higher levels of lipids and decreased levels of glucose. We identified 12 urinary biomarkers of S. mansoni infection, among which hippurate, phenylacetylglycine (PAG) and 2-oxoadipate were particularly robust with regard to disease progression. Thirteen plasma metabolites were found to differentiate infected from control mice, with the lipid components, D-3-hydroxybutyrate and glycerophosphorylcholine showing greatest consistency. Faecal extracts were highly variable in chemical composition and therefore only five metabolites were found discriminatory of infected mice, of which 5-aminovalerate was the most stable and showed a positive correlation with urinary PAG.ConclusionsThe composite metabolic signature of S. mansoni in the mouse derived from perturbations in urinary, faecal and plasma composition showed a coherent response in altered energy metabolism and in gut microbial activity. Our findings provide new mechanistic insight into host-parasite interactions across different compartments and identified a set of temporally robust biomarkers of S. mansoni infection, which might assist in derivation of diagnostic assays or metrics for monitoring therapeutic response.

Quantitative Evaluation of a Handheld Light Microscope for Field Diagnosis of Soil-Transmitted Helminth Infection

We evaluated the Newton Nm1, a commercially available handheld light microscope and compared it with conventional light microscopy for the diagnosis of soil-transmitted helminth infections. A total of 91 Kato-Katz thick smears were examined by experienced microscopists and helminth eggs were counted and expressed as eggs per gram of stool (EPG). Mean egg counts were significantly higher with the conventional light microscope (5,190 EPG versus 2,386 EPG for Ascaris lumbricoides; 826 versus 456 for Trichuris trichiura; both P < 0.05). Using regression coefficients and accounting for intensity of infection, we found that the agreement between the two devices was excellent for both species (κ = 0.90, 95% confidence interval = 0.82-0.99 for A. lumbricoides and κ = 0.96, 95% CI = 0.91-1.00 for T. trichiura). The Newton Nm1 microscope may be a useful tool for the detection and quantification of soil-transmitted helminth infection in clinical, epidemiologic, and public health settings.