You may not have heard of Legionella bacteria and Legionnaires’ Disease in Africa, because it often goes undiagnosed, but everyone should actually understand it because this common bacteria causes serious illness.
Legionnaires’ Disease infects the lungs and causes potentially fatal pneumonia. It is the most well-known and serious form of a group of diseases known as Legionellosis.
Legionnaires’ has a high mortality rate of 10 – 20%, especially in the elderly and those with low immune systems.
The Public Health Authorities in South Africa need to be informed if a confirmed or probable case is suspected.
Legionella bacteria are the Cause of Legionnaires’ Disease1. Infection is caused by breathing in small droplets of water contaminated by the bacteria. It is spread through the air as a spray or vapour from a water source. The disease cannot be passed from one person to another. 2. Legionella bacteria are common in natural water courses such as rivers and ponds. Since Legionella are widespread in the environment, they may contaminate and grow in other water systems such as cooling towers and hot and cold water services. 3. They survive at low temperatures and thrive at temperatures between 20 – 45°C if conditions are suitable, e.g. if a supply of nutrients is present, such as rust, sludge, scale, algae and other bacteria. They are killed by high temperatures. 4. Employers who manage premises with hot / cold water services and / or wet cooling systems (e.g. cooling towers and evaporative condensers) need to assess and control risks. 5. Legionella grows well in warm, motionless water and is also found in humidifiers, showers, air washers, mist machines, hot water heaters, whirlpool spas, fountains, hot springs, plumbing fixtures and dentistry tools. Major sources of Legionella include water distribution systems of large buildings including hotels, hospitals and cooling towers.
Prevention of Legionnaires’ Disease
- Depends on good maintenance of possible sources, including regular monitoring of water quality, cleaning and disinfection
- Water systems are thus the most important element to maintain in the prevention of Legionnaires’ Disease
- UV light and heat are the most effective at killing Legionella bacteria
- Chlorine and ozone will also kill the bacteria, but need longer exposure
- Wherever possible, keep hot water at above 60°C and cold water below 20°C
Source: ESH Trace Heating Ltd.More detail on Legionella at the HSE website
Legionnaires’ Disease in South AfricaUnfortunately, many cases in South Africa are misdiagnosed as the symptoms are common to other respiratory illnesses, so the scale of the problem is unknown. A few cases have been reported. In a South African study conducted from 2012 – 2014, researchers detected Legionella in 1.2% of the 1,805 patients with severe respiratory illness they tested. Most of these also had HIV or tuberculosis infections, too. Due to the larger scale of the problem world-wide, pressure mounted and the first South African Standards were published in 2013. Legionella currently falls under the Occupational Health & Safety (OHS) Act No. 85 of 1993. Risk assessments need to be performed in line with this regulation. SABS Guidelines are available for the risk management of Legionella bacteria and should be used by trades and businesses where water is used and stored and where there is a means of creating and transmitting water droplets which may be inhaled …
Who Should Test for Legionella?According to Rob Stewart, the SABS Technical Specialist: “any cooling system (regardless of size) or open water system that is exposed to prevailing winds or that has the potential to create an aerosol (such as buildings with a centralised air conditioning system, or a building with a complex plumbing system).” “Thus, users of the standard will include any industry that has cooling towers and other water systems, as well as facility managers (hospitals, old age facilities, office blocks, hotels, shopping centers, cruise ships etc), owners of large properties, health and safety officers, air-conditioning companies, and water treatment companies.”
Testing for Legionella Bacteria
The SABS StandardsThe SABS Standards are:
- SANS 893-1, Legionnaires’ disease Part 1: Risk management and
- SANS 893-2, Legionnaires’ disease Part 2: The control of Legionella in water systems
- Lovibond® Legionella Prevention Test Kits for regular weekly / monthly risk monitoring
- Lovibond® Legionella Rapid Test Kits for testing the presence of Legionella bacteria