Gene chip to diagnose infectious disease

Gene chip to diagnose infectious disease
December 9, 2006
new diagnostic tool called a gene chip can tell with a single test if a patient has malaria, Ebola, influenza or a bacterial infection, researchers say.
The so-called GreeneChip can quickly diagnose infectious diseases caused by viruses, bacteria, fungi or parasites, using tissue, blood, urine and stool, the international team of researchers report in the journal Emerging Infectious Diseases.
So when a patient comes in with flu-like symptoms, such as fever, a sore throat, a cough and muscle aches, a doctor armed with such a chip can quickly tell if it is a dangerous strain of flu or a relatively harmless virus.
The GreeneChip is a glass slide with row after row of DNA or RNA samples from nearly 30,000 different viruses, bacteria, fungi and parasites.

"When human fluid and tissue samples are applied to the chip, these probes will stick to any closely related genetic material in the samples," the US National Institute of Allergy and Infectious Diseases, which helped develop the chip, said in a statement.
Doctors have been asking for such a tool for years, although widespread availability of the chip will require more work. An estimated half of all upper respiratory infections in the United States are never diagnosed, in part because it is so cumbersome, expensive and time-consuming to test patients for every single virus or bacteria that might be the cause.
Dr. Ian Lipkin, director of the Greene Infectious Disease Laboratory at Columbia University in New York, noted that hundreds of different infectious agents all can cause similar symptoms.
"Methods that simultaneously screen for multiple agents are important, particularly when early accurate diagnosis can alter treatment or assist in containment of an outbreak," Lipkin said in a statement. The chip is named for his lab.
The researchers tested their chip on samples from patients with respiratory disease, hemorrhagic fever, tuberculosis and urinary tract infections.
The GreeneChip diagnosed the infectious agent as accurately as older and slower methods, such as culturing or growing the bacteria or virus, or using polymerase chain reaction to look at the genetic material and identify the infectious agent that way.
"In addition, the GreeneChip was used in the analysis of an unknown sample from a patient with a viral hemorrhagic fever (VHF)-like syndrome," Columbia University wrote in a statement.
The researchers tested samples from a health care worker who died during an outbreak of deadly Marburg virus in Angola, which ended up killing 90 per cent of its 252 victims.
A PCR test showed no evidence of Marburg virus, and neither did the GreeneChip. But the chip then identified Plasmodium - the parasite that causes malaria.
Had the GreeneChip been available then, the worker could have been treated for malaria.
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