What You Need To Know About Getting Tested For Zika

Photographed by Jessica Nash.
As experts have warned for months, the Zika virus is now in the U.S. and transmitting locally in Florida. So far, there have been more than 30 cases of local transmission. Last week, in a first for the continental U.S., researchers confirmed the virus in three mosquito samples in a small area of Miami Beach already suspected of being a transmission hotspot.

That much you’ve probably heard. What you might not realize is the complexity involved when scientists want to confirm the virus is present in a certain area — or more importantly, a certain person. In Miami Beach, confirming the presence of Zika required many steps.

First, once local transmission was suspected, experts from the U.S. Centers for Disease Control and Prevention (CDC) essentially went door-to-door testing everyone for Zika within a defined radius. The team asked about risk factors, including whether or not patients had traveled to Zika-affected areas or had sexual contact with someone who had traveled. Through a process of elimination, the CDC surmised that the cases were local.

Then, the CDC needed to test thousands upon thousands of mosquitoes in the hopes of finding a single positive sample. (Finding Zika in mosquitoes is the real proof that it’s transmitting locally, but due to the risks of the virus, health officials couldn’t wait to warn the community at large.) To do so, Sharon Isern, PhD, of Florida Gulf Coast University, tells Refinery29 that her lab received (and continues to receive) shipments of mosquitoes collected in different traps around the Miami-Dade area.

"Once we get them, we homogenize them — we blend them up with a sort of heavy-duty paint-shaker," she says. From there, the researchers can test the mosquitoes' RNA to see if any of them have Zika. Each bunch of mosquitoes is from a trap in a specific part of Miami-Dade County, so if it tests positive, experts know where in town to look for the virus.

A large-scale outbreak in the U.S. is still very unlikely, but it is likely that smaller, contained outbreaks (like the one in Miami Beach) may begin to pop up in vulnerable areas such as Louisiana and Texas. More and more of us are already beginning to wonder whether or not we've been exposed to the virus, either because we recently traveled abroad or we’re just worried and want to know: What are you supposed to do if you think you have it? What will testing be like?

We talked to multiple experts to try to answer these questions. The good news is that health officials and doctors are already thinking ahead — and have been for months — to figure out the best ways to prevent and diagnose Zika in the most at-risk patients. The bad news is that testing for Zika is a lot more complicated than you might expect. Here's what you need to know about your risks and how testing actually works.
Do You Really Need To Get Tested?

The CDC has helpfully put together some very specific guidelines for who should be tested and when: If you have symptoms of Zika or you are pregnant (with or without symptoms) and you either live in or have traveled to a place with Zika transmission, or you’ve had sex with someone who lives in or has traveled to a place with Zika transmission, you should be tested. (What a mouthful, right?)

So the people living in the Wynwood and Miami Beach areas of Miami-Dade County, as well as certain areas of Pinellas County in Florida, where we know local transmission is possible, might need to be tested. Outside of that, and people who have traveled or had sex with someone who has been to those specific areas, "We don’t have to start looking for diagnosing Zika when people have no exposure risks," explains Neil Silverman, MD, professor of obstetrics and gynecology at Ronald Reagan UCLA Medical Center.

Complicating things, however, is that "to the best of our knowledge, only about 20% of people who are truly infected will have symptoms," Dr. Silverman says. "So the vast majority will have been asymptomatic." Even if you do get the symptoms of the virus (which include flu-like aches, a rash, and, surprisingly, pinkeye), they're often mild and similar to other illnesses. That’s both good news (because no one wants to be sick) and bad news. It means that people who have been infected aren't necessarily going to the doctor. That makes the virus especially difficult to track.

Plus, if the virus is spreading long distances (such as the recent transmission between Florida and Texas), it's because people carrying the virus are traveling — not mosquitoes. So if you’ve traveled, whether you know for sure if you have the virus or not, the CDC says you need to take precautions, like using bug spray for a few weeks, to prevent yourself from spreading it to mosquitoes back home (which can spread it to other people).

What Testing Is Like

Due to the ambiguity of Zika-related symptoms, doctors can't rely on a patient's symptoms alone to conclude whether or not that person has the virus. They have to confirm the diagnosis using one of two types of diagnostic tests, which can take weeks to complete. One test uses a process called the polymerase chain reaction (PCR) to look for the actual virus in your blood and/or urine. The other looks for traces of antibodies your body creates in response to the virus. However, neither type of test is without its quirks.

For one thing, only a limited amount of labs in the country have gotten the government’s approval to process the tests. These are state and county labs working with the CDC to ensure accurate results. That means that these labs process tests for free, but may take a while to do it. Dr. Silverman says that labs in the state of California can take between two and four weeks for the PCR test and four-to-eight weeks for the antibody test.

The two commercial labs that have been allowed to do these tests can get that time down considerably — PCR results could be back within three days and antibody tests within a week — but Dr. Silverman says that comes with a hefty price: up to $800 for PCR and up to $150 for the antibody test. So if you or your partner may have been exposed to Zika, waiting for results could eat significantly into your time or wallet.

To the best of our knowledge, only about 20% of people who are truly infected will have symptoms.

Neil Silverman, MD
There are other challenges to getting tested, too. For instance, because the PCR test looks for the actual virus, it's only useful if you get it done in the few weeks before your body gets rid of the virus. The CDC recommends PCR testing for those who have traveled to Zika-affected areas within two weeks of returning, Dr. Silverman says: "It's a focused window.”

The antibody test has a larger window within which to work, but it shows cross-reactivity between Zika and similar viruses. That means that if a patient previously had dengue or chikungunya, those antibodies could show up on the test as a false positive for Zika.

Hopefully, this process will be easier one day, especially in rural areas. Keith Pardee, PhD, and his lab at the University of Toronto have been working on one possible way to make that happen: Using a platform they originally designed to help diagnose Ebola in the field, they've developed a quick, cheap test that doctors and researchers can program anywhere.

Once a sample has been taken and prepared for testing, the genetic information is copied using a process called isothermal amplification. PCR accomplishes this with more intensive work, including cycling the sample through different temperatures. But with this test, everything can be done at a single temperature, Dr. Pardee says. Crucially, this test can also distinguish between Zika and similar viruses as well as identify different strains of Zika. The whole process can take as little as an hour and can be done for under a dollar.

For Some, A Diagnosis Is Just The Beginning

For most of us, the Zika virus is a mild infection at worst. But for those who are pregnant, there’s more to worry about: Zika's most well-known and scary effect is its ability to cause birth defects. If someone is infected while pregnant, the virus can cause microcephaly in the developing fetus. Babies with this condition have abnormally small heads and the potential for serious brain damage. So diagnosing people who are pregnant as early as possible and then monitoring their fetuses for abnormalities, is a difficult but important challenge.

“Everyone gets an anatomy scan around 18-to-22 weeks as part of routine obstetric care,” explains Clark Johnson, MD, an assistant professor at Johns Hopkins School of Medicine and a fellow with the Physicians for Reproductive Health. “But when you think there’s a Zika infection, you want to get [the patient] an ultrasound quickly to get a baseline with what’s going on with the fetal head.”

The CDC recommends that those who are at risk for developing fetal effects of Zika get more routine ultrasounds to monitor the baby’s growth.

Sadly, Dr. Johnson adds: “I would reinforce that there’s not exactly treatment for anyone who we think is infected — if you have someone who has or is at risk for developing microcephaly, [for example], there’s nothing to do about that until delivery.”

That’s why timing is so crucial: "Abortion's part of the conversation," Dr. Johnson says. "If someone has symptoms of a Zika infection at 18 weeks, [one question might be] whether or not they want to keep the pregnancy." Indeed, a recent poll indicated that U.S. opinions on controversial late-term abortions may be swayed when Zika-related microcephaly enters the debate.

Meanwhile, researchers are looking into whether currently available drugs might treat Zika. The National Institute of Allergy and Infectious Diseases has several vaccines currently in development, one of which has already made it to human trials. But it could be years before any treatment or vaccine is fully approved and widely available.

Funding for other Zika-fighting efforts is still in limbo. The CDC has provided Florida with $35 million in federal funds to help fight the spread of the virus and President Obama recently urged Congress to provide a plan for more funding as soon as it came back to session. But despite the pleas, the bill failed.


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