Author Information
YungKai Chin
American River College
Geography 350: Data Acquisition in GIS
Spring 2008
Contact Information: ykchin 'at' gmail.com
Abstract
The results from these maps show the spreading of H1N1 flu virus from the south to north, and all cases were reported in populated, urban areas.
Introduction
Not long after the outbreak of Novel Influenza A (H1N1) virus, a website began to put each case as a point and map the virus on Google Map. However, the website is limited to the latest report and focus all reported cases globally. Since April 15 and 17, 2009 when the first two cases were reported in two southern counties, many other cases also have surfaced in many counties in California. This project will try to limit the scope to California counties and shows how the spreading of the virus progressed. Monitoring the virus in each county may help better response in this fall, when it is said that the virus can have a comeback with a more severe illness.
The first Flu Tracking Map
The updated version of FluTracking Map
(Click Image to Enlarge)
Background:
Novel Influenza A (H1N1) virus, commonly referred to as "swine flu", is a type of influenza (flu) virus and was first detected in March, 2009 in Mexico and in April, 2009 in California. The virus can infect people and causes respiratory disease. Although it is commonly named in the media as swine flu, the origin of the virus is still largely unknown. All we know at this point is that it is similar to swine-orgin virus, so in virus' past, it spreaded among swine, but now it can no longer infect swines. It was first reported from Mexico. It can spread from person-to-person. Spread of this novel influenza A (H1N1) virus is thought to be happening in the same way that seasonal flu spreads. Because it is a newly discovered virus, most people are most likely have no immunity to it. Most people infected with this virus in the United States have had mild disease, but some have had more severe illness.
Methods
The base layer, county boundaries (a polygon shapefile), was accquired from the California Spatial Information Library. A geoprocess, dissolve, was then performed, so that each country was one polygon. Also, other unnecessary fields were removed.
The first dataset is based on a Centers for Disease Control and Prevention's (CDC) press release, in which CDC determined that first two cases of influenza A (H1N1) virus occurred in two children from southern California – San Diego and Imperial counties. The latest dataset is based the number released by California Department of Public Health (CDPH). After May 15, 2009, there is no new case reported in California. Both datasets were added to the county shapefile.
Two datasets used in between the initial stage and the final stage (assuming no more influenza A (H1N1) flu case until the next flu season) were acquired from MapCruzin.com which provides both shapefiles (point) and excel spreadsheets of the latest number of the reported cases on day-to-day. Since each case presents a point and the data cover the entry world, spatial join was used to count all points that were within each California county. It would be much better if all data were acquired from one single source, but CDC and CDPH only offer the latest figures.
Classification Method is manual. The sizes of intervals are artificially picked, but they are fixed. First class: zero (no case reported), second: one to eight, third: nine to eighteen, forth: nineteen to thirty-two, and fifth class: thirty-three or more.
Projection is Albers.
Results
The results from these maps show the spreading of H1N1 flu virus from the south to north, and all cases were reported in populated, urban areas, where contacts between people are more frequent and more likely.
Manual classification method is used in order to show a graduate increase of number of cases. The sizes of intervals are artificially picked, but they are fixed. As the result the number of classes seems to grow over time.
Figures and maps April 17, 2009, The first stage. May 2, 2009 May 7, 2009 May 15, 2009.
Analysis
These maps do show the H1N1 flu outbreak in progress. However, It would be much better if all data were acquired from one single source, but CDC and CDPH only offer the latest figures.
Also, another limitation of the data is the number of reported cases. One example is from this article, Swine Influenza A (H1N1) Infection in Two Children - Southern California, the report says that a number of these two patients' siblings and relatives were also ill with a flu. Yet, there were only two reported cases. Thus, I think the number of cases should be much greater what has reported.
Conclusion
In term of the number of deaths, H1N1 flu is relatively mild compared to other flu viruses because each year on average 36,000 thousand people die due to flu illness. From a disaster management stand point, the results can not only show how H1N1 virus spreads, but also show where the future preparation should focus because many experts agree that the next flu season this virus can begin to widespread once again.
References
California Department of Public Health, Latest News, May 15, 2009
April 17, 2009, The first stage.
May 2, 2009
May 7, 2009
May 15, 2009.