Stories From the Field:

MALARIA

Walking The Ground

Ross Boyce is a second-year resident in the Massachusetts General Hospital’s Global Primary Care Program. Before medical school, Ross served as an Infantry Officer in the United States Army. He completed two tours in Iraq, earning three Bronze Star Medals, including one with a Valor Device for heroism in combat. Through the GPC Program, Ross will spend at least four weeks each year in southwestern Uganda. His most recent trip focused on malaria surveillance and GIS mapping at Bugoye Health Center.

As a young Army officer, I learned that there were six key considerations to any military operation: (1) the mission, (2) the enemy, (3) the time available, (4) the troops available, (5) the terrain, and (6) the civilian population, usually referred to by the mnemonic METT-TC. Of these factors, the terrain is often decisive. Throughout history, the side that held the “high ground” often emerged the victor. One of the most celebrated examples is the Battle of Gettysburg, where Brigadier General John Buford positioned his cavalry along the three ridges west of town, a critical maneuver that shaped the outcome of the battle well before the first shot was fired.

Terrain is also an important consideration in combating malaria. Like many vector-borne diseases, malaria transmission is dependent on the complex interaction of mosquitoes, humans, and the environment. The Anopheles mosquito, the main vector of the malaria parasite, lays its eggs in small puddles of water often found in cultivated areas after heavy rains. Once mature, the new females require a blood meal before returning to these puddles to reproduce. The mosquitoes' preference to feed at night and usually inside human dwellings means that factors like housing construction and bed-nets impact transmission rates. Access to prompt, appropriate treatment, which is largely determined by distance, directly affects the prevalence of malaria parasites within the community. These interlinked factors can cause cases to cluster in space and time.

Take for example the story of Yuzonia Subuni, 42, a mother of ten children whose ages range from five to twenty-seven, from the village of Muramba. Yuzonia told us that the recent rains caused pools of standing water, a likely breeding site for mosquitoes, to develop around her home. After her youngest child, Mumber Jowanz, developed seizures, a common symptom of severe malaria, she walked her family more than a mile down the mountainside to the nearest health center. There, three children, all of whom were covered with dozens of mosquito bites, were diagnosed with malaria, and admitted to the inpatient ward where they quickly recovered. Yuzonia and her family, however, are relatively lucky. Compared to many residents of the sub-county, her access to appropriate care was easy – many families in the catchment area are much further from the health center Thousands of children in rural Uganda die each year from complications of malaria. How then do we interrupt the transmission cycle and prevent so many deaths? I would argue that we start by walking the ground.

Our partners from the Mbarara University of Science and Technology (MUST) and I spent the last month doing just that. Using GPS devices and guided by members of the local community, we journeyed hundreds of miles up and down the hills and valleys of the sub-county. We recorded the locations of village health workers, community leaders, and health centers, in addition to outlining political boundaries. On the narrow paths, we also learned a lot about life in the villages in ways we had not been able to understand or appreciate before. In doing so, we gained new insight into malaria risk factors, infrastructure challenges, and health-seeking behaviors.

The end result of this work is a map, a simple tool that most of us with smart phones take for granted. Yet in an area where village boundaries are often marked by a mango tree, such a tool is invaluable. Already, the map is helping us reinterpret routine data gathered from the health center. For example, we can now show that the five villages with the highest number of malaria cases at the Bugoye Health Center are also the five villages closest to the health center. Not only does this information suggests that distance to the clinic is a key determinate of access to care (Chart 1), but it also forces us to ask where residents of other villages, assuming rates of malaria are similar, are seeking care, if at all. Using this information, we can better target future interventions to the most underserved communities.

Going forward, the map will give us the ability to monitor and treat the most productive breeding sites. We can track malaria cases by villages, looking for spatial and temporal trends that may indicate the need for additional interventions. The map can also be used for purposes other than malaria, such as identifying sources of drinking water. In addition, we have shared the map with the members of the local government who, despite the language barrier, instantly grasped its many potential uses. Our coordinates are even going to be used to define the new village, parish and sub-county boundaries on Uganda’s national maps.

Unfortunately, there is still so much work to be done. We need to gather more information about “our enemy” through entomological studies and community-wide parasite surveys. We need to expand the use of village health teams in order to reduce the time and distance to appropriate care. We need to improve our ability to recognize and treat severe malaria within the health centers.  Still, at least we now have a better understanding of the terrain under our feet. For now, we hold the high ground.

This is the second in a series by Ross Boyce.  To read “The Good War”, an update from Ross’s first trip to Uganda, click here.