Consider it part of a grim paradox that Legionnaires' disease has killed seven people so far this summer in the Bronx.
After all, the Ebola virus -- way more medically ferocious -- claimed no lives in New York after it showed up briefly here late last year.
Government's varying responses to these different public health threats owes much to the nature of these microscopic beasts.
Ebola, fatal in 90 percent of cases, spreads through contact with bodily fluids. The familiar Legionnaires', fatal in up to 30 percent of cases, usually comes from inhalation.
Last October, during an Ebola scourge in Liberia, federal officials issued protocols, and states and cities mobilized training efforts, bracing for unfamiliar and scary possibilities. A city doctor who caught Ebola in Africa was hospitalized here -- but survived, while a politicized debate raged over quarantining.
Battling the relatively familiar Legionella, on the other hand, poses a more workaday task for city health officials. This bacteria breeds in mist or vapor contaminated from within cooling towers, hot tubs, and the plumbing and air-conditioning systems of big buildings. So its sources can be found and fixed.
During a 2007 outbreak on Long Island, technicians identified a cooling tower on the rooftop of a Roslyn Heights nursing home as an incubator of Legionella. It was cleaned with a strong bleach compound. Similarly, city workers were acting to disinfect a cluster of cooling towers in the South Bronx found contaminated in recent days.
If only they'd found it earlier, you may say.
In 2005, health officials in the Pataki administration warned hospital administrators around the state to enact plans that could prevent Legionella water droplets from reaching the lungs of those vulnerable.
"The extent of measures taken to prevent health care facility-associated Legionnaires' disease will depend largely on the risk factors for acquiring Legionnaires' disease in the population served by the hospital," said the memo from then-state Health Commissioner Antonia C. Novello.
Whether the notice helped at all is unclear. Outbreaks have persisted since.
Now Mayor Bill de Blasio says he and the City Council are developing "new inspection standards for buildings with cooling and condensing units," with the city willing to step in to inspect if commercial property owners do not.
"We are going to be very aggressive in dealing with this problem," he said at a news conference at Lincoln Medical Center Tuesday. "We do not accept this as an inherent risk that can't be addressed."
The Legionella organism was first pinpointed and named after a 1976 outbreak that sickened 221 people and killed 34, mainly among those who attended an American Legion convention in Philadelphia.
City and state officials took differing positions on travel and quarantine during last year's Ebola preparations. The state Health Department noted Tuesday that it tests water samples collected by the city for Legionella. Cuomo administration officials mostly stayed in the background, and were not immediately available to opine on the city response or say if proposed city measures would require state action.
Now that the city has wrestled with Ebola and Legionnaire's within 10 months, it becomes clear that despite the old expression, the devil you know can be worse.