Date of Award

January 2013

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Kristina Talbert-Slagle



Legionellosis is caused by Legionella pneumophila, resulting in 8,000-18,000 yearly hospitalizations and 4,000 deaths in the United States (Bouwknegt, 2012) (Toshiaki, 2004) (World Health Organization, 2012). L. pneumophila may persist in the built environment due to unique intracellular characteristics. Although the mode of transmission of L. pneumophila is inhalation of aerosolized contaminated water, this bacterium is not transmitted human to human (World Health Organization, 2012). L. pneumophila infection may be facilitated by the increased use of recycled water in Los Angeles County. In a water stressed area such as Los Angeles County, a limited potable water supply may not sustain the growing metropolitan population. Recycled and reclaimed water may help lessen the demand by supplying non-drinking water to industries such as agriculture, water table restoration, and recreation use. To be more cost effective, recycled water has been mandated to receive less treatment than the treatment used for county potable water. Recycled water treatment has less stringent backflow and purification procedures compared to county potable water treatment. The Environmental Health division prioritizes monitoring and treatment of potable water. Monitoring and treating recycled water will be limited. Mapping the cases of non-hospital acquired Legionellosis cases exposed to recycled water pipeline compared to potable water pipeline will show the difference in risk associated with Legionellosis. There was a statistically significant difference in the number of cases within the recycled water pipe-lined area including the infectious zone, compared to the unexposed recycled water pipeline area. The Chi-squared P-value was 0.0013 comparing the exposed Legionellosis cases to unexposed. Individuals exposed to L. pneumophila from recycled water pipeline had a 1.4806 (1.3088, 1.6735) times greater risk of developing Legionellosis compared to individuals who were not exposed to L. pneumophila from recycled water pipeline. The current standard of recycled water cleanliness may not promote the public health; a more stringent standard involving more concentrated disinfection and filtration steps is needed. Public Water Supply Rule 16-D and Section 2.12 of the Rules Governing Water and Electric Services in the City of Los Angeles must include inhaled exposure of L. pneumophila. The first steps to reduce Legionellosis may include standardize of Filtration, Ozonation, Disinfection, and/or Fluorination for the Los Angeles-Glendale Water Plant, the Donald C. Tillman Water Reclamation, the Hyperion Waste-Water, and the Terminal Island Water Reclamation Plant to the degree that is used for potable water treatment.


This is an Open Access Thesis.

Open Access

This Article is Open Access