WHAT WE DO...AND WHOM WE SERVE:
Penetrating the Defenses of the Toughest Microbes
Photomicrograph of a Giardia lamblia cyst seen using a Trichrome stain.
One of the greatest public health improvements in the past century has come from adding chlorine to drinking water. This is one of the main reasons for the dramatic decline of waterborne disease all over the world. However, some emerging waterborne pathogens are highly resistant to chlorine. UW researcher Gwy-Am Shin, PhD, is investigating the effectiveness of an ultraviolet treatment method that can break down the defenses of these toughest of microbes.
Despite the tremendous technical advances in water treatment processes during the 20th century, the burden of waterborne disease worldwide remains high. A World Health Organization study estimated that 4% of all deaths worldwide stem from diseases related to unsafe water, inappropriate sanitation, and poor hygiene.
Waterborne diseases are not just a problem for developing nations. A Cryptosporidium outbreak in Milwaukee, Wisconsin, in 1993 may have infected as many as 400,000 individuals and resulted in 100 deaths. Cryptosporidium is a small microscopic animal (protozoan) that is highly resistant to free chlorine.
Fortunately, chlorination isn’t the only water treatment process. Shin, an assistant professor in our department, is studying the effectiveness of ultraviolet (UV) light in disarming these harmful microbes in water and wastewater.
Gwy-Am Shin
CURRENT RESEARCH
His current research builds on his previous work, which identified the effectiveness of UV irradiation against Cryptosporidium and initiated the widespread use of UV disinfection in drinking water treatment processes in the United States. In UV disinfection, water flows past UV lamps submerged in the water. Although the contact time is only a few seconds, the high UV intensity can penetrate the thick cell wall of Cryptosporidium (the primary reason for the microorganism’s incredible resistance to free chlorine) and destroy its ability to reproduce.
Shin has extended his UV research to other important waterborne pathogens. He is in the second year of a three-year research project, funded by the National Science Foundation, to examine the effectiveness of UV against Giardia. During the past 20 years, Giardia has become recognized as one of the most common causes of waterborne disease in the United States. Giardiasis may lead to weight loss and dehydration, although some people with the infection have no symptoms at all.
Shin collaborates with researchers at Duke University in North Carolina and McGill University in Montreal, Canada. He is working with McGill because it has the lab capacity to perform the animal infectivity assay for Giardia, and with researchers at Duke because of research relations he formed there while attending the University of North Carolina (UNC).
Shin earned his bachelor’s and master’s degrees in microbiology at Seoul National University in South Korea. He did his doctoral studies in environmental microbiology at UNC and stayed on for his postdoctoral work. He was a research assistant professor there when UW hired him in June 2004.
Shin has broadened his research interests to include community health interventions. He is involved—as co-principal investigator providing technical assistance—in a community water quality intervention study in North Carolina looking at the links between water quality and health. “Previous similar studies,” he said, “weren’t very successful because of lack of community involvement, so we made this project community-driven.”
The first step in the project was to hold a seminar to educate community leaders about the project and help them appreciate how water quality affects the community’s health. Then the community leaders educated local residents. “We didn’t lead them,” he said. “We just acted as advisers, showing them how to do water collection from wells and how to do community health surveys. It was much more effective than previous passive interventions.”
Shin’s interest in community water quality issues has expanded to those in developing countries, where the burden of waterborne disease is significantly higher than in developed countries. For example, he organized a water quality workshop in Hanoi, Vietnam, in June 2005 to train local health officials in microbiological assessment of water quality. He is planning to do further water quality projects with collaborators in Vietnam, Thailand, and China.
Water quality is still a problem in the United States, though most years the number of people affected by waterborne illnesses isn’t nearly as high as the Milwaukee outbreak. According to the Centers for Disease Control and Prevention, in 2001 and 2002, 19 states reported a total of 31 outbreaks associated with drinking water, causing illness among an estimated 1020 people, with 51 hospitalizations and seven deaths.
One of Shin's North Carolina collaborators examines Cryptosporidium parvum cysts on a fluorescent microscope.
These figures may not reflect the true incidence of waterborne diseases in the US, because many people don’t become so ill from these diseases that they consult a doctor or they don’t connect their illness with their drinking water.
RESOURCES
CDC’s drinking water site http://www.cdc.gov/ncidod/dpd/healthywater/index.htm.
Eisenberg JNS, Lei X, Hubbard AH, Brookhart MA, Colford JM Jr. The role of disease transmission and conferred immunity in outbreaks: Analysis of the 1993 Cryptosporidium outbreak in Milwaukee. Am J Epidemiol 2005; 1;161(1):62–72.
EPA’s Water on Tap: What you need to know about safe drinking water, http://www.epa.gov/safewater/wot/pdfs/book_waterontap_full.pdf.
EPA’s drinking water information website http://www.epa.gov/safewater/dwh/index.html.
Linden KG, Shin G, Faubert G, Carns W, and Sobsey MD. Inactivation of Giardia lamblia cysts by low pressure UV radiation. Environmental Science and Engineering 2002; 36(11): 2519–2522.
Pruss A, Kay D, Fewtrell L, Bartram J. Estimating the burden of disease from water, sanitation, and hygiene at a global level. Environ Health Perspect 2002; 110(5):537–542.
World Health Organization. Drinking water website. http://www.who.int/topics/drinking_water/en.
GRADUATE STUDENT GOES TO ECUADOR
Laura McLaughlin samples water in Ecuador.
Drinking bacterially contaminated water is a leading cause of death in rural regions of the less developed world. Laura McLaughlin, a third-year graduate student in the Environmental Health program, is intent on preventing those deaths. She is working on double master’s in Environmental Engineering and Environmental and Occupational Health, with a focus on drinking water, and is studying with John Scott Meschke.
In the summer of 2005 McLaughlin spent three months in Ecuador conducting a drinking water treatment project funded through the Puget Sound Partners for Global Health. The research she did there is part of her master’s thesis.
McLaughlin grew up in Oxnard, California, a port city in Ventura County, halfway between Los Angeles and Santa Barbara. “I was sort of a science geek in high school, but I didn’t really know what kind of work I wanted to do. My parents were involved in the Latino community in Oxnard, and my mom taught English as a Second Language (ESL), so I suppose that’s how I got interested in Latin America.”
After McLaughlin graduated from the University of California, Berkeley, with a bachelor of arts in environmental studies and a bachelor of science in civil and environmental engineering, she took time off to travel abroad. Her journeys took her to southern Africa, South America, and Mexico.
Before she returned to the United States, she volunteered in Mexico for three months on a UC Berkeley research project on ultraviolet light disinfection of drinking water. “After that I still hadn’t worked out my travel bug,” McLaughlin said, “so I volunteered to work on an ECODESS (Ecology and Development with Sustainable Sanitation) project in Ecuador.”
As a result of her experience in Ecuador, she was successful in getting the Puget Sound Partners grant for her water treatment research project. McLaughlin worked in Colon Eloy, an Afro-Ecuadorian village in the northern coastal region of Ecuador. Most of the households in the village used a nearby stream for drinking water. McLaughlin’s research compared the effectiveness of drinking water disinfection in households that did and didn’t use chlorine to disinfect the water.
McLaughlin constructed a field lab to collect and process the water samples, and worked in the laboratory at the University at Quito to test for three disease-causing organisms (E. coli, enterococci, and somatic coliphages). Since her return to Seattle, she has been analyzing the data.
During the three weeks she spent collecting samples, she stayed with one of the families in the research project. “I really enjoyed talking to the people and hearing their perspective,” McLaughlin said. “They were so fascinating. It was fun to hang out with them and find out details of their beliefs. For example the villagers distinguish between bacterial diarrheal diseases and those caused by something other than bacteria, like the evil eye or bad wind.”
She didn’t spend all her time in the village working though. “I like salsa dancing and playing soccer,” McLaughlin said. “In the villages, there’s always a discoteca and a soccer field. So I did get to dance a bit, but I didn’t get to play soccer because there wasn’t a women’s or coed team.”
McLaughlin will graduate in June 2006 and head to Finland for a year’s study under the Valle Scholarship and Scandinavian Exchange Program. When she returns, she will complete her Environmental Engineering degree.