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New test spots Zika virus in under an hour, raising hopes for a speedier response

By Divya Kumar, Times Staff Writer
Tubes like these play a key role in a new Zika test developed by Florida researchers that gets results much faster. Human or mosquito samples are mixed with enzymes in the tubes and are warmed. This batch shows what happened with a human urine sample: The bright fluorescent green sample labeled ZV indicates the presence of Zika. The samples labeled CH and D1 indicate the Chikungunya and Dengue viruses respectively. The remaining one is the "negative control" tube. [Image courtesy of Ozlem Yaren]

In a development that could significantly quicken the state's reaction to Zika outbreaks, Florida researchers say they have found a way to test for the virus within an hour instead of the weeks it now takes for results. They also say it's easier and cheaper.

"It's one of the best options we have in the absence of a vaccine," said Barry Alto, a faculty member at the University of Florida's Institute of Food and Agriculture Sciences who collaborated on a recently published study describing a new kit that can be used to test for Zika in humans and mosquitoes.

A person conducting the test uses a small sample of human blood or urine, or a mosquito carcass on specially treated paper. A sample is placed into a tube containing enzymes. After the tube is heated, the solution will turn fluorescent green if Zika is present. The kit also tests for the Chikungunya and Dengue viruses.

Results are available in 20 to 40 minutes, and the enzyme solution doesn't have to be refrigerated, making the kit easy to use in the field.

Using current methods in a laboratory, the passage of days and weeks reduces the usefulness of the results, Alto said.

"In order to better react to an outbreak of Zika virus," he said, "we need to have improved detection methods. We need surveillance info in real time."

While some current testing methods can produce results in about two hours, they require sophisticated laboratories, are expensive and not commonly used, said Ozlem Yaren, of the Foundation for Applied Molecular Evolution, based in Alachua.

The new kits cost $2 to $5, and could be even cheaper in the future, said Yaren, the study's lead author.

"It's like simple cooking," she said. "Everyone should be able to access affordable diagnostics."

Zika, a mosquito-borne virus that can lead to symptoms such as fever, headaches rash and joint pain in adults, can also cause microcephaly in the fetuses of pregnant women infected with the virus.

Last year, officials declared a public health emergency in four Florida counties after the CDC reported more than 1,000 cases in the state. This year, there have been 123 Zika cases reported in the U.S., and 46 in Florida from international travel.

People who are infected can spread the virus locally if they are bitten by other mosquitoes.

Alto said one of the limitations of the new test will be that it does not look for antibodies, which can stay present even after a Zika infection is cleared. Still, he said, quicker detection using the kit could help contain the disease.

Mara Gambineri, communications director for the Florida Department of Health, said while there are no ongoing areas of locally transmitted Zika, faster detection could help in future efforts of combating the disease.

"Detecting mosquitoes that are carrying the Zika virus in a more timely manner allows for faster and better targeting of mosquito control efforts to those areas," she said an email. "Reducing the Zika-infected mosquito population more quickly in those areas should help reduce the risk of transmission to local residents."

Shelly Redovan, executive director of the Florida Mosquito Control Association, said testing for Zika sometimes requires extensive mosquito sampling, which can be impractical at times.

"If it was economical, then it could be a great tool," she said of the new test.

In developing the kit, the Florida researchers faced a regulatory barrier. Unable to use samples from actual Zika patients, they added Zika RNA, a nucleic acid present in all living cells, to healthy human fluids. Now, however, they are testing the kits using patient samples in China, India and the Middle East, where there are fewer regulations on using human samples, Alto said.

"The hope is that we'll be able to resolve some of the regulatory issues and use these in Florida in the near future," he said. "Florida is the frontline in the continental U.S. for some of these mosquito-borne diseases."

Yaren said further validation on clinical samples will be needed.

"Either we will get permission to test those samples or work with facilities that can do the validation for us," she said. "For FDA approval, tests need to be screened against other targets and we need to make sure it does not give any false negatives or false positives. It's a very long process, and we need to follow their guidelines."

Dr. Anthony Scialli, a professor of obstetrics and gynecology, said the new test, if proved accurate, could have a positive impact on pregnant women.

"Having a way to be less anxious sooner, it's a good thing. And if it's positive, she could be counseled sooner, said Scialli, who also is a member of the Organization of Teratology Information Specialists, the organization behind MotherToBabies, a free service giving information on birth defects to expectant mothers.

"The sooner we can counsel women about what the risks may be," he said, "the sooner they can make a decision, if any."

Because there is still no treatment for Zika, prevention of mosquito bites for pregnant women and their partners is still most important, Scialli said.

Redovan said it's important for residents to take precautions.

"Zika will remain a big issue for us," she said. "It has been a very dry season coming up to this point. We've gotten away from mosquito season and it hasn't been on the forefront of people's mind. With rain of recent days, now is the time for people to go out and look for standing water."

Times Staff Writer Kathleen McGrory contributed to this report. Contact Divya Kumar at [email protected] Follow @divyadivyadivya.