The bacteria present in the water can contaminate humans without them drinking it.
1,630 case of legionellosis were identified in France in 2017. In the United States, the disease affected 8,453 people in 2018. In developed countries, few people worry about the quality of water, which has been presumed to be good for years. Except scientists. Researchers from the University of Arizona and Drexel have conducted studies on the water flowing in our homes and the bacteria that can contaminate it: they find that the water we smell can be the source of contamination, in particular to legionellosis. Their results were published in the journal Environmental Science & Technology.
A bacterial infection
Legionnaires’ disease is an acute bacterial infection of the lung caused by bacteria Legionella. In 10 to 25% of cases, the disease is fatal. It is transmitted by the respiratory tract: it is for this reason that the American researchers were interested in the water that one can smell. For example, if the bacteria is present in an air conditioning system or in the shower pipes, it is possible to contract the disease.
The shower, the main transmitter of bacteria
The researchers found that the shower is the most important source of contamination. Their research focused on several sources of diffusion of water droplets: toilet flushing or sinks for example. Showering is associated with the highest risk because it causes repeated inhalation of water. When people are equipped with a water-efficient shower system, the risk of contamination is slightly lower. On the other hand, it is higher when one is exposed to several sources of contamination or when one is more vulnerable to infections, this is particularly the case for the elderly.
Water and its dangers
Water can be the source of many diseases, both because of micro-organisms or chemical compounds present in the water we drink, but also because it can allow certain infections to develop: schistosomiasis is caused by larvae growing in freshwater gastropods, malaria is related to mosquitoes breeding in water, etc. Diarrhea is one of the most common water-related diseases: it can be linked to the consumption of contaminated water. The World Health Organization estimates that two million deaths from diarrheal disease each year are water-related.
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