Climate change - waterborne disease link draw in crowd

Dr. Sharon Roy from CDC
Photo by David Hathcox

June 11, ATLANTA―Drought, disaster and development are drivers making climate change one of the most popular topics at AWWA’s annual conference.

Speakers from the Centers for Disease Control and Prevention explored the implications of climate change on waterborne disease at the H2Open Forum.

Dr. Sharon Roy reviewed the waterborne outbreaks in Carrollton, Ga., in 1987 and in Milwaukee in 1993, noting that they made clear the need for improved disease surveillance and coordination between public health agencies and water utilities, as well as the need to regulate Cryptosporidium in drinking water.

The outbreak investigations uncovered a series of circumstances leading to thousands suffering gastrointestinal illness: heavy precipitation, contamination from raw or treated sewage, disruptions in normal monitoring and plant operations and recycled filter backwash water.

As a result, the Interim Enhanced Surface Water Treatment Rule was promulgated, not only mandating treatment effectiveness but prohibiting the recycling of backwash water.

Roy noted five trends in disease outbreaks:

The number of outbreaks has decreased because of the Safe Drinking Water Act and the additional drinking water regulations;
Public systems account for a decreasing proportion of outbreaks;
There is a decline in outbreaks from systems using surface water;
For the first time, Legionella, rather than gastrointestinal disease, is the cause of a majority of outbreaks; and
Public health officials are discovering an increasing number of deficiencies in premise plumbing and point-of-use devices.

“We need to focus more attention on premise plumbing and groundwater,” she said.

Although premise plumbing is not under the control of water utilities, it may behoove them to be involved, said panel moderator Mark LeChevallier. Utilities could support changes in plumbing codes that would do more to address premise plumbing deficiencies.

Jonathon Yoder, CDC
Photo by David Hathcox

Sometimes investigations do not identify the source of a disease outbreak, said the CDC’s Jonathan Yoder. He offered the example of the recent Salmonella outbreak in Alamosa, Colo., for which a source has yet to be identified. Although the water is implicated, disease can also spread through foodstuffs or person-to-person contact.

There can also be outbreaks within outbreaks, pointed out water consultant Charlotte Smith during the audience discussion. Yoder recommended multidisciplinary investigating teams, and Fred Pointius, another independent consultant, suggested the inclusion of personnel with an understanding of fluid mechanics or contaminant transport on the investigating team.

CDC’s Dr. Jeremy Hess wrapped the session up with a look at the possible effects of climate change on utilities and public health. Increasing ambient and water temperatures and increasing storm intensity will affect water utility operations, he said.

There is a high correlation between intense storms and disease outbreaks in a review of US data from 1948 to 1994 and Canadian data from 1975 to 2001, Hess said.

He also said climate changes could lead to higher concentrations of bacteria, viruses and parasites, depending on their sensitivity to warmer temperatures.

Mary Parmelee, MainStream Editor

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