PDC Avian Influenza - Methodology

Methodology

Human Cases

Tabular data are checked daily from the World Health Organization (WHO) Epidemic and Pandemic Alert and Response (EPR) Outbreak News confirmed case database http://www.who.int/csr/disease/avian_influenza/en/ and http://www.who.int/csr/disease/avian_influenza/updates/en/index.html, converted into spreadsheet format, and finally appended to Environmental Systems Research Institute (ESRI) point and polygon Shapefiles. Specifically:

Polygon Based Maps: Based on open source WHO data, maps depict both provinces, districts, and some cities and villages of AI affected areas. These maps reflect data derived from the World Health Organization Epidemic and Pandemic Alert and Response (EPR) Outbreak News' laboratory-confirmed human case database. Infection data are available from 2004-present, and are updated as new situation reports become available. The availability and frequency of the reports is based solely on the laboratory confirmation of a new case and the subsequent publication of the case; hence the maps are updated accordingly. Most cases are identified utilizing province/district names and then geocoded to provincial or district polygon data, as exact geographic case coordinates are not available from the database. The entire province or district is shaded as "infected for AI" if a case is located within the particular province/district.
Point Based Maps: Point data are geocoded according to city or village names if available, or any other information extracted from the text report (e.g. "the patient was infected in the southern part of Xaingchi province.") If no other information is available, the points are located near the centroid of the district or province polygon. Point data is then further queried to display fatalities, gender, age, and other factors.

Avian Cases

The avian case files include both domesticated birds ("AVI") and migratory wild birds ("FAU"). These cases are taken from the official reports on the website of World Organization for Animal Health (OIE) as updates become available. The textual information in the reports is then converted into a usable GIS format. Since these case descriptions vary in their level of detail, completeness, and accuracy, point locations are based on the highest level of detail available. For cases that do not have latitude and longitude values, point locations were assigned using various sources. These sources include, but are not limited to, gazetteer and administrative files, provincial-level data, and (in some cases) Internet travel sites. Levels of accuracy in the files include town/village place names, district center points, and provincial center points. Because of the varying sources and levels of accuracy, these point locations should not be interpreted as exact locations and should only be used as reference points.

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