NEW YORK -- A Legionnaires' disease outbreak in a New York City neighborhood now counts 60 cases, but new diagnoses are slowing, health officials said Tuesday. They reported progress on inspections for the disease-causing bacteria but still haven’t pinpointed a source.

No one has died in the outbreak on Manhattan's Upper East Side, but 49 patients have required hospitalization, though 34 so far have gone home, city Health Commissioner Dr. Alister Martin said. City data show two new cases were diagnosed from samples taken Thursday through Saturday, compared to as many as 11 per day from earlier samples.

“All of these things together paint an encouraging sign,” Martin said at a virtual news briefing.

It came a day after City Council Speaker Julie Menin, a Democrat and Upper East Side resident, complained that the Health Department wasn't doing and disclosing enough. A message seeking comment was sent Tuesday to Menin's office.

Legionnaires' disease is a form of pneumonia caused by Legionella bacteria, which grow in warm water and can spread in building cooling systems, hot tubs and showerheads. In many cases, people contract the disease by inhaling tiny droplets of contaminated water; Legionnaire's doesn't spread person-to-person.

The illness is treatable, but it is fatal in about 10% of cases, according to the U.S. Centers for Disease Control and Prevention. Seven people died and more than 100 were sickened during an outbreak last year in New York's Harlem neighborhood. The sources turned out to include cooling towers — devices sometimes used for cooling large buildings — at a city-run hospital and the site of the city's public health lab.

Health officials are working to identify the origin of the Upper East Side outbreak, which was first identified on July 2 from two cases in close proximity. The investigation expanded to encompass three heavily residential ZIP codes.

The city said Tuesday it has inspected all 183 cooling towers in the area, and 76 of them came up positive on first-round tests that don't distinguish between live and dead bacteria.

Those buildings included the Guggenheim Museum, Park and Fifth Avenue apartment houses, private schools and more.

The Guggenheim and 56 other buildings so far have completed required cleanups, which entail draining and disinfecting the cooling towers, Martin said. The other 19 buildings that tested positive are due to do so by Thursday.

Martin noted that the city used to await results from second-round tests for live bacteria before ordering such cleanups but this year decided not to hold off. The tests take about two weeks.