A fourth person has died in the Legionnaires' outbreak in the Bronx as two more buildings have tested positive for legionella.

NYC officials have emphasized that "All deceased individuals were older adults and had additional underlying medical problems." (It should be easily treatable if the victim is otherwise healthy.) So far, 65 people have been reported to have Legionnaires', with 55 hospitalized. Twenty people have been discharged.

Last week, Lincoln Medical Center, the Concourse Plaza shopping center and Opera House Hotel tested positive for the disease. Now a Verizon office building and the Streamline Plastic Co. have tested positive. All locations have completed remediation except for Streamline Plastic Co. which should be finished today. All buildings are in the "same 20-square-block area."

The Centers for Disease Control explains, "Legionnaires' disease (LEE-juh-nares) is caused by a type of bacteria called Legionella. The Legionella bacteria are found naturally in the environment, usually in water. The bacteria grow best in warm water, like the kind found in: Hot tubs; Cooling towers; Hot water tanks; Large plumbing systems; Decorative fountains. They do not seem to grow in car or window air-conditioners."

As for how the disease is spread, the CDC says, "People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) containing the bacteria. One example might be from breathing in droplets sprayed from a hot tub that has not been properly cleaned and disinfected. The bacteria are not spread from one person to another person.

NYC Health Commissioner Mary Bassett said, "The water supply in the south Bronx remains entirely safe. We don't know the source of this outbreak, but in recent months we have seen outbreaks associated with cooling towers and that's why we're focusing on them. We're testing every cooling tower we can find in the area."

Still many residents in the South Bronx are buying bottled water, and the NY Times notes, "A study published last year by scientists working for the city’s health department found that the incidence of Legionnaires’ disease was highest in impoverished areas, as well as among people working in the transportation, repair or construction industries. The study, published in the journal Emerging Infectious Diseases, called for steps to be taken to address those findings."

Bronx Borough President Ruben Diaz Jr. said in a statement on Friday, "During the course of our actions fighting the Legionnaire’s Disease outbreak in The Bronx, it has been revealed that there is no inspection mechanism for coolant systems, rooftop water tanks and other standing water infrastructure that could be a breeding ground for this disease and others. The city must create a new inspection system for these systems, just as we inspect other critical systems such as elevators."

There will be a town hall on Monday night with City Council Member Vanessa Gibson. Deputy Health Commissioner Dr. Jay Varma said, "We think it is very possible that there will be an increase in cases over the next seven days. We are also quite confident that after that time, the number of cases will go down. We can never know for sure what the future holds and we are working very aggressively to make sure people at risk - people in senior centers, people at homeless shelters, people with other medical problems - get the message to pay attention to their health."