As our state and nation emerge from the Covid-19 health care crisis, another public health risk looms.

Cases of Legionnaires’ disease, a severe and sometimes deadly form of pneumonia caused by a bacterium known as Legionella pneumophila, are on the rise across the United States, with Pennsylvania showing some of the highest rates of infection and illness year after year.

Philadelphia was home to the first major outbreak of Legionnaires’ disease in the United States in 1976, when 200 people fell ill and 34 others died after attending an American Legion convention at a downtown hotel. The most recent case of Legionnaires’ disease was reported in Jenkins Township, Luzerne County.

READ MORE — Nick Russo: Retired Philly science teacher leads cleanup effort in Cobbs Creek Park

Like Covid, this respiratory disease can impact anyone, especially those with compromised respiratory systems — and the 1.3 million Pennsylvanians who have recovered from Covid are at heightened risk.

According to the U.S. Centers for Disease Control and Prevention, cases of Legionnaires’ disease in Pennsylvania have increased 65.9% over five years. Only four other states — New Hampshire, New York, Ohio, and Rhode Island — and the District of Columbia have rates higher than Pennsylvania over the same period.

However, the numbers may be much higher, as Legionnaires’ disease, frequently fatal but almost entirely preventable, is believed to be severely underdiagnosed. A recent study by the National Academy of Science, Engineering and Medicine estimates that the true number of Legionnaires’ disease cases may be ten times higher than reported.

Recently, concern for contracting Legionnaires’ disease has been magnified. The Covid-19 pandemic forced many public buildings to shut down. When buildings have low to no occupancy, water safety is jeopardized. Stagnant water prevents effective chemical treatment, and dormancy of water allows Legionella pneumophila bacteria to grow.

There are 60-plus species of Legionella, most of which have no major disease implications at all. The pathogen of concern is Legionella pneumophila, which has been the cause of all CDC-led Legionnaires’ disease outbreak investigations since 2006.

Legionella pneumophila bacteria are found naturally in freshwater environments, including waters used as a source by public drinking water systems. The bacteria then enter man-made water systems, grow, and eventually spread via water aerosols from faucets and showerheads, hot water tanks, cooling towers, and plumbing systems. Other systems, like hot tubs, decorative fountains, and water features that are not well controlled or have been dormant, also pose a risk.

Now that schools, malls, office buildings, and other communal settings are reopening and increasing occupancy, or opening and closing intermittently because of Covid variants, the risk for an outbreak is on the rise, as closed buildings often reopen without anyone checking the quality of the water inside.

All U.S. Veterans Administration facilities have water management plans to prevent Legionnaires’ disease that include routine testing. The Centers for Medicare and Medicaid Services (CMS) also requires any facility that receives CMS funding to have in place “policies and procedures that inhibit microbial growth in building water systems that reduce the risk of growth and spread of Legionella and other opportunistic pathogens in water.”

It is irresponsible to wait until case rates become epidemic to act and put in place reasonable measures that would protect the public from a disease we already know how to prevent.

Currently, Pennsylvania has no requirements for managing or testing for this disease, but that can change. Bipartisan legislation (S.B.1125) recently introduced by state Senators Joe Pittman (R-Indiana) and Wayne Fontana (D-Allegheny) would help identify risks associated with Legionnaires’ disease and formalize steps for prevention and mitigation.

The measure would codify the CDC-supported seven-step industry standard (ASHRAE-188) to identify where there is risk of bacterial growth in water systems and provide simple actions that building owners can take to mitigate or reduce that risk by targeting Legionella pneumophila.

The Senate bill would direct both public drinking water providers and certain building owners to assess their respective water systems for risk and adopt common-sense steps to reduce that risk, i.e., flushing clean water through the system, keeping hot and cold water at appropriate temperatures, and monitoring the system regularly.

Everyone has a stake in this measure.

Remediation of a building with unacceptable levels of Legionella pneumophila bacteria is expensive, disruptive, and reputationally damaging. Hospitalization costs for Legionnaires’ disease are significant, with patients paying on average about $38,000 per stay and victims could have life-long health problems.

It is irresponsible to wait until case rates become epidemic to act and put in place reasonable measures that would protect the public from a disease we already know how to prevent.

Dr. Meilin Young is a Pulmonary and Critical Care specialist in the Pittsburgh Region. Learn about her work here.