 The Mel and Enid Zuckerman College of Public Health welcomed Assistant Professor Kacey Ernst, MPH, PhD to the faculty in January, 2008, the first on the faculty specializing in infectious disease and epidemiology. A native of Kansas, Dr. Ernst received her doctorate in 2006 in epidemiology at the University of Michigan in Ann Arbor. In 2001 she earned a Master’s of Public Health degree, also from the University of Michigan. Her research interests are centered in the ecology of infectious diseases.
Prof. Ernst is teaching her first class as a professor in the Spring 2008 semester, a graduate course in Infectious Disease Epidemiology. Working with students is one of the main reasons that she chose to be a professor. “In graduate school I was a TA (teaching assistant) for many classes, primarily for Masters-level epidemiology courses, and I enjoyed it a lot.” Being a professor where she can combine field research, students and teaching and have a self-directed path appealed to her very much.
When asked why she chose to come to the University of Arizona and the Mel and Enid Zuckerman College of Public Health, she replied that she was looking for a newer school in public health where she could help build and establish a program in epidemiology. The epidemiology professors already here were specializing in areas such as cancer, coronary disease, and other non-infectious diseases, so she is excited to be bringing her expertise in vector-borne infectious diseases to the Epidemiology and Biostatistics Division.
Studying Vector-Borne Diseases
Prof. Ernst uses GIS (Geographic Information System software) and spatial statistics to understand the determinants (causes) of vector-borne diseases. A vector-borne disease is one that is carried and transmitted by arthropods or insects, which are called the "vectors," and includes diseases such as the West Nile virus, Lyme disease, and Rocky Mountain Spotted Fever. These diseases are transmitted to humans by mosquitoes, ticks and flies. Spatial statistics in studying diseases involves looking for geographic characteristics of outbreaks, i.e., the locations where people are becoming sick, or other environmental or ecological patterns in the data.
Utilizing special GIS software called ArcView, Prof. Ernst statistically analyzes and visualizes malaria data collected in Kenya, her main research project right now. For over two years she worked in a remote region of the country without running water or electricity to gather data for her research, where the languages were English and Swahili. To enter her research data into her laptop computer there, she ran a gas-powered electrical generator for several hours a day to provide the needed power.
Malaria Clusters in Kenya
The research results to date show that in the area of Kenya where Prof. Ernst was working, malaria was highly clustered in areas with low-lying dips in the terrain. She has found that in these areas water has a tendency to pool when it rains, which increases the mosquito populations, which in turn causes higher malaria rates. Malaria is a big problem in Kenya as a seasonal epidemic during the months with a lot of rain, and the disease virtually disappears in the dry season of the year. This data can be used to help control the mosquitoes in the future, and to educate people on areas to avoid when mosquitoes thrive. Malaria is a very serious health problem there; over one million African children under the age of five years old die each year from malaria, a staggering number. HIV probably kills more Africans per year now, but those deaths are concentrated in the young adult ages, not in young children who malaria kills.
Professor Ernst contracted malaria while in Kenya, but was cured by receiving the right medication. So she actually suffered from the disease that she was studying! This gave her an even deeper, first-hand understanding of what people in Kenya are experiencing when they contract the disease.
Malaria and Mosquito Carriers
Malaria is a parasite which is genetically diverse both within Africa and in other areas of the world, and is transmitted by about 30 types of the anopheles mosquito. Though Americans typically think of malaria as a disease from other continents, malaria was a problem several hundred years ago in the Mississippi, Ohio and Missouri River Valleys and along the Atlantic Coast of the United States. And Southern Arizonans might be surprised to learn that this disease also used to be a problem in the western United States, and specifically in the Tucson area a hundred years ago! The incidence of malaria declined sharply after World War I, and was no longer a major public health problem in the U.S. after World War II when successful programs to reduce the anopheles mosquito population were in effect, although sporadic cases still occur. It’s interesting to note that before 1492, human malaria does not appear to have been present in the New World (western hemisphere), although the native anopheline mosquitoes did transmit the disease once it arrived. Malaria is very difficult to control for economic and political reasons.
Note that another type of mosquitoes is responsible for the current outbreaks of West Nile virus, which is transmitted by a different genus of the species, the culex mosquito. The West Nile virus is sustained in bird populations and so requires different mechanisms to control than malaria.
Future Studies
What diseases besides malaria does Professor Ernst plan to study in the future? “Epidemiology and spatial statistics are tools which can be widely applied to many diseases,” she said. Epidemiologists use these techniques to study Valley Fever, a lung infection that can be deadly which thrives in dry desert areas in Arizona and California. Another disease being studied with epidemiology-based spatial statistics is Dengue Fever, a South American virus which has recently been showing up in Sonora on the Mexican side of the U.S. - Mexico border which is transmitted by the Aedes mosquito. Vector studies have demonstrated that the Aedes mosquito is present in Arizona creating a potential public health threat to Arizonans.
International health issues are of great interest to Prof. Ernst. “Any disease in another part of the world has the potential to come to Arizona in less than 24 hours,” she pointed out. “We are truly a global community now, so we need to study diseases on a global scale as well as local ones.” Besides the two years of study in Kenya for her Ph.D. dissertation, she is also interested in infectious diseases along the U.S.-Mexico border, where Dengue fever, tuberculosis, and other illnesses currently found can be studied.
Doctor of Philosophy, 2006
Epidemology Department, University of Michigan, Ann Arbor, Michigan
Dissertation title: "Malaria in the highlands of western Kenya: Epidemiology of
environmental influences, spatial patterns and disease risk"
Master's of Public Health, 2001
Epidemology Department, University of Michigan, Ann Arbor, Michigan
Master’s project title: "Seasonal influences on predominant malaria vectors in western Kenya: Anopheles funestus important in transmission during the dry season"
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