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Biomedical subjects

P Haggett

Publications and source records attributed to P Haggett.

14 recordsLinked to original sources
PubMed1999

Spatial and temporal patterns in final amendments to provisional disease counts.

This article examines temporal and spatial patterns in the relationship between provisional and amended reports for Hepatitis A and Hepatitis B received from each state by the Centers for Disease Control and Prevention through the U.S. National Notifiable Diseases Surveillance System from 1980 to 1992. It demonstrates that, as the 1980s unfolded, the preliminary disease reports became less representative markers of final disease counts. Practitioners at the state and community levels need to be aware of the temporal and spatial instabilities in such provisional data if they are used to provide early warning of contemporary health aberrations.

Centers for Disease Control and Prevention, U.S.↗
PubMed1997

The importance of long-term records in public health surveillance: the US weekly sanitary reports, 1888-1912, revisited.

BACKGROUND: This paper outlines the ways in which a little-used archive of early public health records may throw light on longer-term trends in international epidemic behaviour and serve as a major source of epidemiological information for historians of urbanization and public health. The Weekly Abstract of Sanitary Reports was the official disease surveillance report of the US Public Health Service and its predecessors, and began to publish urban mortality statistics on a regular basis in 1888. Here, the authors describe the first 25 years of continuous reporting (1888-1912), when the Reports contained not only disease data for US cities, but also records sent back by US consuls based in some 250 cities in many parts of the world. METHODS: The content of the weekly editions of the Reports was systematically sampled and analysed using graphical techniques and the simple statistical method of running means. RESULTS: Relatively complete weekly series of mortality from all causes, and six infectious diseases (diphtheria, enteric or typhoid fever, measles, scarlet fever, tuberculosis and whooping cough) were identified for a total of 100 cities world-wide. CONCLUSION: Reporting coverage for these cities is sufficiently complete that multivariate analysis should be possible to obtain a comparative picture of mortality for many parts of the world. Despite limitations of the data, sources of the type described in this paper form an important comparative database for studying international patterns of mortality.

Communicable Diseases↗
PubMed1995

The application of multidimensional scaling methods to epidemiological data.

This paper illustrates the use of multidimensional scaling methods (MDS) to examine space-time patterns in epidemic data. The paper begins by outlining the principles of MDS. The model is then formally specified and illustrated by application to two data sets. The first is partly a tutorial example. It uses monthly reported measles morbidity data for the 31-year period from January 1960 to December 1990, collected for the 50 states of the USA, plus New York City and the District of Columbia. These data are used to explore the various ways in which MDS may be used to identify changing spatial patterns in geographically-coded data. In addition to their tutorial use, the data are also employed to search for any substantive changes in the geographical structure of measles epidemics in the USA that may have followed the introduction of mass vaccination in 1965. New England appears to have developed an epidemic profile distinct from the rest of the USA, and there is tentative evidence of an urban-rural split in epidemic characteristics. The second data set takes annual reported measles mortality data for New Zealand and the states of Australia from 1860 to 1949. MDS is used to show how the spatial relationships among these geographical units have changed over time in response to changes in the sizes of local susceptible populations.

Australia↗
PubMed1993

Statistical modelling of measles and influenza outbreaks.

This paper reviews the application of statistical models to outbreaks of two common respiratory viral diseases, measles and influenza. For each disease, we look first at its epidemiological characteristics and assess the extent to which these either aid or hinder modelling. We then turn to the models that have been developed to simulate geographical spread. For measles, a distinction is drawn between process-based and time series models; for influenza, it is the scale of the communities (from small groups to global populations) which primarily determines modelling style. Applications are provided from work by the authors, largely using Icelandic data. Finally we consider the forecasting potential of the models described.

Adolescent↗
PubMed1992

The geographic structure of measles epidemics in the northeastern United States.

The incidence of disease across geographic space often produces distinctive regional patterns. In this paper, a modeling approach to the identification of the factors that shape the patterns is presented, and a procedure for fitting the model to observed data is given. The methodology is illustrated by an application to the geographic structure of measles epidemics among 22 states of the northeastern United States, New York City, and Washington, D.C., from 1962 to 1988. The patterns identified are interpreted in terms of the spatial behavior of measles epidemics in the region, and the implications of the methodology for surveillance and control are considered.

Humans↗
PubMed1992

The changing geographical coherence of measles morbidity in the United States, 1962-88.

Geographical coherence may be defined as the degree to which the behaviour of a time series in one geographical area corresponds with the time series behaviour in another. This paper illustrates the concept using the epidemiological time series of reported monthly measles morbidity for the states of the United States for the 27 years from January 1962 to December 1988. Over this period, as measles morbidity has declined in response to vaccination campaigns, and as the seasonal peaking of the disease in late spring has become less pronounced, the geographical coherence has altered at the national, divisional, regional and state levels. There was a steady decline in coherence from 1962 to 1980. In 1981, a dramatic reduction occurred, but there has been some recovery since. The implications for spatial forecasting models of these reducing levels of coherence are discussed.

Cross-Sectional Studies↗
PubMed1984

Island epidemics.

Explore the source record for details and available documents.

Disease Outbreaks↗
PubMed1983

Forecasting epidemic pathways for measles in Iceland: the use of simultaneous equation and logit models.

Six measles transmission chains between pairs and triplets of medical districts in Iceland are identified using monthly data for the 26 years from 1945 to 1970. The years studied are divided into two halves, a calibration period (1945-1957) and a forecast period (1958-1970). Some simultaneous equation models of the chains are developed and fitted using three-stage least squares. The resulting one month ahead forecasts are presented in terms of the expected case levels and as the probability of epidemics occurring. A single equation probability model using a logistic transformation is then formulated and compared with the simultaneous equation approach. The results obtained from the Icelandic study confirm in practice the advantages theoretically expected from setting up forecasting models containing geographically based chain transmission components.

Disease Outbreaks↗
PubMed1982

Methods for the measurement of epidemic velocity from time-series data.

Two approaches to the measurement of epidemic velocity are presented. The first uses the moments of the frequency distribution of reported cases of a disease against time. The second is based upon an analysis of the growth parameter of a logistic model. The methods are illustrated by applications to some hypothetical and actual epidemic waves.

Disease Outbreaks↗
PubMed1980

Changes in the seasonal incidence of measles in Iceland, 1896--1974.

The changing seasonal patterns of reported measles cases in Iceland during this century are analysed. These changes are related to increased population mobility following the development of external and internal transport links, particularly since 1945. The forging of such links has resulted in a shift in the seasonal distribution of cases from one peculiar to the local social and economic conditions in Iceland to one broadly similar to that in other countries of northern temperate latitudes.

Humans↗
PubMed1977

Variola minor in Braganca Paulista county, 1956: a trend-surface analysis.

Trend-surface analysis (TSA), a form of polynomial regression used in geology, ecology and geography, was applied to analysis of the spread of an epidemic of variola minor in a small Brazilian city. Cubic surfaces gave a generalized map of the space-time distribution of the epidemic, allowing those parts of the city to be identified where variola minor was spreading rapidly or slowly. The epidemic spread relatively quickly over the core area of the city, especially to the peripherally located household dwellings in a northeast to south-west direction. The dwellings of adults and pre-school children introducing the disease into their households broadly followed the overall pattern. School child introductory cases from a southern-located school yielded a saddle-shaped contour pattern, centered about the school; but this pattern was not repeated for the school serving the northern half of the city, which showed a ridge-shaped pattern dipping toward the west. Cubic surfaces for the influence of certain household and individual characteristics were investigated, but showed only week trends. The nearest match to the bowl-shaped overall pattern of introductory dates was provided by the vaccination level of the households. From this application, it appears that TSA permits the identification of regional trends in an objective manner and gives a quantitative measure of the importance of these regional trends in terms of the overall variation in the spatial pattern.

Adult↗