September was a busy month for me. I traveled to Los Angeles to attend the 2019 Legionella Conference, which was sponsored by NSF International (formerly known as the National Sanitation Foundation) and the National Environmental Health Association (NEHA). I was a speaker at the pre-conference workshop, and I also gave a presentation on “Emergency Heat and Flush Thermal Disinfection” during the 2019 Legionella Conference. 

The day-long, pre-conference workshop was geared toward health department officials to assist them in responding to reports of a suspected case of Legionnaires’ disease in their jurisdiction. 

After the 2019 Legionella Conference, I was off to Atlanta to participate in the development of a new standard for the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE). It is proposed to be titled ASHRAE 514: Minimizing Risk of Disease and Injury Associated with Building Water Systems. 

The new standard covers all hazards associated with building water systems, including microbiological, chemical and thermal (scalding) hazards. The working group met for three days to go over the first draft of the proposed new standard. 

Later in September, I attended the International Association of Plumbing & Mechanical Officials’ (IAPMO) annual conference and the final round of the Uniform Plumbing Code and Uniform Mechanical Code hearings at the Silver Legacy Hotel & Casino in Reno, Nev. The American Society of Sanitary Engineering (ASSE), which is now a subsidiary of IAPMO, co-located its meeting with IAPMO. 

Having a joint meeting reduced the amount of travel costs for those of us who always attend both industry meetings. They allowed some synergies for the associations, too, such as shared hospitality events, educational sessions and meeting staff. 

Later in the week, I attended the ASSE meetings, which included the central ASSE product standard committee meeting and some working group meetings for pressure-reducing valves and temperature-actuated mixing valves. 

NSF/NEHA 2019 Legionella Conference

Legionellosis is associated with two clinically and epidemiologically distinct illnesses: Legionnaires’ Disease, which is typically characterized by fever, myalgia or muscle pain, cough and clinical or radiographic pneumonia; and Pontiac fever, a milder illness without pneumonia.

The pre-conference workshop I gave at the 2019 Legionella Conference, along with Andrew Ward of NSF, was geared toward health department officials and making them aware of the building water systems and medical devices that can contribute to Legionella bacteria growth if not cleaned and maintained properly. Later in the week, I gave a presentation on how to determine if the water heater(s) in a building can provide a high-temperature heat and flush disinfection if there is a positive test for Legionella bacteria in a building. 

To determine if the water heater is large enough, verify the BTU/hour input of the water heater(s), the heat loss in the circulated hot water system, and the required minimum hot water temperature based on the heat loss in the circuit. It is crucial to ensure the hot water return temperature meets or exceeds the minimum temperature required for disinfection; most disinfection plans require a minimum of 158 F flowing from fixtures for 15 to 20 minutes but may require higher temperatures to provide 158 F at the hot water return connection after the circulating pump. 

Most water heating equipment is not capable of performing this operation because at such high temperatures, the flow rates are so low that, in larger buildings, it could take weeks to flow hot water in excess of 158 F for 20 minutes at every fixture. The risk of scalding would be very high and there is no guarantee that hot water will penetrate “dead legs” and improperly or unbalanced branches. 

Health department officials are like fire department first responders but with respect to reported cases of Legionnaires’ disease. Like a report of a fire, when there is a reported case of Legionnaires’ disease, there is a need for an urgent response to a potentially hazardous condition that requires a closer examination of the situation and an understanding of how to fight (control) or extinguish the hazard. This is to ensure that there is no widespread outbreak. 

Follow a series of steps to perform an investigation into the possible source or cause of Legionnaires’ disease. Investigations into reported cases of Legionnaires’ disease are called epidemiologic investigations. Epidemiology is understood as: “The study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations.” 

In recent years, epidemiology has grown to include the study, analysis and assessment of risk factors associated with building water systems that are often the source of or associated with the growth and proliferation and aerosolization of Legionella bacteria. Epidemiology is a cornerstone of public health investigations. 

Often these investigations help shape public health and code policy decisions through evidence-based gathering of information by identifying risk factors for the growth of bacteria in building water systems. Health officials use this information to minimize the growth and spread of disease by establishing target temperature ranges and water treatment chemical levels to control Legionella bacteria growth and reduce the risk of transmission of bacteria to humans.

What is essential in an epidemiological investigation into reported cases of Legionnaires’ disease is the performance of a risk assessment of a plumbing and mechanical system. The investigator or risk assessor should be properly trained in Legionella bacteria and Legionnaires’ disease but, more importantly, the investigator or risk assessor must be trained in the design, installation and operation of plumbing and mechanical systems, as well as the related engineering and physics disciplines. 

I have seen epidemiological risk assessments of plumbing and mechanical systems by infection control nursing staff, janitorial staff, chemical sales associates and lab technicians. Such persons were seemingly oblivious to the apparent “dead legs,” improper temperature control conditions and improperly piped systems, which are contributing factors to bacterial growth in building water systems. 

Many of these unqualified risk assessors miss many severe problems in plumbing and mechanical systems while on their way to collect samples for Legionella testing. Legionella testing is a great and necessary tool for confirming if there is a problem or whether the system is performing well, but it alone will not correct problems in the system design, installation, operation or maintenance. A qualified Legionella risk assessor with system design experience should be hired to evaluate systems after one or more confirmed cases are associated with a building. 

After verifying a case of Legionnaires’ disease, public health officials should interview the patient about the 10 days before the onset of symptoms to capture, at a minimum, critical demographic, clinical, exposure and reporting details for surveillance purposes using the Supplemental Legionnaires’ Disease Surveillance System Legionellosis Case Report Form available on the Centers for Disease Control and Prevention (CDC) website (www.cdc.gov) or equivalent state-specific case report form.

When public health officials receive a report of a case of Legionnaires’ disease, they should first verify that the case meets the case definition for legionellosis.

The CDC classifies Legionella cases as confirmed or suspected. The following are descriptions of criteria to determine whether to classify a legionellosis case as confirmed or suspected. This is simply officials trying to decide whether the outbreak is the flu or a case of Legionnaires’ disease.

Laboratory Criteria for Diagnosis

A confirmed case classification is a clinically compatible case meeting at least one of the confirmatory laboratory criteria. A suspected case classification is a clinically compatible case meeting at least one of the presumptive (suspect) laboratory criteria.

1. Confirmed cases. One way Legionnaires’ Disease cases are confirmed is by the culture method. This is done by taking a culture from respiratory secretions, lung tissue, pleural fluid, or other normally sterile sites and growing it in a laboratory media.

Cases also are confirmed by the detection of Legionella pneumophila serogroup 1 antigen in urine using validated reagents in a urine antigen test. Lastly, Legionnaires’ cases can be confirmed by the seroconversion, a fourfold or more rise in specific serum antibody titer to L. pneumophila serogroup 1 using validated reagents on specimens collected three to six weeks apart. The antibody titer is a test that detects the presence and measures the number of antibodies within a person's blood.

2. Suspected cases. By seroconversion: fourfold or greater rise in antibody titer to specific species or serogroups of Legionella other than L. pneumophila serogroup 1 (e.g., L. micdadei, L. pneumophila serogroup 6) using validated reagents on specimens collected three to six weeks apart.

By seroconversion: fourfold or greater rise in antibody titer to multiple species of Legionella using pooled antigen and validated reagents on specimens collected three to six weeks apart.

By the detection of specific Legionella antigen or staining of the organism in respiratory secretions, lung tissue or pleural fluid by direct fluorescent antibody (DFA) staining.

By the detection of specific Legionella antigen or staining of the organism in respiratory secretions, lung tissue or pleural fluid by immunohistochemistry (IHC).

By detection of Legionella species by a validated nucleic acid assay (e.g., polymerase chain reaction or PCR). This technology is evolving, so feel free to contact the CDC if you have questions.

Exposure Histories

The incubation period for Legionnaires’ disease is most commonly two to 10 days from the time of exposure to symptom onset, with an average of five to six days. However, public health officials have reported incubation periods up to 26 days under rare circumstances.

The incubation period for Pontiac fever is shorter; 24 to 72 hours after exposure. For surveillance purposes, public health officials should collect exposure histories for the 10 days before the date of onset of symptoms. However, in an outbreak setting where it is essential to consider a wide range of possible sources, use of a 14-day range (or more) may be desirable. 

For definite health-care-associated Legionnaires’ disease, using a more extended period could lead to the exclusion of certain cases unintentionally; for example, cases with at least 10 but fewer than 14 days of continuous exposure to a single healthcare facility. For this reason, CDC recommends using a 10-day period to define definite health-care-associated Legionnaires’ disease.

If the date of the onset of symptoms is difficult to define (e.g., in patients with chronic underlying illness), date determination is deferred to the judgment of the clinicians providing care and the public health officials performing the investigation.

The CDC form gathers patient information, then asks questions such as: Date of symptom onset of legionellosis; Date of first report to public health at any level; Was the patient hospitalized during treatment for legionellosis; What was the outcome of illness; In the 10 days before onset, did the patient spend any nights away from home (excluding health-care settings including name of facility, dates, address info, and room number).

Other questions include:

• In the 10 days before onset, did the patient get in or spend time near a whirlpool spa (i.e., hot tub)?

• In the 10 days before onset, did the patient use a nebulizer, CPAP, BiPAP or any other respiratory therapy equipment for the treatment of sleep apnea, COPD, asthma or for any other reason?

• In the 10 days before onset, did the patient visit or stay in a health-care setting (e.g., hospital, long term care/rehab/skilled nursing facility, clinic)?

• Was this case associated with a healthcare exposure: Definitely: Patient was hospitalized or a resident of a long-term care facility for the entire 10 days prior to onset; No: No exposure to a health-care facility in the 10 days before onset; Possibly: Patient had exposure to a health-care facility for a portion of the 10 days before onset; Other (specify); or Unknown.

Answering these questions should help determine the potential source of the Legionella bacteria. 

Other Meeting Reports

 At the IAPMO annual meeting, Executive Director Russ Chaney gave an update on what is happening with IAPMO codes, standards, activities and IAPMO Labs. His presentation was full of information. This is just a quick summary of what he said, which included the final voting on the Uniform Codes for the 2021 code cycle. 

The Uniform Plumbing Code and the Uniform Mechanical Code follow a three-year code revision cycle. In the past, each year was a struggle to complete the code change process and print the codes promptly. The uniform codes have been moved forward in the code development cycle to start the code revision process a year earlier so that code jurisdictions will have some time to review and add any local amendments before they are adopted. 

In the past, IAPMO published the codes in the second quarter of the year printed on the cover of the code book. This caused a delay because local jurisdictions needed time to review the new code before adoption. It usually resulted in jurisdictions adopting the codes a year or more after they were published. So IAPMO moved the code revision cycle up a year.

During ASSE’s main product standard committee meeting, the group announced it is aggressively working on updating a few standards that have not been updated in a while. It also reported on the progress of the revisions and reaffirmations; the group is on track to have all its standards updated in compliance with ANSI requirements.

One of the working groups that met during the ASSE annual meeting was the one for the ASSE 1017, Temperature Activated Mixing Valves for Hot Water Distribution Systems. There were a lot of discussions to determine if a new standard was needed for the new digital mixing valves. Many thermostatic mixing valve manufacturers historically manufactured their mixing valves with bi-metal or liquid paraffin wax thermostatic elements. Now many manufacturers are coming out with digital mixing valve technology. 

The first digital mixing valve on the market was The Brain by Armstrong International. It is still setting the standard for quality and temperature-control accuracy. However, many other manufacturers are now making their own versions of a digital mixing valve. Digital mixing valves are more accurate than liquid paraffin wax technology and many times more precise than bi-metal coil-type mixing valve technologies. 

The committee discussed creating subcategories under the ASSE 1017 digital mixing valve standard, which will address testing requirements for the power supplies and control circuits associated with digital mixing valves. Another discussion was held about aligning the life cycle testing between the different mixing valve standards. 

Happy Thanksgiving to you all and Happy Holidays!