English: Bellevue-Stratford Hotel, Philadelphia (Photo credit: Wikipedia)

Legionnaire’s disease symptoms include fever, chills, cough, muscle aches, headache, tiredness, loss of appetite, loss of coordination and occasionally diarrhea and vomiting.  Typically takes 2-10 days to incubate.  Many cases go undiagnosed and transmission is not person to person.  It is treatable with antibiotics if diagnosed early enough.


The infection occurs from inhaling water droplets that originated from a water source contaminated with Legionella.  Typical manmade sources include cooling towers, evaporative coolers, hot water systems, showers, whirlpool spas, architectural fountains, room-air humidifiers, ice-making machines and misting equipment.  Environmental sources are freshwater ponds, rivers and creeks. 

A forced draft cooling tower (Photo credit: Wikipedia)

Commonly used method of analysis is the methodology from the Centers for Disease Control (CDC) which involves collecting a sample of the water source. Culture Analysis is considered the “gold standard” and analysis can take 10-14 days.  The OSHA Technical Manual offers the following guidelines for interpreting Legionella analysis results (numbers are in colony forming units per milliliter (cfu/ml)):

ACTION    COOLING TOWER   DOMESTIC WATER    HUMIDIFIER

  1                     100                           10                     1

  2                    1000                         100                    10

Action 1: Prompt cleaning and/or biocide treatment of the system.

Action 2: Immediate cleaning and/or biocide treatment.

As part of the outbreak, the New York City Commissioner of Health and Mental Hygiene (DOHMH) issued a mandatory order to have cooling systems inspected and remediated within 14 days of receipt of the order.  New York City has recently passed new requirements (Local Law 77 of 2015) for the registration of cooling towers and evaporating condensers.  Existing cooling towers and evaporative condensers must be registered with the New York City Building Department (NYC DOB) by September 17, 2015.  Visit the NYC DOB website for more info.  The DOHMH order requires building owners to hire environmental consultants experienced in disinfection using current industry standard protocols including the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Standard 188P and Cooling Technology Institute Guidelines WTB-148.