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Phylogenomic analysis unravels evolution of yellow fever virus within hosts

6 September 2018 - 9:00pm

by Chen Chen, Dong Jiang, Ming Ni, Jing Li, Zhihai Chen, Jingyuan Liu, Hanhui Ye, Gary Wong, Wei Li, Yuanyuan Zhang, Beibei Wang, Yuhai Bi, Danying Chen, Ping Zhang, Xuesen Zhao, Yaxian Kong, Weifeng Shi, Pengcheng Du, Gengfu Xiao, Juncai Ma, George F. Gao, Jie Cui, Fujie Zhang, Wenjun Liu, Xiaochen Bo, Ang Li, Hui Zeng, Di Liu

The yellow fever virus (YFV) recently reemerged in the large outbreaks in Africa and Brazil, and the first imported patients into Asia have recalled the concerns of YFV evolution. Here we show phylogenomics of YFV with serial clinical samples of the 2016 YFV infections. Phylogenetics exhibited that the 2016 strains were close to Angola 1971 strains and only three amino acid changes presented new to other lineages. Deep sequencing of viral genomes discovered 101 intrahost single nucleotide variations (iSNVs) and 234 single nucleotide polymorphisms (SNPs). Analysis of iSNV distribution and mutated allele frequency revealed that the coding regions were under purifying selection. Comparison of the evolutionary rates estimated by iSNV and SNP showed that the intrahost rate was ~2.25 times higher than the epidemic rate, and both rates were higher than the long-term YFV substitution rate, as expected. In addition, the result also hinted that short viremia duration of YFV might further hinder the evolution of YFV.

Burden of leishmaniasis in Brazil and federated units, 1990-2016: Findings from Global Burden of Disease Study 2016

6 September 2018 - 9:00pm

by Juliana Maria Trindade Bezerra, Valdelaine Etelvina Miranda de Araújo, David Soeiro Barbosa, Francisco Rogerlândio Martins-Melo, Guilherme Loureiro Werneck, Mariângela Carneiro

Background

The study presents estimates for the burden of visceral leishmaniasis (VL) and cutaneous and mucocutaneous leishmaniasis (CML) in Brazil and its 27 federated units using data from the Global Burden of Disease Study (GBD) 2016.

Methodology

We report the incidence, years of life lost (YLL), years lived with disability (YLD), and disability-adjusted life years (DALY) for leishmaniasis in Brazil from 1990 to 2016. The metrics are presented as age-standardized rates per 100,000 inhabitants with their respective uncertainty intervals (95%UI) and relative percentages of change.

Principal findings

The age-standardized incidence rate of leishmaniasis decreased 48.5% from 1990 (71.0, 95%UI 24.3–150.7) to 2016 (36.5, 95%UI 24.7–50.9), whereas the age-standardized DALY increased 83.6% over the studied period from 12.2 (95%UI 7.9–18.8) to 22.4 (95%UI 13.3–36.2). The age-standardized incidence rate and YLL for VL increased by 52.9% and 108% from 1990 to 2016, respectively. Considering CML, the age-standardized incidence rate and YLD decreased by 51% and 31.8% respectively for the same period. For VL, similar profiles for male and female were observed, with YLL and DALY increasing over time; with males presenting slightly higher values. The highest YLL rates were among "under 1-year old" children, which increased 131.2% from 1990 to 2016. Regarding CML, the highest values of YLD and DALY were verified among males, and YLD values showed a similar profile, with rates increasing with age. The VL burden increased in some states in the Northeast and Southeast regions and decreased for CML in some Northern states.

Conclusion

The increase of VL burden over the study period might be associated with the difficulties in controlling the disease spread. Information regarding the weight of VL and CML, including the death and disability tolls that they cause, highlights the impact of these neglected diseases on public health and the importance of effective prevention and treatment.

Human rabies in Côte d'Ivoire 2014-2016: Results following reinforcements to rabies surveillance

6 September 2018 - 9:00pm

by Issaka Tiembré, Anaïs Broban, Joseph Bénié, Mathilde Tetchi, Sophie Druelles, Maïna L’Azou

In Côte d’Ivoire, rabies is endemic and remains largely uncontrolled. The numbers of human exposures and rabies cases are unknown and are probably much higher than reported. Data on human rabies cases are collected by the National Institute of Public Health (NIPH) Anti-rabies Center in Abidjan through a network of 28 NIPH local units, which cover the population of the entire country. During 2014, the NIPH initiated a program to reinforce the human rabies surveillance system in those 28 NIPH local units, with specific goals of improving the infrastructure, training, communication, and government involvement. Here, we report the progress and findings during 2014–2016. The reinforced system recorded 50 cases of human rabies (15–18 cases/year; annual incidence = 0.06−0.08 per 100,000) and more than 30,000 animal exposures (annual incidence = 41.8−48.0 per 100,000). Almost one-half of the human rabies cases were in children ≤15 years old. All were fatal and dog bites were the most common route by which rabies virus was transmitted. In the 32 cases where samples of sufficient quality for analysis were available, rabies was confirmed by reverse transcription-polymerase chain reaction RT-PCR. Post-exposure prophylaxis with rabies vaccine was administered to all animal exposure victims presenting at the NIPH local units, although only about 57% completed the full immunization schedule. All available reports were provided by the NIPH local units, indicating effective communication between them and the NIPH Anti-rabies Center. These findings indicate that the reinforcements resulted in highly specific detection of human rabies, provided detailed epidemiological data about these cases, and improved estimates of animal exposure numbers. These represent substantial advances, but further improvements to the surveillance system are needed to increase disease awareness and capture cases that are currently missed by the system. In the future, better communication between local health centers and the NIPH units, surveillance at the local health center level, and increased veterinarian engagement will help provide a more complete picture of the rabies burden in Côte d’Ivoire.

Improving systematic rabies surveillance in Cameroon: A pilot initiative and results for 2014-2016

6 September 2018 - 9:00pm

by Casimir Ledoux Sofeu, Anaïs Broban, Amadou Njifou Njimah, Jean Blaise Momo, Serge Alain Sadeuh-Mba, Sophie Druelles, Maïna L’Azou, Mathurin Cyrille Tejiokem

Canine rabies is endemic in Cameroon, but human rabies exposures and cases are likely underreported because of inadequate surveillance. In 2014, the surveillance network in the West region of Cameroon was reinforced by introducing a new anti-rabies center, a framework for data collection and evaluation, provisions for sample collecting and laboratory confirmation, and training for health professionals. The objective of this observational cohort study was to describe the incidence and characteristics of reported exposures and human and animal rabies cases following this reinforcement of the existing rabies surveillance system. The surveillance network consisted of local, regional, and national health and veterinary authorities in 11 of the 20 West region districts, and was completely integrated within the existing national rabies surveillance network. Animal exposures and suspected rabies exposures, the suspected rabid animals involved, and laboratory confirmation of human and animal rabies cases were recorded in a centralized information database. Between January 2014 and June 2016, the network recorded 1340 animal exposure cases for an overall incidence rate of 38.2 animal exposures per 100,000 people, four confirmed rabies-positive animals, and one confirmed human rabies case out of four clinically suspected cases. In contrast, 62 animal exposures and an overall incidence rate of 6.1 exposures per 100,000 people were reported for the West region districts not participating in the reinforced surveillance. Of the 925 animal exposure victims for whom a detailed case report form was completed, 703 were considered to be at risk of rabies and only 428 (61%) of these received any post-exposure prophylaxis in the form of rabies vaccine. Obstacles encountered within the network included low rates of animal sample submission and animal follow-up by veterinarians. Reinforced rabies surveillance in the West region of Cameroon has provided the most accurate estimate of the region’s disease and exposure burdens to date, and indicates that animal exposures are substantially underreported. The reinforced network also signaled that greater access to post-exposure prophylaxis is needed. Integration of regions not covered by the surveillance network and efforts to improve engagement of veterinary services will be needed to reveal the true burden of rabies in Cameroon.

Bolstering human rabies surveillance in Africa is crucial to eliminating canine-mediated rabies

6 September 2018 - 9:00pm

by Anaïs Broban, Mathurin C. Tejiokem, Issaka Tiembré, Sophie Druelles, Maïna L’Azou

Optimization of sand fly embryo microinjection for gene editing by CRISPR/Cas9

4 September 2018 - 9:00pm

by Ines Martin-Martin, Azadeh Aryan, Claudio Meneses, Zach N. Adelman, Eric Calvo

Background

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology has rapidly emerged as a very effective tool for gene editing. Although great advances on gene editing in the medical entomology field have arisen, no attempts of gene editing have been reported in sand flies, the vectors of Leishmaniasis.

Methodology/Principal findings

Here, we described a detailed protocol for sand fly embryo microinjection taking into consideration the sand fly life cycle, and manipulation and oviposition requirements of this non-model organism. Following our microinjection protocol, a hatching rate of injected embryos of 11.90%-14.22% was achieved, a rate consistent with other non-model organism dipterans such as mosquitoes. Essential factors for the adaptation of CRISPR/Cas9 technology to the sand fly field were addressed including the selection of a target gene and the design and production of sgRNA. An in vitro cleavage assay was optimized to test the activity of each sgRNA and a protocol for Streptococcus pyogenes Cas9 (spCas9) protein expression and purification was described. Relevant considerations for a successful gene editing in the sand fly such as specifics of embryology and double-stranded break DNA repair mechanisms were discussed.

Conclusion and significance

The step-by-step methodology reported in this article will be of significant use for setting up a sand fly embryo microinjection station for the incorporation of CRISPR/Cas9 technology in the sand fly field. Gene editing strategies used in mosquitoes and other model insects have been adapted to work with sand flies, providing the tools and relevant information for adapting gene editing techniques to the vectors of Leishmaniasis. Gene editing in sand flies will provide essential information on the biology of these vectors of medical and veterinary relevance and will rise a better understanding of vector-parasite-host interactions.

Evaluation of Auramine O staining and conventional PCR for leprosy diagnosis: A comparative cross-sectional study from Ethiopia

4 September 2018 - 9:00pm

by Selfu Girma, Charlotte Avanzi, Kidist Bobosha, Kassu Desta, Munir H. Idris, Philippe Busso, Yohannes Tsegaye, Shimelis Nigusse, Tsegaye Hailu, Stewart T. Cole, Abraham Aseffa

Background

Diagnosis of leprosy mainly relies on clinical examination due to the inconsistent sensitivity and poor reproducibility of the current laboratory tests. Utilisation of alternative methods to the standard Ziehl Neelsen (ZN), Fite-Faraco (FF) and Haematoxylin and Eosin (H&E) staining procedures may eventually improve leprosy diagnosis.

Methodology/Principal findings

In this comparative study, the performance of the fluorescent Auramine O (AO) staining and polymerase chain reaction (PCR) was assessed with different skin samples using a combination of ZN, FF and H&E staining as the gold standard. AO, ZN, FF, H&E and PCR tests were performed on slit skin smears (SSS) and/or punch biopsies collected from 141 clinically confirmed leprosy cases and 28 non-leprosy skin samples. DNA was extracted from punch biopsies using two different methods with or without mechanical lysis.Sensitivities were 87.6%, 59.3% and 77% for H&E, ZN and FF, respectively, whereas it reached 65.5% and 77.9% for AO in SSS and tissue sections and 91.1% for PCR in tissue samples. Morover, samples with low bacillary index, sensitivity of AO staining (61.8%) was similar to FF (60%, p>0.05) and lower than PCR (86.6%, p<0.05). Sensitivity of PCR also increased (96.8%, p<0.05) when mechanical lysis was used during DNA extraction compared to enzymatic treatment alone (84.6%).

Conclusions/Significance

Our results showed that for diagnostic purposes, analysis of skin section is more sensitive than SSS, especially for samples with low bacillary load. AO staining on SSS and tissue sections was not significantly better than other routine diagnostic tests but considerably more user friendly. The sensitivity of PCR was higher than current standard methods and increased when combined with more efficient DNA extraction using mechanical and chemical lysis. Therefore, we recommend AO staining for the diagnosis of leprosy in lower health facilities such as health centres and district hospitals and PCR diagnosis at referral level and research centres.

Mosquito excreta: A sample type with many potential applications for the investigation of Ross River virus and West Nile virus ecology

31 August 2018 - 9:00pm

by Ana L. Ramírez, Sonja Hall-Mendelin, Stephen L. Doggett, Glen R. Hewitson, Jamie L. McMahon, Scott A. Ritchie, Andrew F. van den Hurk

Background

Emerging and re-emerging arthropod-borne viruses (arboviruses) cause human and animal disease globally. Field and laboratory investigation of mosquito-borne arboviruses requires analysis of mosquito samples, either individually, in pools, or a body component, or secretion such as saliva. We assessed the applicability of mosquito excreta as a sample type that could be utilized during studies of Ross River and West Nile viruses, which could be applied to the study of other arboviruses.

Methodology/Principal findings

Mosquitoes were fed separate blood meals spiked with Ross River virus and West Nile virus. Excreta was collected daily by swabbing the bottom of containers containing batches and individual mosquitoes at different time points. The samples were analyzed by real-time RT-PCR or cell culture enzyme immunoassay. Viral RNA in excreta from batches of mosquitoes was detected continuously from day 2 to day 15 post feeding. Viral RNA was detected in excreta from at least one individual mosquito at all timepoints, with 64% and 27% of samples positive for RRV and WNV, respectively. Excretion of viral RNA was correlated with viral dissemination in the mosquito. The proportion of positive excreta samples was higher than the proportion of positive saliva samples, suggesting that excreta offers an attractive sample for analysis and could be used as an indicator of potential transmission. Importantly, only low levels of infectious virus were detected by cell culture, suggesting a relatively low risk to personnel handling mosquito excreta.

Conclusions/Significance

Mosquito excreta is easily collected and provides a simple and efficient method for assessing viral dissemination, with applications ranging from vector competence experiments to complementing sugar-based arbovirus surveillance in the field, or potentially as a sample system for virus discovery.

Demonstration of efficient vertical and venereal transmission of dengue virus type-2 in a genetically diverse laboratory strain of <i>Aedes aegypti</i>

31 August 2018 - 9:00pm

by Irma Sánchez-Vargas, Laura C. Harrington, Jeffrey B. Doty, William C. Black 4th, Ken E. Olson

Aedes aegypti is the primary mosquito vector of dengue viruses (DENV; serotypes 1–4). Human-mosquito transmission cycles maintain DENV during epidemics but questions remain regarding how these viruses survive when human infections and vector abundance are minimal. Aedes mosquitoes can transmit DENV within the vector population through two alternate routes: vertical and venereal transmission (VT and VNT, respectively). We tested the efficiency of VT and VNT in a genetically diverse laboratory (GDLS) strain of Ae. aegypti orally infected with DENV2 (Jamaica 1409). We examined F1 larvae from infected females generated during the first and second gonotrophic cycles (E1 and E2) for viral envelope (E) antigen by amplifying virus in C6/36 cells and then performing an indirect immunofluorescence assay (IFA). RT-PCR/nested PCR analyses confirmed DENV2 RNA in samples positive by IFA. We observed VT of virus to larvae and adult male progeny and VNT of virus to uninfected virgin females after mating with males that had acquired virus by the VT route. We detected no DENV2 in 30 pools (20 larvae/pool) of F1 larvae following the first gonotrophic cycle, suggesting limited virus dissemination at 7 days post-infection. DENV2 was detected by IFA in 27 of 49 (55%) and 35 of 51 (68.6%) F1 larval pools (20 larvae/pool) from infected E2 females that received a second blood meal without virus at 10 or 21 days post-infection (E2-10d-F1 and E2-21-F1), respectively. The minimum filial infection rates by IFA for E2-10d-F1 and E2-21d-F1 mosquitoes were 1:36 and 1:29, respectively. The VNT rate from E2-10d-F1 males to virgin (uninfected) GDLS females was 31.6% (118 of 374) at 8 days post mating. Twenty one percent of VNT-infected females receiving a blood meal prior to mating had disseminated virus in their heads, suggesting a potential pathway for virus to re-enter the human-mosquito transmission cycle. This is the first report of VNT of DENV by male Ae. aegypti and the first demonstration of sexual transmission in Aedes by naturally infected males. Our results demonstrate the potential for VT and VNT of DENV in nature as mechanisms for virus maintenance during inter-epidemic periods.

Fine-scale GPS tracking to quantify human movement patterns and exposure to leptospires in the urban slum environment

31 August 2018 - 9:00pm

by Katharine A. Owers, Juliana Odetunde, Rosan Barbosa de Matos, Gielson Sacramento, Mayara Carvalho, Nivison Nery Jr, Federico Costa, Mitermayer G. Reis, James E. Childs, José E. Hagan, Peter J. Diggle, Albert I. Ko

Background

Human movement is likely an important risk factor for environmentally-transmitted pathogens. While epidemiologic studies have traditionally focused on household risk factors, individual movement data could provide critical additional information about risk of exposure to such pathogens. We conducted global positioning system (GPS) tracking of urban slum residents to quantify their fine-scale movement patterns and evaluate their exposures to environmental sources of leptospirosis transmission.

Methodology/Principal findings

We recruited participants from an ongoing cohort study in an urban slum in Brazil and tracked them for 24 hours at 30-second intervals. Among 172 subjects asked to participate in this cross-sectional study, 130 agreed to participate and 109 had good quality data and were included in analyses. The majority of recorded locations were near participant residences (87.7% within 50 meters of the house), regardless of age or gender. Similarly, exposure to environmental sources of leptospirosis transmission did not vary by age or gender. However, males, who have higher infection rates, visited a significantly larger area during the 24-hour period than did females (34,549m2 versus 22,733m2, p = 0.005). Four male participants had serologic evidence of Leptospira infection during the study period. These individuals had significantly larger activity spaces than uninfected males (61,310m2 vs 31,575m2, p = 0.006) and elevated exposure to rodent activity (p = 0.046) and trash deposits (p = 0.031).

Conclusions/Significance

GPS tracking was an effective tool for quantifying individual mobility in the complex urban slum environment and identifying risk exposures associated with that movement. This study suggests that in addition to source reduction, barrier interventions that reduce contact with transmission sources as slum residents move within their communities may be a useful prevention strategy for leptospirosis.

Barcoding blood meals: New vertebrate-specific primer sets for assigning taxonomic identities to host DNA from mosquito blood meals

30 August 2018 - 9:00pm

by Lawrence E. Reeves, Jennifer L. Gillett-Kaufman, Akito Y. Kawahara, Phillip E. Kaufman

The transmission dynamics of mosquito-vectored pathogens are, in part, mediated by mosquito host-feeding patterns. These patterns are elucidated using blood meal analysis, a collection of serological and molecular techniques that determine the taxonomic identities of the host animals from which blood meals are derived. Modern blood meal analyses rely on polymerase chain reaction (PCR), DNA sequencing, and bioinformatic comparisons of blood meal DNA sequences to reference databases. Ideally, primers used in blood meal analysis PCRs amplify templates from a taxonomically diverse range of vertebrates, produce a short amplicon, and avoid co-amplification of non-target templates. Few primer sets that fit these requirements are available for the cytochrome c oxidase subunit I (COI) gene, the species identification marker with the highest taxonomic coverage in reference databases. Here, we present new primer sets designed to amplify fragments of the DNA barcoding region of the vertebrate COI gene, while avoiding co-amplification of mosquito templates, without multiplexed or nested PCR. Primers were validated using host vertebrate DNA templates from mosquito blood meals of known origin, representing all terrestrial vertebrate classes, and field-collected mosquito blood meals of unknown origin. We found that the primers were generally effective in amplifying vertebrate host, but not mosquito DNA templates. Applied to the sample of unknown mosquito blood meals, > 98% (60/61) of blood meals samples were reliably identified, demonstrating the feasibility of identifying mosquito hosts with the new primers. These primers are beneficial in that they can be used to amplify COI templates from a diverse range of vertebrate hosts using standard PCR, thereby streamlining the process of identifying the hosts of mosquitoes, and could be applied to next generation DNA sequencing and metabarcoding approaches.

“Zika is everywhere”: A qualitative exploration of knowledge, attitudes and practices towards Zika virus among women of reproductive age in Iquitos, Peru

30 August 2018 - 9:00pm

by Caroline T. Weldon, Amy R. Riley-Powell, Ines M. Aguerre, Rosa A. Celis Nacimento, Amy C. Morrison, Richard A. Oberhelman, Valerie A. Paz-Soldan

Zika virus was reported in the rainforest city of Iquitos, Peru in 2016. The potential associations between Zika and fetal neurological disorders were reported extensively in the media regarding neighboring Brazil, and led to great concern about the impact Zika could have on people’s health in Iquitos when it arrived. The aim of this study was to explore the knowledge, attitudes, and preventative practices related to Zika virus and its transmission among women of childbearing age in Iquitos, Peru. Six focus group discussions with 46 women of ages 20–35 from an Iquitos district with confirmed Zika cases were conducted to explore: 1) knowledge of Zika transmission, its symptoms, and treatment, 2) attitudes regarding Zika, including perceptions of risk for and severity of Zika, and 3) preventative practices, including awareness of health promotion activities. Participants were knowledgeable about Zika symptoms and knew it was transmitted by mosquitoes, and about half had heard about the association between Zika and microcephaly, but most lacked knowledge about the associated neurological disorders in adults, its sexual transmission, and ways to prevent infection. They expressed concern for pregnant women exposed to the virus and the impact on the fetus. Participants felt at risk of contracting the Zika virus, yet had not changed preventive practices, possibly in part because their perception of the severity of this disease was low. This study reveals knowledge gaps that could be addressed via health promotion messages that might improve prevention practices to help community members protect themselves from Zika virus during this outbreak.

Direct nucleic acid analysis of mosquitoes for high fidelity species identification and detection of <i>Wolbachia</i> using a cellphone

30 August 2018 - 9:00pm

by Sanchita Bhadra, Timothy E. Riedel, Miguel A. Saldaña, Shivanand Hegde, Nicole Pederson, Grant L. Hughes, Andrew D. Ellington

Manipulation of natural mosquito populations using the endosymbiotic bacteria Wolbachia is being investigated as a novel strategy to reduce the burden of mosquito-borne viruses. To evaluate the efficacy of these interventions, it will be critical to determine Wolbachia infection frequencies in Aedes aegypti mosquito populations. However, current diagnostic tools are not well-suited to fit this need. Morphological methods cannot identify Wolbachia, immunoassays often suffer from low sensitivity and poor throughput, while PCR and spectroscopy require complex instruments and technical expertise, which restrict their use to centralized laboratories. To address this unmet need, we have used loop-mediated isothermal amplification (LAMP) and oligonucleotide strand displacement (OSD) probes to create a one-pot sample-to-answer nucleic acid diagnostic platform for vector and symbiont surveillance. LAMP-OSD assays can directly amplify target nucleic acids from macerated mosquitoes without requiring nucleic acid purification and yield specific single endpoint yes/no fluorescence signals that are observable to eye or by cellphone camera. We demonstrate cellphone-imaged LAMP-OSD tests for two targets, the Aedes aegypti cytochrome oxidase I (coi) gene and the Wolbachia surface protein (wsp) gene, and show a limit of detection of 4 and 40 target DNA copies, respectively. In a blinded test of 90 field-caught mosquitoes, the coi LAMP-OSD assay demonstrated 98% specificity and 97% sensitivity in identifying Ae. aegypti mosquitoes even after 3 weeks of storage without desiccant at 37°C. Similarly, the wsp LAMP-OSD assay readily identified the wAlbB Wolbachia strain in field-collected Aedes albopictus mosquitoes without generating any false positive signals. Modest technology requirements, minimal execution steps, simple binary readout, and robust accuracy make the LAMP-OSD-to-cellphone assay platform well suited for field vector surveillance in austere or resource-limited conditions.

Pre-post effects of a tetanus care protocol implementation in a sub-Saharan African intensive care unit

30 August 2018 - 9:00pm

by Riaz Aziz, Soledad Colombe, Gibonce Mwakisambwe, Solomon Ndezi, Jim Todd, Samuel Kalluvya, Halinder S. Mangat, Reed Magleby, Arndt Koebler, Bernard Kenemo, Robert N. Peck, Jennifer A. Downs

Background

Tetanus is a vaccine-preventable, neglected disease that is life threatening if acquired and occurs most frequently in regions where vaccination coverage is incomplete. Challenges in vaccination coverage contribute to the occurrence of non-neonatal tetanus in sub-Saharan countries, with high case fatality rates. The current WHO recommendations for the management of tetanus include close patient monitoring, administration of immune globulin, sedation, analgesia, wound hygiene and airway support [1]. In response to these recommendations, our tertiary referral hospital in Tanzania implemented a standardized clinical protocol for care of patients with tetanus in 2006 and a subsequent modification in 2012. In this study we aimed to assess the impact of the protocol on clinical care of tetanus patients and their outcomes.

Methods and findings

We examined provision of care and outcomes among all patients admitted with non-neonatal tetanus to the ICU at Bugando Medical Centre between 2001 and 2016 in this retrospective cohort study. We compared three groups: the pre-protocol group (2001–2005), the Early protocol group (2006–2011), and the Late protocol group (2012–2016) and determined associations with mortality by univariable logistic regression.We observed a significant increase in provision of care as per protocol between the Early and Late groups. Patients in the Late group had a significantly higher utilization of mechanical ventilation (69.9% vs 22.0%, p< 0.0001), provision of surgical wound care (39.8% vs 20.3%, p = 0.011), and performance of tracheostomies (36.8% vs 6.7%, <0.0001) than patients in the Early group. Despite the increased provision of care, we found no significant decrease in overall mortality in the Early versus the Late groups (55.4% versus 40.3%, p = 0.069), or between the pre-protocol and post-protocol groups (60.7% versus 50.0%, p = 0.28). There was also no difference in 7-day ICU mortality (30.1% versus 27.8%, p = 0.70). Analysis of the causes of death revealed a decrease in deaths related to airway compromise (30.0% to 1.8%, p<0.001) but an increase in deaths due to presumed sepsis (15.0% to 44.6%, p = 0.018).

Conclusion

The overall mortality in patients suffering non-neonatal tetanus is high (>40%). Institution of a standardized tetanus management protocol, in accordance with WHO recommendations, decreased immediate mortality related to primary causes of death after tetanus. However, this was offset by an increase in death due to later ICU complications such as sepsis. Our results illustrate the complexity in achieving mortality reduction even in illnesses thought to require few critical care interventions. Improving basic ICU care and strengthening vaccination programs to prevent tetanus altogether are essential components of efforts to decrease the mortality caused by this lethal, neglected disease.

A long way from Laos

30 August 2018 - 9:00pm

by Jade Ramos-Poblete, Erica Kasper, Anandit Mu

Spinal cord hypometabolism associated with infection by human T-cell lymphotropic virus type 1(HTLV-1)

27 August 2018 - 9:00pm

by Luiz C. F. Romanelli, Débora M. Miranda, Anna B. F. Carneiro-Proietti, Marcelo Mamede, Herika M. M. Vasconcelos, Marina L Martins, Anísia S. D. Ferreira, Daniela V. F. Rosa, Jonas J. Paula, Marco A. Romano-Silva, Rodrigo Nicolato

Background

HTLV-1 infection is endemic in Brazil. About 1 to 2% of the Brazilian population is estimated to be infected, but most infected HTLV-1 individuals do not know about their own infection, which favors the continuity of sexual and vertical virus transmission. In addition, HTLV-1 associated central nervous system diseases and their pathophysiologic mechanisms are not fully understood. This study aimed to evaluate the correlation of spinal cord metabolism, viral and inflammatory profiles with features of neurological presentation in HTLV-1 infected individuals.

Methodology

This is a cross-sectional study of a cohort including 48 HTLV-1 infected individuals clinically classified as asymptomatic-AG (N = 21), symptomatic-SG (N = 11) and HAM/TSP-HG (N = 16) and a nested case-control study with HTLV-1 infected individuals-HIG (N = 48) and HTLV-1 non infected controls-CG (N = 30) that had their spinal cord analysed by Positron Emission Tomography with 18F-Fluordeoxyglucose (18F-FDG PET/CT). HTLV-1 infected individuals had 18F-FDG PET/CT results analyzed with clinical and demographic data, proviral load, cytokines and chemokines in the blood and cerebrospinal fluid (CSF).

Principal Findings

18F-FDG PET/CT showed hypometabolism in the thoracic spinal cord in HTLV-1 infected individuals. The method had an accuracy of 94.4% to identify HAM/TSP. A greater involvement of the thoracic spinal cord was observed, although hypometabolism was also observed in the cervical spinal cord segment in HTLV-1 infected individuals. Individuals with HAM/TSP showed a pro-inflammatory profile in comparison to asymptomatic and symptomatic groups, with a higher level of Interferon-inducible T-cell alpha chemoattractant (ITAC/CXCL11), IL-6, IL-12p70 in the plasma; and ITAC, IL-4, IL-5, IL-8 (CXCL8) and TNF-alpha in the CSF. Using regression, thoracic spinal cord SUV (standardized uptake value) and CSF ITAC level were identified as the HAM/TSP predictors in the multivariate model.

Conclusions

18F-FDG PET/CT imaging showed spinal cord hypometabolism in most HTLV-1 infected individuals, even in the asymptomatic HTLV-1 group. Thoracic spinal cord hypometabolism and CSF-ITAC levels were identified predictors of HAM/TSP.

Significance

Our findings suggested that in most HTLV-1 infected individuals there was compromise of central nervous system (CNS) structures despite of the lack of clinical symptoms. To explain the found hypometabolism, the role of microcirculatory and metabolic factors in the pathogenesis of neurological diseases associated with HTLV-1 infection must be further investigated. It is paramount to evaluate the central nervous function and to compare the performance among HTLV-1 infected individuals considered asymptomatic to the uninfected controls.

Community-directed vector control to supplement mass drug distribution for onchocerciasis elimination in the Madi mid-North focus of Northern Uganda

27 August 2018 - 9:00pm

by Benjamin G. Jacob, Denis Loum, Thomson L. Lakwo, Charles R. Katholi, Peace Habomugisha, Edson Byamukama, Edridah Tukahebwa, Eddie W. Cupp, Thomas R. Unnasch

Background

Onchocerciasis a neglected tropical disease that historically has been a major cause of morbidity and an obstacle to economic development in the developing world. It is caused by infection with Onchocerca volvulus, which is transmitted by black flies of the genus Simulium. The discovery of the potent effect of Mectizan (ivermectin) on O. volvulus microfilariae and the decision by its manufacturer to donate the drug for onchocerciasis spurred the implementation of international programs to control and, more recently, eliminate this scourge. These programs rely primarily on mass distribution of ivermectin (MDA) to the afflicted populations. However, MDA alone will not be sufficient to eliminate onchocerciasis where transmission is intense and where ivermectin MDA is precluded by co-endemicity with Loa loa. Vector control will likely be required as a supplemental intervention in these situations.

Methodology/Principal findings

Because biting by the black fly vectors is often a major nuisance in onchocerciasis afflicted communities, we hypothesized that community members might be mobilized to clear the breeding sites of the vegetation that represents the primary black fly larvae attachment point. We evaluated the effect of such a community based "slash and clear" intervention in multiple communities in Northern Uganda. Slash and Clear resulted in 89–99% declines in vector biting rates. The effect lasted up to 120 days post intervention.

Conclusions/Significance

Slash and clear might represent an effective, inexpensive, community- based tool to supplement ivermectin distribution as a contributory method to eliminate onchocerciasis and prevent recrudescence.

Evidence for transovarial transmission of tick-borne rickettsiae circulating in Northern Mongolia

27 August 2018 - 9:00pm

by Thomas C. Moore, Laura A. Pulscher, Luke Caddell, Michael E. von Fricken, Benjamin D. Anderson, Battsetseg Gonchigoo, Gregory C. Gray

Transstadial transmission of tick-borne rickettsiae has been well documented. Few studies, however, have evaluated the role of transovarial transmission of tick-borne rickettsiae, particularly in nature within the host-vector ecosystem. This cross-sectional study aimed to understand the role of transovarial transmission of tick-borne rickettsiae among feeding ticks at different life stages. Tick eggs laid by engorged wild-caught adult female ticks were pooled and tested for Rickettsia spp. and Anaplasma/Ehrlichia spp. using molecular techniques, while adult fed ticks were tested individually. Additionally, larval and nymphal ticks were collected in the wild from small mammals, pooled and tested for Rickettsia spp. and Anaplasma/Ehrlichia spp. There were 38 fed adult and 618 larvae/nymphs (60 pools total) Dermacentor spp. ticks collected from livestock and rodents. All individual adult ticks and tick pools were positive for Rickettsia spp. While none of the larvae/nymphs were positive for Anaplasma/Ehrlichia spp., two adult fed ticks were positive. Rickettsia spp. DNA was detected in 91% (30/33) of the pooled eggs tested, and one pool of eggs tested positive for Anaplasma/Ehrlichia spp. Sequencing data revealed Rickettsia spp. shared ≥99% identity with R. raoultii ompA. Anaplasma/Ehrlichia spp. shared ≥89% identity with A. ovis 16S ribosomal RNA. This study identified potential transovarial transmission of Rickettsia spp. and Anaplasma spp. among D. nuttalli ticks. Additional studies are needed to further assess the proportion of transovarial transmission occurring in nature to better understand the burden and disease ecology of tick-borne rickettsiae in Mongolia.

Field-collected <i>Triatoma sordida</i> from central Brazil display high microbiota diversity that varies with regard to developmental stage and intestinal segmentation

23 August 2018 - 9:00pm

by Joana L. Oliveira, Juliano C. Cury, Rodrigo Gurgel-Gonçalves, Ana C. Bahia, Fernando A. Monteiro

Background/Methodology

Triatomine bugs are the vectors of Trypanosoma cruzi, the agent of Chagas disease. Vector control has for decades relied upon insecticide spraying, but insecticide resistance has recently emerged in several triatomine populations. One alternative strategy to reduce T. cruzi transmission is paratransgenesis, whereby symbiotic bacteria are genetically engineered to produce T. cruzi-killing proteins in the vector’s gut. This approach requires in-depth knowledge of the vectors’ natural gut microbiota. Here, we use metagenomics (16S rRNA 454 pyrosequencing) to describe the gut microbiota of field-caught Triatoma sordida–likely the most common peridomestic triatomine in Brazil. For large nymphs (4th and 5th stage) and adults, we also studied separately the three main digestive-tract segments–anterior midgut, posterior midgut, and hindgut.

Principal findings

Bacteria of four phyla (12 genera) were present in both nymphs (all five stages) and adults, thus defining T. sordida’s ‘bacterial core’: Actinobacteria (Brevibacterium, Corynebacterium, Dietzia, Gordonia, Nitriliruptor, Nocardia, Nocardiopsis, Rhodococcus, and Williamsia), Proteobacteria (Pseudomonas and Sphingobium), and Firmicutes (Staphylococcus). We found some clear differences in bacterial composition and relative abundance among development stages; overall, Firmicutes and Proteobacteria increased, but Actinobacteria decreased, through development. Finally, the bacterial microbiotas of the bugs’ anterior midgut, posterior midgut, and hindgut were sharply distinct.

Conclusions/Significance

Our results identify the ‘bacterial core set’ of T. sordida and reveal important gut microbiota differences among development stages–particularly between 1st–3rd stage nymphs and adults. Further, we show that, within any given development stage, the vectors’ gut cannot be regarded as a single homogeneous environment. Cultivable, non-pathogenic ‘core’ bacterial species may now be tested as candidates for paratransgenic control of T. cruzi transmission by T. sordida.

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