Cases of Legionnaires’ disease are on the rise in Maine and other New England states, and the reason isn’t known.
Maine typically has 10 cases a year of the bacterial infection that causes Legionnaires’ disease. So far this year, it has documented 18, including 12 in the past three months, said Dr. Stephen Sears, epidemiologist with the Maine Center for Disease Control and Prevention.
Massachusetts, Connecticut and Quebec also have had significant, unexplained increases in recent months, Sears said.
“It’s pretty usual to see sporadic cases,” Sears said. “What’s unusual is that (the increase) has occurred throughout New England and Canada at about the same time.”
In Connecticut, health officials have documented 72 cases this year, compared with 47 at this time last year, according to federal data. Massachusetts has had 211 documented cases this year, compared with 118 last year.
States in other regions of the country are not reporting significant increases in the disease.
Sears said he and infectious-disease experts in Massachusetts and Connecticut recently compared their rising numbers but could not explain them.
“Maybe it’s warmer (weather) into the fall,” he said. “Is it because we’ve had so much rain? Those are all speculations.”
Legionnaires’ disease got its name in 1976, when an outbreak struck people at an American Legion convention in Philadelphia. Legionella bacteria are common in water, and can cause a severe strain of pneumonia when inhaled in water droplets or vapor. The outbreak in Philadelphia, for example, was traced back to the convention center’s air conditioning system.
The disease cannot be spread from person to person. Its symptoms include high fever, chills, cough, chest pain and muscle aches. Most patients take antibiotics and recover, although 5 percent to 30 percent die. The disease is most severe in patients with underlying medical conditions, like cancer.
Maine’s CDC issued an advisory Monday telling the state’s medical community to watch for new cases, test for possible infections and report them. Legionnaires’ is usually suspected when symptoms are severe, especially if a patient reports a risk factor such as recent travel, exposure to whirlpool spas or recent plumbing repairs in the home.
Legionnaires’ disease requires a longer treatment – typically three weeks – with a different antibiotic from those often prescribed for more common types of pneumonia.
“If you know it’s Legionnaires’ you can target your therapy more effectively,” Sears said.
Most of the 18 Mainers who have been diagnosed with legionellosis this year developed the full-blown Legionnaires’ pneumonia and were hospitalized, Sears said. All survived, and have recovered or are recovering, he said.
Although Legionnaires’ disease is associated with mass outbreaks from contaminated water, doctors in Maine say it is now more common to see scattered, individual cases. Institutions such as hotels and hospitals are more careful about sanitizing water and ventilation systems than they were in the past, so more common sources are whirlpool spas, showers and faucets, Sears said.
Homeowners can be exposed, for example, when they turn on a shower after a plumbing repair or when they don’t heat their home’s hot water supply enough to kill the bacteria, said Dr. August Valenti, head of epidemiology and infectious diseases at Maine Medical Center in Portland.
Valenti said he has been diagnosing Legionnaires’ cases since the disease was first identified, and believes it is more common than people know.
“Probably there are more coming in (with the infection) than we realize. We do not always test for Legionnaires’,” he said.
Valenti said he watches for the more severe pneumonia symptoms that can indicate a Legionnaires’ infection, and routinely asks pneumonia patients if they have had work on their home plumbing. He said he treats all pneumonias with antibiotics that cover Legionnaires’ and other forms of pneumonia.
Valenti said he is stumped by the recent increase around the state and the region.
None of the 18 cases diagnosed this year appears to be related to others, according to the CDC.
“We try to make links to see if there is any water system connecting the cases, and we haven’t made any,” Sears said.
The 18 Maine patients range in age from 26 to 89. They live in eight counties, with nine of the 18 living in Cumberland and York counties.
The CDC does not identify the towns where patients live, to make sure that residents of small towns cannot be identified, Sears said.
Alfred DeMaria, state epidemiologist in Massachusetts, said the increase appears to have occurred since August throughout the Northeast and in eastern Canada.
“We have investigated the distribution of our cases and found no common exposures except for a couple of circumstances,” DeMaria wrote in an email Monday.
Some European experts have linked an increase in the disease to climatic conditions, although that has not been proven, DeMaria said.
“The idea is that wet and warm, but not too hot, weather favors the organism and its aerosolization,” he said.
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