Vitals

Recent Legionnaires’ disease outbreaks raise concerns

Why are some regions more susceptible to Legionnaires’ disease?


legionnaires
By Shanley Pierce | December 4, 2019

In September 2019, an outbreak of Legionnaires’ disease at a hot tub state fair display in North Carolina infected 141 people and resulted in four deaths. That same month, health officials from Tyler, Texas, confirmed seven cases and five suspected cases of Legionnaires’ associated with the East Texas State Fair.

Legionnaires’ disease is a severe form of pneumonia marked by coughing, shortness of breath, fever, muscle aches and pains, and headaches.

Since 2000, the United States has seen an 800 percent spike in the disease, according to the Centers for Disease Control and Prevention (CDC), with a reported 9,933 cases of legionellosis in 2018. Legionellosis is the umbrella term for both Legionnaires’ disease and Pontiac fever, a milder form of the infection caused by exposure to a waterborne bacterium called Legionella pneumophila, often found in moist environments. Hot tubs and large buildings, such as hotels and hospitals, are common breeding grounds for the bacterium to grow and spread.

But outbreaks of legionellosis represent only a small fraction of all cases, said Xiang Y. Han, M.D., a pathologist and microbiologist at The University of Texas MD Anderson Cancer Center.

“For all the cases, only 20 percent of those are outbreak-related,” Han said. “Of the 80 percent of the cases, how did those patients get exposed? Why are some regions more susceptible to Legionnaires’ disease? We don’t know.”

In his recent study published in the American Society for Microbiology’s journal, Applied and Environmental Microbiology, Han identified four factors—longterm precipitation, temperature, solar ultraviolet (UV) radiation and sunshine hours—that correlate with incidences of Legionnaires’ disease in the U.S.

Because climate and environment vary dramatically across the country, Han’s findings offer an explanation as to why some regions are more susceptible to the disease than others. Warm temperatures and wet environments have long been known to promote bacterial growth, but Han’s study identified sunshine hours and UV light as two new factors that curb bacterial growth. Prolonged sunshine increases temperatures, but it also increases UV exposure, which kills bacteria.

Based on these four parameters, Han was able to pinpoint the area surrounding the Great Lakes region as having the highest incidence rates in the country, with Ohio and New York as the top two states with the most cases of Legionnaires’ disease.

“The temperature’s getting higher, but the sunlight’s getting stronger, too. That means the UV gets stronger. Past the Ohio river, the further south you go, the lower the incidence of Legionnaires’ disease,” Han explained. “For example, in Houston, we have 2,900 sunshine hours every year. Whereas in Ohio, there are 2,200 hours … 700 hours less.”

Han’s theory for non-outbreak-related exposure to the bacterium relates to the time people spend on the road.

“The true significance [of the study] is that it gives us insights about exposure,” Han said. The waterborne bacterium can accumulate in dust, mist and mud on the road, entering vehicles through ventilation systems, air conditioning and open windows. Heavy rainfall only compounds the problem.

“There’s a lot of opportunity for exposure,” Han said. “But in that regard, a lot of these cases are probably preventable.”

Han advises people to drive with their windows closed, change cabin air filters and have their vehicles maintained regularly to eliminate any growth and spread of Legionnaires’ disease.

Some national experts insist that incidence rates of Legionnaires’ disease are much higher than the CDC claims. A recent report published by the National Academies of Sciences, Engineering, and Medicine found that the rate of legionellosis is approximately 10 times greater than the total number of reported cases, with as many as 70,000 cases each year.

Those with an increased risk of Legionnaires’ disease include adults 50 years or older who have a history of smoking, a weak or compromised immune system, chronic lung disease or an underlying health condition such as diabetes.

The disease takes its name from the first outbreak in which the waterborne bacterium was identified as the cause—a 1976 outbreak in a Philadelphia hotel where the Pennsylvania American Legion was holding a convention.




Social Posts

profile_image

Veterans Affairs

@DeptVetAffairs

Veterans ask, VA answers: Questions on electronic health record modernization. https://t.co/IkeHFZV0zn via #VAntagePoint

39 mins ago
profile_image

Veterans Affairs

@DeptVetAffairs

103-year-old WWII Veteran finally gets the recognition he deserves https://t.co/shJIdq9Ju9 via @CBSEveningNews

11 hours ago
profile_image

MD Anderson Cancer Center

@MDAndersonNews

Watch to learn how we’re enhancing the ability of patients’ own T cells to fight cancer. #endcancer https://t.co/sFMz5eExco

11 hours ago
profile_image

MD Anderson Cancer Center

@MDAndersonNews

Today’s rising #livercancer rates have been driven by non-alcoholic fatty liver disease, which is linked to obesity.But our experts are working with @ScrippsHealth to study an #immunotherapy combination to treat liver cancer and save lives: https://t.co/uwAhLH51uk #endcancer

12 hours ago
profile_image

Veterans Affairs

@DeptVetAffairs

College of Charleston looks to send dozens of Valentine’s Day cards to Veterans https://t.co/fFqeaN3T7o via @ABCNews4

13 hours ago
profile_image

BCMHouston

@bcmhouston

Dorit Donoviel, Ph.D., discusses taking risks in science and what the Translational Research Institute for Space Health is doing to help people in space with @InnoMapHou. https://t.co/wbML42L9Wb #space #spacemedicine

13 hours ago
profile_image

MD Anderson Cancer Center

@MDAndersonNews

Never-smoker Chuck Martinez explains how @MDAProtons helped him overcome #lungcancer with minimal side effects: https://t.co/fpitho7qXV #CancerMoonshot #endcancer

14 hours ago
profile_image

BCMHouston

@bcmhouston

RT @bcm_ocd: Check out this chapter by our researchers in new book Exposure Therapy for Children with Anxiety and OCD. "Efficacy of exposur…

15 hours ago
profile_image

BCMHouston

@bcmhouston

RT @BCMHoustonJobs: Can you recommend anyone for this job in #Houston, TX? https://t.co/mzmp0HSDDd #Healthcare

15 hours ago
profile_image

University of Houston

@UHouston

RT @UH_Pharmacy: Breaking: With 100% chance of rain for Wed, Jan. 22, the "Shine A Light on Mental Health" fair from noon to 2 pm has been…

16 hours ago
profile_image

Texas Children's

@TexasChildrens

For the second consecutive year, Transplant Services at @TexasChildrens was named the top pediatric transplant center in the US, performing a remarkable 106 solid organ transplants in 2019. Learn more: https://t.co/iR6xO02dTC https://t.co/aOPfISdYhs

17 hours ago
profile_image

University of Houston

@UHouston

Which Shasta are YOU? Check out our new Instagram face effects, available now! https://t.co/POQlqNnN3W

17 hours ago
profile_image

Texas Children's

@TexasChildrens

Join us this Saturday, January 25 for All About HER! (Health, Emotions & Relationships) at @TexasChildrens The Woodlands! To register, visit: https://t.co/7dqWlmWZOg https://t.co/J84AYU8aZW

18 hours ago
profile_image

Texas Children's

@TexasChildrens

Feeling the love on #NationalHugDay 🤗 #AstrosCaravan @OrbitAstros @astros https://t.co/fqD7iWP7AH

19 hours ago
profile_image

TexasHeartInstitute

@Texas_Heart

Belly fat, more than excess weight, may be a factor in the risk for multiple heart attacks, according to a new study. Tackle that belly fat with a heart-healthy diet and exercise. https://t.co/8f3YKQOlPJ via @CNN https://t.co/bDi6EYVVHZ

19 hours ago