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Correction: Significance of major international seaports in the distribution of murine typhus in Taiwan

by Chi-Chien Kuo, Nicola Wardrop, Chung-Te Chang, Hsi-Chieh Wang, Peter M. Atkinson

Correction: Meta-transcriptome Profiling of the Human-<i>Leishmania braziliensis</i> Cutaneous Lesion

by Stephen M. Christensen, Laura A. L. Dillon, Lucas P. Carvalho, Sara Passos, Fernanda O. Novais, V. Keith Hughitt, Daniel P. Beiting, Edgar M. Carvalho, Phillip Scott, Najib M. El-Sayed, David M. Mosser

A pilot study to delimit tsetse target populations in Zimbabwe

by Gerald Chikowore, Ahmadou H. Dicko, Peter Chinwada, Moses Zimba, William Shereni, François Roger, Jérémy Bouyer, Laure Guerrini

Background

Tsetse (Glossina sensu stricto) are cyclical vectors of human and animal trypanosomoses, that are presently targeted by the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) coordinated by the African Union. In order to achieve effective control of tsetse, there is need to produce elaborate plans to guide intervention programmes. A model intended to aid in the planning of intervention programmes and assist a fuller understanding of tsetse distribution was applied, in a pilot study in the Masoka area, Mid-Zambezi valley in Zimbabwe, and targeting two savannah species, Glossina morsitans morsitans and Glossina pallidipes.

Methodology/Principal findings

The field study was conducted between March and December 2015 in 105 sites following a standardized grid sampling frame. Presence data were used to study habitat suitability of both species based on climatic and environmental data derived from MODIS and SPOT 5 satellite images. Factors influencing distribution were studied using an Ecological Niche Factor Analysis (ENFA) whilst habitat suitability was predicted using a Maximum Entropy (MaxEnt) model at a spatial resolution of 250 m. Area Under the Curve (AUC), an indicator of model performance, was 0.89 for G. m. morsitans and 0.96 for G. pallidipes. We then used the predicted suitable areas to calculate the probability that flies were really absent from the grid cells where they were not captured during the study based on a probability model using a risk threshold of 0.05. Apart from grid cells where G. m. morsitans and G. pallidipes were captured, there was a high probability of presence in an additional 128 km2 and 144 km2 respectively.

Conclusions/Significance

The modelling process promised to be useful in optimizing the outputs of presence/absence surveys, allowing the definition of tsetse infested areas with improved accuracy. The methodology proposed here can be extended to all the tsetse infested parts of Zimbabwe and may also be useful for other PATTEC national initiatives in other African countries.

Interruption of persistent exposure to leprosy combined or not with recent BCG vaccination enhances the response to <i>Mycobacterium leprae</i> specific antigens

by Fernanda Marques de Carvalho, Luciana Silva Rodrigues, Nádia Cristina Duppre, Iris Maria Peixoto Alvim, Marcelo Ribeiro-Alves, Roberta Olmo Pinheiro, Euzenir Nunes Sarno, Maria Cristina Vidal Pessolani, Geraldo Moura Batista Pereira

Household contacts of multibacillary leprosy patients (HCMB) constitute the group of individuals at the highest risk of developing leprosy. Early diagnosis and treatment of their index cases combined with Bacille Calmette-Guerin (BCG) immunization remain important strategies adopted in Brazil to prevent HCMB from evolving into active disease. In the present study, we assessed the impact of these measures on the immune response to Mycobacterium leprae in HCMB. Peripheral blood mononuclear cells (PBMC) from HCMB (n = 16) were obtained at the beginning of leprosy index case treatment (T0). At this time point, contacts were vaccinated (n = 13) or not (n = 3) in accordance with their infancy history of BCG vaccination and PBMCs were recollected at least 6 months later (T1). As expected, a significant increase in memory CD4 and CD8 T cell frequencies responsive to M. leprae whole-cell sonicate was observed in most contacts. Of note, higher frequencies of CD4+ T cells that recognize M. leprae specific epitopes were also detected. Moreover, increased production of the inflammatory mediators IL1-β, IL-6, IL-17, TNF, IFN-γ, MIP1-β, and MCP-1 was found at T1. Interestingly, the increment in these parameters was observed even in those contacts that were not BCG vaccinated at T0. This result reinforces the hypothesis that the continuous exposure of HCMB to live M. leprae down regulates the specific cellular immune response against the pathogen. Moreover, our data suggest that BCG vaccination of HCMB induces activation of T cell clones, likely through “trained immunity”, that recognize M. leprae specific antigens not shared with BCG as an additional protective mechanism besides the expected boost in cell-mediated immunity by BCG homologues of M. leprae antigens.

Safety and immunogenicity of the <i>Na</i>-GST-1 hookworm vaccine in Brazilian and American adults

by David J. Diemert, Janaína Freire, Vanderson Valente, Carlos Geraldo Fraga, Frederico Talles, Shannon Grahek, Doreen Campbell, Amar Jariwala, Maria Victoria Periago, Martin Enk, Maria Flávia Gazzinelli, Maria Elena Bottazzi, Robert Hamilton, Jill Brelsford, Anna Yakovleva, Guangzhao Li, Jin Peng, Rodrigo Correa-Oliveira, Peter Hotez, Jeffrey Bethony

Trial registration

ClinicalTrials.gov (NCT01261130 for the Brazil trial and NCT01385189 for the US trial)

The clinical features of 590 patients with brucellosis in Xinjiang, China with the emphasis on the treatment of complications

by Bin Jia, Fengbo Zhang, Ying Lu, Wenbao Zhang, Jun Li, Yuexin Zhang, Jianbing Ding

Background

This study aims to analyze the clinical characteristics and treatment outcomes of 590 patients with brucellosis in Xinjiang, China.

Methodology and principal findings

The clinical characteristics, laboratory findings, complications and prognosis of 590 patients infected with brucellosis were retrospectively analyzed. These patients had a mean age of 44.24 ± 15.83 years with 60.5% having a history of close contacting with cattle and sheep. Of them, 53.6% (316 /590) were in acute phase and 21.5% were in chronic phase. Agglutination test showed 98.5% positive with 34% blood culture positive of Brucella. The major symptoms were fatigue (91%), hyperhidrosis(88.1%), fever(86.9%), and joint pain(81%) with 29.8% having enlarged liver, 26.1% having enlarged spleen and 23.2% having osteoarticular complications. Combination of doxycycline plus rifampicin for 12 weeks was an effective regimen for patients without complications. The 3-drug regimen (doxycycline+rifampicin+levofloxacin) for 12 weeks was recommended for these with complications. There were 6 patients died (1.02%) with overall relapse rate of 5.98%.

Conclusions

Brucellosis is mostly associated with contacting with domestic animal production in Xinjiang, China. Clinical symptoms include fever, fatigue, hyperhidrosis, and joint pain with common complication of osteoarticular involvement. Three-drug-regimen of doxycycline+rifampicin+levofloxacin for 12 weeks was effective for these patients with complications.

External quality assessment study for ebolavirus PCR-diagnostic promotes international preparedness during the 2014 – 2016 Ebola outbreak in West Africa

by Heinz Ellerbrok, Sonja Jacobsen, Pranav Patel, Toni Rieger, Markus Eickmann, Stephan Becker, Stephan Günther, Dhamari Naidoo, Livia Schrick, Kathrin Keeren, Angelina Targosz, Anette Teichmann, Pierre Formenty, Matthias Niedrig

During the recent Ebola outbreak in West Africa several international mobile laboratories were deployed to the mainly affected countries Guinea, Sierra Leone and Liberia to provide ebolavirus diagnostic capacity. Additionally, imported cases and small outbreaks in other countries required global preparedness for Ebola diagnostics. Detection of viral RNA by reverse transcription polymerase chain reaction has proven effective for diagnosis of ebolavirus disease and several assays are available. However, reliability of these assays is largely unknown and requires serious evaluation. Therefore, a proficiency test panel of 11 samples was generated and distributed on a global scale. Panels were analyzed by 83 expert laboratories and 106 data sets were returned. From these 78 results were rated optimal and 3 acceptable, 25 indicated need for improvement. While performance of the laboratories deployed to West Africa was superior to the overall performance there was no significant difference between the different assays applied.

Modulation of <i>Mycobacterium tuberculosis</i>-specific humoral immune responses is associated with <i>Strongyloides stercoralis</i> co-infection

by Rajamanickam Anuradha, Saravanan Munisankar, Yukti Bhootra, Chandrakumar Dolla, Paul Kumaran, Thomas B. Nutman, Subash Babu

Background / Objectives

Helminth infections are known to influence T cell responses in latent tuberculosis (LTBI). Whether helminth infections also modulate B cell responses in helminth-tuberculosis co-infection is not known.

Methods

We assessed Mycobacterium tuberculosis (Mtb)–antigen specific IgM and IgG levels, circulating levels of the B cell growth factors, BAFF and APRIL and the absolute numbers of the various B cell subsets in individuals with LTBI, LTBI with coincident Strongyloides stercoralis (Ss) infection (LTBI/Ss) and in those with Ss infection alone (Ss). We also measured the above-mentioned parameters in the LTBI-Ss group after anthelmintic therapy.

Results

Our data reveal that LTBI-Ss exhibit significantly diminished levels of Mtb-specific IgM and IgG, BAFF and APRIL levels in comparison to those with LTBI. Similarly, those with LTBI-Ss had significantly diminished numbers of all B cell subsets (naïve, immature, classical memory, activated memory, atypical memory and plasma cells) compared to those with LTBI. There was a positive correlation between Mtb—antigen specific IgM and IgG levels and BAFF and APRIL levels that were in turn related to the numbers of activated memory B cells, atypical memory B cells and plasma cells. Finally, anthelmintic treatment resulted in significantly increased levels of Mtb—antigen specific IgM and IgG levels and the numbers of each of the B cell subsets.

Conclusions

Our data, therefore, reveal that Ss infection is associated with significant modulation of Mtb-specific antibody responses, the levels of B cell growth factors and the numbers of B cells (and their component subsets).

Structural diversity of <i>Burkholderia pseudomallei</i> lipopolysaccharides affects innate immune signaling

PLoS Neglected Tropical Diseases News - 28 April 2017 - 9:00pm

by Michael H. Norris, Herbert P. Schweizer, Apichai Tuanyok

Burkholderia pseudomallei (Bp) causes the disease melioidosis. The main cause of mortality in this disease is septic shock triggered by the host responding to lipopolysaccharide (LPS) components of the Gram-negative outer membrane. Bp LPS is thought to be a weak inducer of the host immune system. LPS from several strains of Bp were purified and their ability to induce the inflammatory mediators TNF-α and iNOS in murine macrophages at low concentrations was investigated. Innate and adaptive immunity qPCR arrays were used to profile expression patterns of 84 gene targets in response to the different LPS types. Additional qPCR validation confirmed large differences in macrophage response. LPS from a high-virulence serotype B strain 576a and a virulent rough central nervous system tropic strain MSHR435 greatly induced the innate immune response indicating that the immunopathogenesis of these strains is different than in infections with strains similar to the prototype strain 1026b. The accumulation of autophagic vesicles was also increased in macrophages challenged with highly immunogenic Bp LPS. Gene induction and concomitant cytokine secretion profiles of human PBMCs in response to the various LPS were also investigated. MALDI-TOF/TOF was used to probe the lipid A portions of the LPS, indicating substantial structural differences that likely play a role in host response to LPS. These findings add to the evolving knowledge of host-response to bacterial LPS, which can be used to better understand septic shock in melioidosis patients and in the rational design of vaccines.

Risk factors and outcome of <i>Shigella</i> encephalopathy in Bangladeshi children

PLoS Neglected Tropical Diseases News - 28 April 2017 - 9:00pm

by Farzana Afroze, Tahmeed Ahmed, Monira Sarmin, Abu SMSB Shahid, K. M. Shahunja, Lubaba Shahrin, Mohammod Jobayer Chisti

Background

Although, Shigella encephalopathy, a serious extra-intestinal complication of shigellosis, significantly increases the risks of death, data are very limited on predicting factors particularly related to electrolyte profiles in children below five years of age with Shigella encephalopathy. Our objective was to determine the clinical as well as laboratory predicting factors and outcome of children with Shigella encephalopathy.

Methodology/Principal findings

In this unmatched case-control design, children aged 2–59 months having a positive stool culture for Shigella and who had their serum electrolytes been done from July 2012 to June 2015 were studied. Children with Shigella encephalopathy, defined as having abnormal mentation, constituted the cases, and those without encephalopathy constituted the controls. During the study period, we identified a total of 541 children less than five years of age, who had Shigella in their stool culture. Only 139 children fulfilled the study criteria and among them 69 were cases and 70 were controls. The cases more often had fatal outcome compared to the controls (7% vs. 0%, P = 0.02). In logistic regression analysis, the cases were independently associated with shorter duration (1.2 ± 0.4 days) of diarrhea prior to admission, dehydrating diarrhea, sepsis and hyponatremia (p<0.05 for all). Among 139 Shigella isolates, S. flexneri (88/139, 63%) and S. sonnei(34/139, 24%) were the dominant species. S. dysenteriae was not isolated throughout the study period. S.sonnei was more frequently isolated from the cases (24/69, 35%) than the controls (10/70, 14%), whereas the isolation of S. flexneri was comparable between the groups (40/69, 58% vs 48/70, 69%). A total of 94 (67.6%) isolates were resistant to trimethoprim-sulphamethoxazole, 84 (60.4%) to ciprofloxacin, 66/138 (48%) to ampicillin, 5 (3.5%) to ceftriaxone, 17 (12.2%) to mecillinum and 35 (25%) to azithromycin.

Conclusions/Significance

The case-fatality-rate was significantly higher among the children with Shigella encephalopathy compared to those without encephalopathy. Early identification and aggressive management of simple risk factors for Shigella encephalopathy may help to reduce morbidity and deaths in such children especially in resource-limited settings.

Genetic diversity and population structure of the tsetse fly <i>Glossina fuscipes fuscipes</i> (Diptera: Glossinidae) in Northern Uganda: Implications for vector control

PLoS Neglected Tropical Diseases News - 28 April 2017 - 9:00pm

by Robert Opiro, Norah P. Saarman, Richard Echodu, Elizabeth A. Opiyo, Kirstin Dion, Alexis Halyard, Augustine W. Dunn, Serap Aksoy, Adalgisa Caccone

Uganda is the only country where the chronic and acute forms of human African Trypanosomiasis (HAT) or sleeping sickness both occur and are separated by < 100 km in areas north of Lake Kyoga. In Uganda, Glossina fuscipes fuscipes is the main vector of the Trypanosoma parasites responsible for these diseases as well for the animal African Trypanosomiasis (AAT), or Nagana. We used highly polymorphic microsatellite loci and a mitochondrial DNA (mtDNA) marker to provide fine scale spatial resolution of genetic structure of G. f. fuscipes from 42 sampling sites from the northern region of Uganda where a merger of the two disease belts is feared. Based on microsatellite analyses, we found that G. f. fuscipes in northern Uganda are structured into three distinct genetic clusters with varying degrees of interconnectivity among them. Based on genetic assignment and spatial location, we grouped the sampling sites into four genetic units corresponding to northwestern Uganda in the Albert Nile drainage, northeastern Uganda in the Lake Kyoga drainage, western Uganda in the Victoria Nile drainage, and a transition zone between the two northern genetic clusters characterized by high level of genetic admixture. An analysis using HYBRIDLAB supported a hybrid swarm model as most consistent with tsetse genotypes in these admixed samples. Results of mtDNA analyses revealed the presence of 30 haplotypes representing three main haplogroups, whose location broadly overlaps with the microsatellite defined clusters. Migration analyses based on microsatellites point to moderate migration among the northern units located in the Albert Nile, Achwa River, Okole River, and Lake Kyoga drainages, but not between the northern units and the Victoria Nile drainage in the west. Effective population size estimates were variable with low to moderate sizes in most populations and with evidence of recent population bottlenecks, especially in the northeast unit of the Lake Kyoga drainage. Our microsatellite and mtDNA based analyses indicate that G. f. fuscipes movement along the Achwa and Okole rivers may facilitate northwest expansion of the Rhodesiense disease belt in Uganda. We identified tsetse migration corridors and recommend a rolling carpet approach from south of Lake Kyoga northward to minimize disease dispersal and prevent vector re-colonization. Additionally, our findings highlight the need for continuing tsetse monitoring efforts during and after control.

Detecting the impact of temperature on transmission of Zika, dengue, and chikungunya using mechanistic models

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Erin A. Mordecai, Jeremy M. Cohen, Michelle V. Evans, Prithvi Gudapati, Leah R. Johnson, Catherine A. Lippi, Kerri Miazgowicz, Courtney C. Murdock, Jason R. Rohr, Sadie J. Ryan, Van Savage, Marta S. Shocket, Anna Stewart Ibarra, Matthew B. Thomas, Daniel P. Weikel

Recent epidemics of Zika, dengue, and chikungunya have heightened the need to understand the seasonal and geographic range of transmission by Aedes aegypti and Ae. albopictus mosquitoes. We use mechanistic transmission models to derive predictions for how the probability and magnitude of transmission for Zika, chikungunya, and dengue change with mean temperature, and we show that these predictions are well matched by human case data. Across all three viruses, models and human case data both show that transmission occurs between 18–34°C with maximal transmission occurring in a range from 26–29°C. Controlling for population size and two socioeconomic factors, temperature-dependent transmission based on our mechanistic model is an important predictor of human transmission occurrence and incidence. Risk maps indicate that tropical and subtropical regions are suitable for extended seasonal or year-round transmission, but transmission in temperate areas is limited to at most three months per year even if vectors are present. Such brief transmission windows limit the likelihood of major epidemics following disease introduction in temperate zones.

The potential economic burden of Zika in the continental United States

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Bruce Y. Lee, Jorge A. Alfaro-Murillo, Alyssa S. Parpia, Lindsey Asti, Patrick T. Wedlock, Peter J. Hotez, Alison P. Galvani

Background

As the Zika virus epidemic continues to spread internationally, countries such as the United States must determine how much to invest in prevention, control, and response. Fundamental to these decisions is quantifying the potential economic burden of Zika under different scenarios.

Methodology/Principle findings

To inform such decision making, our team developed a computational model to forecast the potential economic burden of Zika across six states in the US (Alabama, Florida, Georgia, Louisiana, Mississippi, and Texas) which are at greatest risk of Zika emergence, under a wide range of attack rates, scenarios and circumstances. In order to accommodate a wide range of possibilities, different scenarios explored the effects of varying the attack rate from 0.01% to 10%. Across the six states, an attack rate of 0.01% is estimated to cost $183.4 million to society ($117.1 million in direct medical costs and $66.3 million in productivity losses), 0.025% would result in $198.6 million ($119.4 million and $79.2 million), 0.10% would result in $274.6 million ($130.8 million and $143.8 million) and 1% would result in $1.2 billion ($268.0 million and $919.2 million).

Conclusions

Our model and study show how direct medical costs, Medicaid costs, productivity losses, and total costs to society may vary with different attack rates across the six states and the circumstances at which they may exceed certain thresholds (e.g., Zika prevention and control funding allocations that are being debated by the US government). A Zika attack rate of 0.3% across the six states at greatest risk of Zika infection, would result in total costs that exceed $0.5 billion, an attack rate of 1% would exceed $1 billion, and an attack rate of 2% would exceed $2 billion.

Determinants of severe dehydration from diarrheal disease at hospital presentation: Evidence from 22 years of admissions in Bangladesh

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Jason R. Andrews, Daniel T. Leung, Shahnawaz Ahmed, Mohammed Abdul Malek, Dilruba Ahmed, Yasmin Begum, Firdausi Qadri, Tahmeed Ahmed, Abu Syed Golam Faruque, Eric J. Nelson

Background

To take advantage of emerging opportunities to reduce morbidity and mortality from diarrheal disease, we need to better understand the determinants of life-threatening severe dehydration (SD) in resource-poor settings.

Methodology/findings

We analyzed records of patients admitted with acute diarrheal disease over twenty-two years at the International Centre for Diarrhoeal Disease Research, Bangladesh (1993–2014). Patients presenting with and without SD were compared by multivariable logistic regression models, which included socio-demographic factors and pathogens isolated. Generalized additive models evaluated non-linearities between age or household income and SD. Among 55,956 admitted patients, 13,457 (24%) presented with SD. Vibrio cholerae was the most common pathogen isolated (12,405 patients; 22%), and had the strongest association with SD (AOR 4.77; 95% CI: 4.41–5.51); detection of multiple pathogens did not exacerbate SD risk. The highest proportion of severely dehydrated patients presented in a narrow window only 4–12 hours after symptom onset. Risk of presenting with SD increased sharply from zero to ten years of age and remained high throughout adolescence and adulthood. Adult women had a 38% increased odds (AOR 1.38; 95% CI: 1.30–1.46) of SD compared to adult men. The probability of SD increased sharply at low incomes. These findings were consistent across pathogens.

Conclusions/significance

There remain underappreciated populations vulnerable to life-threatening diarrheal disease that include adult women and the very poor. In addition to efforts that address diarrheal disease in young children, there is a need to develop interventions for these other high-risk populations that are accessible within 4 hours of symptom onset.

The value of daily platelet counts for predicting dengue shock syndrome: Results from a prospective observational study of 2301 Vietnamese children with dengue

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Phung Khanh Lam, Tran Van Ngoc, Truong Thi Thu Thuy, Nguyen Thi Hong Van, Tran Thi Nhu Thuy, Dong Thi Hoai Tam, Nguyen Minh Dung, Nguyen Thi Hanh Tien, Nguyen Tan Thanh Kieu, Cameron Simmons, Bridget Wills, Marcel Wolbers

Background

Dengue is the most important mosquito-borne viral infection to affect humans. Although it usually manifests as a self-limited febrile illness, complications may occur as the fever subsides. A systemic vascular leak syndrome that sometimes progresses to life-threatening hypovolaemic shock is the most serious complication seen in children, typically accompanied by haemoconcentration and thrombocytopenia. Robust evidence on risk factors, especially features present early in the illness course, for progression to dengue shock syndrome (DSS) is lacking. Moreover, the potential value of incorporating serial haematocrit and platelet measurements in prediction models has never been assessed.

Methodology/Principal findings

We analyzed data from a prospective observational study of Vietnamese children aged 5–15 years admitted with clinically suspected dengue to the Hospital for Tropical Diseases in Ho Chi Minh City between 2001 and 2009. The analysis population comprised all children with laboratory-confirmed dengue enrolled between days 1–4 of illness. Logistic regression was the main statistical model for all univariate and multivariable analyses. The prognostic value of daily haematocrit levels and platelet counts were assessed using graphs and separate regression models fitted on each day of illness. Among the 2301 children included in the analysis, 143 (6%) progressed to DSS. Significant baseline risk factors for DSS included a history of vomiting, higher temperature, a palpable liver, and a lower platelet count. Prediction models that included serial daily platelet counts demonstrated better ability to discriminate patients who developed DSS from others, than models based on enrolment information only. However inclusion of daily haematocrit values did not improve prediction of DSS.

Conclusions/Significance

Daily monitoring of platelet counts is important to help identify patients at high risk of DSS. Development of dynamic prediction models that incorporate signs, symptoms, and daily laboratory measurements, could improve DSS prediction and thereby reduce the burden on health services in endemic areas.

The first “London Declaration”: The Commonwealth and its neglected tropical diseases

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Peter J. Hotez, Ashish Damania, Aparna Barua, Jeffrey Stanaway

Relevant units of analysis for applied and basic research dealing with neglected transmissible diseases: The predominant clonal evolution model of pathogenic microorganisms

PLoS Neglected Tropical Diseases News - 27 April 2017 - 9:00pm

by Michel Tibayrenc, Francisco J. Ayala

The predominant clonal evolution (PCE) model seeks to formulate a common population genetics framework for all micropathogens (namely, parasitic protozoa, fungi and yeasts, bacteria, and viruses). It relies on a definition of clonality that is only based on population structure features (namely, strongly restrained genetic recombination). Its clear-cut properties make it of strong interest for applied and basic research, since it permits the definition of stable, clearly delimited units of analysis below the species level: clonal genotypes and discrete genetic subdivisions (“near-clades”). These units of analysis can be used for clinical and epidemiological studies, vaccine and drug design, species description, and evolutionary studies on natural and experimental populations. In this review, the evolutionary and population genetics background of the model will be only briefly mentioned, while considerable emphasis will be given to its practical significance for the study and control of neglected tropical diseases. The goal of the paper is to make this practical usefulness accessible to a broad audience of readers, including scientists who are not evolution specialists, such as epidemiologists, field scientists, and clinicians. For extensive developments about the evolutionary background of the model, see our previous papers [1–9]. Citations of these former articles lead to the many references quoted in them, which cannot be listed again here.

Improvement of a tissue maceration technique for the determination of placental involvement in schistosomiasis

PLoS Neglected Tropical Diseases News - 24 April 2017 - 9:00pm

by Martha Charlotte Holtfreter, Heinrich Neubauer, Tanja Groten, Hosny El-Adawy, Jana Pastuschek, Joachim Richter, Dieter Häussinger, Mathias Wilhelm Pletz, Benjamin Thomas Schleenvoigt

Schistosomiasis in pregnancy may cause low birth weight, prematurity and stillbirth of the offspring. The placenta of pregnant women might be involved when schistosome ova are trapped in placental tissue. Standard histopathological methods only allow the examination of a limited amount of placental tissue and are therefore not sufficiently sensitive. Thus, placental schistosomiasis remains underdiagnosed and its role in contributing to schistosomiasis-associated pregnancy outcomes remains unclear. Here we investigated an advanced maceration method in order to recover a maximum number of schistosome ova from the placenta. We examined the effect of different potassium hydroxide (KOH) concentrations and different tissue fixatives with respect to maceration success and egg morphology. Placental tissue was kept either in 0.9% saline, 5% formalin or 70% ethanol and was macerated together with Schistosoma mansoni infested mouse livers and KOH 4% or 10%, respectively. We found that placenta maceration using 4% KOH at 37°C for 24 h was the most effective method: placental tissue was completely digested, egg morphology was well preserved and alkaline concentration was the lowest. Ethanol proved to be the best fixative for this method. Here we propose an improved maceration technique in terms of sensitivity, safety and required skills, which may enable its wider use also in endemic areas. This technique may contribute to clarifying the role of placental involvement in pregnant women with schistosomiasis.

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