Raymond Hozalski: Return to Safe Buildings

Raymond Hozalski and Timothy LaPara have been working together on issues related to drinking water for over 10 years. This team of researchers was well poised to leap into action when concerns about the novel coronavirus arose. They now have two active projects related to COVID-19; both projects build on their expertise and represent a continuation of their primary research interests.
See also LaPara: Tracing the Fate of SARS-CoV-2

Raymond Hozalski and Timothy LaPara are investigating pathogens that can flourish in the water systems of unused buildings. Leaving buildings vacant and unused can lead to stagnation within the plumbing. Stagnation can lead to serious concerns.

Many university, commercial, and industrial buildings were shut down during the COVID-19 stay-at-home order. A period of disuse can cause chlorine levels in the water systems to fall and temperatures to change (rise in cold water pipes and fall in hot water pipes). Such an environment leads to a host of water quality changes including rise of toxic metals like lead and growth of opportunistic pathogenic bacteria like Legionella spp. These organisms are known as opportunistic pathogens because they typically cause disease in individuals with weakened immune systems or other chronic health impairments.

Many of the organisms found in our water pipes, including opportunistic pathogens, exist naturally in soil and water. They are usually kept in balance in a regularly working water system. However, if a system sits idle and the microorganisms are allowed to grow unchecked, the levels of such pathogens could become unsafe. Legionella is one genus of pathogenic bacteria that often flourishes in stagnant building water. Like SARS-CoV-2, many species of Legionella , especially Legionella pneumophila , cause respiratory illness in humans and are most infectious in aerosol form where they can be inhaled into the lungs, such as during showering. Legionella can cause Legionnaire’s disease, which can be even more deadly than COVID-19, as well as a less-serious, flu-like ailment called Pontiac fever.

The industry has been aware of these issues related to stagnation; Hozalski and Timothy LaPara are discovering how quickly those issues can arise. They are researching the best practices for flushing water systems prior to re-opening buildings in order to avoid aerosolized opportunistic pathogens. They drew water samples from shower facilities in five buildings on the UMN Twin Cities campuses: the Minneapolis Health and Recreation Center, the St. Paul Gym, two buildings in the new Athletes Village, and Cooke Hall.

To test for Legionella, water samples were collected and molecular or DNA-based assays and culture-based assays were performed. First, the showerhead was removed and the neck sterilized. These steps ensure that the water sample is not contaminated by anything in or on the showerhead or on the outside of the piping. A first-draw sample of the stagnant water is collected, and then additional samples are taken over time during a flushing of 30 to 45 minutes. Then the researchers return 2-3 days later and again 1 week later to collect more first-draw samples. Thus they can assess how the water quality changes after flushing.

Culture-based assays are fairly simple. The water sample is mixed with certain reagents needed to grow the specific organism, in this case Legionella pneumophila, and poured into a tray. Growth of microorganisms can be seen by color changes in the different test wells of the tray after a week of incubation at the proper temperature.

Molecular (DNA-based) assays are more complicated. DNA must be extracted from the sample and then the number of copies of the target gene specific to a given organism of interest are determined using a quantitative PCR test.

Preliminary results suggest that the most concerning organism, Legionella pneumophila, was not present in the stagnant water in the tested buildings, but that other species of Legionella and other opportunistic pathogens were present. Flushing can usually rid the piping of the concerning organisms in under 15 minutes. Hozalski and LaPara Have found that the organisms return just a few days later if the water is allowed to stagnate again, so repeat flushing or regular water use is necessary to keep these organisms at bay.

Timothy LaPara and Raymond Hozalski were able to use established protocols and build on their expertise to address a known consequence of idle buildings and address a collateral consequence of stay-at-home orders. These innovative researchers are looking beyond the immediate concerns of the COVID-19 pandemic to ensure a safe recovery for society.