Drainage systems, an occluded source of sanitation related outbreaks

Blom, Kristina

The malfunctioning plumbing was recognized as a problem already during the cholera outbreak in London by J. Snow in the 19 th century [63] . Later in 1907, it was shown in a sham study that malfunctioning plumbing created aerosols with microorganisms that could be transmitted to humans both indirectly through environmental surfaces and directly through aerosols and cause disease [64] . Sham studies, also in present time support earlier findings and stress the importance of a physical barrier by a water seal between the drainage systems and surroundings [65] . The creation of aerosols has been shown to occur when the plumbing is not correctly designed or if there are leakages, stops or by dried U-traps. Also, aerosols can be created upon flushing the toilet or in situations when water is poured from taps to sinks and drains [66, 67] . As shown in the SARS outbreak at Amoy Gardens, aerosols can enter the ventilation system and be spread to all the other connected rooms igniting a fearsome spread [67] . The outbreak at Amoy Gardens highlights the need for good maintenance practices and water safety programs with recommended actions [68] . In the event of backflow or flooding from the drainage systems of wastewater into the building, prompt actions must be taken to protect health and property [31] . Among public health professionals, it is well known that if wastewater leaks to structures and furnishing harmful substances such as gases and pathogenic microorganisms can enter as well as increased humidity that can promote environmental microorganisms to multiply and cause diseases and mold-associated allergies [31] . Therefore, it is essential that the properties are restored to a dry state as quickly as possible [31] . In recommended guidelines by EPA in the US, these highlight the increased safety risks due to the high threat of infection, in the event of sewage backflow into buildings [31] . Consequences of malfunctioning plumbing can indeed cause outbreaks [7] . In one outbreak in London, 85 patients became infected during 2005 and 2011, with overall mortality at 40%, but for patients with sepsis, mortality was 78%. Yet another outbreak occurred in Southern England with four cases and no deaths. Both outbreaks were caused by multidrug-resistant P. aeruginosa. There had been 391 notifications of blockages in the wastewater system at the hospitals each year. Blockages had been due to patient wipes and paper towels causing backflow to toilets and showers, leakages, etc. near clinical areas [7] . It was first after re-plumbing, replacing toilet bowls, and etc., the infection rates were notably reduced. The authors stressed the importance of hospital design and engineering in controlling and preventing infection, a factor that highlights the need for engagement from the clinical staff, engineers, and janitors. Also, to consider, these outbreaks were identified due to the unusual antibiogram of organisms and could thus be linked to the hospital wastewater systems. Clearly, hospital wastewater system could be a source of many cases of infection with different bacteria. Breathnach et al. concluded: "However, unless the organisms are distinctive in some way, such as being multiply resistant, or several cases with the same species linked in time or place, it is likely that the source of many such infections will remain unrecognized" [7] .