Professor Thomas Clasen


of Water, Sanitation and Health

Keppel Street
United Kingdom

+1 414 243 2302

After obtaining a JD from Georgetown University in 1981, I joined Foley & Lardner, a 1000+ lawyer US firm where I was responsible for international business transactions, becoming a partner in 1987. In 1994 I left the firm to become Vice President, General Counsel and a Director of Everett Smith Group, Ltd., a US$1 billion conglomerate.

My interest in waterborne disease arose from investments in point-of-use water treatment technologies (Exstream and First Water). I received my MSc (Control of Infectious Diseases) and PhD (Prevention of Waterborne Disease) from the University of London, and joined the faculty at LSHTM in 2004.


Faculty of Infectious and Tropical Diseases
Department of Disease Control


Epidemiology and Control of Infectious Diseases (ID301); Water and Sanitation (ID201). Formerly, Adjunct Professor, School of Law, University of Wisconsin, Madison, Wisconsin, USA. Adjunct Professor, Graduate School of Business, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.



My publications include randomized controlled field trials to assess the health impact of water, sanitation and hygiene interventions, systematic reviews of water quality and sanitation interventions to prevent diarrhoeal disease and enteric infection, assessments of water and sanitation interventions in emergency and outbreak response, and cost and cost-effectiveness analyses of water and sanitation interventions in developing countries.  My current research includes a large-scale cluster-randomized trial to assess the impact of rural sanitation on diarrhoea, anthropometrics and helminth infection; a systematic review and field study to compare the health impact of shared sanitation with individual household latrines; field studies to assess and develop interventions to improve the collection and disposal of child faeces; a blinded, randomized controlled field trial of chlorine tablets in India; and a health impact evaluation of a large-scale deployment of water filters and improved cook-stoves in Rwanda; and providing advice on sanitation and water treatment to a large scale trial in Kenya and Bangladesh. 

Research Area
Clinical trials
Health impact analysis
Health outcomes
Disease control
Environmental Health
Global Health
Disease and Health Conditions
Infectious disease
Latin America & Caribbean (developing only)
Least developed countries: UN classification
South Asia
Sub-Saharan Africa (developing only)

Selected Publications

Making Sanitation Count: Developing and Testing a Device for Assessing Latrine Use in Low-Income Settings.
Clasen, T.; Fabini, D.; Boisson, S.; Taneja, J.; Song, J.; Aichinger, E.; Bui, A.; Dadashi, S.; Schmidt, W.P.; Burt, Z.; Nelson, K.L.;
Environ Sci Technol
Assessing Water Filtration and Safe Storage in Households with Young Children of HIV-Positive Mothers: A Randomized, Controlled Trial in Zambia.
Peletz, R. ; Simunyama, M. ; Sarenje, K. ; Baisley, K. ; Filteau, S. ; Kelly, P. ; Clasen, T. ;
PLoS One
Drinking Water Quality, Feeding Practices, and Diarrhea among Children under 2 Years of HIV-Positive Mothers in Peri-Urban Zambia.
Peletz, R. ; Simuyandi, M. ; Sarenje, K. ; Baisley, K. ; Kelly, P. ; Filteau, S. ; Clasen, T. ;
Am J Trop Med Hyg
Water and Sanitation
Clasen, T.; Sugden, S.
Oxford Textbook of Public Health
See all Professor Thomas Clasen's Publications