Hey there, folks! If you’ve ever wondered “How do they test for chicken pox?” then you’re in the right spot. I’ve got the lowdown on how docs figure out if you or your little one has this itchy pesky virus. Chickenpox, caused by the varicella-zoster virus (VZV), ain’t no walk in the park, especially if it’s not clear from just looking at the rash. So, we’re gonna dive deep into the ways they test for it, from swabbing blisters to checking your blood. Stick with me, and I’ll break it all down in plain English, no medical jargon overload!
Basically testing for chickenpox involves a few methods, depending on your symptoms and situation. The most common and reliable is the PCR test, which looks for the virus’s DNA in a sample from your blisters. There’s also blood tests to spot antibodies and a couple other lab tricks like viral cultures. We’ll get into the nitty-gritty of each one, plus why you might need a test and what the results mean. Let’s roll!
Why Test for Chickenpox? When It’s More Than Just a Rash
Before we get into the “how,” let’s chat about the “why” Most of the time, a doctor can spot chickenpox just by eyeballing that classic red, blistery rash—especially if it’s all over the chest, back, and face, spreading like wildfire But sometimes, it ain’t that simple. Maybe the rash looks weird, or you’re at high risk for complications. That’s when testing comes in handy.
Here’s who might need a test for the varicella-zoster virus (VZV):
- Pregnant women: Chickenpox can be risky for both mom and baby.
- Newborns and infants: Their tiny immune systems can’t handle it well.
- Teens and adults: Symptoms hit harder than in kids.
- Folks with weak immune systems: Think HIV, cancer patients, or anyone on heavy meds like chemo or steroids.
- People unsure about immunity: If you don’t know if you’ve had chickenpox or the vaccine, a test can check.
Testing also helps confirm outbreaks, super severe cases, or if there’s a chance a vaccine caused a weird reaction. Plus, if you’ve been exposed and you’re in a risky group, docs might test to see if you’re in the clear. So, yeah, testing ain’t just for kicks—it’s a big deal in certain cases.
The Main Ways They Test for Chicken Pox
Alright, let’s get to the good stuff: how do they actually test for chickenpox? There’s a few methods out there, and I’m gonna walk ya through each one. Doctors pick the best test based on your symptoms, age, and what they’re tryin’ to figure out—like if you’ve got an active infection or just past exposure.
1. PCR Test: The Gold Standard for Spotting VZV
Hands down, the PCR (polymerase chain reaction) test is the MVP when it comes to testing for chickenpox. This bad boy looks for the DNA of the varicella-zoster virus in a sample, usually from your skin. It’s crazy accurate and fast, often giving results quicker than other methods.
- How it works: A doc or nurse swabs fluid from one of your open blisters. If there’s no blisters, they might try other spots, but blisters or scabs are the best bet.
- Why it’s awesome: It can confirm an active chickenpox infection or even shingles (which is VZV waking up later in life). It’s super sensitive, so it rarely misses the virus.
- Heads up: Sometimes, if the sample ain’t taken right, results can be off. But when done proper, it’s the go-to.
I gotta say, if I was worried about chickenpox, I’d want this test. It’s like the detective of the medical world, sniffing out that virus DNA like nobody’s business.
2. Antibody Test: Checking Your Body’s Defenses
Next up is the antibody test, which is usually a blood test. This one don’t look for the virus itself but for the proteins your immune system makes to fight it. There’s two types of antibodies they check for, and they tell different stories.
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IgM Antibodies: If these are present, it means you’ve got a current or super recent chickenpox infection. It’s like your body’s waving a red flag saying, “Yo, we’re fighting this now!”
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IgG Antibodies: These show up if you’ve had chickenpox way back or got the vaccine. It means you’ve got immunity and prob’ly won’t get it again (though shingles is still a sneaky possibility).
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How it’s done: Just a quick blood draw from a vein in your arm. Takes like five minutes, and you might feel a tiny pinch. No biggie.
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Why it’s useful: Great for checking if you’re immune, especially if you’re in a high-risk group or planning stuff like pregnancy.
This test is cool ‘cause it gives a peek into your history with VZV. But it ain’t as good as PCR for confirming an active case right this second.
3. Viral Culture: Growing the Virus in a Lab
This one’s a bit old-school but still used sometimes. With a viral culture, they take a sample from a blister and try to grow the varicella-zoster virus in a lab to see if it’s there.
- How it happens: Similar to PCR, they swab some fluid from a blister. Then, lab folks play gardener, seeing if the virus sprouts up under special conditions.
- The downside: It’s not as accurate as PCR and takes way longer to get results. Sometimes, it misses the virus even if it’s there.
- When it’s used: Usually only if PCR ain’t an option or they’re double-checking something weird.
Honestly, I wouldn’t hold my breath for this one. It’s like waiting for paint to dry compared to the speedy PCR test.
4. Direct Fluorescent Antibody (DFA) Test: A Quick Peek
The DFA test is another way to spot VZV directly from a sample. It’s faster than a culture but still not as reliable as PCR.
- How it’s done: They take a swab from a blister, slap it on a slide, add a special fluorescent dye, and look at it under a fancy microscope. If the virus is there, it lights up like a Christmas tree.
- Pros and cons: It’s quick, which is neat, but it misses the mark more often than PCR. Docs might use it if they need a fast answer and PCR ain’t ready.
This test feels a bit like a shortcut to me. It’s handy in a pinch, but I’d trust PCR over it any day.
How Do These Tests Feel? What to Expect
Now, I know some of y’all are prob’ly wondering, “Does this hurt?” or “What do I gotta do to prep?” Lemme ease your mind. Testing for chickenpox is pretty straightforward, whether it’s a blood draw or a blister swab.
- Blood Test: If they’re checking for antibodies, they’ll stick a small needle in your arm to grab some blood. You might feel a lil sting, and maybe a bruise pops up after, but it fades quick. No prep needed—just roll up your sleeve and you’re good.
- Blister Swab: For PCR, DFA, or culture, a nurse gently rubs a cotton swab on one of your blisters to get some fluid. It don’t hurt, maybe just feels a tad weird. Again, no special prep. Just don’t go poppin’ those blisters yourself before the doc sees ya!
Both types take under five minutes. It’s quicker than waiting for a coffee order, trust me. And there’s basically zero risk with either. No need to stress about it.
What Do the Results Tell Ya?
Once the test is done, what do those results even mean? I gotcha covered. Here’s the breakdown, depending on what they find.
- Positive for VZV DNA (PCR Test): If they spot the virus’s DNA in your blister sample, you’ve likely got active chickenpox (or shingles, depending on your age and symptoms). Time to rest up and follow doc’s orders.
- Positive IgM Antibodies (Blood Test): This says you’ve got a fresh or recent infection. Your body’s in battle mode against chickenpox right now.
- Positive IgG Antibodies (Blood Test): This means you’ve had chickenpox before or got the vaccine. You’re immune to getting it again, but watch out for shingles down the road.
- Negative Results: If no virus or antibodies show up, you might not have chickenpox, or it could be too early to detect. Docs might retest or look at symptoms closer.
If you’re in a high-risk group—like pregnant or with a weak immune system—and results show an infection, your doc might start antiviral meds pronto to dodge serious issues. For most healthy folks, though, chickenpox clears up in a week or two with some TLC at home.
A Quick Comparison of Chickenpox Tests
To make this crystal clear, here’s a lil table comparing the main tests for chickenpox. Check it out to see which does what.
| Test Type | What It Checks For | Sample Needed | Speed | Accuracy | Best For |
|---|---|---|---|---|---|
| PCR Test | VZV DNA | Blister fluid/swab | Fast (same day) | Very High | Confirming active infection |
| Antibody Test (IgM/IgG) | Immune response to VZV | Blood | Moderate | Good, but not for active cases | Checking immunity or recent infection |
| Viral Culture | Growing VZV in lab | Blister fluid/swab | Slow (days) | Less Accurate | Backup if PCR unavailable |
| DFA Test | VZV presence with fluorescent dye | Blister fluid/swab | Fast | Less Accurate | Quick check, but not the best |
See? PCR is the champ for spotting an active case of chickenpox, while blood tests help with the bigger picture of immunity.
When Should You Get Tested for Chicken Pox?
Not everyone with a rash needs a test, so when should you actually push for one? Here’s my take on it, based on what I’ve learned over the years.
- Weird Symptoms: If your rash don’t look like typical chickenpox, or you’ve got fever, headache, and fatigue but no clear cause, a test can settle the debate.
- High-Risk Situations: Like I said earlier, if you’re pregnant, a newborn, an adult, or got a shaky immune system, testing is smart—especially if you’ve been around someone with chickenpox or shingles.
- After Exposure: Been near someone with chickenpox and ain’t sure if you’re immune? A test can check if you’ve got antibodies or if you’re at risk of catching it.
- Outbreak Confirmation: If a bunch of folks in your school or community are getting sick, docs might test to confirm it’s VZV causing the chaos.
If you’re just a healthy kid with the classic itchy spots, your doc might not bother with a test and just treat the symptoms. But if there’s any doubt, don’t be shy—ask about it!
What Happens If You’ve Got Chicken Pox?
Say the test comes back positive for chickenpox. What now? Don’t panic; most cases ain’t a huge deal, especially in kids. Here’s the game plan.
- Rest and Relax: Stay home, chill out, and keep away from others so you don’t spread it. Chickenpox is crazy contagious.
- Symptom Relief: Use stuff like oatmeal baths or calamine lotion for the itch. Over-the-counter meds can help with fever, but check with a doc first.
- Watch for Trouble: If things get worse—think high fever, trouble breathing, or weird behavior—call your doctor ASAP. That’s rare, but it happens.
- Antivirals for Some: If you’re high-risk, docs might give ya antiviral meds to lessen the severity. Gotta start ‘em early, though.
Most folks bounce back in a week or two. It’s just a waiting game, honestly. Keep them hands clean so you don’t get infections from scratching!
Can You Prevent Chicken Pox? Heck Yeah!
Before I wrap this up, let’s talk prevention. Testing is one thing, but stopping chickenpox before it starts is even better. The best way? Get vaccinated. I can’t stress this enough.
- Chickenpox Vaccine: Kids should get two doses—first at 12-15 months, second at 4-6 years. If you’re over 13 and never had it or the shot, you need two doses at least 28 days apart.
- Why It Works: This vaccine keeps most folks from getting chickenpox. Even if you do catch it after, it’s usually way milder.
- Shingles Vaccine Too: Since VZV can come back as shingles later, adults 50 and up (or 19+ with weak immunity) should get the Shingrix vaccine. Two doses, 2-6 months apart. Even if you’ve had shingles, get it anyway—it can strike again.
Vaccines are like a shield against this virus. If you ain’t sure about your status, talk to your doc. They might test for immunity or just jab ya to be safe.
Wrapping Up: Testing Ain’t So Scary!
So, there ya have it—everything you need to know about how they test for chicken pox. Whether it’s a PCR test swabbing your blisters, a blood test checking antibodies, or something else, these methods help docs nail down if you’ve got the varicella-zoster virus messing with ya. Testing is especially key for high-risk folks or when symptoms are funky. And hey, if you test positive, just take it easy and follow the doc’s advice.
Polymerase chain reaction (PCR)
PCR is the most useful laboratory test for confirming suspected varicella and herpes zoster. PCR can detect VZV DNA rapidly and sensitively in skin lesions (vesicles, scabs, maculopapular lesions).
- Vesicular lesions or scabs, if present, are the best for sampling.
- Adequate collection of specimens from maculopapular lesions in vaccinated people can be a challenge.
- However, one study1 that compares a variety of specimens from the same patients vaccinated with one dose suggests that maculopapular lesions collected with proper technique are a highly reliable specimen types for the detection of VZV.
- Other sources, such as nasopharyngeal secretions, saliva, urine, bronchial washings, and cerebrospinal fluid are less likely to provide an adequate sample; they often lead to false negative results.
DFA tests, viral culture, and Tzanck smears
Other viral isolation techniques for the confirmation of varicella are direct fluorescent antibody assay (DFA) and viral culture. However, these techniques are generally not recommended because they are less sensitive than PCR. In the case of viral culture, these techniques take longer to generate results.
Like DFA, a Tzanck smear has a rapid turnaround time but is not recommended because of its limited sensitivity and is not specific for VZV. Moreover, real-time PCR protocols can be completed within one day.
Serologic methods have limited use for laboratory confirmation of herpes zoster and should only be used when suitable specimens for PCR testing are not available.
IgM serologic testing is considerably less sensitive than PCR testing of skin lesions. IgM serology provides evidence for a recent active VZV infection. However, it cannot distinguish between primary infection and reinfection or reactivation from latency. This is because specific IgM antibodies are produced with each exposure to VZV. IgM tests are also inherently prone to poor specificity.
Measuring acute and convalescent sera also has limited value, since it is difficult to detect an increase in IgG for laboratory diagnosis of herpes zoster.
Paired acute and convalescent sera showing a four-fold rise in IgG antibodies have excellent specificity for varicella. However, they are not as sensitive as PCR of skin lesions for the diagnosis of varicella. People with a prior history of vaccination or disease may have very high baseline titers and may not achieve a four-fold increase in the convalescent sera. The usefulness of this method for diagnosing varicella is further limited as it requires two office visits. A single positive IgG ELISA result cannot confirm a varicella case.
- The preferred diagnosis method is a demonstration of VZV DNA by PCR tests from a clinical specimen, ideally scabs, vesicular fluid, or cells from the base of a lesion.
- PCR is also useful for confirming breakthrough varicella. Other methods, such as DFA and culture, are available for diagnosis but are less sensitive and specific than PCR.
- Positive serologic test for varicella-zoster immunoglobulin M (IgM) antibody when a varicella-like rash is present.
- Four-fold or greater rise in serum varicella immunoglobulin G (IgG) antibody titer by any standard serologic assay between acute and convalescent sera.
For both unvaccinated and vaccinated people, PCR is the most reliable method for confirming a VZV infection.
Learn about guidelines for collecting and shipping specimens for VZV testing (varicella and herpes zoster). These include methods for VZV serologic assays and VZV PCR/genotyping, sources for suitable supplies, and how to submit specimen to CDC.
PCR testing and genotyping can distinguish between wild-type VZV and vaccine-type (Oka/Merck) strains of VZV.
Such testing is used in situations when it is important to recognize the two VZV strains, like in suspected vaccine adverse events. Examples of possible varicella vaccine-adverse events include:
- Varicella or a varicella-related complication in a vaccinated person 7 to 42 days after vaccination.
- Herpes zoster in a vaccinated person.
- Suspected secondary vaccine-strain VZV transmission.
Samples of blood, cerebrospinal fluid, biopsy, or autopsy specimens may also be tested for vaccine-strain/wild-type VZV discrimination to confirm etiology and to identify a vaccine-adverse event. However, these specimens and can lead to false negative results.
The CDC Herpesvirus Laboratory and APHL Vaccine Preventable Diseases Reference Centers can distinguish wild-type VZV from Oka strain using both strain differential real-time PCR and PCR combined with restriction fragment length polymorphism. Each center (WI, CA, NY, MN) receives specimens from designated states.
A single serologic IgG test can determine if a person has antibodies to VZV from past varicella disease or who may be candidates for varicella-zoster immune globulin (VZIG). The product available in the United States is VariZIG.
Commercial enzyme-linked immunosorbent assays (ELISAs) are the recommendation for screening. Whole infected cell (wc) ELISA is the most commonly used test to determine if a person has antibodies to VZV from past varicella disease. Wc ELISA taken from blood samples can readily detect seroconversion to natural infection with VZV.
Routine testing for varicella immunity following vaccination is unnecessary because commercially available VZV IgG assays are not sensitive enough to detect all seroconversions after a vaccination.
The more sensitive purified glycoprotein ELISA (gpELISA) has been used in research settings to detect seroconversion after vaccination. However, testing with gpELISA is not available commercially.
IgG avidity in research settings determines if a person who is IgG positive for VZV was infected with the virus in the past or more recently.
The laboratory at CDC developed an IgG avidity assay, which determines if the most recent VZV rash was due to primary infection (varicella) or reactivation (herpes zoster).
- High avidity is an indicator of a remote infection.
- Low avidity is an indicator of VZV primary infection.
People infected in the past tend to have antibodies with a high affinity for binding to the antigen. People with a more recent infection tend to have a low affinity.
Vaccinated people undergo antibody affinity maturation following vaccination, which leads to moderate to high IgG avidity VZV antibody. Measurements of VZV avidity in vaccinated people are unlikely to distinguish remote infection (or vaccination) from recent (breakthrough) infection with VZV. This test is not available commercially.
How Do I Know if a Spot is Chickenpox? | This Morning
FAQ
How do doctors check for chickenpox?
Health care providers can usually diagnose chickenpox or shingles with a visual examination. But in some cases, your provider may also order a chickenpox or shingles test to confirm the diagnosis. These tests are also sometimes ordered to check for immunity to the varicella zoster virus (VZV).
How do I confirm chicken pox?
Chickenpox also can be confirmed with lab tests, including blood tests or a tissue study of samples of affected skin.Apr 19, 2023
Can a blood test detect chickenpox?
For chickenpox testing, a blood test can detect the presence of antibodies against the varicella-zoster virus. This test is useful if you’ve never had chickenpox and are unsure if you are immune. In some cases, a sample of fluid from a blistering rash may be collected for testing.
How is chickenpox diagnosed?
Chickenpox is a viral infection in which a person develops very itchy blisters all over the body. It was more common in the past. The illness is rare today because of the chickenpox vaccine. Your health care provider can most often diagnose chickenpox by looking at the rash and asking questions about the person’s medical history.
How do I know if I have chickenpox?
If you have a painful rash on one side of your body and a history of chickenpox, your healthcare provider may recommend a shingles test. The test involves collecting a sample of fluid from the blisters for laboratory analysis. In certain cases, a blood test may also be performed.
What happens after a chickenpox test?
After testing for varicella, the results will indicate whether you have been infected with the virus. If the test shows that you have antibodies to varicella, it means that you have had chickenpox in the past or have been vaccinated against it.
Why should I get tested for chickenpox?
Why Get Tested? To diagnose, as necessary, a current, recent, or past case of chickenpox or shingles; to determine whether you have developed immunity to the varicella zoster virus (VZV) or whether there is the potential for reactivating a VZV infection prior to receiving immunosuppressive drugs
What does a positive chickenpox test mean?
In adults and individuals with a weakened immune system, a positive test result for varicella indicates that they have had chickenpox in the past or have been vaccinated against it. They are not at immediate risk for developing chickenpox.