Moscow
University
 A
researcher in California studying under a California Sea Grant
used a technique designed for tracking pathogens in sewage to
discover that potentially harmful human viruses are contaminating
coastal waters in Southern California at major river mouths.
Although it
is not yet known whether the viruses are dangerous, their very
presence indicates that human waste is finding its way into urban
waterways. Some groups have started testing creeks and drainage
culverts for indications of human contamination.
The risk of
contamination from human waste seems to be a large one, according
to results from a survey of 12 river mouths in Los Angeles, Orange
and San Diego counties. Sunny Jiang of UC Irvine conducted the
surveys, where she discovered that four of the 12 sites sampled
tested positive for the human adenovirus. Those four were the
Los Angeles, San Gabriel, Santa Ana, and Tijuana river mouths.
The Los Angeles river mouth is the only one of the four that also
showed high fecal bacteria levels, which is the standard criteria
for evaluating the quality of water, closing beaches, and monitoring
compliance with federal clean water laws.
Since high
bacteria counts were not found in the river mouths, despite the
presence of the virus, Jiang said she feels current water quality
standards are "not adequately indicating human health risks."
"The
presence of the virus does not correlate with high levels of bacteria,"
said Jiang. "Therefore, you don't have a beach closure and
are potentially exposing people to health risks." The adenovirus
is considered to be a pathogen and is in the same group of enteric
viruses that includes hepatitis A. When it gets inside a person,
it attacks the gastrointestinal track or the respiratory system,
sometimes with fatal consequences. Usually, it just causes sore
throat, diarrhea, fever, and nausea. Over a hundred viruses in
human waste can live for up to 130 days in seawater. None are
routinely tested by health officials in California.
When Jiang
was a graduate student at the University of South Florida ten
years ago, she developed a technique that tracks viruses in human
sewage. Her method proved that raw sewage from septic tanks was
leaking into coral reef ecosystems in the Florida Keys.
For the California
study, she began to track the adenovirus, which is a direct sign
of human viral contamination. The virus is the only one in its
class that contains remnants of DNA instead of RNA, which makes
detection much simpler. Jiang's findings and those of her colleagues
are published in the January issue of Applied and Environmental
Microbiology.
Jiang pointed
out that her virus-detection is not yet able to determine whether
adenoviruses are alive or dead. However, she said, "Even
if one (type of virus) is dead, maybe other harmful pathogens
are alive." The main advantage of testing for the adenovirus
is that it definitely proves human waste is contaminating waters,
she said.
Normal bacterial
counts are unable to distinguish animal waste from that of humans.
Therefore, rivers that wander through wilderness areas might show
misleadingly high counts of bacteria while streams running through
suburban neighborhoods could have dangerous human pathogens while
bacterial counts are normal. Distinguishing the difference is
crucial to keep people safe.
Right now,
Jiang's virus-detection system works somewhat awkwardly. In order
to get enough viruses to accurately portray water quality, she
must draw 20-liter water samples. "Everything we are doing
is in the research stage, but in theory we think the adenovirus
can be used as an indicator for human viral pollution. We need
to reconsider our monitoring and coastal water standards."
Groups have
just started asking for viral testing to properly identify the
sources of chronic water pollution, although such testing is not
required. Jiang is currently working with the Public Facilities
and Resources Department in Orange County to test chronically
polluted waters in the Aliso Creek watershed. She is also working
with professors at UC Irvine on a project that is looking at the
impact of the Santa Ana River on beach pollution in Huntington
Beach. They hope to start sampling offshore waters near a sewage
outfall pipe to see if human waste may be the reason behind a
number of beach closures in Huntington Beach.
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