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Ending AIDS: trends in the incidence of HIV in eastern and southern Africa

While great progress has been made in the control and management of the HIV epidemic there is still much to be done. Using trends in the rate of new HIV infections in eastern and southern Africa we assess the current state of the epidemic and evaluate the future prospects for controlling it. If we let an incidence of 1 per 1,000 people represent a control threshold then this has been reached, or will probably be reached by 2020, in eastern Africa and is reachable by 2020 in those southern African countries that do not have particularly strong social and economic ties to South Africa if they continue to scale up their treatment programmes. In South Africa and its immediate neighbours Lesotho, Mozambique and Swaziland, the prospects are less certain. These countries are unlikely to reach the control threshold by 2020 but with sufficient political will and commitment to treatment for all could do so by 2030.\n\nThere are two important caveats. First, reaching the control threshold still leaves 35 thousand new infections a year. As the lessons of polio remind us, finding the last few, hard to reach cases will demand more focussed strategies. Second, ending AIDS will not end HIV and about 35 million people will have to be kept on ART for the next 30 to 40 years unless and until a cure is discovered. Even if we assume a modest cost of, say, US$100 per person per year for ART treatment and support, this corresponds to a continuing financial commitment of US$3.5 Bn per year although this is substantially less than the approximately US$ 40 Bn per year currently committed to HIV and AIDS.

epidemiology

A scoping review of health-based survey instruments validated in Brunei Darussalam

This study sought to map and review validated health-based survey instruments in Brunei Darussalam. A scoping search of relevant articles was carried out. Six health-based survey tools have been psychometrically evaluated in Brunei Darussalam, 4 in Brunei-Malay (SF-36v2, EQ-5D/VAS, CPQ{pi}_14, and m-SEQ-12) and 2 in English (OFER and WPBA) languages. Two studies (m-SEQ-12, CPQ11-14) translated tools in English into Brunei-Malay. Two studies (SF-36v2, EQ-5D) cross-culturally adapted the Malaysian and Singaporean versions of the tools into Brunei-Malay. Four studies were adult- and hospital-based, among healthcare workers (OFER,WPBA) and patients with chronic diseases (SF-36v2, EQ-5D); and 2 studies (m-SEQ-12, CPQ11-14) were non-adult-and secondary school-based. Pretesting was carried out in 4 studies (SF-36v2, EQ-5D, CPQ11-14, and m-SEQ-12) on a sample of 5 to 20 volunteers. The sample size for validation ranged from 40 to 457. Reliability tests, Cronbachs alpha and intra-class coefficient (n=3), Cohens Kappa (n=1), and 5-point scale qualitative assessment (n=1) were measured. Validity tests included face validity (n=2), discriminant validity (n=2), convergent validity (n=2), construct validity (n=2), factorial validity (n=2), and 5-point scale qualitative assessment (n=1). There is a need for more psychometric evaluation of questionnaires in Brunei Darussalam. Importantly, large heterogeneous participants, more languages, and varied psychometric tests should be considered.

epidemiology

Disentangling the contribution of childhood and adulthood circumstances and genetics to phenotypic aging: prospective cohort study

ObjectivesTo evaluate the extent to which childhood and adulthood circumstances and genetics contribute to phenotypic aging, using a multi-system-based signature of aging that has been shown to capture mortality and morbidity risk.\n\nDesignProspective population-based cohort study.\n\nSettingUnited States (U.S.).\n\nParticipants2,339 adults (aged 51+ years) from U.S. Health and Retirement Study, who participated in the Core Survey, the 2016 Venous Blood Study, the 2015 Life History Mail Survey, the Enhanced Face-To-Face interview (2006-2016), and were part of the genetic sample.\n\nMain outcomes measurePhenotypic Age, a validated aging measure based on a linear combination of chronological age and nine multi-system biomarkers. For most analyses, we examined \"PhenoAgeAccel\", which represents phenotypic aging after accounting for chronological age (i.e. whether a person appears older [positive value] or younger [negative value] than expected, physiologically).\n\nResultsThe Shapley Value Decomposition approach revealed that together all 11 domains (four childhood and adulthood circumstances domains, five polygenic scores [PGSs] domains, demographics, and behaviors domains) accounted for about 30% of variance in PhenoAgeAccel. Among the four circumstances domains, adulthood adversity was the largest contributor (9%), while adulthood socioeconomic status (SES), childhood adversity, and childhood SES accounted for 2.8%, 2.1%, 0.7%, respectively. Collectively, all PGSs contributed 3.8% of variance in PhenoAgeAccel. Further, six subpopulations/clusters--identified using a hierarchical cluster analysis based on childhood and adulthood SES and adversity--showed differences in average levels of phenotypic aging. Finally, there was a significant gene-by-environment interaction between a previously validated PGS for coronary artery disease and the most apparently disadvantaged subpopulation/cluster--suggesting a multiplicative effect of adverse environment coupled with genetic risk on phenotypic aging.\n\nConclusionsSocioenvironmental circumstances during both childhood and adulthood account for a sizable proportion of the difference in phenotypic aging among U.S. older adults. The detrimental effects may further be exacerbated among persons with a genetic predisposition to coronary artery disease.

epidemiology

Interferon-alpha2 but not interferon-gamma serum levels are associated with intramuscular fat in obese patients with nonalcoholic fatty liver disease

BackgroundIntramuscular triglycerides (IMTGs) represent an important energy supply and a dynamic fat-storage depot that can expand during periods of elevated lipid availability and a fatty ac-id source. Ultrasonography (US) of human skeletal muscles is a practical and reproducible method to assess both IMTG presence and entity.\n\nAlthough a crosstalk between cytokines in skeletal muscle and adipose tissue has been suggested in obesity, condition leading to hepatic steatosis (HS) or better defined as nonalcoholic fatty liver disease and cancer, there are still questions to be answered about the role of interferons (IFNs), alpha as well as gamma, and IMTG in obesity. We aimed at discovering any correlation between IFNs and IMTG.\n\nMethodsWe analysed anthropometric data, metabolic parameters and imaging features of a population of obese subjects with low-prevalence of co-morbidities but HS. The levels of serum IFNs were detected by a magnetic bead-based multiplex immunoassays.\n\nResultsSerum concentrations of IFN-alpha2 were increased, while serum levels of IFN-gamma were decreased confronted with those of controls; the severity of IMTG, revealed at US as Heckmatt scores, was inversely predicted by IFN-alpha2 serum concentrations; IMTG scores were not predicted by serum levels of IFN-gamma; IMTG scores were predicted by HS severity, ascertained at US; HS severity was predicted by visceral adipose tissue, assessed by US, but the latter was not instrumental to IMTG.\n\nDiscussion & ConclusionThis study has added some pieces of observation about the cytokine network regulating the interplay between IMTG and obesity in obese patients with HS.

epidemiology

Personal clinical history predicts antibiotic resistance in urinary tract infections

The prevalence of antibiotic resistance in urinary tract infections (UTIs) often renders the prescribed antimicrobial treatment ineffective, highlighting the need for personalized prediction of resistance at time of care. Here, crossing a 10-year longitudinal dataset of over 700,000 community-acquired UTIs with over 6,000,000 personally-linked records of antibiotic purchases, we show that the resistance profile of infections can be predicted based on patient-specific demographics and clinical history. Age, gender, and retirement home residence had strong, yet differential and even non-monotonic, associations with resistance to different antibiotics. Resistance profiles were also associated with the patients records of past urine samples and antibiotic usage, with these associations persisting for months and even longer than a year. Drug usage selected specifically for its own cognate resistance, which led indirectly, through genetic linkage, also to resistance to other, even mechanistically unrelated, drugs. Applying machine learning models, these association patterns allowed good personalized predictions of resistance, which could inform and better optimize empirical prescription of antibiotics.

epidemiology

Point of Care Diagnostic Deployment and Targeted Treatment of Antimicrobial Resistant Non-Typhoidal Salmonella: a New Mathematical Model and Cost-Benefit Analysis

Invasive non-typhoidal Salmonella (NTS) is among the leading causes of blood stream infections in sub-Saharan Africa and other developing regions, especially among pediatric populations. Invasive NTS can be difficult to treat and have high case-fatality rates, in part due to emergence of strains resistant to broad-spectrum antibiotics. Furthermore, improper treatment contributes to increased antibiotic resistance and death. Point of care (POC) diagnostic tests that rapidly identify invasive NTS infection, and differentiate between resistant and non-resistant strains, may greatly improve patient outcomes and decrease resistance at the community level. Here we present for the first time a model for NTS dynamics in high risk populations that can analyze the potential advantages and disadvantages of four strategies involving POC diagnostic deployment, and the resulting impact on antimicrobial treatment for patients. Our analysis strongly supports the use of POC diagnostics coupled with targeted antibiotic use for patients upon arrival in the clinic for optimal patient and public health outcomes. We show that even the use of imperfect POC diagnostics can significantly reduce total costs and number of deaths, provided that the diagnostic gives results quickly enough that patients are likely to return or stay to receive targeted treatment.

epidemiology

Transforming summary statistics from logistic regression to the liability scale: application to genetic and environmental risk scores

1. Abstract1.1. ObjectiveStratified medicine requires models of disease risk incorporating genetic and environmental factors. These may combine estimates from different studies and models must be easily updatable when new estimates become available. The logit scale is often used in genetic and environmental association studies however the liability scale is used for polygenic risk scores and measures of heritability, but combining parameters across studies requires a common scale for the estimates.\n\n1.2. MethodsWe present equations to approximate the relationship between univariate effect size estimates on the logit scale and the liability scale, allowing model parameters to be translated between scales.\n\n1.3. ResultsThese equations are used to build a risk score on the liability scale, using effect size estimates originally estimated on the logit scale. Such a score can then be used in a joint effects model to estimate the risk of disease, and this is demonstrated for schizophrenia using a polygenic risk score and environmental risk factors.\n\n1.4. ConclusionThis straightforward method allows conversion of model parameters between the logit and liability scales, and may be a key tool to integrate risk estimates into a comprehensive risk model, particularly for joint models with environmental and genetic risk factors.

epidemiology

Anterior fontanelle size among term neonates on the first day of life born at University of Gondar Hospital, Northwest Ethiopia

BackgroundAnterior fontanelle is the largest, prominent and most important fontanelle, which is used for clinical evaluation. It is mainly characterized by its size and shape variation and is possibly influenced by gender, race and genetics. Understanding the variation of anterior fontanelle is used for recognition of different medical disorders and abnormal skeletal morphogenesis.\n\nObjectiveTo determine the mean size of anterior fontanelle among term neonates on the first day of life born at University of Gondar Hospital, Gondar town, Northwest Ethiopia, 2018\n\nMethodsDescriptive cross sectional study design was undertaken in 384 term and apparently healthy neonates, using standard methods. Descriptive analysis, student t-test, one way ANOVA and Pearson correlation coefficient were implemented.\n\nResultsIn this study, the mean size of anterior fontanelle in term neonates was 3.00 {+/-} 0.62 cm (range 1.70 - 5.50 cm). The mean size of anterior fontanelle was 3.10 {+/-} 0.66 cm for males, and 2.88 {+/-} 0.57 cm for females. There was statistically significant difference in anterior fontanelle size in neonates of different genders (p<0.001), mode of delivery (p<0.001) and duration of labour (p=0.006). However, the size of anterior fontanelle was not significantly affected by the birth order, onset of labour and sociodemographic variables of the mother except occupation of the mother (p=0.01). There was a significant positive correlation between the mean size of anterior fontanelle with birth weight (r=0.11; p=0.04) and head circumference (r=0.17; p=0.001).\n\nConclusionsAt term, male neonates had significantly larger anterior fontanelle than female neonates and anterior fontanelle size has a direct relationship with birth weight and head circumference.

epidemiology

HIV-Attributed Causes of Death in the Medical Ward at the Chris Hani Baragwanath Hospital, South Africa

BackgroundThere are sparse data in Africa on the association between HIV infection and deaths from underlying medical conditions. Using records from the Chris Hani Baragwanath Hospital (CHBH) in Soweto, South Africa, we determined mortality from medical conditions associated with HIV.\n\nMethodsFrom January 2006 to December 2009 AB collected data on 15,725 deaths including age, sex, day of admittance and death, HIV status, ART initiation and CD4+ cell counts and reviewed the underlying cause of death using medical notes. Conditions known to be associated with HIV were cases; conditions not associated with HIV were controls. We calculate the HIV odds-ratios for cases relative to controls and HIV-attributable deaths as the fraction of those with each condition, the disease-attributable fraction (DA), and as the fraction of all deaths, the population-attributable fraction (PAF).\n\nInterpretationThe high prevalence of HIV among those that died in the medical wards at the CHBH, especially in those below the age of 50 years, demonstrates the impact of the HIV-epidemic on adult mortality and hospital services and the extent to which early antiretroviral treatment would have reduced the burden of both. Of the deaths included in the analysis the prevalence of HIV was 61% and the prevalence of AIDS related conditions was 69%. The HIV-attributable fraction was 36% in the whole sample and 60% in those that were HIV-positive. Cryptococcosis, Kaposis sarcoma and Pneumocystis jeroveci are highly predictive of HIV while TB, gastroenteritis and anaemia are very strongly associated with HIV. The greatest number of deaths attributable to HIV was among those dying of TB or of other respiratory conditions.\n\nFundingNo funding was received for this study.

epidemiology

Real-time analysis of the diphtheria outbreak in forcibly displaced Myanmar nationals in Bangladesh

BackgroundBetween August and December 2017, more than 625,000 Rohingya from Myanmar fled into Bangladesh, settling in informal makeshift camps in Coxs Bazar district, joining 212,000 Rohingya already present. In early November, a diphtheria outbreak was reported in the camps, with 440 cases being reported during the first month. A rise in cases during early December led to a collaboration between teams from Medecins sans Frontieres - who were running a provisional diphtheria treatment centre - and the London School of Hygiene & Tropical Medicine with the goal to use transmission dynamic models to forecast the potential scale of the outbreak and the resulting resource needs.\n\nMethodsWe first adjusted for delays between symptoms onset and case presentation using the observed distribution of reporting delays from previously reported cases. We then fit a compartmental transmission model to the adjusted incidence stratified by age-group and location. Model forecasts with a lead-time of two weeks were issued on 12th, 20th, 26th and 30th December and communicated to decision-makers.\n\nResultsThe first forecast estimated that the outbreak would peak on 16th December in Balukhali camp with 222 (95% prediction interval 126-409) cases and would continue to grow in Kutupalong camp, requiring a bed capacity of 200 (95% PI 142-301). On 16th December, a total of 70 cases were reported, lower than forecasted. Subsequent forecasts were more accurate: on 20th December we predicted a total of 701 cases (95% PI 477-901) and 105 (95% PI 72-135) hospitalizations until the end of the year, with 616 cases actually reported during this period.\n\nConclusionsReal-time modelling enabled feedback of key information about the potential scale of the epidemic, resource needs, and mechanisms of transmission to decision-makers at a time when this information was largely unknown. By December 20th, the model generated reliable forecasts and helped support decision-making on operational aspects of the outbreak response, such as hospital bed and staff needs, and with advocacy for control measures. Although modelling is only one component of the evidence base for decision-making in outbreak situations, suitable analysis and forecasting techniques can be used to gain insights into an ongoing outbreak.

epidemiology

Individual-based network model for Rift Valley Fever in Kabale District, Uganda, to guide mitigation measures: A One Health Model

Rift Valley fever (RVF) is a zoonotic disease which causes significant morbidity and mortality among ungulate livestock and humans in endemic regions. In the major RVF epizootic regions of East Africa, the causative agent of the disease, Rift Valley fever virus (RVFV), is primarily transmitted by multiple mosquito species in Aedes, Culex, and Mansonia genera during both epizootic and enzootic periods in a complex transmission cycle largely driven by the environment. However, recent RVFV activity in Uganda demonstrated that RVFV could also spread into new regions through livestock movements, and underscored the need to develop effective mitigation strategies to reduce transmission and prevent spread among cattle operations. We simulated RVFV transmission among cattle in different sub counties of Kabale District in Uganda using real world livestock data in a network-based model. This model considered livestock as spatially explicit factors in different sub-counties subjected to specific vector mosquito and environmental factors, and was configured to investigate and quantitatively evaluate the relative impacts of mosquito control, livestock movement regulations, and diversity in cattle populations on the spread of the RVF epizootic. We concluded that cattle movement should be restricted during periods of high vector mosquito abundance to control the epizootic spreading among sub-counties. On the other hand we found that mosquito control would only be sufficient to control the epizootic when mosquito abundance was low. Importantly, simulation results also showed that cattle populations with a higher diversity with regard to indigenous combined with exotic breeds led to reduced numbers of infected cattle compared to more homogenous cattle populations.

epidemiology

Discrepancies between observed data and predictions from mathematical modelling of the impact of screening interventions on Chlamydia trachomatis prevalence

Mathematical modelling studies of C. trachomatis transmission predict that interventions to screen and treat chlamydia infection will reduce prevalence to a greater degree than that observed in empirical population-based studies. We investigated two factors that might explain this discrepancy: partial immunity after natural infection clearance and differential screening coverage according to infection risk. We used four variants of a compartmental model for heterosexual C. trachomatis transmission, parameterized using data from England about sexual behaviour and C. trachomatis testing, diagnosis and prevalence, and Markov Chain Monte Carlo methods for statistical inference. A model in which partial immunity follows natural infection clearance and the proportion of tests done in chlamydia-infected people decreases over time fitted the data best. The model predicts that partial immunity reduced susceptibility to reinfection by 72% (95% Bayesian credible interval 57-86%). The estimated screening rate was 4.6 (2.6-6.5) times higher for infected than for uninfected women in 2000; this decreased to 2.1 (1.4-2.9) in 2011. Other factors not included in the model could have further reduced the expected impact of screening. Future mathematical modelling studies investigating the effects of screening interventions on C. trachomatis transmission should incorporate host immunity and changes over time in the targeting of screening.

epidemiology

Medical Nonadherence, Cannabis Use, and Renal Outcome in Systemic Lupus Erythematosis

Background/ObjectiveNon-adherence to recommended medical therapy has been associated with poorer outcomes in systemic lupus erythematosus (SLE). The present research investigated the association of medical non-adherence and cannabis use on renal outcomes of SLE.\n\nMethodsThis was a prospective 5-year longitudinal outcome study of 276 female SLE patients 30.4% who chronically used medical cannabis and 69.5% who did not. Outcomes were determined at 5 years after enrollment in the study.\n\nResultsCannabis use in SLE patients was associated with an increased prevalence of neuropsychiatric SLE (p<0.05), opioid analgesic use (p<0.01), cigarette smoking (p<0.001), and non-adherence to the medical regimen (non-cannabis: 3% non-adherence vs. cannabis use: 95% non-adherence, p<0.001). Within the 5-year period, the cannabis group demonstrated a 53% increase in mortality (p=0.12) and 127% increase in end-stage renal disease requiring dialysis (p<0.001). With logistic regression analysis adjusting for SLE disease activity (SLEDAI-2K), cannabis use was an independent predictor of end-stage renal disease: Odds ratio 2.65 (CI 1.32 - 5.32, p<0.01). Adjusting for SLE disease damage (SLICC/ACR-DI), cannabis use remained an independent predictor of end-stage renal disease: Odds ratio 2.0 (CI 1.26 - 6.23, p<0.01). With multivariable analysis adjusting for non-adherence, the effect of cannabis on end-stage renal disease could be largely attributed to an increase in non-adherence to medical therapy.\n\nConclusionsNon-adherence to recommended therapy and medical cannabis use are associated with a significant increase in the development of end-stage renal disease in SLE.

epidemiology

Chikungunya in Colombia: a description of an epidemic within the framework of a COPCORD study

During 2014 and 2015 the chikungunya virus reached Colombia unleashing an epidemic that spread throughout the whole territory. Concurrently, the Colombian Rheumatology Association was conducting a Community Oriented Program for Control of Rheumatic Diseases (COPCORD) to establish rheumatic disease prevalence in the country. Chikungunya infected patients were identified within the COPCORD population. The aim of this study was to describe the demographics, clinical characteristics and disability of patients with clinical suspicion of chikungunya infection. To confirm chikungunya infection, ELISA IgM and IgG serology was performed. From the 6528-surveyed people of the COPCORD study, 548 where included in the study because of clinical suspicion of chikungunya virus infection. Of those, 295 were positive for IgG or IgM chikungunya serology with 151 patients fulfilling WHO clinical criteria for chikungunya infection (true positives). Most patients were > 45 years (57.7%), and females (69.7%). Patients with low income and low socio-economic strata had increased risk of chikungunya infection (p = 0.00; OR: 2.36, CI: 1.47-3.77 and p = 0.00; OR: 2.81, CI: 1.90-4.17 respectively). True positive patients were associated with symmetric arthritis (p = 0.00; OR: 22.49, CI: 12.71-39.80) of ankles (p = 0.00; OR: 16.06, CI: 7.57-34.08), hands (p = 0.00; OR: 16.12, CI: 8.25-39.79), feet (p = 0.00; OR: 16.35, CI: 7.41-36.05) and elbows (p = 0.00; OR: 14.00, CI: 3.03-64.70). Most patients developed mild to moderate disability (95.2 to 100%). Our study showed that poverty and low socioeconomic status are associated with increased risk of chikungunya infection. Also, we found two distinctive phenotypes of chikungunya infection; those with positive chikungunya serology and typical clinical symptoms (true positives) and those with positive serology without clinical symptoms (false negatives). Finally, a distinctive clinical picture presented by chikungunya infected patients was found which should be considered as the hallmark for diagnostic clinical criteria.

epidemiology

Importance of vitamin D in critically ill children with subgroup analyses of sepsis and respiratory tract infections: a systematic review and meta-analysis

BackgroundCritical care and sepsis remain high priority concerns in children. Observational studies report high prevalence of vitamin D deficiency and present mixed results regarding the correlation between vitamin D status and adverse outcomes. Associations between deficiency and mortality, particularly in children with sepsis, remain unclear. We performed a systematic review and meta-analysis to address this uncertainty.\n\nMethodsPubMed, OVID and Google Scholar were searched for observational studies in critically ill children. We obtained pooled prevalence estimates for vitamin D deficiency and odds ratios for the association of mortality in critically ill children treated in intensive care units, with subgroup analysis for children with sepsis. Meta-regression and sensitivity analyses were used to investigate heterogeneity.\n\nFindingsForty-eight studies were included. The total sample size was 7,199, with 1,679 (23%) children acting as controls in case-control studies. Of 5,520 critically ill children, 2,664 (48%) were vitamin D deficient (< 50 nmol/L). Results of the random effects model demonstrated a pooled prevalence of vitamin D deficiency of 54.9% (95% CI 48.0-61.6, I2=95.0%, 95% CI 94.0-95.8, p < 0.0001). In subgroup analysis of children with sepsis (16 studies, 788 total individuals) we observed higher prevalence of deficiency (63.8%, 95% CI 49.9-75.7, I2=90.5%, 95% CI 86.2-93.5%, p < 0.0001). In patients admitted to intensive care for respiratory tract infections (24 studies, 1,683 total individuals), prevalence was 49.9% (95% CI 37.6-62.2; I2 = 93.9%, 95% CI 92.1-95.3, p < 0.0001). Only one identified study assessed vitamin D levels in sepsis and mortality. The meta-regression model with all available variables (year of publication, total study sample size, quality score, study design, country group and clinical setting) explained 37.52% of I2 (F = 5.1119, p = 0.0005) with clinical setting and country groups being significant predictors for prevalence.\n\nOur meta-analysis (18 studies, 2,463 total individuals) showed an increased risk of death in vitamin D deficient critically ill children both with the random (OR 1.81, 95% CI 1.24-2.64, p-value = 0.002) and fixed effects (OR 1.72, 95% CI 1.27-2.33, p= 0.0005) models with low heterogeneity (I2 = 25.7%, 95% CI 0.0-58.0, p = 0.153) and low evidence of publication bias (p = 0.084, Eggers test).\n\nInterpretationCirculating vitamin D deficiency is common amongst critically ill children, particularly in those with sepsis. Our results suggest that vitamin D deficiency in critically ill children is associated with increased mortality. Clinical trials, studies with larger sample sizes and standardized approaches are needed to further assess associations between circulating levels of vitamin D and mortality or other outcomes in the pediatric population.\n\nFundingNone\n\nRegistrationPROSPERO (CRD42016050638)\n\nCopyrightOpen access article under terms of CC BY

epidemiology

Identification of meteorological factors affecting migration of wild birds into miyazaki and its relation to circulation of highly pathogenic avian influenza virus

Aim of our study is to establish models for predicting the number of migratory wild birds based on the meteorological data. From 136 species of wild birds, which have been observed at Futatsudate in Miyazaki, Japan, from 2008 to 2016, we selected the potential high-risk species, which can introduce highly pathogenic avian influenza (HPAI) virus into Miyazaki; we defined them as \"risky birds\". We then performed regression analysis to model the relationship between the number of risky birds and meteorological data. We selected 10 wild bird species as risky birds: Mallard (Anas platyrhynchos), Northern pintail (Anas acuta), Eurasian wigeon (Anas penelope), Eurasian teal (Anas crecca), Common pochard (Aythya ferina), Eurasian coot (Fulica atra), Northern shoveler (Anas clypeata), Common shelduck (Tadorna tadorna), Tufted duck (Aythya fuligula), and Herring gull (Larus argentatus). We succeeded in identifying five meteorological factors associated with their migration: station pressure, mean value of global solar radiation, minimum of daily maximum temperature, days with thundering, and days with daily hours of daylight under 0.1 h. We could establish some models for predicting the number of risky birds based only on the published meteorological data, without manual counting. Dynamics of migratory wild birds has relevance to the risk of HPAI outbreak, so our data could contribute to save the cost and time in strengthening preventive measures against the epidemics.

epidemiology

Herd Immunity Alters the Conditions for Performing Dose Schedule Comparisons: An Individual-based Model of Pneumococcal Carriage

BACKGROUND BACKGROUND METHODS RESULTS DISCUSSION CONCLUSIONS LIST OF ABBREVIATIONS Ethics approval and consent... Consent for publication Availability of data and... Competing interests Funding Authors' contributions DECLARATIONS REFERENCES Mass vaccination of infants and toddlers with pneumococcal conjugate vaccines (PCVs) has led to large declines in pneumococcal disease in countries around the world [1]. These vaccines currently contain 10 or 13 different capsular polysaccharides from Streptococcus pneumoniae, each conjugated to a protein carrier. In S. pneumoniae, the chemical structure of the capsular polys ...

epidemiology

Herd protection against Plasmodium falciparum infections conferred by mass antimalarial drug administrations and the implications for malaria elimination

IntroductionAll nations of the Greater Mekong Subregion have committed to elimination of malaria by the year 2030. Elimination efforts rely on increasing access to diagnosis and treatment. However, asymptomatic infections pose a major challenge for these efforts. One approach towards eliminating asymptomatic reservoirs is targeted mass antimalarial drug administration (MDA). Here we present a fine scale spatiotemporal analysis of malaria incidence and prevalence in villages undergoing MDA.\n\nMethodsFour villages along the Myanmar-Thailand border were selected for a MDA pilot study based on clinical records and prevalence surveys. Passive detection of clinical episodes was facilitated through community based malaria clinics in each village. All villagers were screened using venous blood and ultra-sensitive qPCR (uPCR) for detection of parasites at baseline and every subsequent 3 months until month 18 (M18). A final screening was done at M24. MDAs were conducted on M0, M1 and M2 in two villages and on M9, M10, M11 in the remaining two villages. Which villages received early or deferred MDA was decided using restricted randomization. MDA participation, clinical episodes and uPCR detected infections were mapped to participant houses. Scan statistics were used to test for clusters of malaria episodes, malaria infections and non-adherence to MDA. Mixed effects regressions were used to test for risk factors for clinical episodes after MDA.\n\nResultsNeighborhood level MDA adherence was a major predictor for clinical episodes of malaria post-MDA, suggesting a strong herd effect. Each village had a cluster of P. falciparum infections at M0. After M0, there were no clusters of uPCR detectable P. falciparum infections. Clinical episodes of P. falciparum occurred in one village only which had a cluster of non-adherence to MDA and a high mosquito vector human biting rate. Individuals with subclinical P.falciparum infections were more likely to have subsequent clinical episodes than individuals who had no subclinical infections. Individuals who lived in a house with someone who had a clinical episode were more likely to also have a clinical episode subsequently than individuals residing in a house free of P.falciparum infections.\n\nConclusionTo our knowledge this is the first study to show a herd effect from MDA for malaria. These data and results have significance for spatial targeting of interventions for malaria elimination. Clusters of non-adherence to MDA participation can lead to failed elimination if they occur among individuals with asymptomatic infections and given sufficient mosquito vector exposure. Community participation, which can be facilitated through community engagement, is key to MDA success.

epidemiology