Biomedical subjects

W Wint

Publications and source records attributed to W Wint.

5 recordsLinked to original sources

PubMed2005

Cattle movements and bovine tuberculosis in Great Britain.

For 20 years, bovine tuberculosis (BTB) has been spreading in Great Britain (England, Wales and Scotland) and is now endemic in the southwest and parts of central England and in southwest Wales, and occurs sporadically elsewhere. Although its transmission pathways remain poorly understood, the disease's distribution was previously modelled statistically by using environmental variables and measures of their seasonality. Movements of infected animals have long been considered a critical factor in the spread of livestock diseases, as reflected in strict import/export regulations, the extensive movement restrictions imposed during the 2001 foot-and-mouth disease outbreak, the tracing procedures after a new case of BTB has been confirmed and the Government's recently published strategic framework for the sustainable control on BTB. Since January 2001 it has been mandatory for stock-keepers in Great Britain to notify the British Cattle Movement Service of all cattle births, movements and deaths. Here we show that movements as recorded in the Cattle Tracing System data archive, and particularly those from areas where BTB is reported, consistently outperform environmental, topographic and other anthropogenic variables as the main predictor of disease occurrence. Simulation distribution models for 2002 and 2003, incorporating all predictor categories, are presented and used to project distributions for 2004 and 2005.

Agriculture↗

PubMed2004

Ecological sources of zoonotic diseases.

Although of zoonotic origin, pathogens or infections posing a global threat to human health such as human immunodeficiency virus, severe acute respiratory syndrome or emerging influenza type A viruses may actually have little in common with known, established zoonotic agents, as these new agents merely underwent a transient zoonotic stage before adapting to humans. Evolution towards person-to-person transmission depends on the biological features of the pathogen, but may well be triggered or facilitated by external factors such as changes in human exposure. Disease emergence may thus be depicted as an evolutionary response to changes in the environment, including anthropogenic factors such as new agricultural practices, urbanisation, or globalisation, as well as climate change. Here the authors argue that in the case of zoonotic diseases emerging in livestock, change in agricultural practices has become the dominant factor determining the conditions in which zoonotic pathogens evolve, spread, and eventually enter the human population. Livestock pathogens are subjected to pressures resulting from the production, processing and retail environment which together alter host contact rate, population size and/or microbial traffic flows in the food chain. This process is illustrated by two study cases: a) livestock development in the 'Eurasian ruminant street' (the area extending from central Asia to the eastern Mediterranean basin) and the adjacent Arabian peninsula b) poultry production in Southeast Asia. In both scenarios, environmental factors relating to demography, land pressure and imbalances in production intensification have led to an unstable epidemiological situation, as evidenced by the highly pathogenic avian influenza upsurge early in 2004, when the main outbreaks were located in areas which had both large scale, peri-urban commercial holdings and a high density of smallholder poultry units.

Adaptation, Physiological↗

PubMed2001

Agro-climatic classification systems for estimating the global distribution of livestock numbers and commodities.

Investment in agricultural research in developing countries is being increasingly targeted at those agro-climatic zones and issues where the economic and environmental benefits may be expected to be greatest. This first requires that the zones themselves be defined, along with information on domestic livestock numbers and commodity output within agro-climatic zones in different countries. Different methods for classifying agro-climatic zones were compared. These included methods based on estimated length of growing period (LGP) using rainfall and temperature data, the ratio of precipitation to potential evapotranspiration (PET), and on more detailed agronomic models, remote sensing data and land use information. Zonation based on LGP has already been linked to existing national livestock data. By defining agro-climatic zones and relating concentrations of livestock populations to those of humans, it is possible to make realistic estimates of livestock populations and the production of livestock commodities for most developing countries. Detailed agro-climatic analyses of Mainland East Asia and Sri Lanka have recently been undertaken using the GROWEST agronomic model. Using this model as the basis of agro-climatic classification appears to be significantly superior, particularly in temperate environments, to approaches based solely on LGP. Different ways of subdividing countries and continents into agro-climatic or agro-ecological zones (AEZs) are reviewed in this paper. In addition, we show how the numbers of production and commodities from domestic livestock can be allocated to such zones. We also indicate how some of this information can be applied.

Agriculture↗

PubMed2001

Spatial trypanosomosis management: from data-layers to decision making.

The use of geographical information systems (GIS) in the management of African animal trypanosomosis in sub-Saharan Africa offers potential in assisting decisions on allocation of resources, prioritization of control areas, and planning and management of field operations. Here, Guy Hendrickx and colleagues review approaches being used to develop reliable data-layers and to incorporate these data into GIS models. They argue that techniques should be further refined to produce more-detailed data layers and to include a dynamic element, a problem rarely addressed until now.

Africa South of the Sahara↗

PubMed2001

Predicting the distribution of urinary schistosomiasis in Tanzania using satellite sensor data.

In this paper, remotely sensed (RS) satellite sensor environmental data, using logistic regression, are used to develop prediction maps of the probability of having infection prevalence exceeding 50%, and warranting mass treatment according to World Health Organization (WHO) guidelines. The model was developed using data from one area of coastal Tanzania and validated with independent data from different areas of the country. Receiver operating characteristic (ROC) analysis was used to evaluate the model's predictive performance. The model allows reasonable discrimination between high and low prevalence schools, at least within those geographical areas in which they were originally developed, and performs reasonably well in other coastal areas, but performs poorly by comparison in the Great Lakes area of Tanzania. These results may be explained by reference to an ecological zone map based on RS-derived environmental data. This map suggests that areas where the model reliably predicts a high prevalence of schistosomiasis fall within the same ecological zone, which has common intermediate-host snail species responsible for transmission. By contrast, the model's performance is poor near Lake Victoria, which is in a different ecological zone with different snail species. The ecological map can potentially define a template for those areas where existing models can be applied, and highlight areas where further data and models are required. The developed model was then used to provide estimates of the number of schoolchildren at risk of high prevalence and associated programme costs.

Adolescent↗