This is the disease that caused an outbreak in New York and keeps the United States on alert: traces detected in museum

New York health authorities are maintaining surveillance due to a legionellosis outbreak that has already infected 63 people in the Upper East Side of Manhattan, while investigations continue to identify the source of the Legionella bacteria, traces of which were detected in the cooling towers of 76 buildings, including the Metropolitan Museum of Art (MET), one of the main tourist icons of the United States.

Although authorities insisted that there is no immediate risk to those visiting the museum, the finding forced cleaning and disinfection work in the facilities, as well as follow-up tests to confirm the elimination of the bacteria.

The case has once again brought to the forefront a rare but potentially deadly disease that causes outbreaks each year associated with contaminated water systems and can cause a severe form of pneumonia.

According to the New York City Department of Health, the outbreak began on July 2 and, as of Tuesday night, had left 63 people ill, of whom at least 49 required hospitalization. Unlike an outbreak that occurred last year in Harlem, where seven people died and more than a hundred were affected, no deaths have been reported this time.

Authorities also noted that the rate of spread appears to be slowing. While some days saw up to 11 new daily cases, the most recent samples confirmed only two new infections between Sunday and Monday.

As part of the epidemiological investigation, inspectors reviewed 183 cooling towers distributed across three zip codes in the Upper East Side. Traces of Legionella were found in 76 of them, leading to mandatory cleaning and disinfection processes.

Among the buildings with positive results are the Metropolitan Museum of Art, residential buildings located on Park Avenue and Fifth Avenue, a rehabilitation center, and a senior residence. Days earlier, authorities had also reported preliminary positive results at the Guggenheim Museum.

The MET confirmed that it suspended scheduled activities during the usual Wednesday closing day to facilitate decontamination work and reiterated that there is no danger to employees or visitors.

Legionellosis, also known as Legionnaires’ disease, is a serious respiratory infection caused by the Legionella bacteria. According to the United States Centers for Disease Control and Prevention (CDC), it is a severe type of pneumonia that may require hospitalization and, although treatable with antibiotics, can cause potentially fatal complications.

The bacteria can also cause a second illness known as Pontiac fever, a much milder infection that usually causes fever, muscle pain, and headache, but does not progress to pneumonia.

In rare cases, Legionella can also cause infections outside the lungs, such as heart conditions or wound infections.

Unlike other respiratory pathogens, legionellosis is not transmitted from person to person.

The CDC explains that infection occurs when a person inhales small droplets of water—or aerosols—that contain the bacteria. These aerosols can be generated in different systems where water is stored or circulates, especially when there is inadequate maintenance.

Places where Legionella can proliferate include:

In fact, the CDC warns that the bacteria can grow in the windshield washer fluid reservoir of some vehicles when it is filled only with water, which is why they recommend using commercial cleaning fluids and following the manufacturer’s instructions.

Symptoms usually appear between two and 14 days after exposure to the bacteria, although in some cases they may take longer.

As it is a pneumonia, the manifestations are similar to those of other severe respiratory infections. The main symptoms include:

To confirm the diagnosis, a chest X-ray can identify pneumonia, although specific tests are later required to determine if Legionella is the cause. These include a urine test and laboratory tests performed on sputum samples or lung washes.

The CDC points out that most healthy people exposed to the bacteria do not develop the disease. However, some groups are at higher risk of complications.

These include older adults and people with chronic illnesses or conditions that affect their immune system, who are more likely to develop a severe infection and require hospitalization.

Precisely for this reason, U.S. health authorities have maintained close surveillance over the outbreak recorded in Manhattan, where several of the inspected buildings house vulnerable populations, such as older adults.

Legionnaires’ disease requires treatment with specific antibiotics. The CDC indicates that most patients recover when they receive timely medical care, although hospitalization is often needed.

Early diagnosis and treatment significantly increase the chances of recovery and reduce the risk of complications.

However, the disease can cause respiratory failure and, in the most severe cases, death.

CDC statistics show that approximately one in ten people who develop legionellosis dies due to complications associated with the infection. This risk increases considerably among those who acquire the disease during a stay in a healthcare facility, where mortality can reach one in four patients.

Experts agree that the main strategy to prevent outbreaks is to prevent the growth and spread of the bacteria in water systems.

To this end, building owners and managers must implement water management programs that allow monitoring and controlling the presence of Legionella, especially in cooling towers and other systems where water may remain stagnant.

While investigations continue in New York to establish the original source of the outbreak, authorities maintain inspection and disinfection work in dozens of buildings with the aim of breaking the chain of exposure and preventing new cases of a disease that, although rare, can become a serious public health threat when it finds the right conditions to spread.

EDWIN CAICEDO

Environment and Health Journalist

@CaicedoUcros