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Ecology and epidemiology of rabies in humans, domestic animals and wildlife in Namibia, 2011-2017

16 April 2019 - 9:00pm

by Emmanuel H. Hikufe, Conrad M. Freuling, Rauna Athingo, Albertina Shilongo, Emmy-Else Ndevaetela, Maria Helao, Mathews Shiindi, Rainer Hassel, Alec Bishi, Siegfried Khaiseb, Juliet Kabajani, Jolandie van der Westhuizen, Gregorio Torres, Andrea Britton, Moetapele Letshwenyo, Karin Schwabenbauer, Thomas C. Mettenleiter, Nicolai Denzin, Susanne Amler, Franz J. Conraths, Thomas Müller, Adrianatus Maseke

Rabies is a fatal zoonotic disease that causes a heavy burden on societies. Namibia, a country in southern Africa, is aiming at controlling the disease in its main reservoir, the domestic dog. To facilitate the implementation comprehensive information on the ecology and epidemiology of the disease and surveillance is of utmost importance. The study presented assesses the baseline data for both human and animal rabies surveillance in Namibia in recent times and establishes correlations with ecological and socio-economic data in order to provide an up-to-date picture on the epidemiology of rabies in Namibia. For instance, it was important to identify the main drivers in the epidemiology, and whether the control strategy by mass vaccination of dogs is undermined by cycles of rabies in wildlife. Rabies in humans was reported mainly from the Northern Communal Areas (NCAs), with a total of 113 cases from 2011 to 2017, representing an incidence of between 1.0 and 2.4 annual human rabies deaths per 100,000 inhabitants. Kavango, the region with the highest human rabies incidence was also the region with the lowest animal rabies surveillance intensity. Generally, the vast majority (77%) of dog samples originated from communal farm land, followed by urban areas (17%), while only a small fraction (3%) was submitted from freehold farm areas. In contrast, kudu and eland submissions were almost exclusively from freehold farmland (76%) and urban areas (19%), whereas the submission of cattle samples was evenly distributed among freehold farms (46%) and communal farm land (46%). The likelihood of sample submission decreased exponentially with distance to one of the two laboratories. Overall, 67% (N = 1,907) of all samples submitted tested rabies-positive, with the highest positivity rate observed in kudus (89%) and jackals (87%). The transmission cycle of rabies in dogs appears restricted to the northern communal areas of Namibia, whilst rabies in wildlife species is predominately reported from farmland in central Namibia, mostly affecting kudu (Tragelaphus strepsiceros) and livestock with a likely reservoir in wildlife canids such as jackals or bat-eared foxes. The analysis confirms the presence of two independent transmission cycles in Namibia with little geographic overlap, thus allowing for a sustainable control of rabies in dogs in the NCAs.

The case-area targeted rapid response strategy to control cholera in Haiti: a four-year implementation study

16 April 2019 - 9:00pm

by Stanislas Rebaudet, Gregory Bulit, Jean Gaudart, Edwige Michel, Pierre Gazin, Claudia Evers, Samuel Beaulieu, Aaron Aruna Abedi, Lindsay Osei, Robert Barrais, Katilla Pierre, Sandra Moore, Jacques Boncy, Paul Adrien, Florence Duperval Guillaume, Edouard Beigbeder, Renaud Piarroux

Background

In October 2010, Haiti was struck by a large-scale cholera epidemic. The Haitian government, UNICEF and other international partners launched an unprecedented nationwide alert-response strategy in July 2013. Coordinated NGOs recruited local rapid response mobile teams to conduct case-area targeted interventions (CATIs), including education sessions, household decontamination by chlorine spraying, and distribution of chlorine tablets. An innovative red-orange-green alert system was also established to monitor the epidemic at the communal scale on a weekly basis. Our study aimed to describe and evaluate the exhaustiveness, intensity and quality of the CATIs in response to cholera alerts in Haiti between July 2013 and June 2017.

Methodology/principal findings

We analyzed the response to 7,856 weekly cholera alerts using routine surveillance data and severity criteria, which was based on the details of 31,306 notified CATIs. The odds of CATI response during the same week (exhaustiveness) and the number of complete CATIs in responded alerts (intensity and quality) were estimated using multivariate generalized linear mixed models and several covariates. CATIs were carried out significantly more often in response to red alerts (adjusted odds ratio (aOR) [95%-confidence interval, 95%-CI], 2.52 [2.22–2.87]) compared with orange alerts. Significantly more complete CATIs were carried out in response to red alerts compared with orange alerts (adjusted incidence ratio (aIR), 1.85 [1.73–1.99]). Over the course of the eight-semester study, we observed a significant improvement in the exhaustiveness (aOR, 1.43 [1.38–1.48] per semester) as well as the intensity and quality (aIR, 1.23 [1.2–1.25] per semester) of CATI responses, independently of funds available for the strategy. The odds of launching a CATI response significantly decreased with increased rainfall (aOR, 0.99 [0.97–1] per each accumulated cm). Response interventions were significantly heterogeneous between NGOs, communes and departments.

Conclusions/significance

The implementation of a nationwide case-area targeted rapid response strategy to control cholera in Haiti was feasible albeit with certain obstacles. Such feedback from the field and ongoing impact studies will be very informative for actors and international donors involved in cholera control and elimination in Haiti and in other affected countries.

The gendered impact of Buruli ulcer on the household production of health and social support networks: Why decentralization favors women

15 April 2019 - 9:00pm

by Ines Elvire Agbo, Roch Christian Johnson, Ghislain Emmanuel Sopoh, Mark Nichter

Background

Buruli ulcer [BU] is a chronic and debilitating neglected tropical skin disease caused by Mycobacterium ulcerans. The treatment of moderate to severe BU affects the well-being of entire households and places a strain on both gender relations within households and social relations with kin asked for various types of support. In this paper, we employ the conceptual lenses provided by the Household Production of Health approach to understanding the impact of illness on the household as a unit of analysis, gender studies, and social support related research to better understand BU health care decision making and the psychosocial experience of BU hospitalization.

Methods

An ethnography attentive to circumstance and the nested contexts within which stakeholders respond to BU was conducted employing semi-structured interviews, illness narratives, and case studies. An iterative process of data collection with preliminary analyses and reflection shaped subsequent interviews. Interviews were conducted with 45 women in households having a member afflicted with BU in two communes of Benin with high prevalence rates for BU. The first commune [ZE] has a well-established decentralized BU treatment program and a well-functioning referral network linked to the Allada reference hospital specializing in the care of BU and other chronic ulcers. The second commune [Ouinhi] is one of the last regions of the country to introduce a decentralized BU treatment program. A maximum variation purposeful sample was selected to identify information-rich health care decision cases for in-depth study.

Principal findings

Study results demonstrated that although men are the primary decision makers for healthcare decisions outside the home, women are largely responsible for arranging care for the afflicted in hospital in addition to managing their own households. A woman’s agency and ability to influence the decision-making process is largely based on whatever social support and substitute labor she can mobilize from her own network of kin relations. When support wanes, women are placed in a vulnerable position and often end up destitute. Decentralized BU treatment is preferred because it enables a woman to remain in her own household as a patient or caretaker of an ill family member while engaging in child care and petty revenue earing activities. Remaining in the hospital (a liminal space) as either patient or caretaker also renders a woman vulnerable to rumor and innuendo about sexual liaisons and constitutes a form of social risk. Social risk in some cases eclipses the physical risk of the disease in what we would describe as a hierarchy of risks.

Conclusion

This study illustrates the importance of decentralized treatment programs for NTDs such as BU. Such programs enable patients to remain in their homes while being treated, and do not displace women responsible for the welfare of the entire household. When women are displaced the well-being of the entire household is placed in jeopardy.

Clinical features and genetic background of the sympatric species <i>Paracoccidioides brasiliensis</i> and <i>Paracoccidioides americana</i>

15 April 2019 - 9:00pm

by Priscila Marques de Macedo, Marcus de Melo Teixeira, Bridget M. Barker, Rosely Maria Zancopé-Oliveira, Rodrigo Almeida-Paes, Antonio Carlos Francesconi do Valle

Introduction

The agents of paracoccidioidomycosis, historically identified as Paracoccidioides brasiliensis, are in fact different phylogenetic species. This study aims to evaluate associations between Paracoccidioides phylogenetic species and corresponding clinical data.

Methods

Paracoccidioides strains from INI/Fiocruz patients (1998–2016) were recovered. Socio-demographic, epidemiological, clinical, serological, therapeutic and prognostic data of the patients were collected to evaluate possible associations of these variables with the fungal species identified through partial sequencing of the ADP-ribosylation factor (arf) and the 43-kDa-glycoprotein (gp43) genes.

Results

Fifty-four fungal strains were recovered from 47 patients, most (72.3%) infected in Rio de Janeiro state, Brazil. Forty-one cases were caused by Paracoccidioides brasiliensis and six by Paracoccidioides americana (former PS2). P. brasiliensis was responsible for severe lymph abdominal forms, whereas patients infected with P. americana presented a high rate of adrenal involvement. However, no statistically significant associations were found for all variables studied. P. americana presented 100% reactivity to immunodiffusion, even when tested against antigens from other species, while negative results were observed in 9 (20%) cases caused by P. brasiliensis, despite being tested against a homologous antigen.

Conclusions

P. brasiliensis and P. americana are sympatric and share similar clinical features and habitat, where they may compete for similar hosts.

A combination of incidence data and mobility proxies from social media predicts the intra-urban spread of dengue in Yogyakarta, Indonesia

15 April 2019 - 9:00pm

by Aditya Lia Ramadona, Yesim Tozan, Lutfan Lazuardi, Joacim Rocklöv

Only a few studies have investigated the potential of using geotagged social media data for predicting the patterns of spatio-temporal spread of vector-borne diseases. We herein demonstrated the role of human mobility in the intra-urban spread of dengue by weighting local incidence data with geo-tagged Twitter data as a proxy for human mobility across 45 neighborhoods in Yogyakarta city, Indonesia. To estimate the dengue virus importation pressure in each study neighborhood monthly, we developed an algorithm to estimate a dynamic mobility-weighted incidence index (MI), which quantifies the level of exposure to virus importation in any given neighborhood. Using a Bayesian spatio-temporal regression model, we estimated the coefficients and predictiveness of the MI index for lags up to 6 months. Specifically, we used a Poisson regression model with an unstructured spatial covariance matrix. We compared the predictability of the MI index to that of the dengue incidence rate over the preceding months in the same neighborhood (autocorrelation) and that of the mobility information alone. We based our estimates on a volume of 1·302·405 geotagged tweets (from 118·114 unique users) and monthly dengue incidence data for the 45 study neighborhoods in Yogyakarta city over the period from August 2016 to June 2018. The MI index, as a standalone variable, had the highest explanatory power for predicting dengue transmission risk in the study neighborhoods, with the greatest predictive ability at a 3-months lead time. The MI index was a better predictor of the dengue risk in a neighborhood than the recent transmission patterns in the same neighborhood, or just the mobility patterns between neighborhoods. Our results suggest that human mobility is an important driver of the spread of dengue within cities when combined with information on local circulation of the dengue virus. The geotagged Twitter data can provide important information on human mobility patterns to improve our understanding of the direction and the risk of spread of diseases, such as dengue. The proposed MI index together with traditional data sources can provide useful information for the development of more accurate and efficient early warning and response systems.

Non-typhoid <i>Salmonella</i> blood stream infection in Kuwait: Clinical and microbiological characteristics

15 April 2019 - 9:00pm

by M. John Albert, Dieter Bulach, Wadha Alfouzan, Hidemasa Izumiya, Glen Garter, Khaled Alobaid, Fatemah Alatar, Abdul Rashid Sheikh, Laurent Poirel

Non-typhoid Salmonella (NTS) bacteremia is a significant cause of morbidity and mortality worldwide. It is considered to be an emerging and neglected tropical disease in Africa. We studied this in two tertiary hospitals–Al Farwaniya and Al Amiri–in Kuwait, a subtropical country, from April 2013-May 2016. NTS bacteremia was present in 30 of 53,860 (0.75%) and 31 of 290,36 (1.33%) blood cultures in the two hospitals respectively. In Al Farwaniya hospital, one-third of the patients were from some tropical developing countries of Asia. About 66% of all patients (40/61) had diarrhea, and of these, 65% had the corresponding blood serovar isolated from stool culture. A few patients had Salmonella cultured from urine. Patients were either young or old. Most of the patients had co-morbidities affecting the immune system. Two patients each died in both hospitals. The number of different serovars cultured in each hospital was 13, and most infections were due to S. Enteritidis (all sequence type [ST]) 11) and S. Typhimurium (all ST19) except in subgroup of expatriate patients from tropical developing countries in Al Farwaniya hospital. About quarter of the isolates were multidrug-resistant. Most patients were treated with a cephalosporin with or without other antibiotics. S. Enteritidis and S. Typhimurium isolates were typed by pulsed field-gel electrophoresis (PFGE) and a selected number of isolates were whole-genome sequenced. Up to four different clades were present by PFGE in either species. Whole-genome sequenced isolates showed antibiotic-resistance genes that showed phenotypic correlation, and in some cases, phenotypes showed absence of specific genes. Whole-genome sequenced isolates showed presence of genes that contributed to blood-stream infection. Phylogeny by core genome analysis showed a close relationship with S. Typhimurium and S. Enteritidis from other parts of the world. The uniqueness of our study included the finding of a low prevalence of infection, mortality and multidrug-resistance, a relatively high prevalence of gastrointestinal infection in patients, and the characterization of selected isolates of S. Typhimurium and S. Enteritidis serovars by whole-genome sequencing that shed light on phylogeny, virulence and resistance. Similarities with studies from developing countries especially Africa included infection in patients with co-morbidities affecting the immune system, predominance of S. Typhimurium and S. Enteritidis serovars and presence of drug-resistance in isolates.

<i>Aedes aegypti</i> HPX8C modulates immune responses against viral infection

15 April 2019 - 9:00pm

by Ju-Mei Wang, Yang Cheng, Zuo-Kun Shi, Xiao-Feng Li, Long-Sheng Xing, Hong Jiang, Dan Wen, Yong-Qiang Deng, Ai-Hua Zheng, Cheng-Feng Qin, Zhen Zou

Mosquitoes act as vectors of numerous pathogens that cause human diseases. Dengue virus (DENV) transmitted by mosquito, Aedes aegypti, is responsible for dengue fever epidemics worldwide with a serious impact on human health. Currently, disease control mainly relies on vector targeted intervention strategies. Therefore, it is imperative to understand the molecular mechanisms underlying the innate immune response of mosquitoes against pathogens. In the present study, the expression profiles of immunity-related genes in the midgut responding to DENV infection by feeding were analyzed by transcriptome and quantitative real-time PCR. The level of Antimicrobial peptides (AMPs) increased seven days post-infection (d.p.i.), which could be induced by the Toll immune pathway. The expression of reactive oxygen species (ROS) genes, including antioxidant genes, such as HPX7, HPX8A, HPX8B, HPX8C were induced at one d.p.i. and peaked again at ten d.p.i. in the midgut. Interestingly, down-regulation of the antioxidant gene HPX8C by RNA interference led to reduction in the virus titer in the mosquito, probably due to the elevated levels of ROS. Application of a ROS inhibitor and scavenger molecules further established the role of oxygen free radicals in the modulation of the immune response to DENV infection. Overall, our comparative transcriptome analyses provide valuable information about the regulation of immunity related genes in the transmission vector in response to DENV infection. It further allows us to identify novel molecular mechanisms underlying the host-virus interaction, which might aid in the development of novel strategies to control mosquito-borne diseases.

Low population Japanese encephalitis virus (JEV) seroprevalence in Udayapur district, Nepal, three years after a JE vaccination programme: A case for further catch up campaigns?

15 April 2019 - 9:00pm

by Lance Turtle, Hannah E. Brindle, William Schluter, Brian Faragher, Ajit Rayamajhi, Rajendra Bohara, Santosh Gurung, Geeta Shakya, Sutee Yoksan, Sameer Dixit, Rajesh Rajbhandari, Bimal Paudel, Shailaja Adhikari, Tom Solomon, Mike J. Griffiths

The live attenuated Japanese encephalitis (JE) vaccine SA14-14-2 has been used in Nepal for catch-up campaigns and is now included in the routine immunisation schedule. Previous studies have shown good vaccine efficacy after one dose in districts with a high incidence of JE. The first well-documented dengue outbreak occurred in Nepal in 2006 with ongoing cases now thought to be secondary to migration from India. Previous infection with dengue virus (DENV) partially protects against JE and might also influence serum neutralising antibody titres against JEV. This study aimed to determine whether serum anti-JEV neutralisation titres are: 1. maintained over time since vaccination, 2. vary with historic local JE incidence, and 3. are associated with DENV neutralising antibody levels. We conducted a cross-sectional study in three districts of Nepal: Banke, Rupandehi and Udayapur. Udayapur district had been vaccinated against JE most recently (2009), but had been the focus of only one campaign, compared with two in Banke and three in Rupandehi. Participants answered a short questionnaire and serum was assayed for anti-JEV and anti-DENV IgM and IgG (by ELISA) and 50% plaque reduction neutralisation titres (PRNT50) against JEV and DENV serotypes 1–4. A titre of ≥1:10 was considered seropositive to the respective virus. JEV neutralising antibody seroprevalence (PRNT50 ≥ 1:10) was 81% in Banke and Rupandehi, but only 41% in Udayapur, despite this district being vaccinated more recently. Sensitivity of ELISA for both anti-JEV and anti-DENV antibodies was low compared with PRNT50. DENV neutralising antibody correlated with the JEV PRNT50 ≥1:10, though the effect was modest. IgM (indicating recent infection) against both viruses was detected in a small number of participants. We also show that DENV IgM is present in Nepali subjects who have not travelled to India, suggesting that DENV may have become established in Nepal. We therefore propose that further JE vaccine campaigns should be considered in Udayapur district, and similar areas that have had fewer vaccination campaigns.

Case report: A retrospective serological analysis indicating human exposure to tick-borne relapsing fever spirochetes in Sonora, Mexico

11 April 2019 - 9:00pm

by Edwin Vázquez-Guerrero, Norma P. Adan-Bante, Mónica C. Mercado-Uribe, César Hernández-Rodríguez, Lourdes Villa-Tanaca, Job E. Lopez, J. Antonio Ibarra

Challenges and opportunities for control and elimination of soil-transmitted helminth infection beyond 2020

11 April 2019 - 9:00pm

by Matthew C. Freeman, Oladele Akogun, Vicente Belizario Jr., Simon J. Brooker, Theresa W. Gyorkos, Rubina Imtiaz, Alejandro Krolewiecki, Seung Lee, Sultani H. Matendechero, Rachel L. Pullan, Jürg Utzinger

Broken drug markets in infectious diseases: Opportunities outside the private sector?

11 April 2019 - 9:00pm

by Jonathan D. Alpern, Stephen J. Dunlop, William M. Stauffer

Author summary: A subset of anti-infective drugs are increasingly unavailable for patients in the United States due to pricing or withdrawal from the market. Timely market solutions are needed. We assert that solutions to ensure access to some essential anti-infective agents lie outside capital markets and that public-private partnerships may be the most viable solution.

Reversal of liver fibrosis after splenectomy in a patient with advanced schistosomiasis japonica: A case report with 4-year follow-up

11 April 2019 - 9:00pm

by Langui Song, Beibei Zhang, Jiahua Liu, Min Wang, Xiaohe Ma, Lifu Wang, Xiaoying Wu, Zhongdao Wu, Tianping Wang

Relationship between toxoplasmosis and obsessive compulsive disorder: A systematic review and meta-analysis

10 April 2019 - 9:00pm

by Tooran Nayeri Chegeni, Shahabeddin Sarvi, Afsaneh Amouei, Mahmood Moosazadeh, Zahra Hosseininejad, Sargis A. Aghayan, Ahmad Daryani

Background

A few studies investigated the relationship between toxoplasmosis and mental disorders, such as obsessive compulsive disorder (OCD). However, the specific nature of the association between Toxoplasma gondii (T. gondii) infection and OCD is not yet clear. The aim of this study was to collect information on the relationship between OCD and toxoplasmosis and assess whether patients with toxoplasmosis are prone to OCD.

Methods

For the purpose of this study, 6 major electronic databases and the Internet search engine Google Scholar were searched for the published articles up to July 30th, 2018 with no restriction of language. The inverse variance method and the random effect model were used to combine the data. The values of odds ratio (OR) were estimated at 95% confidence interval (CI).

Results

A total of 9 case-control and 3 cross-sectional studies were included in our systematic review. However, 11 of these 12 articles were entered into the meta-analysis containing 9873 participants, out of whom 389 were with OCD (25.96% positive for toxoplasmosis) and 9484 were without OCD (17.12% positive for toxoplasmosis). The estimation of the random effect model indicated a significant common OR of 1.96 [95% CI: 1.32–2.90].

Conclusion

This systematic review and meta-analysis revealed that toxoplasmosis could be as an associated factor for OCD (OR = 1.96). However, further prospective investigations are highly recommended to illuminate the underlying pathophysiological mechanisms of T. gondii infection in OCD and to better investigate the relationship between OCD and T. gondii infection.

Strategies for tackling <i>Taenia solium</i> taeniosis/cysticercosis: A systematic review and comparison of transmission models, including an assessment of the wider Taeniidae family transmission models

10 April 2019 - 9:00pm

by Matthew A. Dixon, Uffe C. Braae, Peter Winskill, Martin Walker, Brecht Devleesschauwer, Sarah Gabriël, Maria-Gloria Basáñez

Background

The cestode Taenia solium causes the neglected (zoonotic) tropical disease cysticercosis, a leading cause of preventable epilepsy in endemic low and middle-income countries. Transmission models can inform current scaling-up of control efforts by helping to identify, validate and optimise control and elimination strategies as proposed by the World Health Organization (WHO).

Methodology/Principal findings

A systematic literature search was conducted using the PRISMA approach to identify and compare existing T. solium transmission models, and related Taeniidae infection transmission models. In total, 28 modelling papers were identified, of which four modelled T. solium exclusively. Different modelling approaches for T. solium included deterministic, Reed-Frost, individual-based, decision-tree, and conceptual frameworks. Simulated interventions across models agreed on the importance of coverage for impactful effectiveness to be achieved.Other Taeniidae infection transmission models comprised force-of-infection (FoI), population-based (mainly Echinococcus granulosus) and individual-based (mainly E. multilocularis) modelling approaches. Spatial structure has also been incorporated (E. multilocularis and Taenia ovis) in recognition of spatial aggregation of parasite eggs in the environment and movement of wild animal host populations.

Conclusions/Significance

Gaps identified from examining the wider Taeniidae family models highlighted the potential role of FoI modelling to inform model parameterisation, as well as the need for spatial modelling and suitable structuring of interventions as key areas for future T. solium model development. We conclude that working with field partners to address data gaps and conducting cross-model validation with baseline and longitudinal data will be critical to building consensus-led and epidemiological setting-appropriate intervention strategies to help fulfil the WHO targets.

Efficacy of China-made praziquantel for treatment of Schistosomiasis haematobium in Africa: A randomized controlled trial

10 April 2019 - 9:00pm

by Xin-Yao Wang, Jian He, Saleh Juma, Fatma Kabole, Jia-gang Guo, Jian-Rong Dai, Wei Li, Kun Yang

Background

In the roadmap on the neglected tropical diseases (NTD) the World Health Organization (WHO) aims at attaining at least 75% coverage of preventive chemotherapy in pre-school and school-age children by 2020. A randomized controlled trial was used to compare the effectiveness of praziquantel in treating Schistosoma haematobium in Africa using two different sources for the drug, Merck Limited Partnership (KgaA), Germany and Nanjing Pharmaceutical Factory (NPF), China.

Methods

More than 6,000 participants testing positive for S. haematobium infection were enrolled from three villages (shehias) situated in the northern, middle and southern part of Pemba Island, Zanzibar. Applying criteria of inclusion and exclusion, resulted in a study population of 152 people (84 males, 68 females). A randomized controlled trial was conducted assigning participants to either praziquantel from NPF or Merck KGaA. After one month, the cure rate of S. haematobium and adverse events were compared to evaluate effectiveness. The ratio of male to female, the ratio of light/high infection intensity, and the average value of age were calculated between the two drug manufacturers. Chi-squared test and T-test were used for consistency analysis.

Results

Out of the total of 73 cases receiving praziquantel from NPF, the cure rate achieved was 97.3% (73/75), while the 74 cases receiving the drug from Merck KgaA reached a similar cure rate (96.1% or 74/77). There was no significant difference between the two outcomes (χ2 = 0.003, P = 0.956). Among the 75 patients treat, only one (a 16-years old female student), who had received the drug made in China had slight adverse reactions manifested as dizziness, headache and abdominal pain.

Conclusion

The efficacy of China-made praziquantel does not differ significantly from praziquantel made by Merck KGaA in Germany.

Trial registration

ClinicalTrials.gov, NCT03133832

Whole cell matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of <i>Leptospira</i> spp. in Thailand and Lao PDR

10 April 2019 - 9:00pm

by Piengchan Sonthayanon, Janthima Jaresitthikunchai, Suthee Mangmee, Tipparat Thiangtrongjit, Vanaporn Wuthiekanun, Premjit Amornchai, Paul Newton, Rattanaphone Phetsouvanh, Nicholas PJ Day, Sittiruk Roytrakul

Leptospirosis is a zoonosis with a worldwide distribution, caused by pathogenic spirochetes of the genus Leptospira. The classification and identification of leptospires can be conducted by both genotyping and serotyping which are time-consuming and established in few reference laboratories. This study used matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as rapid and accurate tool for the identification of leptospires. The whole cell protein spectra of 116 Leptospira isolates including 15 references Leptospira spp. (pathogenic, n = 8; intermediate, n = 2; non-pathogenic, n = 5) and 101 Leptospira spp. clinical isolates was created as an in-house MALDI-TOF MS database. Ninety-seven clinical isolates from Thailand and Laos was validated with these protein spectra and revealed 98.9% correct identification when compared with 16S rRNA gene sequences method. Moreover, MALDI-TOF MS could identify spiked leptospires whole cell in urine. Biomarkers for differentiation of leptospires phylogeny and specific protein spectra for most found Leptospira spp. in this area (L. interrogans, L. kirschneri, L. borgpetersenii) based on MALDI-MS algorithm were demonstrated.

Epidemiological features of a recent zoonotic cutaneous leishmaniasis outbreak in Zagora province, southern Morocco

9 April 2019 - 9:00pm

by Adil El Hamouchi, Othmane Daoui, Mouad Ait Kbaich, Idris Mhaidi, Sofia El Kacem, Ikram Guizani, M’hammed Sarih, Meryem Lemrani

Background

Leishmania major is an endemic vector-borne disease in Morocco that causes zoonotic cutaneous leishmaniasis (ZCL), especially in arid pre-Saharan regions where its unique vector and reservoir are Phlebotomus papatasi and Meriones shawi, respectively, and may cause epidemics. In late 2017, the Zagora province, an endemic focus for ZCL in southern Morocco, had CL outbreak. The main objective of our investigation was to analyze the epidemiological features of this latest ZCL outbreak.

Methodology/Principal findings

We analyzed epidemiological features of this latest ZCL outbreak. The Regional Delegation of Health, Zagora, recorded 4,402 CL patients between October 2017 and end of March 2018. Our findings showed that 24 municipalities were affected and majority (55.1%) of infected cases belonged to the Tinzouline rural municipality. Majority of patients were females (57.2%). While all age group patients were affected, those aged <10 years were the most affected (42.1%). During this outbreak over 5 days in December 2017, we conducted a survey in Tinzouline and recruited and sampled 114 CL patients to confirm CL diagnosis by parasitological (direct examination and culture) and molecular (ITS1-PCR) methods and identify the etiological agent of infection using ITS1-PCR-RFLP and sequencing. We completed a detailed questionnaire including clinical and epidemiological data for each patient and found 72.8% of patients presenting multiple lesions (≥2), with an average number of lesions of 5.16 ± 0.5. Lesions were more prevalent in the upper limbs, with the most common type being the ulcerocrusted lesion (60.5%). We detected no associations between lesion type and patients’ sex or age.

Conclusions/Significance

Among 114 clinically diagnosed CL patients, we confirmed 90.35% and identified L. major as the species responsible for this outbreak. Self-medication using various products caused superinfection and inflammation of lesions and complicated the diagnosis and treatment. Thus, ZCL remains a major public health problem in the Zagora province, and commitment of all stakeholders is urgently required to implement a sustainable regional control program.

Improved estimates for extinction probabilities and times to extinction for populations of tsetse (<i>Glossina</i> spp)

9 April 2019 - 9:00pm

by Damian Kajunguri, Elisha B. Are, John W. Hargrove

A published study used a stochastic branching process to derive equations for the mean and variance of the probability of, and time to, extinction in population of tsetse flies (Glossina spp) as a function of adult and pupal mortality, and the probabilities that a female is inseminated by a fertile male. The original derivation was partially heuristic and provided no proofs for inductive results. We provide these proofs, together with a more compact way of reaching the same results. We also show that, while the published equations hold good for the case where tsetse produce male and female offspring in equal proportion, a different solution is required for the more general case where the probability (β) that an offspring is female lies anywhere in the interval (0, 1). We confirm previous results obtained for the special case where β = 0.5 and show that extinction probability is at a minimum for β > 0.5 by an amount that increases with increasing adult female mortality. Sensitivity analysis showed that the extinction probability was affected most by changes in adult female mortality, followed by the rate of production of pupae. Because females only produce a single offspring approximately every 10 days, imposing a death rate of greater than about 3.5% per day will ensure the eradication of any tsetse population. These mortality levels can be achieved for some species using insecticide-treated targets or cattle—providing thereby a simple, effective and cost-effective method of controlling and eradicating tsetse, and also human and animal trypanosomiasis. Our results are of further interest in the modern situation where increases in temperature are seeing the real possibility that tsetse will go extinct in some areas, without the need for intervention, but have an increased chance of surviving in other areas where they were previously unsustainable due to low temperatures.

Estimating the current burden of Chagas disease in Mexico: A systematic review and meta-analysis of epidemiological surveys from 2006 to 2017

9 April 2019 - 9:00pm

by Audrey Arnal, Etienne Waleckx, Oscar Rico-Chávez, Claudia Herrera, Eric Dumonteil

Background

In Mexico, estimates of Chagas disease prevalence and burden vary widely. Updating surveillance data is therefore an important priority to ensure that Chagas disease does not remain a barrier to the development of Mexico's most vulnerable populations.

Methodology/Principal findings

The aim of this systematic review and meta-analysis was to analyze the literature on epidemiological surveys to estimate Chagas disease prevalence and burden in Mexico, during the period 2006 to 2017. A total of 2,764 articles were screened and 36 were retained for the final analysis. Epidemiological surveys have been performed in most of Mexico, but with variable study scale and geographic coverage. Based on studies reporting confirmed cases (i.e. using at least 2 serological tests), and taking into account the differences of sample sizes, the national estimated seroprevalence of Trypanosoma cruzi infection was 3.38% [95%CI 2.59–4.16], suggesting that there are 4.06 million cases in Mexico. Studies focused on pregnant women, which may transmit the parasite to their newborn during pregnancy, reported an estimated seroprevalence of 2.21% [95%CI 1.46–2.96], suggesting that there are 50,675 births from T. cruzi infected pregnant women per year, and 3,193 cases of congenitally infected newborns per year. Children under 18 years had an estimated seropositivity rate of 1.51% [95%CI 0.77–2.25], which indicate ongoing transmission. Cases of T. cruzi infection in blood donors have also been reported in most states, with a national estimated seroprevalence of 0.55% [95%CI 0.43–0.66].

Conclusions/Significance

Our analysis suggests a disease burden for T. cruzi infection higher than previously recognized, highlighting the urgency of establishing Chagas disease surveillance and control as a key national public health priority in Mexico, to ensure that it does not remain a major barrier to the economic and social development of the country's most vulnerable populations.

The role of perceptions and knowledge of leprosy in the elimination of leprosy: A baseline study in Fatehpur district, northern India

5 April 2019 - 9:00pm

by Anna T. van ‘t Noordende, Ida Korfage, Suchitra Lisam, Mohammed A. Arif, Anil Kumar, Wim H. van Brakel

Background

With the introduction of new interventions to prevent leprosy, such as post-exposure prophylaxis (PEP) given to contacts of leprosy patients, it is necessary to update our understanding of knowledge and perception of leprosy among the populations where these interventions will be introduced, in order to tailor communication optimally to the current situation. This study is a baseline study of the PEP++ project and aimed to assess the knowledge, attitudes and practices regarding leprosy in Fatehpur, India.

Methodology

The study used a community-based cross-sectional design with a mixed-methods approach. We assessed knowledge, attitudes, and practices with the KAP measure, and stigma with the Explanatory Model Interview Catalogue community stigma scale (EMIC-CSS) and the Social Distance Scale (SDS). In addition, semi-structured interviews and focus group discussions were conducted with all participant groups. The quantitative data were analysed using stepwise multivariate regression. The qualitative data were analysed using open, inductive coding and content analysis.

Findings

A total of 446 participants were included in the study: 100 persons affected by leprosy, 111 close contacts, 185 community members and 50 health care workers. In addition, 24 in-depth interviews were conducted and 35 people were included in focus group discussions. 12.5% of the participants had adequate knowledge of leprosy, while 22% had poor knowledge. Knowledge on cause (answered correctly by 10% of the participants), mode of transmission (5%) and symptoms of leprosy (16%) was especially poor. The mean EMIC-CSS score was 15.3 (95%CI 14.6–16.0) and mean SDS score 7.2 (95%CI 6.6–7.8). Better knowledge of leprosy was associated with lower levels of social distance towards persons affected by leprosy.

Conclusion

This study revealed poor knowledge regarding leprosy and high levels of stigma and fear and desire to keep social distance towards persons affected by leprosy. Community education that takes cultural beliefs, knowledge gaps and fears into consideration could improve knowledge, reduce misconceptions and positively influence the perception of leprosy.

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