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1.
N Engl J Med ; 380(19): 1804-1814, 2019 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-31067370

RESUMO

BACKGROUND: Nipah virus is a highly virulent zoonotic pathogen that can be transmitted between humans. Understanding the dynamics of person-to-person transmission is key to designing effective interventions. METHODS: We used data from all Nipah virus cases identified during outbreak investigations in Bangladesh from April 2001 through April 2014 to investigate case-patient characteristics associated with onward transmission and factors associated with the risk of infection among patient contacts. RESULTS: Of 248 Nipah virus cases identified, 82 were caused by person-to-person transmission, corresponding to a reproduction number (i.e., the average number of secondary cases per case patient) of 0.33 (95% confidence interval [CI], 0.19 to 0.59). The predicted reproduction number increased with the case patient's age and was highest among patients 45 years of age or older who had difficulty breathing (1.1; 95% CI, 0.4 to 3.2). Case patients who did not have difficulty breathing infected 0.05 times as many contacts (95% CI, 0.01 to 0.3) as other case patients did. Serologic testing of 1863 asymptomatic contacts revealed no infections. Spouses of case patients were more often infected (8 of 56 [14%]) than other close family members (7 of 547 [1.3%]) or other contacts (18 of 1996 [0.9%]). The risk of infection increased with increased duration of exposure of the contacts (adjusted odds ratio for exposure of >48 hours vs. ≤1 hour, 13; 95% CI, 2.6 to 62) and with exposure to body fluids (adjusted odds ratio, 4.3; 95% CI, 1.6 to 11). CONCLUSIONS: Increasing age and respiratory symptoms were indicators of infectivity of Nipah virus. Interventions to control person-to-person transmission should aim to reduce exposure to body fluids. (Funded by the National Institutes of Health and others.).


Assuntos
Infecções por Henipavirus/transmissão , Vírus Nipah , Adolescente , Adulto , Fatores Etários , Animais , Bangladesh/epidemiologia , Líquidos Corporais/virologia , Criança , Busca de Comunicante , Transmissão de Doença Infecciosa/prevenção & controle , Feminino , Infecções por Henipavirus/epidemiologia , Infecções por Henipavirus/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Adulto Jovem , Zoonoses/transmissão
2.
Sci Rep ; 9(1): 7385, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089148

RESUMO

Since its emergence in 2012, 2,260 cases and 803 deaths due to Middle East respiratory syndrome coronavirus (MERS-CoV) have been reported to the World Health Organization. Most cases were due to transmission in healthcare settings, sometimes causing large outbreaks. We analyzed epidemiologic and clinical data of laboratory-confirmed MERS-CoV cases from eleven healthcare-associated outbreaks in the Kingdom of Saudi Arabia and the Republic of Korea between 2015-2017. We quantified key epidemiological differences between outbreaks. Twenty-five percent (n = 105/422) of MERS cases who acquired infection in a hospital setting were healthcare personnel. In multivariate analyses, age ≥65 (OR 4.8, 95%CI: 2.6-8.7) and the presence of underlying comorbidities (OR: 2.7, 95% CI: 1.3-5.7) were associated with increased mortality whereas working as healthcare personnel was protective (OR 0.07, 95% CI: 0.01-0.34). At the start of these outbreaks, the reproduction number ranged from 1.0 to 5.7; it dropped below 1 within 2 to 6 weeks. This study provides a comprehensive characterization of MERS HCA-outbreaks. Our results highlight heterogeneities in the epidemiological profile of healthcare-associated outbreaks. The limitations of our study stress the urgent need for standardized data collection for high-threat respiratory pathogens, such as MERS-CoV.

3.
Lancet Infect Dis ; 19(5): 537-545, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30930106

RESUMO

BACKGROUND: Madagascar accounts for 75% of global plague cases reported to WHO, with an annual incidence of 200-700 suspected cases (mainly bubonic plague). In 2017, a pneumonic plague epidemic of unusual size occurred. The extent of this epidemic provides a unique opportunity to better understand the epidemiology of pneumonic plagues, particularly in urban settings. METHODS: Clinically suspected plague cases were notified to the Central Laboratory for Plague at Institut Pasteur de Madagascar (Antananarivo, Madagascar), where biological samples were tested. Based on cases recorded between Aug 1, and Nov 26, 2017, we assessed the epidemiological characteristics of this epidemic. Cases were classified as suspected, probable, or confirmed based on the results of three types of diagnostic tests (rapid diagnostic test, molecular methods, and culture) according to 2006 WHO recommendations. FINDINGS: 2414 clinically suspected plague cases were reported, including 1878 (78%) pneumonic plague cases, 395 (16%) bubonic plague cases, one (<1%) septicaemic case, and 140 (6%) cases with unspecified clinical form. 386 (21%) of 1878 notified pneumonic plague cases were probable and 32 (2%) were confirmed. 73 (18%) of 395 notified bubonic plague cases were probable and 66 (17%) were confirmed. The case fatality ratio was higher among confirmed cases (eight [25%] of 32 cases) than probable (27 [8%] of 360 cases) or suspected pneumonic plague cases (74 [5%] of 1358 cases) and a similar trend was seen for bubonic plague cases (16 [24%] of 66 confirmed cases, four [6%] of 68 probable cases, and six [2%] of 243 suspected cases). 351 (84%) of 418 confirmed or probable pneumonic plague cases were concentrated in Antananarivo, the capital city, and Toamasina, the main seaport. All 50 isolated Yersinia pestis strains were susceptible to the tested antibiotics. INTERPRETATION: This predominantly urban plague epidemic was characterised by a large number of notifications in two major urban areas and an unusually high proportion of pneumonic forms, with only 23% having one or more positive laboratory tests. Lessons about clinical and biological diagnosis, case definition, surveillance, and the logistical management of the response identified in this epidemic are crucial to improve the response to future plague outbreaks. FUNDING: US Agency for International Development, WHO, Institut Pasteur, US Department of Health and Human Services, Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases, Models of Infectious Disease Agent Study of the National Institute of General Medical Sciences, AXA Research Fund, and the INCEPTION programme.

4.
Trends Parasitol ; 35(5): 369-379, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30738632

RESUMO

Mathematical models play an increasingly important role in our understanding of the transmission and control of infectious diseases. Here, we present concrete examples illustrating how mathematical models, paired with rigorous statistical methods, are used to parse data of different levels of detail and breadth and estimate key epidemiological parameters (e.g., transmission and its determinants, severity, impact of interventions, drivers of epidemic dynamics) even when these parameters are not directly measurable, when data are limited, and when the epidemic process is only partially observed. Finally, we assess the hurdles to be taken to increase availability and applicability of these approaches in an effort to ultimately enhance their public health impact.

5.
Science ; 361(6404): 755-756, 2018 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-30139861
6.
Euro Surveill ; 23(23)2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29897042

RESUMO

BackgroundClusters of dengue cases have recently become more frequent in areas of southern France colonised by the vector mosquito Aedes albopictus. In July 2015, a 2-month outbreak of dengue virus serotype 1 (DENV-1) was reported in Nîmes. Aim: We conducted a serosurvey in the affected area at the end of the vector activity period to determine the true extent of dengue transmission. Methods: We collected capillary blood from consenting household members, and information on their medical and travel histories, and exposure to mosquito bites. Recent infections were identified using IgM and IgG anti-DENV ELISA, followed, when positive, by plaque reduction neutralisation tests on serum against DENV 1-4 and West Nile virus. The prevalence estimator was calibrated on reference demographic data. We quantified the spatial clustering of dengue cases within the affected community and inferred the transmission tree. Results: The study participation rate was 39% (564/1,431). Three of 564 participants tested positive for DENV-1 infection (after marginal calibration, 0.41%; 95% confidence interval: 0.00-0.84). The spatial analysis showed that cases were clustered at the household level. Most participants perceived the presence of mosquitos as abundant (83%) and reported frequent mosquito bites (57%). We incidentally identified six past West Nile virus infections (0.9%; 95% CI: 0.2-1.6). Conclusion: This serosurvey confirms the potential for arboviral diseases to cause outbreaks - albeit limited for now - in France and Europe.

7.
Emerg Infect Dis ; 24(2): 284-293, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29350150

RESUMO

Fiji recently experienced a sharp increase in reported typhoid fever cases. To investigate geographic distribution and environmental risk factors associated with Salmonella enterica serovar Typhi infection, we conducted a cross-sectional cluster survey with associated serologic testing for Vi capsular antigen-specific antibodies (a marker for exposure to Salmonella Typhi in Fiji in 2013. Hotspots with high seroprevalence of Vi-specific antibodies were identified in northeastern mainland Fiji. Risk for Vi seropositivity increased with increased annual rainfall (odds ratio [OR] 1.26/quintile increase, 95% CI 1.12-1.42), and decreased with increased distance from major rivers and creeks (OR 0.89/km increase, 95% CI 0.80-0.99) and distance to modeled flood-risk areas (OR 0.80/quintile increase, 95% CI 0.69-0.92) after being adjusted for age, typhoid fever vaccination, and home toilet type. Risk for exposure to Salmonella Typhi and its spatial distribution in Fiji are driven by environmental factors. Our findings can directly affect typhoid fever control efforts in Fiji.

8.
PLoS Negl Trop Dis ; 11(4): e0005471, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28369149

RESUMO

BACKGROUND: Dengue is a mosquito-borne virus that causes extensive morbidity and economic loss in many tropical and subtropical regions of the world. Often present in cities, dengue virus is rapidly spreading due to urbanization, climate change and increased human movements. Dengue cases are often heterogeneously distributed throughout cities, suggesting that small-scale determinants influence dengue urban transmission. A better understanding of these determinants is crucial to efficiently target prevention measures such as vector control and education. The aim of this study was to determine which socioeconomic and environmental determinants were associated with dengue incidence in an urban setting in the Pacific. METHODOLOGY: An ecological study was performed using data summarized by neighborhood (i.e. the neighborhood is the unit of analysis) from two dengue epidemics (2008-2009 and 2012-2013) in the city of Nouméa, the capital of New Caledonia. Spatial patterns and hotspots of dengue transmission were assessed using global and local Moran's I statistics. Multivariable negative binomial regression models were used to investigate the association between dengue incidence and various socioeconomic and environmental factors throughout the city. PRINCIPAL FINDINGS: The 2008-2009 epidemic was spatially structured, with clusters of high and low incidence neighborhoods. In 2012-2013, dengue incidence rates were more homogeneous throughout the city. In all models tested, higher dengue incidence rates were consistently associated with lower socioeconomic status (higher unemployment, lower revenue or higher percentage of population born in the Pacific, which are interrelated). A higher percentage of apartments was associated with lower dengue incidence rates during both epidemics in all models but one. A link between vegetation coverage and dengue incidence rates was also detected, but the link varied depending on the model used. CONCLUSIONS: This study demonstrates a robust spatial association between dengue incidence rates and socioeconomic status across the different neighborhoods of the city of Nouméa. Our findings provide useful information to guide policy and help target dengue prevention efforts where they are needed most.


Assuntos
Dengue/epidemiologia , Dengue/transmissão , Transmissão de Doença Infecciosa , Meio Ambiente , Fatores Socioeconômicos , Adulto , Cidades/epidemiologia , Humanos , Incidência , Nova Caledônia/epidemiologia , Topografia Médica
9.
Infect Dis Poverty ; 6(1): 30, 2017 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-28179024

RESUMO

BACKGROUND: School-based deworming is widely implemented in various countries to reduce the burden of soil-transmitted helminths (STHs), however, the frequency of drug administration varies in different settings. In this study, we compared the impact of a single annual treatment and 4-monthly treatment over a follow-up among Kenyan school children, and investigated the factors associated with residual infection. METHODS: We performed a secondary analysis of data from a randomized trial investigating whether deworming for STHs alters risk of acquiring malaria. Children received either a single treatment or 4-monthly albendazole treatments were followed longitudinally from February 2014 to October 2014. The relative impact of treatment and factors associated with residual infections were investigated using mixed-effects regression models. Predisposition to infection was assessed based on Spearman's rank and Kendall's Tau correlation coefficients. RESULTS: In the 4-monthly treatment group, the proportion of children infected with hookworm decreased from 59.9 to 5.7%, while Ascaris lumbricoides infections dropped from 55.7 to 6.2%. In the single treatment group, hookworm infections decreased over the same time period from 58.7 to 18.3% (12.6% absolute difference in reduction, 95% CI: 8.9-16.3%), and A. lumbricoides from 56.7 to 23.3% (17.1% absolute difference in reduction, 95% CI: 13.1-21.1%). There was strong evidence for predisposition to both STH types. Residual hookworm infection among children on 4-monthly treatment were associated with male sex and baseline nutritional status, whereas A. lumbricoides infection was associated with individual and school-level infection at baseline, latrine cleanliness at schools. CONCLUSIONS: This study found that 4-monthly treatment w more effective than single annual treatment. Repeated treatments led to dramatic reductions in the intensities of STHs, but did not completely clear infections among school children in Kenya, a presumed reflection of reinfection in a setting where there is ongoing transmission.


Assuntos
Anti-Helmínticos/administração & dosagem , Ascaríase/tratamento farmacológico , Ascaríase/epidemiologia , Infecções por Uncinaria/tratamento farmacológico , Infecções por Uncinaria/epidemiologia , Estudantes , Adolescente , Albendazol/administração & dosagem , Ancylostomatoidea/efeitos dos fármacos , Animais , Ascaris lumbricoides/isolamento & purificação , Criança , Pré-Escolar , Feminino , Humanos , Quênia/epidemiologia , Estudos Longitudinais , Masculino , Instituições Acadêmicas , Resultado do Tratamento
10.
PLoS Med ; 14(1): e1002218, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28095468

RESUMO

BACKGROUND: The International Health Regulations outline core requirements to ensure the detection of public health threats of international concern. Assessing the capacity of surveillance systems to detect these threats is crucial for evaluating a country's ability to meet these requirements. METHODS AND FINDINGS: We propose a framework to evaluate the sensitivity and representativeness of hospital-based surveillance and apply it to severe neurological infectious diseases and fatal respiratory infectious diseases in Bangladesh. We identified cases in selected communities within surveillance hospital catchment areas using key informant and house-to-house surveys and ascertained where cases had sought care. We estimated the probability of surveillance detecting different sized outbreaks by distance from the surveillance hospital and compared characteristics of cases identified in the community and cases attending surveillance hospitals. We estimated that surveillance detected 26% (95% CI 18%-33%) of severe neurological disease cases and 18% (95% CI 16%-21%) of fatal respiratory disease cases residing at 10 km distance from a surveillance hospital. Detection probabilities decreased markedly with distance. The probability of detecting small outbreaks (three cases) dropped below 50% at distances greater than 26 km for severe neurological disease and at distances greater than 7 km for fatal respiratory disease. Characteristics of cases attending surveillance hospitals were largely representative of all cases; however, neurological disease cases aged <5 y or from the lowest socioeconomic group and fatal respiratory disease cases aged ≥60 y were underrepresented. Our estimates of outbreak detection rely on suspected cases that attend a surveillance hospital receiving laboratory confirmation of disease and being reported to the surveillance system. The extent to which this occurs will depend on disease characteristics (e.g., severity and symptom specificity) and surveillance resources. CONCLUSION: We present a new approach to evaluating the sensitivity and representativeness of hospital-based surveillance, making it possible to predict its ability to detect emerging threats.


Assuntos
Surtos de Doenças , Hospitais/estatística & dados numéricos , Vigilância da População/métodos , Bangladesh/epidemiologia , Infecções do Sistema Nervoso Central/epidemiologia , Surtos de Doenças/prevenção & controle , Hospitalização/estatística & dados numéricos , Humanos , Infecções Respiratórias/epidemiologia , Sensibilidade e Especificidade
11.
Lancet Infect Dis ; 17(3): 330-338, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28017559

RESUMO

BACKGROUND: Since late 2015, an epidemic of yellow fever has caused more than 7334 suspected cases in Angola and the Democratic Republic of the Congo, including 393 deaths. We sought to understand the spatial spread of this outbreak to optimise the use of the limited available vaccine stock. METHODS: We jointly analysed datasets describing the epidemic of yellow fever, vector suitability, human demography, and mobility in central Africa to understand and predict the spread of yellow fever virus. We used a standard logistic model to infer the district-specific yellow fever virus infection risk during the course of the epidemic in the region. FINDINGS: The early spread of yellow fever virus was characterised by fast exponential growth (doubling time of 5-7 days) and fast spatial expansion (49 districts reported cases after only 3 months) from Luanda, the capital of Angola. Early invasion was positively correlated with high population density (Pearson's r 0·52, 95% CI 0·34-0·66). The further away locations were from Luanda, the later the date of invasion (Pearson's r 0·60, 95% CI 0·52-0·66). In a Cox model, we noted that districts with higher population densities also had higher risks of sustained transmission (the hazard ratio for cases ceasing was 0·74, 95% CI 0·13-0·92 per log-unit increase in the population size of a district). A model that captured human mobility and vector suitability successfully discriminated districts with high risk of invasion from others with a lower risk (area under the curve 0·94, 95% CI 0·92-0·97). If at the start of the epidemic, sufficient vaccines had been available to target 50 out of 313 districts in the area, our model would have correctly identified 27 (84%) of the 32 districts that were eventually affected. INTERPRETATION: Our findings show the contributions of ecological and demographic factors to the ongoing spread of the yellow fever outbreak and provide estimates of the areas that could be prioritised for vaccination, although other constraints such as vaccine supply and delivery need to be accounted for before such insights can be translated into policy. FUNDING: Wellcome Trust.


Assuntos
Surtos de Doenças/prevenção & controle , Modelos Estatísticos , Febre Amarela/epidemiologia , Vírus da Febre Amarela/isolamento & purificação , Aedes/virologia , Angola , Animais , República Democrática do Congo , Humanos , Esquemas de Imunização , População Rural/estatística & dados numéricos , Viagem , População Urbana/estatística & dados numéricos , Vacinação , Febre Amarela/mortalidade , Febre Amarela/transmissão
12.
Parasit Vectors ; 9(1): 408, 2016 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-27457129

RESUMO

BACKGROUND: In 2012, the Kenyan Ministries of Health and of Education began a programme to deworm all school-age children living in areas at high risk of soil-transmitted helminths (STH) and schistosome infections. The impact of this school-based mass drug administration (MDA) programme in Kenya is monitored by the Kenya Medical Research Institute (KEMRI) as part of a five-year (2012-2017) study. This article focuses on the impact of MDA on STH infections and presents the overall achieved reductions from baseline to mid-term, as well as yearly patterns of reductions and subsequent re-infections per school community. METHODS: The study involved a series of pre- and post-intervention, repeat cross-sectional surveys in a representative, stratified, two-stage sample of schools across Kenya. The programme contained two tiers of monitoring; a national baseline and mid-term survey including 200 schools, and surveys conducted among 60 schools pre- and post-intervention. Stool samples were collected from randomly selected school children and tested for helminth infections using Kato-Katz technique. The prevalence and mean intensity of each helminth species were calculated at the school and county levels and 95 % confidence intervals (CIs) were obtained by binomial and negative binomial regression, respectively, taking into account clustering by schools. RESULTS: The overall prevalence of STH infection at baseline was 32.3 % (hookworms: 15.4 %; Ascaris lumbricoides: 18.1 %; and Trichuris trichiura: 6.7 %). After two rounds of MDA, the overall prevalence of STH had reduced to 16.4 % (hookworms: 2.3 %; A. lumbricoides: 11.9 %; and T. trichiura: 4.5 %). The relative reductions of moderate to heavy intensity of infections were 33.7 % (STH combined), 77.3 % (hookworms) and 33.9 % (A. lumbricoides). For T. trichiura, however, moderate to heavy intensity of infections increased non-significantly by 18.0 % from baseline to mid-term survey. CONCLUSION: The school-based deworming programme has substantially reduced STH infections, but because of ongoing transmission additional strategies may be required to achieve a sustained interruption of transmission.


Assuntos
Helmintíase/parasitologia , Helmintos/isolamento & purificação , Solo/parasitologia , Adolescente , Animais , Anti-Helmínticos/uso terapêutico , Criança , Pré-Escolar , Estudos Transversais , Feminino , Helmintíase/tratamento farmacológico , Helmintíase/epidemiologia , Helmintíase/transmissão , Helmintos/classificação , Helmintos/efeitos dos fármacos , Helmintos/genética , Humanos , Quênia/epidemiologia , Masculino , Prevalência , Instituições Acadêmicas/estatística & dados numéricos , Adulto Jovem
13.
Malar J ; 15: 157, 2016 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-26969283

RESUMO

BACKGROUND: Malaria among school children is increasingly receiving attention, yet the burden of malaria in this age group is poorly defined. This study presents data on malaria morbidity among school children in Bungoma county, western Kenya. METHOD: This study investigated the burden and risk factors of Plasmodium falciparum infection, clinical malaria, and anaemia among 2346 school children aged 5-15 years, who were enrolled in an individually randomized trial evaluating the effect of anthelmintic treatment on the risks of malaria. At baseline, children were assessed for anaemia and nutritional status and information on household characteristics was collected. Children were followed-up for 13 months to assess the incidence of clinical malaria by active detection, and P. falciparum infection and density evaluated using repeated cross-sectional surveys over 15 months. RESULTS: On average prevalence of P. falciparum infection was 42% and ranged between 32 and 48% during the five cross-sectional surveys. Plasmodium falciparum prevalence was significantly higher among boys than girls. The overall incidence of clinical malaria was 0.26 episodes per person year (95% confidence interval, 0.24-0.29) and was significantly higher among girls (0.23 versus 0.31, episodes per person years). Both infection prevalence and clinical disease varied by season. In multivariable analysis, P. falciparum infection was associated with being male, lower socioeconomic status and stunting. The risk of clinical malaria was associated with being female. CONCLUSION: These findings show that the burden of P. falciparum parasitaemia, clinical malaria and anaemia among school children is not insignificant, and suggest that malaria control programmes should be expanded to include this age group.


Assuntos
Malária Falciparum/epidemiologia , Parasitemia/epidemiologia , Adolescente , Anemia/epidemiologia , Anemia/etiologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Seguimentos , Humanos , Quênia/epidemiologia , Malária Falciparum/complicações , Masculino , Prevalência , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores de Risco , Instituições Acadêmicas
14.
Am J Trop Med Hyg ; 94(5): 1045-54, 2016 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-26903608

RESUMO

Water, sanitation, and hygiene (WaSH) technologies and behaviors can prevent infection by soil-transmitted helminth species independently, but may also interact in complex ways. However, these interactions are poorly understood. The purpose of this study was to characterize how school and home WaSH exposures were associated with Ascaris lumbricoides infection and to identify relevant interactions between separate WaSH technologies and behaviors. A study was conducted among 4,404 children attending 51 primary schools in western Kenya. We used multivariable mixed effects logistic regression to characterize how various WaSH exposures were associated with A. lumbricoides infection after annual school-based deworming. Few WaSH behaviors and technologies were independently associated with A. lumbricoides infection. However, by considering relevant interdependencies between variables, important associations were elucidated. The association between handwashing and A. lumbricoides depended largely upon the pupils' access to an improved water source. Among pupils who had access to improved water sources, A. lumbricoides prevalence was lower for those who handwashed both at school and home compared with neither place (odds ratio: 0.38, 95% confidence interval: 0.18-0.83; P = 0.01). This study contributes to a further understanding of the impact of WaSH on A. lumbricoides infection and shows the importance of accounting for interactions between WaSH technologies and behaviors.


Assuntos
Ascaríase/tratamento farmacológico , Ascaríase/epidemiologia , Ascaris lumbricoides , Higiene , Saneamento , Abastecimento de Água , Animais , Anti-Helmínticos/administração & dosagem , Anti-Helmínticos/uso terapêutico , Ascaríase/prevenção & controle , Criança , Características da Família , Feminino , Humanos , Quênia/epidemiologia , Masculino , Instituições Acadêmicas
15.
J Infect Dis ; 213(2): 266-75, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26170395

RESUMO

BACKGROUND: School children living in the tropics are often concurrently infected with plasmodium and helminth parasites. It has been hypothesized that immune responses evoked by helminths may modify malaria-specific immune responses and increase the risk of malaria. METHODS: We performed a randomized, open-label, equivalence trial among 2436 school children in western Kenya. Eligible children were randomized to receive either 4 repeated doses or a single dose of albendazole and were followed up during 13 months to assess the incidence of clinical malaria. Secondary outcomes were Plasmodium prevalence and density, assessed by repeat cross-sectional surveys over 15 months. Analysis was conducted on an intention-to-treat basis with a prespecified equivalence range of 20%. RESULTS: During 13 months of follow-up, the incidence rate of malaria was 0.27 episodes/person-year in the repeated treatment group and 0.26 episodes/person-year in the annual treatment group (incidence difference, 0.01; 95% confidence interval, -.03 to .06). The prevalence and density of malaria parasitemia did not differ by treatment group at any of the cross-sectional surveys. CONCLUSIONS: Our findings suggest that repeated deworming does not alter risks of clinical malaria or malaria parasitemia among school children and that school-based deworming in Africa may have no adverse consequences for malaria. CLINICAL TRIALS REGISTRATION: NCT01658774.


Assuntos
Albendazol/uso terapêutico , Anti-Helmínticos/uso terapêutico , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Adolescente , Albendazol/administração & dosagem , Anti-Helmínticos/administração & dosagem , Criança , Esquema de Medicação , Feminino , Helmintíase/tratamento farmacológico , Helmintíase/epidemiologia , Helmintíase/prevenção & controle , Humanos , Quênia/epidemiologia , Masculino , Parasitemia , Fatores de Risco
16.
PLoS Negl Trop Dis ; 9(9): e0004108, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26421808

RESUMO

BACKGROUND: The implementation of soil-transmitted helminth (STH) treatment programmes occurs in varied environmental, social and economic contexts. Programme impact will be influenced by factors that affect the reduction in the prevalence and intensity of infections following treatment, as well as the subsequent rate of reinfection. To better understand the heterogeneity of programme impact and its underlying reasons, we investigated the influence of contextual factors on reduction in STH infection as part of the national school based deworming (SBD) programme in Kenya. MATERIALS AND METHODS: Data on the prevalence and intensity of infection were collected within the monitoring and evaluation component of the SBD programme at baseline and after delivery of two annual treatment rounds in 153 schools in western Kenya. Using a framework that considers STH epidemiology and transmission dynamics, capacity to deliver treatment, operational feasibility and financial capacity, data were assembled at both school and district (county) levels. Geographic heterogeneity of programme impact was assessed by descriptive and spatial analyses. Factors associated with absolute reductions of Ascaris lumbricoides and hookworm infection prevalence and intensity were identified using mixed effects linear regression modelling adjusting for baseline infection levels. PRINCIPAL FINDINGS: The reduction in prevalence and intensity of A. lumbricoides and hookworms varied significantly by county and within counties by school. Multivariable analysis of factors associated with programme impact showed that absolute A. lumbricoides reductions varied by environmental conditions and access to improved sanitation at schools or within the community. Larger reduction in prevalence and intensity of hookworms were found in schools located within areas with higher community level access to improved sanitation and within counties with higher economic and health service delivery indicator scores. CONCLUSIONS: The study identifies factors associated with the impact of school-based deworming and in particular highlights how access to water, sanitation and hygiene and environmental conditions influence the impact of deworming programmes.


Assuntos
Antinematódeos/administração & dosagem , Doenças Negligenciadas/terapia , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/terapia , Avaliação de Programas e Projetos de Saúde , Serviços de Saúde Escolar/estatística & dados numéricos , Ancilostomíase/epidemiologia , Ancilostomíase/terapia , Ancilostomíase/transmissão , Animais , Ascaríase/epidemiologia , Ascaríase/terapia , Ascaríase/transmissão , Assistência à Saúde , Humanos , Quênia/epidemiologia , Doenças Negligenciadas/epidemiologia , Prevalência , Saúde Pública , Fatores Socioeconômicos , Tricuríase/epidemiologia , Tricuríase/terapia , Água/parasitologia
17.
BMJ Open ; 5(10): e008950, 2015 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-26482774

RESUMO

INTRODUCTION: In recent years, an unprecedented emphasis has been given to the control of neglected tropical diseases, including soil-transmitted helminths (STHs). The mainstay of STH control is school-based deworming (SBD), but mathematical modelling has shown that in all but very low transmission settings, SBD is unlikely to interrupt transmission, and that new treatment strategies are required. This study seeks to answer the question: is it possible to interrupt the transmission of STH, and, if so, what is the most cost-effective treatment strategy and delivery system to achieve this goal? METHODS AND ANALYSIS: Two cluster randomised trials are being implemented in contrasting settings in Kenya. The interventions are annual mass anthelmintic treatment delivered to preschool- and school-aged children, as part of a national SBD programme, or to entire communities, delivered by community health workers. Allocation to study group is by cluster, using predefined units used in public health provision-termed community units (CUs). CUs are randomised to one of three groups: receiving either (1) annual SBD; (2) annual community-based deworming (CBD); or (3) biannual CBD. The primary outcome measure is the prevalence of hookworm infection, assessed by four cross-sectional surveys. Secondary outcomes are prevalence of Ascaris lumbricoides and Trichuris trichiura, intensity of species infections and treatment coverage. Costs and cost-effectiveness will be evaluated. Among a random subsample of participants, worm burden and proportion of unfertilised eggs will be assessed longitudinally. A nested process evaluation, using semistructured interviews, focus group discussions and a stakeholder analysis, will investigate the community acceptability, feasibility and scale-up of each delivery system. ETHICS AND DISSEMINATION: Study protocols have been reviewed and approved by the ethics committees of the Kenya Medical Research Institute and National Ethics Review Committee, and London School of Hygiene and Tropical Medicine. The study has a dedicated web site. TRIAL REGISTRATION NUMBER: NCT02397772.


Assuntos
Albendazol/administração & dosagem , Anti-Helmínticos/administração & dosagem , Controle de Doenças Transmissíveis/métodos , Infecções por Uncinaria/tratamento farmacológico , Infecções por Uncinaria/epidemiologia , Solo/parasitologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Análise Custo-Benefício , Estudos Transversais , Feminino , Humanos , Quênia , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Saúde Pública , Projetos de Pesquisa , Características de Residência , Instituições Acadêmicas , Inquéritos e Questionários , Adulto Jovem
18.
Parasit Vectors ; 8: 560, 2015 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-26496983

RESUMO

BACKGROUND: Lymphatic filariasis (LF) is one of the neglected tropical diseases targeted for global elimination. The ability to interrupt transmission is, partly, influenced by the underlying intensity of transmission and its geographical variation. This information can also help guide the design of targeted surveillance activities. The present study uses a combination of geostatistical and mathematical modelling to predict the prevalence and transmission intensity of LF prior to the implementation of large-scale control in sub-Saharan Africa. METHODS: A systematic search of the literature was undertaken to identify surveys on the prevalence of Wuchereria bancrofti microfilaraemia (mf), based on blood smears, and on the prevalence of antigenaemia, based on the use of an immuno-chromatographic card test (ICT). Using a suite of environmental and demographic data, spatiotemporal multivariate models were fitted separately for mf prevalence and ICT-based prevalence within a Bayesian framework and used to make predictions for non-sampled areas. Maps of the dominant vector species of LF were also developed. The maps of predicted prevalence and vector distribution were linked to mathematical models of the transmission dynamics of LF to infer the intensity of transmission, quantified by the basic reproductive number (R0). RESULTS: The literature search identified 1267 surveys that provide suitable data on the prevalence of mf and 2817 surveys that report the prevalence of antigenaemia. Distinct spatial predictions arose from the models for mf prevalence and ICT-based prevalence, with a wider geographical distribution when using ICT-based data. The vector distribution maps demonstrated the spatial variation of LF vector species. Mathematical modelling showed that the reproduction number (R0) estimates vary from 2.7 to 30, with large variations between and within regions. CONCLUSIONS: LF transmission is highly heterogeneous, and the developed maps can help guide intervention, monitoring and surveillance strategies as countries progress towards LF elimination.


Assuntos
Filariose Linfática/epidemiologia , Filariose Linfática/transmissão , Modelos Teóricos , Topografia Médica , Wuchereria bancrofti/isolamento & purificação , África ao Sul do Saara/epidemiologia , Animais , Controle de Doenças Transmissíveis/métodos , Monitoramento Epidemiológico , Prevalência , Análise Espaço-Temporal
19.
Trans R Soc Trop Med Hyg ; 109(10): 609-18, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26286946

RESUMO

Due to the increasing global spread of arboviruses, the geographic extent of virus co-circulation is expanding. This complicates the diagnosis of febrile conditions and can have direct effects on the epidemiology. As previously demonstrated, subsequent infections by two closely related viruses, such as those belonging to the Japanese encephalitis virus (JEV) serocomplex, can lead to partial or complete cross-immunity, altering the risk of infections or the outcome of disease. Two flaviviruses that may interact at population level are West Nile virus (WNV) and Usutu virus (USUV). These pathogens have antigenic cross-reactivity and affect human and animal populations throughout Europe. This systematic review investigates the overlap of WNV and USUV transmission cycles, not only geographically but also in terms of host and vector ranges. Co-circulation of WNV and USUV was reported in 10 countries and the viruses were found to infect 34 common bird species belonging to 11 orders. Moreover, four mosquito species are potential vectors for both viruses. Taken together, these data suggest that WNV and USUV transmission overlaps substantially in Europe and highlight the importance of further studies investigating the interactions between the two viruses within host and vector populations.


Assuntos
Doenças das Aves/epidemiologia , Doenças das Aves/transmissão , Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/transmissão , Encefalite por Arbovirus/epidemiologia , Encefalite por Arbovirus/transmissão , Infecções por Flavivirus/epidemiologia , Infecções por Flavivirus/transmissão , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/transmissão , Animais , Doenças das Aves/virologia , Aves , Doenças Transmissíveis Emergentes/veterinária , Doenças Transmissíveis Emergentes/virologia , Culex/virologia , Surtos de Doenças/veterinária , Vírus da Encefalite Japonesa (Subgrupo)/fisiologia , Encefalite por Arbovirus/veterinária , Encefalite por Arbovirus/virologia , Europa (Continente)/epidemiologia , Infecções por Flavivirus/veterinária , Infecções por Flavivirus/virologia , Humanos , Prevalência , Febre do Nilo Ocidental/veterinária , Febre do Nilo Ocidental/virologia
20.
Trans R Soc Trop Med Hyg ; 109(8): 529-31, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26101292

RESUMO

BACKGROUND: The diagnosis of lymphatic filariasis (LF) is based typically on either microfilaraemia as assessed by microscopy or filarial antigenaemia using an immuno-chromatographic test. While it is known that estimates of antigenaemia are generally higher than estimates of microfilaraemia, the extent of the difference is not known. METHODS: This paper presents the results of an extensive literature search for surveys that estimated both microfilaraemia and antigenaemia in order to better understand the disparity between the two measures. RESULTS AND CONCLUSIONS: In some settings there was a very large disparity, up to 40-70%, between estimates of microfilaraemia and antigenaemia. Regression analysis was unable to identify any predictable relationship between the two measures. The implications of findings for risk mapping and surveillance of LF are discussed.


Assuntos
Antígenos de Helmintos/isolamento & purificação , Portador Sadio/sangue , Filariose Linfática/sangue , Microfilárias/isolamento & purificação , Wuchereria bancrofti/isolamento & purificação , Animais , Portador Sadio/epidemiologia , Filariose Linfática/epidemiologia , Humanos , Inquéritos e Questionários
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