Health officials in Hong Kong saw a record number of Legionnaires’ disease cases in the city in 2015 as 66 cases were seen, significantly higher than the 41 cases reported in 2014 (the previous high).


Since reporting of Legionnaires’ notifications were documented in 1997, 307 Legionnaires’ cases have been seen, including 2015. The first year Hong Kong saw double-digit cases was in 2005 when they recorded 11.

Last week, The Centre for Health Protection (CHP) of the Department of Health announced  its revised risk-based strategy for environmental investigation and sampling for cases of Legionnaires’ disease recommended by the CHP’s Scientific Committee on Emerging and Zoonotic Diseases (SCEZD) in view of the local epidemiology as well as prevention and control practices overseas. Click HERE for more details.

Legionnaires’ disease gained national notoriety in 1976 when the Centers for Disease Control and Prevention (CDC) discovered it during an epidemic of pneumonia among American legion members at a convention in Philadelphia.

The causative organism is the bacteria, Legionella pneumophila. Other species have also been implicated in Legionnaires’ disease. The legionella bacteria are found throughout nature, because of this most people become exposed to it but few develop symptoms.

The primary place in nature it’s found is water sources particularly at warmer temperatures; lakes, rivers and moist soil.

It is also found in man-made facilities (frequently the source of outbreaks) such as air-conditioning ducts and cooling towers, humidifiers, whirlpools and hospital equipment.

People get exposed through inhaling infectious aerosols from these water sources. There is no transmission from person to person.

The infection can appear in two clinical forms: Legionnaires’ disease and Pontiac fever.

Both conditions are typified by headache, fever, body aches and occasionally abdominal pain and diarrhea.

Legionnaires’ disease is the cause of pneumonia where a non-productive cough is typical. Fatality rates of this form of the infection are around 15 % even with improvements in treatment.

Pontiac fever is a self-limiting flu-like illness that does not progress to pneumonia or death. Diagnosis is usually made by typical symptoms in an outbreak setting.

Diagnosis of Legionnaires’ disease depends on identifying the bacteria in microbiological culture, detecting the antigen in urine samples or a fourfold increase in antibody titer.

Certain health conditions make you more susceptible to infection to include increasing age, smoking, chroniclung disease, malignancy and diabetes mellitus.

Legionnaires’ disease is treatable with antibiotics.