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Meteorological factors and risk of hemorrhagic fever with renal syndrome in Guangzhou, southern China, 2006–2015

PLoS Neglected Tropical Diseases News - 27 June 2018 - 9:00pm

by Yuehong Wei, Yang Wang, Xiaoning Li, Pengzhe Qin, Ying Lu, Jianmin Xu, Shouyi Chen, Meixia Li, Zhicong Yang

Background

The epidemic tendency of hemorrhagic fever with renal syndrome (HFRS) is on the rise in recent years in Guangzhou. This study aimed to explore the associations between meteorological factors and HFRS epidemic risk in Guangzhou for the period from 2006–2015.

Methods

We obtained data of HFRS cases in Guangzhou from the National Notifiable Disease Report System (NNDRS) during the period of 2006–2015. Meteorological data were obtained from the Guangzhou Meteorological Bureau. A negative binomial multivariable regression was used to explore the relationship between meteorological variables and HFRS.

Results

The annual average incidence was 0.92 per 100000, with the annual incidence ranging from 0.64/100000 in 2009 to 1.05/100000 in 2012. The monthly number of HFRS cases decreased by 5.543% (95%CI -5.564% to -5.523%) each time the temperature was increased by 1°C and the number of cases decreased by 0.075% (95%CI -0.076% to -0.074%) each time the aggregate rainfall was increased by 1 mm. We found that average temperature with a one-month lag was significantly associated with HFRS transmission.

Conclusions

Meteorological factors had significant association with occurrence of HFRS in Guangzhou, Southern China. This study provides preliminary information for further studies on epidemiological prediction of HFRS and for developing an early warning system.

Multi locus sequence typing of <i>Burkholderia pseudomallei</i> isolates from India unveils molecular diversity and confers regional association in Southeast Asia

PLoS Neglected Tropical Diseases News - 27 June 2018 - 9:00pm

by Veeraraghavan Balaji, Susmitha Perumalla, Rajamani Perumal, Francis Yesurajan Inbanathan, Suresh Kumar Rajamani Sekar, Miracle Magdelene Paul, Rani Diana Sahni, John Antony Jude Prakash, Ramya Iyadurai

Objectives

Burkholderia pseudomallei, the causative agent for melioidosis, has become a public health problem in India and across the world. Melioidosis can be difficult to diagnose because of the inconsistent clinical presentations of the disease. This study aims to determine the genetic diversity among the clinical isolates of B. pseudomaelli from India in order to establish a molecular epidemiology and elucidate the Southeast Asian association.

Methods

Molecular typing using multi locus sequence typing was performed on thirty one archived B. pseudomallei clinical isolates, previously characterised from specimens obtained from patients admitted to the Christian Medical College & Hospital, Vellore from 2015 to 2016. Further investigations into the genetic heterogeneity and evolution at a regional and global level were performed using insilico tools.

Results

Multi locus sequence typing (MLST) of the isolates from systemic and localized forms of melioidosis, including blood, pus, tissue, and urine specimens, revealed twenty isolates with novel sequence types and eleven with previously reported sequence types. High genetic diversity was observed using MLST with a strong association within the Southeast Asian region.

Conclusions

Molecular typing of B. pseudomallei clinical isolates using MLST revealed high genetic diversity and provided a baseline molecular epidemiology of the disease in India with a strong Southeast Asian association of the strains. Future studies should focus on whole genome based Single-Nucleotide-Polymorphism (SNP) which has the advantage of a high discriminatory power, to further understand the novel sequence types reported in this study.

A cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus infection in China, 1996: A retrospective serological study

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Jianli Hu, Chao Shi, Zhifeng Li, Xiling Guo, Yanhua Qian, Wenwen Tan, Xian Li, Xian Qi, Xiaoju Su, Minghao Zhou, Hua Wang, Yongjun Jiao, Changjun Bao

Background

A cluster of eleven patients, including eight family members and three healthcare workers with fever and thrombocytopenia occurred in Yixing County, Jiangsu Province, China, from October to November 1996. However, the initial investigation failed to identify its etiology. Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS bunyavirus (SFTSV), which was first discovered in 2009. The discovery of novel SFTSV resulted in our consideration to test SFTSV on the remaining samples of this cluster in September 2010.

Methodology/Principal findings

We retrospectively analyzed the epidemiological and clinical data of this cluster. The first case, one 55-year-old man with fulminant hemorrhagic diseases, died on October 14, 1996. His younger brother (the second case) developed similar hemorrhagic diseases after nursing him and then died on November 3. From November 4 to November 15, nine other patients, including six family members and three medical staffs, developed fever and thrombocytopenia after exposure to the second case. The sera of six patients were collected on November 24, 1996. IgM antibodies against SFTSV were detected in all of the six patients’ sera using enzyme-linked immunosorbent assay (ELISA), while IgG antibodies were detected in one patient’s serum using an indirect immunofluorescence assay (IFA). We also found that IgG antibodies against SFTSV were still detected in four surviving patients’ sera 14 years after illness onset.

Conclusions and significance

The mysterious pathogen of the cluster in 1996 was proved to be SFTSV on the basis of its epidemiological data, clinical data and serological results. It suggests that SFTSV has been circulating in China for more than 10 years before being identified in 2009, and SFTSV IgG antibodies can persist for up to 14 years.

Low prevalence of HTLV1/2 infection in a population of immigrants living in southern Italy

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Loredana Alessio, Carmine Minichini, Mario Starace, Laura Occhiello, Mara Caroprese, Giovanni Di Caprio, Caterina Sagnelli, Luciano Gualdieri, Mariantonietta Pisaturo, Lorenzo Onorato, Gaetano Scotto, Margherita Macera, Stefania De Pascalis, Evangelista Sagnelli, Nicola Coppola

Aims

To assess the prevalence of HTLV-1 and HTLV-2 infections in a cohort of immigrants living in southern Italy.

Findings

We screened for antibody to HTLV-1/2 infection 1,498 consecutive immigrants born in endemic areas (sub-Saharan Africa or southern-Asia) by a commercial chemiluminescent microparticle immunoassay. If confirmed in a Western blot assay, which differentiates anti-HTLV-1 from anti-HTLV-2, the positive sera were tested for specific HTLV RNA by a home-made PCR. The immigrants investigated were more frequently males (89.05%), young (median age 26 years), with a low level of education (median schooling 6 years), born in sub-Saharan Africa (79.70%). They had been living in Italy for a median period of 5 months. Only one (0.07%) subject was anti-HTLV-1 -positive/HTLV-1 RNA-negative; he was an asymptomatic 27-year-old male from Nigeria with 6 years’ schooling who stated unsafe sexual habits and unsafe injection therapy.

Conclusions

The data suggest screening for HTLV1 and HTLV-2 infections all blood donors to Italy from endemic countries at least on their first donation; however, a cost-effectiveness study is needed to clarify this topic.

Seroposotivity of <i>Brucella</i> spp. and <i>Leptospira</i> spp. antibodies among abattoir workers and meat vendors in the city of Mwanza, Tanzania: A call for one health approach control strategies

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Mariam M. Mirambo, Georgies F. Mgode, Zakaria O. Malima, Matata John, Elifuraha B. Mngumi, Ginethon G. Mhamphi, Stephen E. Mshana

Introduction

Brucellosis and leptospirosis are among neglected tropical zoonotic diseases particularly in the resource limited countries. Despite being endemic in these countries, there is paucity of information on its magnitude. This study investigated seropositivity of Brucella spp. and Leptospira spp., and associated factors among abattoir workers and meat vendors in the city of Mwanza, Tanzania.

Methodology

A community based cross-sectional study was conducted in Mwanza city from May to July 2017. Socio-demographic and other relevant information were collected. Detection of Brucella spp. and Leptospira spp. antibodies were done using slide agglutination test and microscopic agglutination test, respectively. Data were analyzed using STATA version 13 Software.

Findings

A total of 250 participants (146 abattoir workers and 104 meat vendors) were enrolled with median age of 31 (IQR: 25–38) years. The overall, seropositivity of Brucella spp. antibodies was 48.4% (95% Cl: 42–54). Seropositivity of B. abortus was significantly higher than that of B. melitensis (46.0%, 95%Cl: 39–52 vs. 23.6%, 95% Cl: 18–28, P<0.001) while seropositivity of both species was 21.2% (95%Cl: 16–26). The seropositivity of Leptospira spp. was 10.0% (95% CI: 6–13) with predominance of Leptospira kirschneri serovar Sokoine which was detected in 7.2% of the participants. Being abattoir worker (OR: 2.19, 95% CI 1.06–4.54, p = 0.035) and long work duration (OR: 1.06, 95%CI: 1.01–1.11, p = 0.014) predicted presence of both B.abortus and B. melitensis antibodies. Only being married (p = 0.041) was significantly associated with seropositivity of Leptospira spp. Primary education was the only factor independently predicted presence of Brucella spp. antibodies among abattoir workers on sub-analysis of occupational exposure. None of factors were found to be associated with presence of Brucella spp. antibodies among meat vendors on sub-analysis.

Conclusion

Seropositivity of B.abortus antibodies among abattoir workers and meat vendors is high and seem to be a function of being abattoir worker, having worked for long duration in the abattoir and having primary education. In addition, a significant proportion of abattoir workers and meat vendors in the city was seropositive for Leptospira kirschneri serovar Sokoine. There is a need to consider ‘one health approach’ in devising appropriate strategies to control these diseases in the developing countries.

Integrated approach in the control and management of skin neglected tropical diseases in Lalo, Benin

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Yves Thierry Barogui, Gabriel Diez, Esai Anagonou, Roch Christian Johnson, Inès Cica Gomido, Hermione Amoukpo, Zoulkifl Salou Bachirou, Jean Gabin Houezo, Raoul Saizonou, Ghislain Emmanuel Sopoh, Asiedu Kingsley

Background

Neglected Tropical Diseases (NTDs) are a group of several communicable diseases prevalent in the tropical and subtropical areas. The co-endemicity of these diseases, the similarity of the clinical signs, and need to maximize limited financial and human resources have necessitated implementation of integrated approach. Our study aims to share the lessons of this integrated approach in the fight against Buruli ulcer (BU), leprosy and yaws in a rural district in Benin.

Method

It is a cross-sectional study using a single set of activities data conducted from May 2016 to December 2016. Health workers and community health volunteers involved in this study were trained on integrated approach of the Buruli ulcer, leprosy and yaws. Village chiefs were briefed about the activity. The trained team visited the villages and schools in the district of Lalo in Benin. After the education and awareness raising sessions, all persons with a skin lesion who presented voluntarily to the team were carefully examined in a well-lit area which respected their privacy. Suspected cases were tested as needed. The socio-demographic information and the characteristics of the lesions were collected using a form. A descriptive analysis of the epidemiological, clinical and laboratory variables of the cases was made using Excel 2013 and SPSS version 22.00.

Principal findings

In the study period, 1106 people were examined. The median (IQR) age of those examined was 11 (8; 27) years. Of 34 (3.1%) suspected BU cases, 15 (1.4%) were confirmed by PCR. Only three cases of leprosy were confirmed. The 185 (16.7%) suspected cases of yaws were all negative with the rapid test. The majority of cases were other skin conditions, including fungal infections, eczema and traumatic lesions.

Conclusion

The integrated approach of skin NTD allows optimal use of resources and surveillance of these diseases. Sustaining this skin NTD integrated control will require the training of peripheral health workers not only on skin NTD but also on basic dermatology.

Genetic diversity and spatial-temporal distribution of <i>Yersinia pestis</i> in Qinghai Plateau, China

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Xiaoqing Xu, Yujun Cui, Youquan Xin, Xiaoyan Yang, Qingwen Zhang, Yong Jin, Haihong Zhao, Jian He, Xing Jin, Cunxiang Li, Juan Jin, Xiang Li, Haisheng Wu, Zhizhen Qi

Background

Plague, caused by the bacterium Yersinia pestis, is a highly infectious, zoonotic disease. Hundreds of human plague cases are reported across the world annually. Qinghai Plateau is one of the most severely affected plague regions in China, with more than 240 fatal cases of Y. pestis in the last 60 years. Conventional epidemiologic analysis has effectively guided the prevention and control of local plague transmission; however, molecular genetic analysis is more effective for investigating population diversity and transmission. In this report, we employed different genetic markers to analyze the population structure of Y. pestis in Qinghai Plateau.

Methodology/Principal finding

We employed a two-step hierarchical strategy to analyze the phylogeny of 102 Qinghai Plateau isolates of Y. pestis, collected between 1954 and 2011. First, we defined the genealogy of Y. pestis by constructed minimum spanning tree based on 25 key SNPs. Seven groups were identifi7ed, with group 1.IN2 being identified as the dominant population. Second, two methods, MLVA and CRISPR, were applied to examine the phylogenetic detail of group 1.IN2, which was further divided into three subgroups. Subgroups of 1.IN2 revealed a clear geographic cluster, possibly associated with interaction between bacteriophage and Y. pestis. More recently, Y. pestis populations appear to have shifted from the east toward the center and west of Qinghai Plateau. This shift could be related to destruction of the local niche of the original plague focus through human activities. Additionally, we found that the abundance and relative proportion of 1.IN2 subgroups varied by decade and might be responsible for the fluctuations of plague epidemics in Qinghai Plateau.

Conclusion/Significance

Molecular genotyping methods provided us with detailed information on population diversity and the spatial-temporal distribution of dominant populations of Y. pestis, which will facilitate future surveillance, prevention, and control of plague in Qinghai Plateau.

Forecasting the effectiveness of indoor residual spraying for reducing dengue burden

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Thomas J. Hladish, Carl A. B. Pearson, Diana Patricia Rojas, Hector Gomez-Dantes, M. Elizabeth Halloran, Gonzalo M. Vazquez-Prokopec, Ira M. Longini

Background

Historically, mosquito control programs successfully helped contain malaria and yellow fever, but recent efforts have been unable to halt the spread of dengue, chikungunya, or Zika, all transmitted by Aedes mosquitoes. Using a dengue transmission model and results from indoor residual spraying (IRS) field experiments, we investigated how IRS-like campaign scenarios could effectively control dengue in an endemic setting.

Methods and findings

In our model, we found that high levels of household coverage (75% treated once per year), applied proactively before the typical dengue season could reduce symptomatic infections by 89.7% (median of 1000 simulations; interquartile range [IQR]:[83.0%, 94.8%]) in year one and 78.2% (IQR: [71.2%, 88.0%]) cumulatively over the first five years of an annual program. Lower coverage had correspondingly lower effectiveness, as did reactive campaigns. Though less effective than preventative campaigns, reactive and even post-epidemic interventions retain some effectiveness; these campaigns disrupt inter-seasonal transmission, highlighting an off-season control opportunity. Regardless, none of the campaign scenarios maintain their initial effectiveness beyond two seasons, instead stabilizing at much lower levels of benefit: in year 20, median effectiveness was only 27.3% (IQR: [-21.3%, 56.6%]). Furthermore, simply ceasing an initially successful program exposes a population with lowered herd immunity to the same historical threat, and we observed outbreaks more than four-fold larger than pre-intervention outbreaks. These results do not take into account evolving insecticide resistance, thus long-term effectiveness may be lower if new, efficacious insecticides are not developed.

Conclusions

Using a detailed agent-based dengue transmission model for Yucatán State, Mexico, we predict that high coverage indoor residual spraying (IRS) interventions can largely eliminate transmission for a few years, when applied a few months before the typical seasonal epidemic peak. However, vector control succeeds by preventing infections, which precludes natural immunization. Thus, as a population benefits from mosquito control, it gradually loses naturally acquired herd immunity, and the control effectiveness declines; this occurs across all of our modeled scenarios, and is consistent with other empirical work. Long term control that maintains early effectiveness would require some combination of increasing investment, complementary interventions such as vaccination, and control programs across a broad region to diminish risk of importation.

Polymorphisms and haplotypes in the promoter of the TNF-α gene are associated with disease severity of severe fever with thrombocytopenia syndrome in Chinese Han population

PLoS Neglected Tropical Diseases News - 25 June 2018 - 9:00pm

by Bo Xing, Xiao-Kun Li, Shao-Fei Zhang, Qing-Bin Lu, Juan Du, Pan-He Zhang, Zhen-Dong Yang, Ning Cui, Chen-Tao Guo, Wu-Chun Cao, Xiao-Ai Zhang, Wei Liu

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that is caused by a novel bunyavirus, SFTSV. We assessed whether the single nucleotide polymorphisms (SNPs) in the tumor necrosis factor-alpha (TNF-α) were associated with risk to severity of SFTS. Five TNF-α SNPs (SNP1: T-1031C; SNP2: C-863A; SNP3: C-857T; SNP4: G-308A; SNP5: G-238A) were genotyped in 987 hospitalized SFTS patients and 633 asymptomatic/mild SFTSV-infected subjects of Chinese Han origin. Multivariate logistic regression analysis was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). The hospitalized SFTS patients had significantly lower frequency of G-238A A allele than those with mild/asymptomatic infection (P = 0.006). Furthermore, T-1031C C allele (P < 0.001) and G-238A A allele (P < 0.001) were significantly associated with decreased risk of death. Multiple haplotypes were significantly associated with decreased risk of SFTS hospital admission (SNP1-2, CC; SNP1-3, CCC; SNP1-4, CCCG; SNP1-5, CCCGA; SNP2-4, CCGA; SNP3-5, CGA; SNP4-5, GA) and death (SNP1-2, CA; SNP1-3, CAG; SNP1-4, CACG; SNP1-5, CACGG; SNP2-3, AC; SNP2-4, ACG; SNP2-5, ACGG) after correction for multiple comparisons. By using the ELISA assay, we observed that TNF-α concentration of hospitalized patients was significantly increased in acute phase than in convalescent phase (P < 0.001). Elevated TNF-α concentration was also revealed from fatal patients (P < 0.001). The -238A allele was associated with decreased serum TNF-α levels in SFTS patients in acute phase (P = 0.01). Our findings suggest that polymorphisms in TNF-α gene may play a role in mediating the risk to disease severity of SFTS in Chinese Han population.

Risk of adverse swallowing events and choking during deworming for preschool-aged children

PLoS Neglected Tropical Diseases News - 22 June 2018 - 9:00pm

by James Wyatt Kernell, Rosalie V. DePaola, Alec M. Maglione, Lacey N. Ahern, Naomi G. Penney, David G. Addiss

Background

In areas where the prevalence of soil-transmitted helminthiasis (STH) is >20%, the World Health Organization (WHO) recommends that deworming medication be given periodically to preschool-age children. To reduce risk of choking-related deaths in children <3 years old, WHO recommends that deworming tablets be crushed and given with water. Little is known about how widely this is practiced or its effectiveness.

Methodology and principal findings

Albendazole distributions for STH were observed for children 1–4 years old in 65 sites in India and Haiti. Information was recorded on child demographics; child demeanor immediately before, as well as struggling or resistance during albendazole administration; tablet form (i.e., crushed or not); and adverse swallowing events (ASEs), including choking, spitting; coughing; gagging; vomiting; and expelling a crushed tablet in a “cloud” of powder. Of 1677 children observed, 248 (14.8%) had one or more ASEs. ASE risk was 3.6% with whole tablets, 25.4% with crushed tablets, and 34.6% when crushed tablets were mixed with water. In multivariate analysis, ASE risk was significantly associated with children 1 year (OR 2.7) or 2 years (OR 2.9) of age; male gender (OR 1.6); non-content child demeanor (fearful, fussy, or combative) before albendazole administration (OR 4.3); child struggling when given albendazole (OR 2.1); and giving water, either after the tablet or mixed with it (OR 5.8). Eighteen (1.1%) children choked, none fatally; 17 choking incidents occurred with crushed tablets. In a multivariate analysis that controlled for distribution site, the only significant risk factor for choking was non-content demeanor (OR 20.6).

Conclusions and significance

Deworming-related choking deaths in young children are preventable. In our sample, risk of choking could have been reduced by 79.5% if deworming tablets were not given to young children who were fussy, fearful, or combative or who struggled to resist tablet administration, with only an 18.4% reduction in drug coverage.

Intranasal monkeypox marmoset model: Prophylactic antibody treatment provides benefit against severe monkeypox virus disease

PLoS Neglected Tropical Diseases News - 21 June 2018 - 9:00pm

by Eric M. Mucker, Suzanne E. Wollen-Roberts, Adrienne Kimmel, Josh Shamblin, Darryl Sampey, Jay W. Hooper

Concerns regarding outbreaks of human monkeypox or the potential reintroduction of smallpox into an immunological naïve population have prompted the development of animal models and countermeasures. Here we present a marmoset model of monkeypox and smallpox disease utilizing a relevant poxvirus via a natural exposure route. We found that 1000 plaque forming units (PFU) of Monkeypox virus was sufficient to recapitulate smallpox disease, to include an incubation period of approximately 13 days, followed by the onset of rash, and death between 15 and 17 days. Temporally accurate manifestation of viremia and oral shedding were also features. The number of lesions ranged from no lesions to 299, the most reported in a marmoset exposed to a poxvirus. To both evaluate the efficacy of our antibodies and the applicability of the model system, marmosets were prophylactically treated with two monoclonal antibodies, c7D11 and c8A. Of three marmosets, two were completely free of disease and a single marmoset died 8 days after the mock (n = 1) or PBS control(s) (n = 2). Evaluation of the serum levels of the three animals provided a possible explanation to the animal succumbing to disease. Interestingly, more females had lesions (and a greater number of lesions) and lower viral burden (viremia and oral shedding) than males in our studies, suggesting a possible gender effect.

Vector competence of <i>Aedes aegypti</i>, <i>Culex tarsalis</i>, and <i>Culex quinquefasciatus</i> from California for Zika virus

PLoS Neglected Tropical Diseases News - 21 June 2018 - 9:00pm

by Bradley J. Main, Jay Nicholson, Olivia C. Winokur, Cody Steiner, Kasen K. Riemersma, Jackson Stuart, Ryan Takeshita, Michelle Krasnec, Christopher M. Barker, Lark L. Coffey

Zika virus (ZIKV) has emerged since 2013 as a significant global human health threat following outbreaks in the Pacific Islands and rapid spread throughout South and Central America. Severe congenital and neurological sequelae have been linked to ZIKV infections. Assessing the ability of common mosquito species to transmit ZIKV and characterizing variation in mosquito transmission of different ZIKV strains is important for estimating regional outbreak potential and for prioritizing local mosquito control strategies for Aedes and Culex species. In this study, we evaluated the laboratory vector competence of Aedes aegypti, Culex quinquefasciatus, and Culex tarsalis that originated in areas of California where ZIKV cases in travelers since 2015 were frequent. We compared infection, dissemination, and transmission rates by measuring ZIKV RNA levels in cohorts of mosquitoes that ingested blood meals from type I interferon-deficient mice infected with either a Puerto Rican ZIKV strain from 2015 (PR15), a Brazilian ZIKV strain from 2015 (BR15), or an ancestral Asian-lineage Malaysian ZIKV strain from 1966 (MA66). With PR15, Cx. quinquefasciatus was refractory to infection (0%, N = 42) and Cx. tarsalis was infected at 4% (N = 46). No ZIKV RNA was detected in saliva from either Culex species 14 or 21 days post feeding (dpf). In contrast, Ae. aegypti developed infection rates of 85% (PR15; N = 46), 90% (BR15; N = 20), and 81% (MA66; N = 85) 14 or 15 dpf. Although MA66-infected Ae. aegypti showed higher levels of ZIKV RNA in mosquito bodies and legs, transmission rates were not significantly different across virus strains (P = 0.13, Fisher’s exact test). To confirm infectivity and measure the transmitted ZIKV dose, we enumerated infectious ZIKV in Ae. aegypti saliva using Vero cell plaque assays. The expectorated plaque forming units PFU varied by viral strain: MA66-infected expectorated 13±4 PFU (mean±SE, N = 13) compared to 29±6 PFU for PR15-infected (N = 13) and 35±8 PFU for BR15-infected (N = 6; ANOVA, df = 2, F = 3.8, P = 0.035). These laboratory vector competence results support an emerging consensus that Cx. tarsalis and Cx. quinquefasciatus are not vectors of ZIKV. These results also indicate that Ae. aegypti from California are efficient laboratory vectors of ancestral and contemporary Asian lineage ZIKV.

Zika: An emerging disease requiring prevention and awareness

PLoS Neglected Tropical Diseases News - 21 June 2018 - 9:00pm

by Rebekah Elliott, Tuhina Banerjee, Santimukul Santra

Historic <i>Treponema pallidum</i> genomes from Colonial Mexico retrieved from archaeological remains

PLoS Neglected Tropical Diseases News - 21 June 2018 - 9:00pm

by Verena J. Schuenemann, Aditya Kumar Lankapalli, Rodrigo Barquera, Elizabeth A. Nelson, Diana Iraíz Hernández, Víctor Acuña Alonzo, Kirsten I. Bos, Lourdes Márquez Morfín, Alexander Herbig, Johannes Krause

Treponema pallidum infections occur worldwide causing, among other diseases, syphilis and yaws. In particular sexually transmitted syphilis is regarded as a re-emerging infectious disease with millions of new infections annually. Here we present three historic T. pallidum genomes (two from T. pallidum ssp. pallidum and one from T. pallidum ssp. pertenue) that have been reconstructed from skeletons recovered from the Convent of Santa Isabel in Mexico City, operational between the 17th and 19th century. Our analyses indicate that different T. pallidum subspecies caused similar diagnostic presentations that are normally associated with syphilis in infants, and potential evidence of a congenital infection of T. pallidum ssp. pertenue, the causative agent of yaws. This first reconstruction of T. pallidum genomes from archaeological material opens the possibility of studying its evolutionary history at a resolution previously assumed to be out of reach.

The sero-prevalence of brucellosis in cattle and their herders in Bahr el Ghazal region, South Sudan

PLoS Neglected Tropical Diseases News - 20 June 2018 - 9:00pm

by Nuol Aywel Madut, Adrian Muwonge, George William Nasinyama, John Bwalya Muma, Jacques Godfroid, Ambrose Samuel Jubara, James Muleme, Clovice Kankya

Background

Brucellosis is a worldwide recognized bacterial zoonotic disease. There is currently no information on bovine brucellosis sero-prevalence in South Sudan regardless of the economic, social and public health impact on populations. Therefore, for the first time in 33 years, we report the sero-prevalence of brucellosis in cattle and their herders. Furthermore, we characterize the drivers associated with the disease at the human-animal interface in Bahr el Ghazal region, South Sudan.

Methods

A total of 893 and 87 animal and human sera respectively were examined between December 2015 and May 2016. Rose Bengal Plate Test (RBPT) and Competitive Enzyme Linked Immuno Sorbent Assay (c-ELISA) were used in parallel to detect anti-Brucella antibodies. Questionnaires were administered to collect relevant metadata used for the association analysis in R version 3.2.3. Odds Ratio (OR) and Confidence Intervals (CI) were determined.

Results

Overall bovine brucellosis prevalence was 31% (95%CI = 28.0–34.2), with the highest 63% (95%CI = 53–70) and lowest 10% (95%CI = 4.5–20.1) prevalence estimates in Wau and Gogrial states respectively. The bovine sero-prevalence was approximately equally distributed among the male 30.4% (26.9–34.2) and the females 32.5% (26.8–38.7). Poor body condition (OR = 0.22; 95%CI = 0.07–0.54) and larger herd sizes (OR = 0.05; 95%CI = 0.008–0.173) were protective factors for brucellosis, while the opposite was true for the second (OR = 1.70; 95%CI = 1.08–2.67) and third (OR = 2.5; 95%CI = 1.46–4.47) lactation stage. The overall brucellosis sero-prevalence in herders was estimated at 33.3% (23.9–44.3).

Conclusion

We report a high prevalence of anti-Brucella antibodies in cattle and their herders in Bahr el Ghazal, indicating an enzootic status in the cattle population being an important source of infection for humans. This represents a genuine public health challenge. Therefore, there is need to raise awareness and build capacity and infrastructure in this fragile state to underwrite future public health strategies for brucellosis.

Scientometrics analysis of research activity and collaboration patterns in Chagas cardiomyopathy

PLoS Neglected Tropical Diseases News - 18 June 2018 - 9:00pm

by Gregorio González-Alcaide, Alejandro Salinas, José M. Ramos

Background

Chagas cardiomyopathy is a serious and common complication of Chagas disease.

Methods

Through bibliometric and Social Network Analysis, we examined patterns of research on Chagas cardiomyopathy, identifying the main countries, authors, research clusters, and topics addressed; and measuring the contribution of different countries.

Results

We found 1932 documents on Chagas cardiomyopathy in the MEDLINE database. The most common document type was ‘journal article’, accounting for 79.6% of the total (n = 1538), followed by ‘review’ (n = 217, 11.2%). The number of published records increased from 156 in 1980–1984 to 311 in 2010–2014. Only 2.5% were clinical trials. Brazil and the USA dominated the research, participating in 53.1% and 25.7%, respectively, of the documents. Other Latin American countries where Chagas is endemic contributed less, with Bolivia, where Chagas disease is most prevalent, producing only 1.8% of the papers. We observed a high rate of domestic collaboration (83.1% of the documents published in 2010–2016) and a lower but significant rate of international collaboration (32.5% in the same time period). Although clinical research dominated overall, the USA, Mexico and several countries in Europe produced a considerable body of basic research on animal models. We identified four main research clusters, focused on heart failure and dysfunction (physical symptoms, imaging techniques, treatment), and on myocarditis and parasitemia in animal models.

Conclusions

Research on Chagas cardiomyopathy increased over the study period. There were more clinical than basic studies, though very few of the documents were clinical trials. Brazil and the USA are currently leading the research on this subject, while some highly endemic countries, such as Bolivia, have contributed very little. Different approaches could help to redress this imbalance: encouraging researchers to conduct more clinical trials, launching international collaborations to help endemic countries contribute more, and strengthening links between basic and clinical research.

Mapping dengue risk in Singapore using Random Forest

PLoS Neglected Tropical Diseases News - 18 June 2018 - 9:00pm

by Janet Ong, Xu Liu, Jayanthi Rajarethinam, Suet Yheng Kok, Shaohong Liang, Choon Siang Tang, Alex R. Cook, Lee Ching Ng, Grace Yap

Background

Singapore experiences endemic dengue, with 2013 being the largest outbreak year known to date, culminating in 22,170 cases. Given the limited resources available, and that vector control is the key approach for prevention in Singapore, it is important that public health professionals know where resources should be invested in. This study aims to stratify the spatial risk of dengue transmission in Singapore for effective deployment of resources.

Methodology/principal findings

Random Forest was used to predict the risk rank of dengue transmission in 1km2 grids, with dengue, population, entomological and environmental data. The predicted risk ranks are categorized and mapped to four color-coded risk groups for easy operation application. The risk maps were evaluated with dengue case and cluster data. Risk maps produced by Random Forest have high accuracy. More than 80% of the observed risk ranks fell within the 80% prediction interval. The observed and predicted risk ranks were highly correlated (ρ ≥0.86, P <0.01). Furthermore, the predicted risk levels were in excellent agreement with case density, a weighted Kappa coefficient of more than 0.80 (P <0.01). Close to 90% of the dengue clusters occur in high risk areas, and the odds of cluster forming in high risk areas were higher than in low risk areas.

Conclusions

This study demonstrates the potential of Random Forest and its strong predictive capability in stratifying the spatial risk of dengue transmission in Singapore. Dengue risk map produced using Random Forest has high accuracy, and is a good surveillance tool to guide vector control operations.

Accuracy of dengue clinical diagnosis with and without NS1 antigen rapid test: Comparison between human and Bayesian network model decision

PLoS Neglected Tropical Diseases News - 18 June 2018 - 9:00pm

by Chaitawat Sa-ngamuang, Peter Haddawy, Viravarn Luvira, Watcharapong Piyaphanee, Sopon Iamsirithaworn, Saranath Lawpoolsri

Differentiating dengue patients from other acute febrile illness patients is a great challenge among physicians. Several dengue diagnosis methods are recommended by WHO. The application of specific laboratory tests is still limited due to high cost, lack of equipment, and uncertain validity. Therefore, clinical diagnosis remains a common practice especially in resource limited settings. Bayesian networks have been shown to be a useful tool for diagnostic decision support. This study aimed to construct Bayesian network models using basic demographic, clinical, and laboratory profiles of acute febrile illness patients to diagnose dengue. Data of 397 acute undifferentiated febrile illness patients who visited the fever clinic of the Bangkok Hospital for Tropical Diseases, Thailand, were used for model construction and validation. The two best final models were selected: one with and one without NS1 rapid test result. The diagnostic accuracy of the models was compared with that of physicians on the same set of patients. The Bayesian network models provided good diagnostic accuracy of dengue infection, with ROC AUC of 0.80 and 0.75 for models with and without NS1 rapid test result, respectively. The models had approximately 80% specificity and 70% sensitivity, similar to the diagnostic accuracy of the hospital’s fellows in infectious disease. Including information on NS1 rapid test improved the specificity, but reduced the sensitivity, both in model and physician diagnoses. The Bayesian network model developed in this study could be useful to assist physicians in diagnosing dengue, particularly in regions where experienced physicians and laboratory confirmation tests are limited.

A real-time medical cartography of epidemic disease (Nodding syndrome) using village-based lay mHealth reporters

PLoS Neglected Tropical Diseases News - 15 June 2018 - 9:00pm

by Raquel Valdes Angues, Austen Suits, Valerie S. Palmer, Caesar Okot, Robert A. Okot, Concy Atonywalo, Suzanne K. Gazda, David L. Kitara, Moka Lantum, Spencer S. Peter

Background

Disease surveillance in rural regions of many countries is poor, such that prolonged delays (months) may intervene between appearance of disease and its recognition by public health authorities. For infectious disorders, delayed recognition and intervention enables uncontrolled disease spread. We tested the feasibility in northern Uganda of developing real-time, village-based health surveillance of an epidemic of Nodding syndrome (NS) using software-programmed smartphones operated by minimally trained lay mHealth reporters.

Methodology and principal findings

We used a customized data collection platform (Magpi) that uses mobile phones and real-time cloud-based storage with global positioning system coordinates and time stamping. Pilot studies on sleep behavior of U.S. and Ugandan medical students identified and resolved Magpi-programmed cell phone issues. Thereafter, we deployed Magpi in combination with a lay-operator network of eight mHealth reporters to develop a real-time electronic map of child health, injury and illness relating to NS in rural northern Uganda. Surveillance data were collected for three consecutive months from 10 villages heavily affected by NS. Overall, a total of 240 NS-affected households and an average of 326 children with NS, representing 30 households and approximately 40 NS children per mHealth reporter, were monitored every week by the lay mHealth team. Data submitted for analysis in the USA and Uganda remotely pinpointed the household location and number of NS deaths, injuries, newly reported cases of head nodding (n = 22), and the presence or absence of anti-seizure medication.

Conclusions and significance

This study demonstrates the feasibility of using lay mHealth workers to develop a real-time cartography of epidemic disease in remote rural villages that can facilitate and steer clinical, educational and research interventions in a timely manner.

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