Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Study suggests surface water contaminated with salmonella more common than thought

A new University of Georgia study suggests that health agencies investigating Salmonella illnesses should consider untreated surface water as a possible source of contamination.

Researchers, whose results appear in the March issue of the journal Applied and Environmental Microbiology, tested water over a one-year period in rivers and streams in a region of south Georgia known for its high rate of sporadic salmonella cases. The team found Salmonella in 79 percent of water samples, with the highest concentrations and the greatest diversity of strains in the summer and after rainfall.

“Streams are not routinely tested for Salmonella, and our finding is an indication that many more could be contaminated than people realize,” said Erin Lipp, associate professor in the UGA College of Public Health. “We found our highest numbers in the summer months, and this is also the time when most people get sick.”

Lipp, who co-authored the study with former UGA graduate student Bradd Haley and Dana Cole in the Georgia Division of Public Health, said that although contaminated water used to irrigate or wash produce has been linked to several well-publicized outbreaks of salmonellosis in recent years, the environmental factors that influence Salmonella levels in natural waters are not well understood. She said understanding how Salmonella levels change in response to variables such as temperature and rainfall are critical to predicting—and ultimately preventing—the waterborne transmission of the bacteria.

The team studied streams in the upper reaches of the Suwannee River Basin, which begins in south Georgia and flows into central Florida. The study area contains a mix of forested lands, row crops, pasturelands, wetlands and small cities. The researchers chose sampling sites near a variety of those environments but found little variation in Salmonella concentrations by location. The diversity of Salmonella strains, however, was highest near a farm containing cattle and a pivot irrigation system, suggesting that close proximity to livestock and agriculture increase the risk of contamination. The researchers also found a strong and direct correlation between rainfall for the two days preceding sample collection and the concentration of Salmonella, suggesting that runoff contributes to the contamination.

Salmonella can be found in the intestinal tracts of several species of animals and in humans. The bacteria are shed in feces, but Lipp said recent data suggest that they can persist and possibly grow in water if given the right conditions. Her study found that the diversity and concentration of Salmonella increased as temperatures increased. The highest concentrations and greatest diversity of strains were found in August, the warmest month of the year. Lipp adds that her study, which was funded by the National Oceanic and Atmospheric Administration Joint Program on Climate Variability and Human Health, lends support to the idea that Salmonella illnesses could increase as a result of global warming.

Lipp notes that her study area had 58 cases of Salmonella illness per 100,000 people in 2007, the last year for which figures are available, compared to a state average of 22 cases per 100,000 people and a national average of 15 cases per 100,000 people. She said the exact mechanisms by which people in her study area are being exposed to environmental Salmonella are unclear, but the most commonly detected strain in the studied streams was among the top ten associated with human infections in the health district. The porous nature of the soil in the study area means that surface water and groundwater are prone to mixing, especially after rainfalls, and Lipp said that poorly sited wells might be a factor in many illnesses. Another possibility, especially common among children, is so called incidental exposure by which people become infected with the bacteria when playing in or near contaminated waterways.

“Understanding the environmental factors that contribute to salmonella illnesses can guide our efforts to educate people about how they can avoid being sickened through the proper construction and maintenance of wells, basic hygiene such as hand washing and good food safety practices,” Lipp said. “We also have the potential to decrease the likelihood of larger outbreaks related to produce, because in many cases contaminated irrigation water, and not the produce itself, may be the cause of the outbreak.”

Sam Fahmy | University of Georgia
Further information:

More articles from Studies and Analyses:

nachricht Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung

nachricht High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>