Developing a Global GIS Based Model on Avian Influenza in Humans

Presented by
Mr. Mike Napier – GIS Analysist
Pacific Disaster Center

Avian Influenza (AI), also known as the bird flu, is a viral disease caused by a virus in the family orthomyxoyiridae. The three main types of the AI virus, classified on the basis of their surface proteins (there are15 subtypes with the hemagglutinin (HA) protein and 9 subtypes with the neuraminidase (NA) protein) are: type A (affects multiple species, (chickens, turkeys, ducks, whales, seals, and other birds); type B (occurs only in humans); and type C (occurs in humans and swine). Depending on the type of hemaglutinin Type A may be HPAI (High Pathogenic Avian Influenza or LPAI (Low Pathogenic Avian Influenza) with HPAI being the most contagious and lethal (marked by a mortality rate of 100 percent in fowl populations). Three ways birds can shed the virus is by way of saliva, nasal secretions, and feces.

The disease is transmitted when a bird or human becomes exposed with feces or respiratory secretions. Although still uncommon, the number of confirmed cases in the human population continues to rise posing the threat of a global pandemic. Most importantly, experts believe that should this virus become anthroponotic (human to human transmittable); it may infect 20-50% of the total human population and result in 2-50 million deaths.

The goal of the Pacific Disaster Center project is to create a geospatial data based model to (a) better understand the parameters associated with the present occurrence and distribution of AI outbreaks and (b) extrapolate this knowledge to identify geographic areas that may be susceptible to future AI outbreaks . The initial components of the supporting GIS (Geographical Information System) data base were compile from existing global data sources (temperature, elevation, reservoir areas, population density, poultry density, swine density, major wetlands, migratory routes of key reservoir species, habitat, seasonality of outbreaks etc.) and from documented human and animal case studies available in the public domain. A preliminary model has been constructed based on an integration of the above information within the framework of an initial assumed model of AI occurrence and distribution. Special emphasis in the study has been placed on Southeast Asia in general and Thailand and Vietnam in particular.

The present study is providing a basis for assessing the nature and controls on present HPAI outbreaks; a means of identifying geographic areas that may be susceptible to future AI outbreaks; guidance for possible control and early detection strategies; and to serve as a basis for future analyses augmented with molecular epidemiology.

The Pacific Disaster Center research team consists of Mr. Mike Napier (Project Lead); Dr. Allen Clark; Ms. Darlene Williams and Mr. John Fujita.