Matthew Smallman-Raynor

Avian influenza A (H5N1) age distribution in humans.

To the Editor: A total of 229 confirmed human cases of avian influenza A (H5N1) were reported to the World Health Organization (WHO) from 10 countries of Africa, Asia, and Europe in the 30 months leading up to July 4, 2006 (1). WHO has highlighted the skewed age distribution of these confirmed cases toward children and young adults, with relatively few cases in older age categories (2). An explanation for this age bias is currently lacking, although a range of behavioral, biological, demographic, and data-related factors may account for the observed pattern (2,3).

The Spatial Dynamics of Poliomyelitis in the United States: From Epidemic Emergence to Vaccine-Induced Retreat, 1910-1971.

Abstract This article seeks to advance an understanding of the spatial dynamics of one of the great emergent viral diseases of the twentieth century—poliomyelitis. From an apparently rare clinical condition occurring only sporadically or in small outbreaks before the late nineteenth century, poliomyelitis had, by the early 1950s, developed into a globally distributed epidemic disease. But, from 1955, continued growth was suddenly and dramatically reversed by the mass administration of inactivated (killed) and live (attenuated) poliovirus vaccines. After almost half a century of vaccine control, the world now stands on the brink of the global eradication of the disease. Against this background, the article draws upon information included in the U.S. Public Health Services Public Health Reports and the U.S. Centers for Disease Control and Preventions Morbidity and Mortality Weekly Report to examine the spatial dynamics of poliomyelitis during the phases of epidemic emergence (1910–1955) and vaccine-induced retreat (1955–1971) in the United States. It is shown that epidemic emergence was accompanied by shifts in the spatial center of activity from early diffusion poles in the northeastern states, to the western seaboard, and then finally to cover all the states of the Union. This was accompanied by accelerating epidemic propagation. The introduction of mass vaccination from the mid-1950s realigned spatial transmission of the disease, producing increased spatial volatility in the geographical center of activity and heightened dependence of epidemic outbreaks upon endemic reservoirs in the most populous states. Finally, the empirical results are generalized to suggest that the emergence and reemergence of many infectious diseases is a distinctively geographical process.

Late stages of epidemiological transition: health status in the developed world

Drawing on the example of twentieth century Europe, this paper examines themes in the spatial development of the late stages of epidemiological transition in developed countries. A preliminary analysis of mortality trends for sample countries in four European regions (north, Scandinavia, south and east) suggests that, as the epidemiological transition progressed to its later stages during the period 1901-1975, spatial variability in the importance of classical infectious diseases increased. This trend was countered by a spatial convergence in the importance of disease groupings that typify late transition. An apparently new epidemiological phase in late transition, linked to the emergence and re-emergence of infectious and parasitic diseases, is illustrated with reference to tuberculosis and the acquired immunodeficiency syndrome (AIDS).

Epidemic Diffusion Processes in a System of U.S. Military Camps: Transfer Diffusion and the Spread of Typhoid Fever in the Spanish-American War, 1898

This article examines the geographical transmission of an epidemic disease in the makeshift encampments of a mobilized army. The choice of location (the southern and eastern United States), the time (an eight-month period of mobilization in the U.S. war with Spain, May to December 1898) and the epidemic disease (typhoid fever) are conditioned by the reports collated by three eminent figures in the history of medicine–Major Walter Reed, Major Victor C. Vaughan, and Major Edward O. Shakespeare–and published in the historic 1904 Report on the Origin and Spread of Typhoid Fever in U.S. Military Camps During the Spanish War of 1898. The Report includes information on the daily occurrence of some 19,000 cases of typhoid fever in 89 volunteer regiments of the U.S. Army. When geo-coded to the locations of army camps, this information is used (i) to reconstruct the spread of typhoid fever with the campwise movements of infected regiments and (ii) to model the diffusion process that drove the spread of the disease. To handle the high degree of regimental mobility in the camp system, a novel process referred to as transfer diffusion is introduced. It is shown that, for the entire system of camps, the spread of typhoid was underpinned by a temporally ordered sequence of diffusion processes in which each process was associated with a discrete stage of the epidemic cycle. The processes reflected the spatial transfer of regiments (epidemic buildup), the geographical proximity of camps (epidemic peak), and the position of camps in the transient population size hierarchy (epidemic fadeout). Importantly, however, the strength and timing of the processes varied by corps. While the findings underscore the singular impact of military mobilization on the spatial dynamics of epidemic diseases, it is suggested that the particular approach adopted in this article may be extended to the study of epidemic transmission in analogous camp settings.

The Geographical Spread of Avian Influenza A (H5N1): Panzootic Transmission (December 2003–May 2006), Pandemic Potential, and Implications

The World Health Organization (WHO) believes that the advent of highly pathogenic avian influenza A (H5N1) has moved the world closer to a further global pandemic of human influenza than at any time since the Hong Kong (H3N2) pandemic of 1968–1969. The immediacy of the perceived threat is underscored by the current classification of the world at Phase 3 of WHOs operative six-phase system of pandemic alert, with H5N1 having met all the prerequisites for the onset of a human pandemic but one: the efficient and sustained person-to-person transmission of the virus. With preparations for an anticipated pandemic now recognized as a global health priority, the purpose of this article is to provide a foundation for geographical research on avian influenza A (H5N1). The article introduces geographers to the complex nature and ecology of H5N1, the principal data sources available to analyze the global occurrence of the virus in birds and humans, and evidence regarding its geographical origins and international dispersal during the first thirty months of the ongoing panzootic in wild birds and poultry, from December 2003 through May 2006. Key epidemiological facets of the disease in humans are examined. We conclude with a review of the incurred and projected economic costs of H5N1, global plans for pandemic aversion and mitigation, and prospects for the future geographical expansion of the virus. Areas in which geographers can make an effective contribution to knowledge about the virus and the disease are considered.

The geographical spread of cholera in the Crimean War: epidemic transmission in the camp systems of the British Army of the East, 1854–55

Abstract The epidemic of Asiatic cholera that decimated the commands of the British Army during the Crimean War (1853–56) spread as two discrete waves of infection. This paper presents a geographical examination of the diffusion of the first, and more severe, cholera wave (June 1854–February 1855) in the encampments of the British Army during the Bulgarian (1854) and the Crimean (1854–55) phases of the conflict. To these ends, we draw on the information included in the monumental report, The Medical and Surgical History of the British Army which Served in Turkey and the Crimea, prepared by the Army Medical Department and presented to Parliament in 1858. The History includes textual accounts of the progress of the epidemic wave, and numerical evidence regarding cholera-related morbidity and mortality in 66 regiments of the British Army. This information is first used to reconstruct the routes by which cholera spread in the British camp system of Bulgaria. Using techniques of multidimensional scaling, it is shown that the spread process was mediated through a camp connectivity space in which similarities in the regimental patterns of occupancy with two camps (Devna and Varna) were to govern the sequence of epidemic transmission. Within the Crimea, the magnitude and velocity of cholera transmission on the plateau before Sebastopol is shown to have been conditioned by a complex of factors relating to the size of incoming drafts, prior service in Bulgaria, and location within the siege camp.

Spatiotemporal patterns of pandemic influenza-related deaths in Allied naval forces during 1918.

This paper draws on the mortality records of the French, US and UK Royal navies to reconstruct the spatiotemporal evolution of the 1918–1919 influenza pandemic in global Allied naval forces. For a total of 7658 deaths attributed to respiratory diseases (French and US navies) and all diseases (UK Royal Navy) at 514 locations worldwide, techniques of spatial point pattern analysis were used to generate weekly maps of global mortality intensity in 1918. The map sequence for the main period of pandemic mortality, mid-August to mid-November 1918, revealed a near-simultaneous development of mutiple foci of high disease intensity in three distant locations (Europe, North America, West Africa). Given the relatively slow speed of naval ships in convoy at this time (<12 knots), our findings suggest that the pandemic influenza virus was circulating on three continents at the observed onset of the main mortality wave.

Epidemiological spaces: the use of multidimensional scaling to identify cholera diffusion processes in wake of the Philippines insurrection, 1899–1902

Between 1902 and 1904 an epidemic of cholera, fuelled initially by the operations of the Philippine-American War (1899–1902), swept through the Philippine Islands in two waves. In earlier papers, the authors showed that spatially contagious spread dominated the waves at the geographical levels of province, island and nation (Smallman-Raynor and Cliff 1998a, b). To explore the visualization and analysis of epidemic transmission in an alternative metric, the present paper uses multidimensional scaling (MDS) to translate the spread corridors followed by the waves from conventional geographical space into non-Euclidean cholera spaces. The re-mapping confirms the importance of contagious diffusion in the spread of the epidemic, but also picks out the moments in time in which spread driven through the population hierarchy switched in. In addition, the analysis illustrates the utility of constructing non-Euclidean spaces to identify disease diffusion processes.

Common acute childhood infections and appendicitis: a historical study of statistical association in 27 English public boarding schools, 1930-1934.

Although the involvement of common childhood infections in the aetiology of acute appendicitis has long been conjectured, supporting evidence is largely restricted to a disparate set of clinical case reports. A systematic population-based analysis of the implied comorbid associations is lacking in the literature. Drawing on a classic epidemiological dataset, assembled by the School Epidemics Committee of the United Kingdoms Medical Research Council (MRC) in the 1930s, this paper presents a historical analysis of the association between termly outbreaks of each of six common childhood infections (chickenpox, measles, mumps, rubella, scarlet fever and whooping cough) and operated cases of acute appendicitis in 27 English public boarding schools. When controlled for the potential confounding effects of school, year and season, multivariate negative binomial regression revealed a positive association between the level of appendicitis activity and the recorded rate of mumps (beta=0.15, 95% CI 0.07-0.24, P<0.001). Non-significant associations were identified between appendicitis and the other sample infectious diseases. Subject to data caveats, our findings suggest that further studies are required to determine whether the comorbid association between mumps and appendicitis is causal.

The geographical transmission of smallpox in the Franco-Prussian War: prisoner of war camps and their impact upon epidemic diffusion processes in the civil settlement system of Prussia, 1870–71

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