By: Candess Zona-Mendola

Summer brings the typical effects of sun, sand, and fun. But when it comes to disease, summer can also be a time of year when concerning pathogens are on the rise. We recently discussed that E. coli is a bacterium that is on the rise during the summer months. This particular season is also the peak time for another dangerous bacterium, Legionnaires’ disease. The instances that could lead to exposure are common during the warm season. These include: extended hotel stays, the abundance of air conditioning, and immersion into man-made water sources.

Since 2000, the Center for Disease Control and Prevention’s surveillance of the bacterium shows infections are on the rise. In 2015 alone, there were 6,000 reported cases. But, as the disease is underreported, the number of infections is believed to be much higher – closer to 25,000 cases. The Occupational Safety & Health Administration estimates the disease claims up to 4,000 lives per year.

Never Heard of Legionnaires’ Disease?

It is not uncommon for someone to have never heard of the disease. In fact, its discovery is relatively new in comparison to older diseases, like salmonella. But this severe, and at times lethal, form of pneumonia should not be underestimated.

Let’s Have a Little History Lesson

In 1976, the disease was discovered in Philadelphia shortly after the annual American Legion convention. The outbreak reached 200 victims, and 29 people died.

In July of 1976, attendees of the convention began to experience symptoms of chest pains and high fevers within days after the convention. A short time later, they died. The city was puzzled as to the cause. The attendees travelled from different cities, stayed in different places, and ate food from all over the city. The mystery was so concerning, that the Centers for Disease Control and Prevention (CDC) sprang into action. For many Americans, this was their first exposure to the organization. During an interview at the time for TIME magazine, the then- CDC Director David Sencer commented, “I think we will [find the source]. But there are times when disease baffles us all. It may be a sporadic, a onetime appearance.”

Fear swept the nation. Close friends and families did not attend funerals of some of the American Legion members for fear of contracting the disease. The mystery illness was coined “The Philly Killer.” The media called it the “greatest epidemiological puzzle of the century.” The CDC investigators and epidemiologists worked tirelessly to obtain samples and interview the victims and/or their families. What is a virus? Was it foul play? What happened here?

Then, a few months later, the case counts began to dwindle. Public interest became null. Fear subsided. But still, no answer to the question, “what killed these men?”

A Breakthrough

Five months later, there was a breakthrough. CDC epidemiologist Joseph McCade found a bacteria isolated from the convention location’s air conditioning system. McCade told the New York Times in 1977 that he needed to press on and find out what killed these men. He claimed he felt “haunted” by the mystery. Research had not found a bacterium that looked quite like it. The source and pathogen were discovered. The CDC concluded that the bacteria were present in water vapor from the air conditioning system and inhaled by the infected attendees. In honor of those who died, the mystery illness was named Legionnaires’ disease.

More Outbreaks, A Common Denominator Found

The 1976 outbreak was far from the last of its kind. A 1985 outbreak of Legionnaires’ disease in the United Kingdom lead investigators to another air conditioner culprit. A 1999 outbreak in the Netherlands after a flower exhibition led to the discovery that the bacteria also contaminated sprinklers and whirlpool spas. A 2001 outbreak in Murica, Spain was also linked to cooling towers. Different countries, same bacteria, similar sources? The statistics stacked up, Legionella was found in man-made water sources.

But it is Still a Problem!

Despite the findings, Legionnaires’ disease is still a problem in the United States. As recent as 2015, the disease claimed the lives of 12 people in New York and sickened another 120 people. Again, the culprit was an air conditioning system. In 2014, 302 people in Portugal became ill with Legionnaires’ disease from the air conditioning unit at a fertilizer plant.

The CDC reports that the majority of those afflicted with Legionnaires’ disease will require hospitalization. And 1 out of 10 people who get Legionnaires’ disease will die, a staggering statistic from a lesser known disease. There is no vaccine.

The symptoms are relatively common and flu-like in nature. One may have a cough, shortness of breath, a headache, muscle aches, and a fever. In some instances, the fever can reach up to 107 degrees Fahrenheit. More severe cases develop into a serious form of pneumonia. This is especially true for those with respiratory issues, smokers (present and former), those who are immunocompromised, or the elderly.

The diagnosis of Legionnaires’ disease is also difficult, as it mirrors pneumonia. Usually a physician will order an xray or examine the phlegm of an infected person for the presence of Legionella bacteria. As Legionella bacteria multiply within human cells, strong antibiotics are used to quell the infection.

How Do You Catch It?

Legionella bacteria live in freshwater. In man-made water sources, like fountains, air conditioners, sprinklers, showers, faucets, etc., Legionella bacteria can grow well. If these sources are not properly maintained, Legionella can become a problem and lead to illness. The small droplets of contaminated water are released into the air and are breathed in by people. This is especially true for “potable” water sources, like hot tubs.

The Scary Truth, But a Solution, Too

The risk of Legionnaires’ disease being spread by large-scale water systems cannot be completely eliminated. This is because the presence of the bacteria is common in fresh water. However, as it is only when these bacteria are overgrown that the disease becomes a problem, the risk for infection can be reduced by proper maintenance of the water features. Hot tubs should especially be maintained with the proper chlorine levels, as Legionella grow best in warm water.