Legionnaires' disease is caused by bacteria known as the Legionella pneumophila, which is usually found in soil and water, causing severe lung infection. Those who are infected with the disease develop symptoms two to 10 days following their exposure including diarrhea, abdominal pain, muscle pain, headaches, tiredness, shortness of breath, dry cough, and fever. For severe cases, people usually get neurological symptoms like confusion, and respiratory failure likely occurs.
According to the US Centers for Disease Control and Prevention (CDC), one in 10 people infected with Legionnaires' disease dies from it. The number of cases of the disease has been on the rise over the past decades in many countries such as Europe, Japan, New Zealand, Canada, and the United States.
Who is at risk?
The majority of people exposed to the Legionella bacteria don't get infected, but risk factors include those who are over 50, those with a history of smoking and drinking alcohol, and those who have a chronic illness such as lung or kidney diseases, diabetes, or cancer. According to the World Health Organization, of reported patients, 60 to 70 percent are male, and 75 to 80 percent are over 50 years of age.
Meanwhile, as of December 13, Hong Kong has a total of 103 cases of Legionnaires' disease this 2018, the South China Morning Post reported. Since late November, three people with links to a Tseung Kwan O housing estate have been diagnosed with the disease, so the health scare has put residents on alert to remind them the potentially deadly bacteria is always a risk.
The outbreak in a Tseung Kwan O started with a 76-year-old woman and a 61-year-old man, as per the Center of Health Protection (CHP) on November 26. On December 4, the third case was reported which involved a 69-year-old man from The Wings IIIA estate. The two male patients were still in a critical condition on Friday night, while the woman has been discharged, according to the Hospital Authority.
How people get infected?
Legionella bacteria multiply very in warm water, at about 20 to 45 degrees Celsius. They usually found in environments containing water, including home respiratory devices, water fountains, Jacuzzis, cooling towers, hot and cold water systems, as well as water tanks.
People can get Legionnaires' disease after breathing contaminated droplets and mist generated by artificial water systems, or when they are handling garden soil, compost, and potting mixes. Most of the outbreaks were linked to poorly maintained air conditioning and water systems, humidifiers and Jacuzzis, the CHP noted. Generally, the disease cannot be transmitted by person-to-person contact.
Treatments and preventions
There's no available vaccine for Legionnaires' disease at the moment. Pneumonia caused by the disease can be treated with antibiotics, and the majority of the cases were successfully treated. Healthy people get better after being infected, but they usually need hospital care. The CHP, along with other hospitals, has been using the urinary antigen detection test to detect and diagnose the disease because it is quicker and more sensitive compared to traditional methods.
The key for preventing the disease is good maintenance of the water systems. The CHP also urged the public to stop smoking and drinking alcohol, observe personal hygiene, avoid using water filters, clean and disinfect water taps and shower heads frequently.
