A review of data needed to parameterize a dynamic model of measles in developing countries

<p>Abstract</p> <p>Background</p> <p>Dynamic models of infection transmission can project future disease burden within a population. Few dynamic measles models have been developed for low-income countries, where measles disease burden is highest. Our objective was to review the literature on measles epidemiology in low-income countries, with a particular focus on data that are needed to parameterize dynamic models.</p> <p>Methods</p> <p>We included age-stratified case reporting and seroprevalence studies with fair to good sample sizes for mostly urban African and Indian populations. We emphasized studies conducted before widespread immunization. We summarized age-stratified attack rates and seroprevalence profiles across these populations. Using the study data, we fitted a "representative" seroprevalence profile for African and Indian settings. We also used a catalytic model to estimate the age-dependent force of infection for individual African and Indian studies where seroprevalence was surveyed. We used these data to quantify the effects of population density on the basic reproductive number <it>R</it>₀.</p> <p>Results</p> <p>The peak attack rate usually occurred at age 1 year in Africa, and 1 to 2 years in India, which is earlier than in developed countries before mass vaccination. Approximately 60% of children were seropositive for measles antibody by age 2 in Africa and India, according to the representative seroprevalence profiles. A statistically significant decline in the force of infection with age was found in 4 of 6 Indian seroprevalence studies, but not in 2 African studies. This implies that the classic threshold result describing the critical proportion immune (<it>p</it>_c) required to eradicate an infectious disease, <it>p</it>_c= 1-1/<it>R</it>₀, may overestimate the required proportion immune to eradicate measles in some developing country populations. A possible, though not statistically significant, positive relation between population density and <it>R</it>₀for various Indian and African populations was also found. These populations also showed a similar pattern of waning of maternal antibodies. Attack rates in rural Indian populations show little dependence on vaccine coverage or population density compared to urban Indian populations. Estimated <it>R</it>₀values varied widely across populations which has further implications for measles elimination.</p> <p>Conclusions</p> <p>It is possible to develop a broadly informative dynamic model of measles transmission in low-income country settings based on existing literature, though it may be difficult to develop a model that is closely tailored to any given country. Greater efforts to collect data specific to low-income countries would aid in control efforts by allowing highly population-specific models to be developed.</p

MicroMotility: State of the art, recent accomplishments and perspectives on the mathematical modeling of bio-motility at microscopic scales

Mathematical modeling and quantitative study of biological motility (in particular, of motility at microscopic scales) is producing new biophysical insight and is offering opportunities for new discoveries at the level of both fundamental science and technology. These range from the explanation of how complex behavior at the level of a single organism emerges from body architecture, to the understanding of collective phenomena in groups of organisms and tissues, and of how these forms of swarm intelligence can be controlled and harnessed in engineering applications, to the elucidation of processes of fundamental biological relevance at the cellular and sub-cellular level. In this paper, some of the most exciting new developments in the fields of locomotion of unicellular organisms, of soft adhesive locomotion across scales, of the study of pore translocation properties of knotted DNA, of the development of synthetic active solid sheets, of the mechanics of the unjamming transition in dense cell collectives, of the mechanics of cell sheet folding in volvocalean algae, and of the self-propulsion of topological defects in active matter are discussed. For each of these topics, we provide a brief state of the art, an example of recent achievements, and some directions for future research

Asthma control in adolescents 10 to 11 y after exposure to the World Trade Center disaster

Background: Little is known about asthma control in adolescents who were exposed to the World Trade Center (WTC) attacks of 11 September 2001 and diagnosed with asthma after 9/11. This report examines asthma and asthma control 10–11 y after 9/11 among exposed adolescents. Methods: The WTC Health Registry adolescent Wave 3 survey (2011–2012) collected data on asthma diagnosed by a physician after 11 September 2001, extent of asthma control based on modified National Asthma Education and Prevention Program criteria, probable mental health conditions, and behavior problems. Parents reported healthcare needs and 9/11-exposures. Logistic regression was used to evaluate associations between asthma and level of asthma control and 9/11-exposure, mental health and behavioral problems, and unmet healthcare needs. Results: Poorly/very poorly controlled asthma was significantly associated with a household income of ≤$75,000 (adjusted odds ratio (AOR): 3.0; 95% confidence interval (CI): 1.1–8.8), having unmet healthcare needs (AOR: 6.2; 95% CI: 1.4–27.1), and screening positive for at least one mental health condition (AOR: 5.0; 95% CI: 1.4–17.7), but not with behavioral problems. The impact of having at least one mental health condition on the level of asthma control was substantially greater in females than in males. Conclusions: Comprehensive care of post-9/11 asthma in adolescents should include management of mental health-related comorbidities. The collapse and burning of the World Trade Center (WTC) towers on 11 September 2001 (9/11) exposed hundreds of thousands of people to a complex mixture of dust, debris, and jet fuel combustion byproducts (1). It is estimated that over 25,000 persons in lower Manhattan developed asthma symptoms after exposure to the WTC terrorist attacks and the subsequent rescue and recovery efforts (1). In the years immediately following 9/11, new-onset asthma rates were elevated among exposed adults and many of those affected continued to experience respiratory symptoms (i.e., coughing, shortness of breath) years later (1,2). An estimated 25,000 children were living or attending school in lower Manhattan near the WTC on 9/11, and potentially were in the path of the dust cloud of building debris and smoke after the collapse of the towers, as well as for several months following the attacks, and could have inhaled particulate matter and toxic substances (3,4). Associations between 9/11-related exposures and both asthma diagnosis and persistent respiratory symptoms among children and adolescents have been documented (4,5,6). A previous report found that 2 to 3 y after 9/11, over half of children under 18 y of age who were enrolled in the World Trade Center Health Registry (Registry) reported new or worsening respiratory symptoms (53%), and 5.7% reported a post-9/11 diagnosis of asthma, both of which were associated with exposure to the dust cloud that resulted from the collapse of buildings on 9/11 (4). A subsequent study of Registry enrollees under 18 y old found that respiratory symptoms persisted up to 7 y post-9/11 (5). The WTC Environmental Health Center which collected clinical data on a sample of children an average of 7.8 y after 9/11, reported new onset provider-diagnosed asthma in 21.4% of children, and found that dust cloud exposure was associated with pulmonary function abnormalities, such as isolated low forced vital capacity pattern and an obstructive pattern consistent with asthma (6). Although the association between asthma and 9/11-exposure in children and adolescents has been documented, little is known about asthma control in this population. Large population-based surveys consistently show that poor asthma control is common in many children with asthma (7,8). Asthma control is affected by many factors, including healthcare access (9,10), socioeconomic status (9,10), and comorbid mental health conditions (11,12,13). It has been observed that adolescents with symptomatic asthma are more likely than adolescents without asthma to have lower perceived well-being, more negative behaviors, and a greater number of physical and mental health comorbidities (14). Several studies found that depression has been associated with uncontrolled asthma (11,12). In adults with 9/11-related asthma, having at least one mental health condition has been associated with poorly controlled asthma (15). However, little is known about the association between mental health conditions and the level of asthma control especially among 9/11-exposed adolescents. Previous studies of adult Registry enrollees found that those with unmet healthcare needs are more likely to have severe mental health symptoms, comorbid mental and physical health problems, and have lower quality of life (1,16). Unmet healthcare needs among adolescents have been shown to be associated with poorer health status and functioning, including asthma control (17). Poorly controlled asthma has also been associated with unmet healthcare needs related to cost or access barriers (18), such as an inability to pay for asthma medications and not having access to asthma specialists (19). The goal of this study was to evaluate asthma control 10–11 y after 9/11 among Registry as children, and to determine whether poor asthma control is associated with specific factors including adolescent 9/11-exposure, adverse mental health, behavior problems, and unmet healthcare needs