What's in the Water?

It may be tiny, but the parasite known as Cryptosporidium certainly packs a punch.  

Last summer, the microscopic, single-celled protozoan infected hundreds of Utah pools with the “swimming pool virus,” leaving thousands of Utahns with deadly flu-like symptoms.  After pools in 20 Utah counties were forced to close, swimmers were left with fewer options to keep cool in the sweltering summer heat.

In 1993, the protozoan parasite had plunged over 400,000 Milwaukee, Wis. residents into the throes of a deadly outbreak of very similar flu-like symptoms.  After weeks of severe stomach cramping, fever, vomiting, and diarrhea, 104 people died, and Cryptosporidium made its mark as a force to be reckoned with.

Literally meaning “hidden germ,” Cryptosporidium is a deadly, waterborne protozoan parasite that wreaks gastrointestinal havoc on its victims.   Usually found in drinking water, Cryptosporidium sneaks its way into the body through the digestive tract.  Once inside, Cryptosporidium wastes no time in spawning its microscopic offspring into the intestines, creating a debilitating and sometimes life-threatening illness.

“Cryptosporidium has been recognized by the World Health Organization as a significant global health threat,” said Anhong Zhou, assistant professor of biological engineering at Utah State University.  “It causes dehydration and malnutrition that is responsible for the deaths of 11,000 children each day and 5 million people a year worldwide, making it the second leading cause of death, behind cardiovascular disease.”

Adding to Cryptosporidium’s danger, the Environmental Protection Agency says that Cryptosporidium can be found in any surface water source—including local canals, swimming pools, and drinking water.  In fact, the Cryptosporidium responsible for the Milwaukee outbreak was delivered to residents through the city water supply, which had coincidentally passed all water quality tests and was presumed safe.

“Unfortunately, there is no effective antimicrobial treatment to eradicate this pathogen,” said Zhou.  “Chlorine and filtration are rarely enough to keep Cryptosporidium out of our drinking water.”

 Zhou says that the key to solving the problem lies in developing early detection methods.  Unfortunately, the current method for detecting Cryptosporidium is far from ideal; besides costing $250-500 to conduct the test, it takes 2-3 weeks to complete.

Zhou’s research, however, is one step ahead of the pesky protozoan; the solution is a DNA biosensor, and once Zhou puts the double-helix touch on the standard technique, Cryptosporidium will have finally met its match in his DNA-based biosensors.

So what exactly are biosensors?  Put simply, a biosensor is a device that monitors changes in environmental conditions. Even something as simple as a canary in a mine used to detect gas could technically be considered a biosensor.  Blood glucose monitors, familiar to most people, are used by diabetics and are the most widespread biosensor.   

By using organisms that are super sensitive to toxic substances, biosensors alert people to the presence of hazardous materials, like Cryptosporidium, long before humans could recognize them.

DNA biosensors are a recently developed, rapid, and ultra-sensitive technique that are widely used for biomedical diagnosis and environmental microorganism detection.  Zhou has found that these DNA-based biosensors are especially helpful in detecting Cryptosporidium.

“The known unique genetic information of Cryptosporidium has inspired me to develop specific biosensors that will possibly detect its different genotypes of Cryptosporidium,” said Zhou.  “Because the 22 different strains of Cryptosporidium have similar genomes, some only differing by a single base, a DNA-based biosensor will allow us to more readily detect Cryptosporidium,  as well as the source in an epidemic.”

Zhou says that his new DNA-based biosensors will quicken response time, cut testing costs to just under $20, and dramatically improve reliability.

To assist in his groundbreaking research, Zhou has enlisted several undergraduates to help out with the research, allowing them an extraordinary opportunity for hands-on lab experience early in their academic careers.  Zhou’s work with undergraduates earned him the Outstanding Undergraduate Research Mentor award for USU’s College of Engineering in 2007.

Zhou hopes to use his research to create a portable biosensor that can be used to detect species-specific genes of Cryptosporidium.  He plans to work with the Utah Department of Environmental Quality to validate this new sensor in the field.  Zhou is also working to get patents for his biosensors so he can commercialize his new technology.

“There is no doubt about the potential for the application of this biosensor technique in human healthcare,” said Zhou.  “Success of this research would be directly beneficial to finding effective treatment of Cryptosporidiosis and related water and food safety issues resulting from this protozoan parasite.”