Space and digital technology against malaria

By Janet Rosalie Anne H. Polita
MediaCore, PCASTRD

Malaria is more than a simple burning itch and red spots caused by mosquito bites.  It’s a disease with warning signs like chills, vomiting, fever, nausea, and headache, which may be life-threatening depending on the type of parasite that caused the infection.

 World Health Organization reports show that malaria causes as many as a shocking 3 million deaths annually.  Locally, records at the National Statistics Office show that malaria is one of the top ten major diseases that afflict Filipinos. It is found in 72 out of 75 provinces in the Philippines .

The pursuit to solve malaria incidence has spurred numerous scientific researches.  Strategies to reduce the incidence of mosquito-borne diseases have been adopted and tested.   One strategy tested is through the use of remote sensing (RS) and geographic information system (GIS).

Remote sensing and geographic information system

A team of scientists from the Department of Parasitology of the University of the Philippines Manila used RS and GIS to determine the environmental factors that support mosquito and snail populations spreading parasitic diseases like malaria and schistosomiasis.  The “sample” areas are the towns of Kapalong and Asuncion in Davao del Norte.

Remote sensing is the use of devices such as lasers, radio frequency receivers, radar systems, and sonar to collect data and information. GIS, on the other hand, is a special-purpose digital database that uses geo-references as the primary means of storing and accessing information.

 “RS and GIS coupled with an updated data can help health management officers battle malaria in their areas,” project leader and professor Lydia Leonardo said.   These technologies have varied uses in health research such as improving decision-informing tool, monitoring, surveillance, and forecasting of diseases, she added.

Environmental factors related to malaria

Through RS and GIS, Dr. Leonardo’s team was able to assess and describe the local and landscape-level features that influence the disease situation and disease vector distribution through production of prevalence maps.

The maps particularly revealed that malaria infected barangays are found more in the upland while schistosomiasis endemic barangays are in the lowland.  Moreover, malaria prevalence was high in areas covered with dipterocarp forest.  A dipterocarp forest is dominated by trees of the dipterocarp species such as red lauan, tanguile, tiaong, white lauan, almon, bagtikan, and mayapis of the Philippine mahogany group, and apitong and yakal.

Meanwhile, schistosomiasis areas abound with grassland and agricultural land.

The map showed that proximity to water source favors high prevalence of malaria and schistosomiasis in particular areas.

According to Dr. Hilario, soil type is another significant factor that affects the distribution of the diseases.  Malaria infected barangays are composed of Camansa sandy clay loam that are in hilly and mountainous regions.  Shistosomiasis endemic barangays are composed of San Miguel silty clay loam developed from recent alluvium washed from the upland and deposited by rivers along their routes.

“Climate and topography are two big factors that explain the widespread [occurrence] of the two diseases in the municipalities,” Dr. Hilario said.  The two sites have rugged, mountainous, and moderately to steeply sloping areas in its northern part and wide alluvial plains on the southern lowland area.  The prevailing climate is unpronounced dry and wet seasons.

“With the relation found between the diseases and the environmental factors, our health management officers can now come up with statistical models, “ Dr. Leonardo said.  “These models may be used to predict epidemic or outbreak of the disease,” she added.  

 Dr. Leonardo emphasized that health officers should also be trained on the use of GIS software to better understand and manage malaria.  They should continue updating their prevalence data for better management of the disease, she advised.

The study, which received funding support from the Department of Science and Technology’s Philippine Council for Advanced Science and Technology Research and Development was the first of its kind in the country.  It was implemented under the council’s space technology applications programs, which aims to provide knowledge and skill to Filipino remote sensing practitioners on the use of advanced Earth observation technology and prepare them for the use of similar spaceborne data in the future.

“Our study demonstrates that malaria can be eliminated thru the use of cutting edge technologies like RS and GIS,” Dr. Leonardo said.  “But of course, it can be attained if there exists concerted efforts from the local government and the community”.