COURTESY OF MIKE NAPIER, PACIFIC DISASTER CENTER
Global positioning systems and geographic informational systems were key tools in recent efforts to control a dengue fever outbreak. Mike Napier, GIS analyst with the Pacific Disaster Center, used the equipment recently in data collection efforts in Nahiku and Hana on Maui.
Among specialists tramping around Hana, Maui, during the dengue fever outbreak was a researcher carrying global positioning equipment. Tracking systems help
map dengue’s pathSpecialists used GPS receivers
to determine where cases
were clustered statewideBy Helen Altonn
haltonn@starbulletin.comMike Napier, geography information system analyst with the Pacific Disaster Center on Maui, said the GPS receiver was in his backpack with an antenna above his head.
"It looks like something out of 'Star Wars,'" he said.
He wore a personal computer with geographic information systems capable of assembling, manipulating and displaying geographically referenced information.
The purpose of his yearlong project, beginning with the initial report of dengue fever in Nahiku, Maui, was to identify areas where the disease was occurring and, more specifically, where individual cases were, "fighting the mosquitoes and the rain," he said.
State epidemiologist Paul Effler said the dengue outbreak was the first time GPS and GIS were used to pinpoint areas for public health in Hawaii.
He said, "Basically, it's just a recent thing that we've been able to map locations using satellites to get accurate information."
This was important in the dengue outbreak because many affected residents did not live on streets with numbers, he said. "The only way to determine clustering of cases ... was using the GPS system."
Napier said, "To a degree, you could do it with pins on a map, but you couldn't get a very accurate reading of where they were."
With GPS the locations could be pinpointed precisely, he said. Effler and Tracy Ayers, state influenza surveillance coordinator, participated in the survey, and Ayers used GPS to identify some Oahu dengue sites, Napier said.
Effler planned to take Napier's maps to San Diego to report on the dengue project at an infectious disease conference being held tomorrow through Monday.
GPS has become an important tool in public health in the past five years, Effler said, because it allows researchers to analyze factors that may identify areas predisposed to transmission of diseases related to the environment.
"Now we can overlay rainfall, temperature, mosquito and ecological data onto a certain map so we can look at the information in spatial relationships," Effler said.
He said the Health Department hopes to work with the Pacific Disaster Center to start monitoring mosquitoes for a potential West Nile virus outbreak. The federal research and development facility is managed by the East-West Center.
Effler said mosquito detection stations can be established to monitor the populations and knock them out if they hit certain levels. Mosquitoes can be tested, but the only way of knowing accurately where samples were collected is with GIS, he said.
With the West Nile virus that is spreading across the mainland, Effler said a couple of things are needed for an outbreak: enough mosquitoes to transmit it and enough of certain bird species that develop virus in their blood.
If monitoring shows high bird counts and mosquito populations overlapping in certain areas, most likely wilderness areas, they can be taken out before a virus is transported to humans, Effler said.
Napier said about 80 houses in the Hana area were identified as points on the map after positive dengue cases were confirmed.
The first goal was to define relationships of the cases by time and distance as they spread, he said.
"In the future it will help us to identify areas that have characteristics similar to the Nahiku-Hana area in the state and tag those as possible areas to watch," Napier said.
Statewide, a total of 122 dengue cases were identified from May 2001 to February this year.
State Health Department
