NY Travel Clinic

Prevention and diagnosis of Legionnaires’ disease

An outbreak of Legionnaires’ disease in New York City should be a warning about how serious this illness is and should prompt us to learn how to protect ourselves from it.  You will be surprised about some of the sources of the disease. If you travel in the US or abroad, read this article to learn how to prevent it.  There are over 18 000 cases of the disease in the US each year and it causes thousands of deaths.  Legionnaires’ disease occurs throughout North America, Europe, Asia, Africa, Australia, and South America.

Legionnaires’ disease is caused by bacteria of the genus Legionella.  Most cases of Legionnaires’ diseaseare caused by Legionella pneumophila, but all species of Legionella can cause it.  The potentially fatal disease causes a severe form of pneumonia.

Where the bacterium lurks

The bacterium is found in water and potting mixes.Infection can occur if you breathe in water droplets containing Legionella bacteria. Sources of the bacterium include cooling towers in air conditioning systems, hot tubs and whirlpools, pools,and water systems in hotels, hospitals and nursing homes.  A shower, faucet or water from the ventilation system in a large building can spread the disease. Contaminated potting soil is a source of the bacterium and some people have become infected after gardening or using potting soil. Water-mist devices used to keep produce fresh at the supermarket can be a source of the bacterium. Other sources include physical therapy equipment, decorative fountains and humidifiers.  Wherever there is water mist or vapor, think Legionella.  Legionnaires’ disease can’t be spread from one person to another.

Electronic faucets are more likely to become contaminated with high levels of Legionella compared with manually operated faucets.


Symptoms of Legionnaires’ disease usually occur two to 10 days after exposure to Legionella bacteria and include headache, high fever, chills and muscle pain.  Legionnaires’ disease presents with pneumonia.

By the second or third day, other symptoms include cough with mucus and maybe blood, chest pain and shortness of breath. Nausea, vomiting and diarrhea, and confusion can occur.

It occasionally can cause infections in the heart.

Pontiac fever is a mild form of Legionnaires’ and can produce symptoms such as fever, chills, and headache.  Pontiac fever symptoms usually clear within two to five days.

People at high risk of getting sick include current or former smokers, older people, those with a chronic lung disease (like COPD or emphysema) and those who take drugs that suppress the immune system.  People with a weak immune system caused from diseases like cancer, diabetes, or kidney failure are at high risk too.


Proper cleaning and disinfection of water systems, pools, spas and hot tubs is essential to prevent the disease.  Before you book a hotel, ask if they clean their cooling towers and have them email you a copy of their disinfection work.  Although you can’t avoid all buildings with cooling towers, you can be vigilant about your symptoms and go to a doctor immediately if you have symptoms of the disease.

Avoid hot tubs and whirlpools, electronic fountains and public fountains.  Avoid buying produce that’s been sprayed with a mist and wear a mask when you garden.  If you smoke, quit.


Legionnaires’ disease is treated with antibiotics, but treatment must be started quickly to prevent serious complications or death. Treatment might require hospitalization.

The best way to prevent Legionnaires’ disease is to be vigilant about sources of water mist, avoid sources of the causative bacterium, and to go to a doctor if you have the above symptoms.