Fractional derivative models for the spread of diseases

This thesis considers the mathematical modelling of disease, using fractional differential equations in order to provide a tool for the description of memory effects. In Chapter 3 we illustrate a commensurate fractional order tumor model, and we find a critical value of the fractional derivative dependent on the parameter values of the model. For fractional derivatives of orders less than the critical value an unstable equilibrium point of the system becomes stable. In order to show changes in the observed areas of attraction of two stable points in the system, we then consider a fractional order SIR epidemic model and investigate the change from a monostable to a bistable system.;Chapter 4 considers a model for virus dynamics where the fractional orders for populations are different, called an incommensurate system. An approximate analytical solution for the characteristic equation of the incommensurate model is found when the different fractional orders are similar and close to the critical value of the fractional order of the commensurate system. In addition, the instability boundary is found as a function of both parameters. A comparison between analytical and numerical results shows the high accuracy of this approximation.;Chapter 5 consists of two parts, in the first part we generalise the integer Fisher's equation to be a space-time fractional differential equation and consider travelling wave solutions. In the second part we generalise an integer SIR model with spatial heterogeneity, which was studied by Murray [117], to a space-time fractional derivative model. We apply the (G0/G)-expansion method and find travelling wave solutions, although in this case we must consider the Jumarie's modified Riemann-Liouville fractional derivative. Finally, we consider the effect of changing the orders of time and space fractional derivatives on the location and speed of the travelling wave solution.This thesis considers the mathematical modelling of disease, using fractional differential equations in order to provide a tool for the description of memory effects. In Chapter 3 we illustrate a commensurate fractional order tumor model, and we find a critical value of the fractional derivative dependent on the parameter values of the model. For fractional derivatives of orders less than the critical value an unstable equilibrium point of the system becomes stable. In order to show changes in the observed areas of attraction of two stable points in the system, we then consider a fractional order SIR epidemic model and investigate the change from a monostable to a bistable system.;Chapter 4 considers a model for virus dynamics where the fractional orders for populations are different, called an incommensurate system. An approximate analytical solution for the characteristic equation of the incommensurate model is found when the different fractional orders are similar and close to the critical value of the fractional order of the commensurate system. In addition, the instability boundary is found as a function of both parameters. A comparison between analytical and numerical results shows the high accuracy of this approximation.;Chapter 5 consists of two parts, in the first part we generalise the integer Fisher's equation to be a space-time fractional differential equation and consider travelling wave solutions. In the second part we generalise an integer SIR model with spatial heterogeneity, which was studied by Murray [117], to a space-time fractional derivative model. We apply the (G0/G)-expansion method and find travelling wave solutions, although in this case we must consider the Jumarie's modified Riemann-Liouville fractional derivative. Finally, we consider the effect of changing the orders of time and space fractional derivatives on the location and speed of the travelling wave solution

Child Maltreatment Prevention Readiness Assessment in Oman

Objectives: This study aimed to evaluate Oman’s readiness for implementing large-scale child maltreatment prevention (CMP) programmes. Methods: This cross-sectional study was conducted between May and August 2016 in Oman. Participants, referred to as key informants, were individuals with influence and decision-making powers over CMP. The multidimensional Readiness Assessment for the Prevention of Child Maltreatment tool, developed by the World Health Organization with the help of collaborators from middle- and low-income countries, was used to assess 10 dimensions of readiness, each with a maximum score of 10. Results: A total of 49 participants were included in this study (response rate = 98%). The mean total score for the 10 dimensions was 50.17 out of 100 possible points. The participants showed high mean readiness scores on legislation, mandates and policies (9.08) followed by knowledge of CMP (7.55), institutional resources and links (6.12), willingness to address the problem (5.35), informal social resources (5.15) and current programme implementation and evaluation (5.10). Participants had low scores in readiness in association with human and technical resources (2.44), attitudes towards CMP (2.90), scientific data on CMP (3.06) and material resources (3.46). Conclusion: The results of this study indicate that Oman has a moderate level of readiness to implement largescale evidence-based prevention programmes against child maltreatment; however, several dimensions still need to be strengthened. It is important to develop a national strategy that outlines a framework for organising and prioritising efforts towards CMP.Keywords: Child Maltreatment; Program Development; Attitude; World Health Organization; Oman

Non-suicidal self-strangulation among adolescents in Saudi Arabia: Case series of the choking game

AbstractAdolescence is known to be a time of exploration and initiation of risky behaviors. Much attention has been given to risk behaviors such as smoking, violence, and sexual promiscuity; other serious behaviors such as self-strangulation or the choking game, which is carried out by adolescents in response to peer pressures or to gain a transient sense of euphoria, have received little attention, with the available literature coming from the developed world.This is the first report of cases of non-suicidal self-strangulation from the Arab World. In this case series, we report 5 cases of non-suicidal self-strangulation that presented to the Emergency Department of a tertiary care hospital in Riyadh, Saudi Arabia during 2010–2012. All of the 5 cases were young male adolescents aged 10–13 years. This activity resulted in the death of 2 boys; one boy sustained hypoxic ischemic insult to the brain with clinical deficits; and the remaining 2 were fortunate to be discharged home in healthy condition. None of the cases had underlying mental health problems, and multidisciplinary involvement ruled out suicide and homicide activities.Non-suicidal self-strangulation is a fatal behavior that adolescents engage in. Increased efforts are needed to address this serious and preventable public health issue. Awareness and education of adolescents and their parents is crucial. Awareness of healthcare providers is also necessary in order to avoid misdiagnosis of such cases

Rapid Assessment Tool for Haemophilus influenzae type b Disease in Developing Countries1

Haemophilus influenzae type b disease prevalence in children provides estimates of national disease prevalence

Global research priorities for interpersonal violence prevention: A modified Delphi study

© 2017, World Health Organization. All rights reserved. Objective To establish global research priorities for interpersonal violence prevention using a systematic approach. Methods Research priorities were identified in a three-round process involving two surveys. In round 1, 95 global experts in violence prevention proposed research questions to be ranked in round 2. Questions were collated and organized according to the four-step public health approach to violence prevention. In round 2, 280 international experts ranked the importance of research in the four steps, and the various substeps, of the public health approach. In round 3, 131 international experts ranked the importance of detailed research questions on the public health step awarded the highest priority in round 2. Findings In round 2, “developing, implementing and evaluating interventions” was the step of the public health approach awarded the highest priority for four of the six types of violence considered (i.e. child maltreatment, intimate partner violence, armed violence and sexual violence) but not for youth violence or elder abuse. In contrast, “scaling up interventions and evaluating their cost-effectiveness” was ranked lowest for all types of violence. In round 3, research into “developing, implementing and evaluating interventions” that addressed parenting or laws to regulate the use of firearms was awarded the highest priority. The key limitations of the study were response and attrition rates among survey respondents. However, these rates were in line with similar priority-setting exercises. Conclusion These findings suggest it is premature to scale up violence prevention interventions. Developing and evaluating smaller-scale interventions should be the funding priority

The Relationship between Gram-Negative Colonisation and Bloodstream Infections in Neonates: A Systematic Review and Meta-Analysis.

OBJECTIVES: Neonates admitted to Neonatal Intensive Care Units (NICU) are at significant risk of developing bloodstream infections (BSIs). Gram-negative bacteria (GNB) both colonise and infect, but the association between these entities is unclear. By conducting a systematic literature review, we aimed to explore the impact of factors on the association between GN colonisation and GN-BSI at both baby level and unit level. METHODS: We searched Medline, Embase, and Cochrane Library. Observational cohort studies published after 2000 up to June 2016 reporting data on the total number of neonates (0-28 days) colonised with GNB assessed by rectal/skin swab culture and the total number of neonates with GN-BSI (same bacteria) were included. Studies were excluded if data on skin/rectal colonisation, neonates, and GNB could not been identified separately. The meta-analyses along with multivariate meta-regression with random-effect model were performed to investigate factors associated with the GN colonisation and GN-BSI at baby-level and unit-level. RESULTS: 27 studies fulfilled our inclusion criteria, 15 for the baby-level and 12 for the unit-level analysis. Study heterogeneity was high, with suboptimal overall quality of reporting assessed by the STROBE-NI statement (44.8% of items adequately reported). In 1,984 colonised neonates, 157 (7.9%) developed GN-BSI compared with 85 of 3,583 (2.4%) non-colonised neonates. Considerable heterogeneity across studies was observed. Four factors were included in the meta-regression model: Gross domestic product (GDP), pathogen, outbreak, and frequency of screening. There was no statistically significant impact of these factors on GN colonisation and GN-BSI in baby level. We were unable to perform the multivariate meta-regression due to the insufficient reported data for unit level. CONCLUSIONS: Study limitations include the small number and the high heterogeneity of the included studies. While this report shows a correlation between colonisation and BSI risk, this data currently doesn't support routinely screening for GNB. The analysis of large cohorts of colonised neonates with clinical outcomes is still needed to define the major determinants leading from colonisation to infection

Ventilator-associated pneumonia in children after cardiac surgery in The Netherlands

We conducted a retrospective cohort study in an academic tertiary care center to characterize ventilator-associated pneumonia (VAP) in pediatric patients after cardiac surgery in The Netherlands. All patients following cardiac surgery and mechanically ventilated for ≥24 h were included. The primary outcome was development of VAP. Secondary outcomes were duration of mechanical ventilation and length of ICU stay. A total of 125 patients were enrolled. Their mean age was 16.5 months. The rate of VAP was 17.1/1,000 mechanical ventilation days. Frequently found organisms were Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Pseudomonas aeruginosa. Patients with VAP had longer duration of ventilation and longer ICU stay. Risk factors associated with the development of VAP were a PRISM III score of ≥10 and transfusion of fresh frozen plasma. The mean VAP rate in this population is higher than that reported in general pediatric ICU populations. Children with VAP had a prolonged need for mechanical ventilation and a longer ICU sta

The Pathophysiology of Inhalational Brucellosis in Balb/c Mice

To characterize the clinical presentation and pathophysiology of inhalational brucellosis, Balb/c mice were challenged with Brucella melitensis 16M in a nose-only aerosol exposure chamber. A low dose of 1000 cfu/animal of B. melitensis resulted in 45% of mice with tissue burdens eight weeks post-challenge. The natural history of brucellosis in mice challenged by higher aerosol doses was examined by serial euthanizing mice over an eight week period. Higher challenge doses of 1.00E+05 and 5.00E+05 cfu resulted in positive blood cultures 14 days post-challenge and bacterial burdens were observed in the lung, liver and/or spleens 14 days post-challenge. In addition, the progression of brucellosis was similar between mice challenged by the intranasal and aerosol routes. The results from this study support the use of the Balb/c aerosol nose-only brucellosis mouse model for the evaluation of therapeutics against inhalational brucellosis

Pattern of medical waste management: existing scenario in Dhaka City, Bangladesh

<p>Abstract</p> <p>Background</p> <p>Medical waste is infectious and hazardous. It poses serious threats to environmental health and requires specific treatment and management prior to its final disposal. The problem is growing with an ever-increasing number of hospitals, clinics, and diagnostic laboratories in Dhaka City, Bangladesh. However, research on this critical issue has been very limited, and there is a serious dearth of information for planning. This paper seeks to document the handling practice of waste (e.g. collection, storage, transportation and disposal) along with the types and amount of wastes generated by Health Care Establishments (HCE). A total of 60 out of the existing 68 HCE in the study areas provided us with relevant information.</p> <p>Methods</p> <p>The methodology for this paper includes empirical field observation and field-level data collection through inventory, questionnaire survey and formal and informal interviews. A structured questionnaire was designed to collect information addressing the generation of different medical wastes according to amount and sources from different HCE. A number of in-depth interviews were arranged to enhance our understanding of previous and existing management practice of medical wastes. A number of specific questions were asked of nurses, hospital managers, doctors, and cleaners to elicit their knowledge. The collected data with the questionnaire survey were analysed, mainly with simple descriptive statistics; while the qualitative mode of analysis is mainly in narrative form.</p> <p>Results</p> <p>The paper shows that the surveyed HCE generate a total of 5,562 kg/day of wastes, of which about 77.4 per cent are non-hazardous and about 22.6 per cent are hazardous. The average waste generation rate for the surveyed HCE is 1.9 kg/bed/day or 0.5 kg/patient/day. The study reveals that there is no proper, systematic management of medical waste except in a few private HCE that segregate their infectious wastes. Some cleaners were found to salvage used sharps, saline bags, blood bags and test tubes for resale or reuse.</p> <p>Conclusion</p> <p>The paper reveals that lack of awareness, appropriate policy and laws, and willingness are responsible for the improper management of medical waste in Dhaka City. The paper also shows that a newly designed medical waste management system currently serves a limited number of HCE. New facilities should be established for the complete management of medical waste in Dhaka City.</p

Seroepidemiology of Varicella and value of self-reported history of Varicella infection in Iranian medical students

Objectives: We conducted this study to assess the seroprevalence of Varicella zoster virus (VZV) antibodies in a group of Iranian medical sciences students that were at risk of Varicella and the value of self-reported history as a predictor of immunity. Material and Methods: 255 medical, nursing and obstetrics students who had not entered as a student or worked in a hospital from 3 different schools were enrolled in the study in 2012 (Qazvin province, Iran). Demographics and other information as well as the history of Varicella were obtained through a self-administered questionnaire. Blood samples were collected to determine the Varicella IgG levels via an enzyme-linked immunosorbent assay. A statistical analysis was performed by calculating prevalences and their 95% confidence intervals. Sensitivity, specificity, positive and negative predictive values, Cohen's kappa and positive and negative likelihood ratios of recalled history were determined. p < 0.05 was considered statistically significant. Results: The mean age of participants was 21.3±4.3 years. Seropositivity rate was 74.5%. The relationships between marital status, number of family members, and acquired VZV history with immunity against the virus were statistically significant. The overall rate of reported history was 57%. The positive and negative predictive values of self-reported history of Varicella were 91% and 47.3%, respectively. Conclusions: Immunization of students of Iranian medical sciences seems logical in the near future. Also, they should be tested for Varicella immunity regardless of the history of previous infection