Xanthogranulomatous pyelonephritis with associated renal cell carcinoma.

Xanthogranulomatous pyelonephritis is associated with obstruction, stones and infection. CT is the mainstay of diagnosis, but appearances can mimic other conditions, including renal cell carcinoma. Nephrectomy is commonly recommended, but conservative treatment with antibiotics has been described after tissue diagnosis. We present a case of xanthogranulomatous pyelonephritis with concomitant renal cell carcinoma, which was an association that was suggested in 1988 and supported by subsequently reported cases. Conservative management of biopsy or cytology proven xanthogranulomatous pyelonephritis is unsafe, as an area of synchronous malignant tumour may be missed: we recommend it only in patients unfit for nephrectomy.

Deep coal mining and meningococcal meningitis in England and Wales, 1931-38: Ecological study, with implications for deep shaft mining activities worldwide.

The hypothesized role of deep coal mining in the development of community-based outbreaks of meningococcal meningitis has gone largely unexplored. Taking the coalfields of Britain as a historical testbed, techniques of linear and binomial logistic regression were used to assess the association between meningococcal meningitis rates and male occupation rates for coal mining in England and Wales during the national epidemic of 1931-32 and in its aftermath. Adjusting for the epidemiological effects of age, residential density, recent changes in the number of families, housing stock and low social class, the analysis yielded evidence of a significant and positive association between coal mining occupation rates and notified levels of meningitis activity in the epidemic period. Communities in areas of the world that currently maintain substantial deep coal extraction industries may be at increased risk for the epidemic transmission of meningococcal meningitis.

Variola minor in coalfield areas of England and Wales, 1921-34: Geographical determinants of a national smallpox epidemic that spread out of effective control.

This paper uses techniques of binary logistic regression to identify the spatial determinants of the last national epidemic of smallpox to spread in England and Wales, the variola minor epidemic of 1921-34. Adjusting for age and county-level variations in vaccination coverage in infancy, the analysis identifies a dose-response gradient with increasing odds of elevated smallpox rates in local government areas with (i) medium (odds ratio [OR] = 5.32, 95% Confidence Interval [95% CI] 1.96-14.41) and high (OR = 11.32, 95% CI 4.20-31.59) coal mining occupation rates and (ii) medium (OR = 16.74, 95% CI 2.24-125.21) and high (OR = 63.43, 95% CI 7.82-497.21) levels of residential density. The results imply that the spatial transmission of variola virus was facilitated by the close spatial packing of individuals, with a heightened transmission risk in coal mining areas of the country. A syndemic interaction between common respiratory conditions arising from exposure to coal dust and smallpox virus transmission is postulated to have contributed to the findings. We suggest that further studies of the geographical intersection of coal mining and acute infections that are transmitted via respiratory secretions are warranted.

Influenza epidemics in Iceland over 9 decades: changes in timing and synchrony with the United States and Europe.

Influenza epidemics exhibit a strongly seasonal pattern, with winter peaks that occur with similar timing across temperate areas of the Northern Hemisphere. This synchrony could be influenced by population movements, environmental factors, host immunity, and viral characteristics. The historical isolation of Iceland and subsequent increase in international contacts make it an ideal setting to study epidemic timing. The authors evaluated changes in the timing and regional synchrony of influenza epidemics using mortality and morbidity data from Iceland, North America, and Europe during the period from 1915 to 2007. Cross-correlations and wavelet analyses highlighted 2 major changes in influenza epidemic patterns in Iceland: first was a shift from nonseasonal epidemics prior to the 1930s to a regular winter-seasonal pattern, and second was a change in the early 1990s when a 1-month lag between Iceland and the United States and Europe was no longer detectable with monthly data. There was a moderate association between increased synchrony and the number of foreign visitors to Iceland, providing a plausible explanation for the second shift in epidemic timing. This suggests that transportation might have a minor effect on epidemic timing, but efforts to restrict air travel during influenza epidemics would likely have a limited impact, even for island populations.

Infectious diseases: emergence and re-emergence; a geographical analysis

Reprinted 2010.(AU)

Controlling the geographical spread of infectious disease: plague in Italy, 1347-1851.

After the establishment of the first quarantine station in the Republic of Ragusa (modern-day Dubrovnik) in 1377, the states and principalities of Italy developed a sophisticated system of defensive quarantine in an attempt to protect themselves from the ravages of plague. Using largely unknown and unseen historical maps, this paper reconstructs the extent and operation of the system used. It is shown that a cordon sanitaire existed around the coast of Italy for several centuries, consisting of three elements: (i) an outer defensive ring of armed sailing boats in the Mediterranean and the Adriatic, (ii) a middle coastal ring of forts and observation towers, and (iii) an inner defensive ring of land-based cavalry. The principles established, although not especially successful at the time against a disease of (then) unknown aetiology, are still used today in attempts to control the spread of infections of animal and human populations.

An exploratory method for estimating the changing speed of epidemic waves from historical data.

BACKGROUND: Historical data are necessary to establish long-term trends in disease incidence but pose analytical problems since their accuracy and reliability may be poorly specified. METHODS: A robust measure of the spatial velocity, R(0A), of epidemic waves from space-time series is proposed using binary data. The method was applied to the historical records of influenza morbidity for the island of Iceland over a 61-year period of influenza seasons from 1915-16 to 1975-76. RESULTS: The onset of influenza waves tended to speed up over the period studied and the three pandemic waves associated with viral shifts in influenza A [Spanish influenza H1N1 (1918-19), Asian influenza H2N2 (1957-58) and Hong Kong influenza H3N2 (1968-69)] spread more rapidly around the island and struck earlier in the influenza season than did inter-pandemic waves, even when the latter were equally intensive as measured by total number of cases and case incidence. DISCUSSION: The potential for using R(0A) in a real-time context is explored using French influenza data. CONCLUSIONS: The new measure of wave velocity appears to be applicable to those historical time series where breakdown into regional or local areas is available. The study is being extended to (i) other countries where similar influenza time series are available and (ii) to other diseases within Iceland.

A swash-backwash model of the single epidemic wave.

While there is a large literature on the form of epidemic waves in the time domain, models of their structure and shape in the spatial domain remain poorly developed. This paper concentrates on the changing spatial distribution of an epidemic wave over time and presents a simple method for identifying the leading and trailing edges of the spatial advance and retreat of such waves. Analysis of edge characteristics is used to (a) disaggregate waves into 'swash' and 'backwash' stages, (b) measure the phase transitions of areas from susceptible, S, through infective, I, to recovered, R, status (S --> I --> R) as dimensionless integrals and (c) estimate a spatial version of the basic reproduction number, R(0). The methods used are illustrated by application to measles waves in Iceland over a 60-year period from 1915 to 1974. Extensions of the methods for use with more complex waves are possible through modifying the threshold values used to define the start and end points of an event.

The spatial structure of epidemic emergence: geographical aspects of poliomyelitis in north-eastern USA, July-October 1916.

The great epidemic of poliomyelitis which swept New York City and surrounding territory in the summer of 1916 eclipsed all previous global experience of the disease. We draw on epidemiological information that is included in the seminal US Public Health Bulletin 91, 'Epidemiologic studies of poliomyelitis in New York City and the northeastern United States during the year 1916' (Washington DC, 1918), to re-examine the spatial structure of the epidemic. For the main phase of transmission of the epidemic, July-October 1916, it is shown that the maximum concentration of activity of poliomyelitis occurred within a 128-km radius of New York City. Although the integrity of the poliomyelitis cluster was maintained up to approximately 500 km from the metropolitan focus, the level and rate of propagation of disease declined with distance from the origin of the epidemic. Finally, it is shown that the geographical transmission of the epidemic in north-eastern USA probably followed a process of mixed contagious-hierarchical diffusion.

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

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 Service's Public Health Reports and the U.S. Centers for Disease Control and Prevention's 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.

Time, travel and infection.

The collapse of geographical space over the last 200 years has had profound effects on the circulation of human populations and on the transfer of infectious diseases. Three examples are used to illustrate the process: (a) the impact of the switch from sail to steamships in importing measles into Fiji over a 40-year period; (b) changes in measles epidemic behaviour in Iceland over a 150-year period; and (c) changes in the spread of cholera within the United States over a 35-year period. In each case, the link between time, travel and disease has been an intimate one.

Impact of infectious diseases on war.

Wartime epidemics of infectious diseases have decimated the fighting strength of armies, caused the suspension and cancellation of military operations, and brought havoc to the civil populations of belligerent and nonbelligerent states. This article summarizes the principal factors that have contributed to the spread of infectious diseases in past wars and reviews the associated demographic losses in military and civil populations. Drawing on the detailed epidemiologic records for the United States Army, case studies of the spread of infectious diseases in relation to military mobilization are presented for the American Civil War, Spanish-American War,and World War I. The article concludes with a brief overview of infectious disease activity in high- and low-intensity conflicts of the late twentieth and early twenty-first centuries.