Microbial threats associated with extreme events

Today kicked off the first day of the Water Microbiology Conference at UNC Chapel Hill, and I attended a side event on microbial threats associated with extreme events. Several interesting case studies were presented, including success stories and lessons learned from flooding in Canada, earthquakes in New Zealand, and tsunamis in Japan. A common theme seemed to be the microbial risks of contaminated drinking water and ruptured sewer mains. In some of the case studies presented, residents were boiling water at home for up to six weeks, and in others, untreated wastewater discharges continued for nearly two weeks!

Flood damage in Estes Park, Colorado, Sept. 20, 2013. The U.S. Army Corps of Engineers has deployed personnel to Colorado under the direction of the Federal Emergency Management Agency, for the assessments and evaluation associated with ensuring the safety of drinking water and wastewater systems in the affected areas.

Flood damage in Estes Park, Colorado, Sept. 20, 2013. The U.S. Army Corps of Engineers deployed personnel to Colorado under the direction of the Federal Emergency Management Agency, to assess and evaluate drinking water and wastewater systems in the affected areas. (image from Flickr, licensed under CC BY-NC-ND 2.0)

Interventions have been implemented to control behavior at the household level that could mitigate these microbial risks. For example, the boil water notice, which is often used to prevent people from consuming tap water that may be contaminated. State agencies and public health departments also sometimes post notices about sewer overflow discharge points, advising people not to swim or come in contact with water in that area.

Sewer overflow discharge point sign

Sewer overflow discharge point sign at Harlem Park in New York (image from j-NO, licensed under CC BY-NC-ND 2.0)

I started thinking about this: what if state agencies issued sewer overflow notices to residents in the aftermath of an extreme event? Most residents are not even aware when their wastewater treatment system is overflowing or spilling untreated waste into the environment. If people were made aware of this, perhaps they could temporarily minimize the amount of water sent down the drain of each household (which might reduce the flow at the treatment plant, preventing overflows). For example, what if residents had the option to only flush waste from their toilets into the sewer, and temporarily divert greywater to a field, a yard, or another location?

Another suggestion that came out of the meeting is the importance of being able to mobilize a team to collect samples following extreme events, in order to have baseline data about the presence of pathogens in the environment and the subsequent health outcomes in the aftermath of extreme events. A working group is currently being convened by faculty at the UNC Water Institute to address the topic of microbial risks associated with extreme events. Among other things, they will be characterizing the types of microbial agents that could present risks associated with each type of extreme event (e.g. earthquakes, floods, droughts, etc.). I think that working towards the development of a better understanding of the risks associated with extreme events will continue to become more important, as the frequency of these events increases worldwide.

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