Blood draw
Zika Virus (IgM & IgG)
IgM and IgG against Zika for recent or past infection.
€ 107,00
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Infections · Blood
Zika virus IgG
Antibodies that point to a past infection with the Zika virus; strongly affected by cross-reaction.
At a glance
- Measured in blood
- In 1 test panel
- No special preparation
Explanation
Zika virus IgG: what is measured?
The Zika virus is transmitted by a mosquito and occurs in parts of Central and South America, the Caribbean, Asia and Africa. After an infection, the immune system makes IgG antibodies (defense proteins), which appear later than IgM and then remain detectable for a long time. IgG therefore points to an infection that happened some time ago. According to the LCI guideline (RIVM), serology is assessed from about six days after the start of symptoms or if the time of onset is unknown; in the first week, a PCR is the appropriate test.
What can it detect?
- A past infection with the Zika virus, even if it caused no symptoms
Result
What does the result mean?
Positive result
IgG antibodies were found. That fits an infection with the Zika virus some time ago, but the result does not say when. More importantly, the Zika virus closely resembles other viruses from the same family, such as dengue and yellow fever virus. A positive IgG can therefore also be due to a previous dengue infection or a vaccination against yellow fever. The LCI guideline (RIVM) therefore prescribes a neutralization test in a specialized laboratory to confirm the result. A past infection probably gives long-lasting protection, but exactly how long is not known.
Negative result
No IgG antibodies were found. This makes a previous Zika infection less likely. Shortly after an infection, IgG is not yet detectable, so with recent symptoms a negative result does not rule out an infection; a PCR and an IgM test are then appropriate. A negative result says nothing about protection in the future; there is no vaccination against Zika.
After an abnormal result
With a positive result, a neutralization test is done in a specialized laboratory to distinguish it from dengue and other related viruses. With a pregnancy or a wish to become pregnant, the doctor assesses, together with the travel history, whether further testing is needed. There is no treatment against the virus itself and no vaccination. Zika is notifiable (group C) in a number of situations: in pregnancy, with complications such as Guillain-Barré syndrome or a birth defect, and with hospital admission within four weeks after the start of the infection.
Reliability
How reliable is the test?
According to the LCI guideline (RIVM) on Zika virus infection, serology is hard to interpret because of cross-reaction with other viruses from the flavivirus family. With IgG this plays an especially large role, because dengue is common in the same travel destinations and the antibodies remain for years. A positive result must be confirmed with a neutralization test. The test is mainly used to find out whether someone has had an infection in the past, for example when planning a pregnancy, and not to detect a current infection.
What can affect the result?
- Cross-reaction with dengue, yellow fever virus and other related viruses, including after a vaccination against yellow fever, can give a falsely positive result.
- IgG appears later than IgM; shortly after an infection the result may still be negative.
- The result does not say when the infection occurred.
- How long and how well a past infection protects against a new infection is not certain.
Who it is for
Who is the test useful for?
Useful for
The result can be meaningful when planning a pregnancy or during pregnancy after a stay in an area where Zika occurs, or with past symptoms that fitted Zika. For people without such a question the result changes little: a positive IgG can also be due to a past dengue infection or a yellow fever vaccination and says nothing about a current infection.
How common is it?
The Zika virus is not transmitted in the European Netherlands, because the mosquito that spreads the virus does not occur here; infections are picked up while traveling. In the Caribbean Netherlands there was an outbreak in 2016 and 2017. Since November 2016, a Zika infection has been diagnosed in fourteen pregnant women in the Netherlands, with one child born with an abnormally small head and one case of Guillain-Barré syndrome.
RIVM and the RIVM LCI guideline on Zika virus infection
Drawbacks and risks
- A falsely positive result due to cross-reaction with dengue or a yellow fever vaccination can lead to unnecessary worry and to postponing a pregnancy.
- A positive result says nothing about the time of infection, so around a pregnancy it often gives no clarity.
Get tested
Zika virus IgG: test panels
Zika virus IgG is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and resultsMore explanations
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