DUBAI // Bacteria that can cause deadly legionnaires' disease are present in the water supply of some homes, experts say. More than a third of the samples, obtained from households where people have suffered unexplained health complaints as well as dental clinics, which are required to test regularly, proved positive for Legionella pneumophila.
The bacterium is dormant during the cool winter months, but thrives in temperatures above 25°C, making it a hazard during the summer. Although often associated with air-conditioning systems, the bug can thrive in water, including roof tanks, taps, pipes and showers. The flu-like disease is caught by inhaling droplets of infected water. It can be fatal, although it is usually not dangerous to healthy people.
Dr Ulrich Wernery, the scientific director of the Central Veterinary Research Laboratory in Dubai, said of 147 water samples it had tested in a six-year period from 2004, 53 were positive. Only three of the 21 samples tested so far this year have been positive, but that number is expected to rise as the weather gets warmer. Two of the positive samples were sent by Homeinspections, a Dubai company which specialises in decontaminating water and air-conditioning systems.
Joe Coleman, the owner of Homeinspections, said his team discovered the bacteria in two properties. One is a high-rise building in Dubai Marina the other was a villa in Al Barsha. There are eight types of Legionella bacteria, although only one, L.pneumophila, causes disease in people. Mr Coleman said temperatures between 25°C and 35°C were "the optimum conditions" for the bacteria to multiply. This month, his company decontaminated the water system of a three-bedroom villa in Al Barsha.
The tenant told The National that the incident had caused strain between him and his landlord. "It is a new compound of 12 villas and we have been living there for over a year," said the tenant, who did not want to be named. The tenant decided to test the water as he was concerned that some form of bacterial contamination could be the cause of asthma-like symptoms suffered by one of his children.
"The tests came out highly positive for L.pneumophila in the water," he said, although no link had been established between the child's ill health and the contamination. The tenant paid the Dh4,800 (US$1,300) clean-up bill as his landlord denied responsibility. However, the tenant suspects that the problem could have started as the villa was being completed. "I know they [contractors] do not clean up properly on handover," he said.
He suspects the contamination could have started from the water tank on the roof of the building. Dr Eivind Linge, a general practitioner at the Scandinavian Dental Clinic, said the fact that water tanks were on roofs, and thus exposed to heat, "is a very big health hazard". The clinic, like other dental offices in Dubai, tested its water and was monitored by Dubai Municipality, he said. The Emirates' desert climate makes it harder to control bacterial contamination in summer, with complicated procedures required.
"Now in the summer, we shock-chlorinate our water system once every month," said Dr Linge. But he was quick to point out that the prevalence of L.pneumophila and other bacteria would not immediately translate into large numbers of people getting sick. The number of positives is not dramatically out of line with previous findings elsewhere. A 1980s study of hot-tap water systems in Chicago found that 30 per cent were contaminated, while a German study put the figure at 28 per cent.
Dr Tasmeen Khan, a family doctor at The City Hospital in Dubai, said she was not aware of any increased illnesses caused by the bacteria. Any patients with a form of pneumonia which did not behave in the "normal manner" would be tested for the bacteria, she said. "It is impossible to say what the prevalence or incidence is because it is not a reportable disease, we do not report to the Ministry of Health as we do other diseases," she said.
"Of course, it is something I consider with cases of pneumonia but no more than I have done when I worked in the United States." Dr Khan said it was likely that the elderly and those with depleted immune systems were more vulnerable, but no more so than they would be to other bacteria. "People do not need to go out and test their water systems. You have no way of knowing if you are going to get it, you could be exposed every day and be fine," she said.
Redha Salman, the director of the public health and safety department of Dubai Municipality, said it monitored hotels and dental clinics for Legionella contamination. In addition, municipality inspectors make surprise spot checks, with around 50 samples being tested per month. He was not willing to say how many of these samples are contaminated. The same checks, however, are not made on residential buildings. "At the moment, we are implementing it at high-risk areas," said Mr Salman.
Only buildings where proper maintenance was an issue were at risk, he said. "Dubai is known for buildings that are well-maintained," said Mr Salman. Both Mr Coleman and Dr Linge said there was little consistency on maintenance standards and scheduling. "The developer might be paying but the companies cost-cut," said Mr Coleman. "We need to get some form of consistency of cleaning services." Dr Linge said clear guidelines on how facilities should be designed and maintained would help to reduce any health risk.
"You look around Dubai and Sharjah and you will find many clinics that do not have the capacity to comply with these things at all," Dr Linge said. "It would be interesting to check the quality of the water in these places." @Email:firstname.lastname@example.org