Typhoid Fever and Its Association with Environmental Factors in the Dhaka Metropolitan Area of Bangladesh: A Spatial and Time-Series Approach

PLoS Negl Trop Dis PLOS Neglected Tropical Diseases, 24 January 2013

Ashraf M. Dewan, Robert Corner, Masahiro Hashizume, and Emmanuel T. Ongee

“Typhoid fever is a major cause of death worldwide with a major part of the disease burden in developing regions such as the Indian sub-continent. Bangladesh is part of this highly endemic region, yet little is known about the spatial and temporal distribution of the disease at a regional scale. This research used a Geographic Information System to explore, spatially and temporally, the prevalence of typhoid in Dhaka Metropolitan Area (DMA) of Bangladesh over the period 2005–9. This paper provides the first study of the spatio-temporal epidemiology of typhoid for this region. The aims of the study were: (i) to analyse the epidemiology of cases from 2005 to 2009; (ii) to identify spatial patterns of infection based on two spatial hypotheses; and (iii) to determine the hydro-climatological factors associated with typhoid prevalence. Case occurrences data were collected from 11 major hospitals in DMA, geocoded to census tract level, and used in a spatio-temporal analysis with a range of demographic, environmental and meteorological variables. Analyses revealed distinct seasonality as well as age and gender differences, with males and very young children being disproportionately infected. The male-female ratio of typhoid cases was found to be 1.36, and the median age of the cases was 14 years. Typhoid incidence was higher in male population than female (χ2 = 5.88, p<0.05). The age-specific incidence rate was highest for the 0–4 years age group (277 cases), followed by the 60+ years age group (51 cases), then there were 45 cases for 15–17 years, 37 cases for 18–34 years, 34 cases for 35–39 years and 11 cases for 10–14 years per 100,000 people. Monsoon months had the highest disease occurrences (44.62%) followed by the pre-monsoon (30.54%) and post-monsoon (24.85%) season.

Spatial regression between typhoid incidence (per 100,000 people) and distance to water bodies.

Spatial regression between typhoid incidence (per 100,000 people) and distance to water bodies. A) Shows spatial distribution of the t-value, B) shows the parameter estimates.

“The Student’s t test revealed that there is no significant difference on the occurrence of typhoid between urban and rural environments (p>0.05). A statistically significant inverse association was found between typhoid incidence and distance to major waterbodies. Spatial pattern analysis showed that there was a significant clustering of typhoid distribution in the study area. Moran’s I was highest (0.879; p<0.01) in 2008 and lowest (0.075; p<0.05) in 2009. Incidence rates were found to form three large, multi-centred, spatial clusters with no significant difference between urban and rural rates. Temporally, typhoid incidence was seen to increase with temperature, rainfall and river level at time lags ranging from three to five weeks. For example, for a 0.1 metre rise in river levels, the number of typhoid cases increased by 4.6% (95% CI: 2.4–2.8) above the threshold of 4.0 metres (95% CI: 2.4–4.3). On the other hand, with a 1°C rise in temperature, the number of typhoid cases could increase by 14.2% (95% CI: 4.4–25.0).”

Decelerating Spread of West Nile Virus by Percolation in a Heterogeneous Urban Landscape

PLoS Comput BiolPLoS Computational Biology 7(7), 2011

Krisztian Magori, Waheed I. Bajwa, Sarah Bowden, and John M. Drake

“Vector-borne diseases are emerging and re-emerging in urban environments throughout the world, presenting an increasing challenge to human health and a major obstacle to development. Currently, more than half of the global population is concentrated in urban environments, which are highly heterogeneous in the extent, degree, and distribution of environmental modifications. Because the prevalence of vector-borne pathogens is so closely coupled to the ecologies of vector and host species, this heterogeneity has the potential to significantly alter the dynamical systems through which pathogens propagate, and also thereby affect the epidemiological patterns of disease at multiple spatial scales. One such pattern is the speed of spread. Whereas standard models hold that pathogens spread as waves with constant or increasing speed, we hypothesized that heterogeneity in urban environments would cause decelerating travelling waves in incipient epidemics.

The spatial structure of annual WNV outbreaks in NYC, demonstrated for the year of 2003.

The spatial structure of annual WNV outbreaks in NYC, demonstrated for the year of 2003. Speed of WNV spread was estimated from point locations of WNV-positive mosquito pools (circles) and WNV-positive dead birds (triangles). Dark and light cyan areas represent transmission-inhibiting and transmission-promoting land-cover types. The black crosses represent the approximate location of Central Park, La Guardia Airport and the John F. Kennedy International Airport respectively, where NOAA collects weather data. The first five locations where WNV was detected in 2003 are labeled as A, B, C, D, and E, respectively. The first estimate of wave-speed was calculated using the convex hull method as (1) the increase of the square root area of the polygon encompassing ABCDE (black) relative to the square root area of the polygon encompassing ABCD (red) locations (convex hull method).

“To test this hypothesis, we analysed data on the spread of West Nile virus (WNV) in New York City (NYC), the 1999 epicentre of the North American pandemic, during annual epizootics from 2000–2008. These data show evidence of deceleration in all years studied, consistent with our hypothesis. To further explain these patterns, we developed a spatial model for vector-borne disease transmission in a heterogeneous environment. An emergent property of this model is that deceleration occurs only in the vicinity of a critical point. Geostatistical analysis suggests that NYC may be on the edge of this criticality. Together, these analyses provide the first evidence for the endogenous generation of decelerating travelling waves in an emerging infectious disease. Since the reported deceleration results from the heterogeneity of the environment through which the pathogen percolates, our findings suggest that targeting control at key sites could efficiently prevent pathogen spread to remote susceptible areas or even halt epidemics.”

Global Mapping of Infectious Disease

Philosophical Transactions of the Royal Society B, 04 February 2013

Simon I. Hay, Katherine E. Battle, David M. Pigott, David L. Smith, Catherine L. Moyes, Samir Bhatt, John S. Brownstein, Nigel Collier, Monica F. Myers, Dylan B. George, and Peter W. Gething

“The primary aim of this review was to evaluate the state of knowledge of the geographical distribution of all infectious diseases of clinical significance to humans. A systematic review was conducted to enumerate cartographic progress, with respect to the data available for mapping and the methods currently applied. The results helped define the minimum information requirements for mapping infectious disease occurrence, and a quantitative framework for assessing the mapping opportunities for all infectious diseases. This revealed that of 355 infectious diseases identified, 174 (49%) have a strong rationale for mapping and of these only 7 (4%) had been comprehensively mapped.

A schematic overview of a niche/occurrence mapping process (for example boosted regression trees (BRT)) that uses pseudo-absence data guided by expert opinion. Consensus based definitive extent layers of infectious disease occurrence at the national level (a) are combined with accurately geo-positioned occurrence (presence) locations (b) to generate pseudo-absence data (c). The presence (b) and pseudo-absence data (c) are then used in the BRT analyses, alongside a suite of environmental covariates (d ) to predict the probability of occurrence of the target disease (e).

A schematic overview of a niche/occurrence mapping process (for example boosted regression trees (BRT)) that uses pseudo-absence data guided by expert opinion. Consensus based definitive extent layers of infectious disease occurrence at the national level (a) are combined with accurately geo-positioned occurrence (presence) locations (b) to generate pseudo-absence data (c). The presence (b) and pseudo-absence data (c) are then used in the BRT analyses, alongside a suite of environmental covariates (d ) to predict the probability of occurrence of the target disease (e).

“A variety of ambitions, such as the quantification of the global burden of infectious disease, international biosurveillance, assessing the likelihood of infectious disease outbreaks and exploring the propensity for infectious disease evolution and emergence, are limited by these omissions. An overview of the factors hindering progress in disease cartography is provided. It is argued that rapid improvement in the landscape of infectious diseases mapping can be made by embracing non-conventional data sources, automation of geo-positioning and mapping procedures enabled by machine learning and information technology, respectively, in addition to harnessing labour of the volunteer ‘cognitive surplus’ through crowdsourcing.”

Developing Context-sensitive Livability Indicators for Transportation Planning: A Measurement Framework

Journal of Transport GeographyJournal of Transport Geography, Volume 26, January 2013, Pages 51–64

Harvey J. Miller, Frank Witlox, and Calvin P. Tribby


  • Community livability concepts are receiving new emphases in transportation planning.
  • This paper provides a framework for constructing quantitative livability indicators.
  • We critically review indicator construction methods based on multicriteria analysis.
  • We discuss methods for capturing diverse stakeholder perspectives and geographic context.
  • We also discuss strategies for integrating indicators into transportation planning.

“New emphases on livability and sustainability are creating demands for measuring and applying these concepts in transportation policy and planning. However, livability and sustainability are complex, multidimensional concepts that require careful measurement if they are to be applied meaningfully in plan evaluation and benchmarking.


Conceptual foundation of multidimensional indicators.

“This paper provides a framework for constructing and applying quantitative livability and sustainability indicators. In addition to critically reviewing principles of constructing indicators describing a multidimensional concept such as livability or sustainability, we also discuss methods for capturing local context, a critical feature for transportation planning. Specifically, we review methods for incorporating diverse stakeholder perspectives into indicator construction and spatial analytic tools for geographic entities and relationships. We also discuss spatial decision support systems and the Geodesign concept for organizing these tools and technologies as well as integrating livability indicators into the overall planning process.”

Mapping Different Forms of Mobility in the Milan Urban Region

Journal of MapsJournal of Maps, Volume 8, Issue 4, December 2012

Fabio Manfredini and Paolo Dilda

“The increase in urban mobility is one of the key issues of contemporary cities. The need for new types of data and representations useful to describe the new forms of daily urban mobility is widely known. The wider urban scale – named urban region – is the scale at which most of the urban and socio-economical phenomena are visible. Urban growth patterns, settlements and activities distribution, demographics and economics dynamics can be fully understood and interpreted at this macro scale, which is not recognizable on the administrative boundaries. The aim of this paper is to present three approaches to mobility mapping based on different data sources, both traditional and innovative, for the Milan urban region (Northern Italy). Traditional sources for the analysis of daily mobility are Census data or surveys based on interviews to mobile populations. They provide a very partial picture of the mobility practices in urban areas, because they collect only flows for job and study purposes. Innovative sources of data are mobile phone activity data that have been used for building a sequence of mobility maps in a typical working day. The Main Map is therefore composed of two parts: a representation of systematic and non-systematic mobility in the Milan urban region; and a sequence of maps created by using telephone traffic data showing daily mobility patterns. These maps can provide useful information for understanding the recent changes that had occurred in the Milan urban region, but they can also offer a methodological reference for the analysis of mobility in general.”

Health, Poverty, and Place in Accra, Ghana: Mapping Neighborhoods

Journal of MapsJournal of Maps, Volume 8, Issue 4, December 2012

Gregory M. Verutes, Magdalena B. Fiocco, John R. Weeks, and Lloyd L. Coulter

“The overall objective of our research project is to understand the spatial inequality in health in Accra, the capital city of Ghana. We also utilize GIS technology to measure the association of adverse health and mortality outcomes with neighborhood ecology. We approached this in variety of ways, including multivariate analysis of imagery classification and census data. A key element in the research has been to obtain in-person interviews from 3200 female respondents in the city, and then relate health data obtained from the women to the ecology of the neighborhoods in which they live. Detailed maps are a requirement for these field-based activities. However, commercially available street maps of Accra tend to be highly generalized and not very useful for the kind of health and social science research being undertaken by this project. The purpose of this paper is to describe street maps that were created for the project’s office in downtown Accra and used to locate households of respondents. They incorporate satellite imagery with other geographic layers to provide the most important visual interpretation of the linkage between imagery and neighborhoods. Ultimately, through a detailed analysis of spatial disparities in health in Accra, Ghana, we aim to provide a model for the interpretation of urban health inequalities in cities of urbanizing and often poor countries.”

Mapping the Evolution of Racially Mixed and Segregated Neighborhoods in Chicago

Journal of MapsJournal of Maps, Volume 8, Issue 4, December 2012

Jonathan Chipman, Richard Wright, Mark Ellis & Steven R. Holloway

“The Chicago metropolitan region consists of a spatially complex mosaic of neighborhoods, in which measures of racial and ethnic composition vary dramatically. Understanding these patterns and their evolution has been hindered by ambiguities in the use of terms like ‘diverse’ or ‘segregated’, which are often posited as opposite ends of a one-dimensional scale. Using a new taxonomy of neighborhood composition, we have mapped the evolving patterns of Chicago’s neighborhoods in 1990, 2000, and 2010, and tabulated census tracts that have undergone transitions or remained stable. Looking beyond the Chicago metropolitan area, we have developed an interactive atlas of similar maps for states and metropolitan areas across the United States.”

Federal Seafood Safety Response to the Deepwater Horizon Oil Spill

Proceedings of the National Academy of Sciences (PNAS), December 11, 2012 vol. 109 no. 50 20274-20279

Gina M. Ylitaloa, Margaret M. Krahn, Walton W. Dickhoff, John E. Stein, Calvin C. Walker, Cheryl L. Lassitter, E. Spencer Garrett, Lisa L. Desfosse, Karen M. Mitchell, Brandi T. Noble, Steven Wilson, Nancy B. Beck, Ronald A. Benner, Peter N. Koufopoulos, and Robert W. Dickey

“Following the 2010 Deepwater Horizon oil spill, petroleum-related compounds and chemical dispersants were detected in the waters of the Gulf of Mexico. As a result, there was concern about the risk to human health through consumption of contaminated seafood in the region. Federal and Gulf Coast State agencies worked together on a sampling plan and analytical protocols to determine whether seafood was safe to eat and acceptable for sale in the marketplace.


“Sensory and chemical methods were used to measure polycyclic aromatic hydrocarbons (PAHs) and dispersant in >8,000 seafood specimens collected in federal waters of the Gulf. Overall, individual PAHs and the dispersant component dioctyl sodium sulfosuccinate were found in low concentrations or below the limits of quantitation. When detected, the concentrations were at least two orders of magnitude lower than the level of concern for human health risk. Once an area closed to fishing was free of visibly floating oil and all sensory and chemical results for the seafood species within an area met the criteria for reopening, that area was eligible to be reopened. On April 19, 2011 the area around the wellhead was the last area in federal waters to be reopened nearly 1 y after the spill began. However, as of November 9, 2011, some state waters off the Louisiana coast (Barataria Bay and the Delta region) remain closed to fishing.”

Spatial Analysis of the Crime Distribution: A Case Study in João Pessoa-PB-Brazil

8th FIG Regional Conference 2012: Surveying towards Sustainable Development, Montevideo, Uruguay, 26 – 29 November 2012

Anderson Marcolino de SANTANA and Lucilene Antunes Correia Marques de SÁ

“Technological advancement the information has spread with great speed. This fact has contributed to the violence news become more frequent in the media. An important characteristic for the analysis location crime is understood that the event occurs at locations not accidental or unexpected. It’s this feature that makes maximum Cartography is a powerful tool for research, it involves location. Thus, the article aims at reporting the experience of understanding aimed at mapping the spatial distribution of the occurrences crimes of violence against property in João Pessoa – Paraíba – Brazil, in the month of May 2012, presenting the phenomenon in thematic maps, which show the points where there are crimes with firearms and knives, as well as the map of high-density areas of crime. Specifically with the conclusion of this article can be identified as the cartography is useful for spatial analysis and may subsidize actions of municipal, state and federal, and local civil society, aimed at combating violence and crime in the city.

Map Kernel: Violent Crime sheets in the city of João Pessoa.

Map Kernel: Violent Crime sheets in the city of João Pessoa.

“The results shows that the mapping crime or any other phenomenon is important because it allows to know how it is distributed through space, and thus able to monitor mitigation policies. Therefore, the Cartography occupies an important place among the sciences to help fight crime, since based on a map with the spatial distribution of crimes in an area can provide efficient operational safety features. By analyzing the maps it is clear that the amount of crimes using firearms was very big, so it would be interesting to disarmament campaigns in neighborhoods, followed by installation of core security on site, minimizing the increase in cases of crimes violence against property. Cartography and crime mapping analysis can assist in planning, and implementation of action plans to minimize the cost of operations and more effectively, since the study area is already known and the whole strategy can be applied.”

Spatial Analysis of a Community-based Selection on Indigents Receiving the User Fee Exemption in Burkina Faso

2nd Global Symposium on Health Systems Research, 31 October – 3 November 2012, Beijing, China

V. Riddle, E. Bonnet, A. Nikiema, and K. Kadio

“Over recent decades, Burkina Faso has improved the geographic accessibility of its health centres. However, patients are still required to pay point-of-service user fees, which excludes the most  vulnerable from access to care. In 2010, 259 village committees in the Ouargaye district selected 2649  indigents to be exempted from user fees. The 26 health centre management committees that fund this  exemption retained 1097 of those selected indigents.

“Spatial analysis showed that the management  committees retained the indigents who were geographically closer to the health centres, in contrast  to the selections of the village committees which were more diversified. Using village committees to  select indigents would seem preferable to using management committees. It is not yet known whether  the management committees’ selections were due to a desire to maximize the benefits of exemption  by giving it to those most likely to use it, or to the fact that they did not personally know the indigents  who were more geographically distant from them, or that some villages are not represented at the  management committees.”