Diagnosing Zika virus
With the majority of infected individuals not presenting symptoms of the Zika virus, detecting a local spread has proved challenging. When symptoms are present, it can take up to two weeks to show up in the body. Medical professionals can now test for signs of the virus in the body, and based on that make a diagnosis. Investigations of outbreaks can take several weeks when they occur too.
If symptoms are present and a person suspects a Zika virus infection, it is strongly advisable to consult a medical doctor (normally a general practitioner or GP) as soon as possible. Symptoms may be mild and flu-like, but if there is reason to suspect an infection, such as signs appearing following recent travel to a high-risk area or a mosquito bite, a doctor will wish to assess the nature of ailments and potentially test for the virus.
A doctor will conduct a medical overview of a person’s overall health history, as well as any recent travels around the world. A doctor may also ask specific questions regarding a sexual partner (where relevant) and whether they have recently travelled (where have they visited and on what dates). A doctor will ask about possible exposure to mosquitoes and if any bites have occurred recently.
A doctor will likely suggest a test for the Zika virus if he or she suspects possible exposure. Tests may also rule out other infections of a similar nature, also carried by the same mosquito.
What tests are used for a Zika virus diagnosis?
Currently, there are two available tests for diagnosing the Zika virus using blood and urine samples. A blood sample will be taken intravenously (through a vein in the arm) using a needle and syringe and sent to the laboratory for analysis. The sample will be assessed for the presence of antibodies (proteins) in the bloodstream (which are normally produced by the body’s immune system as a defence mechanism to fend off the presence of an infection).
A urine sample will be requested in a cup provided and sent to a laboratory for analysis. Signs of viral infection will be assessed and a diagnosis of which virus is present in the body made – Zika, dengue fever, yellow fever or chikungunya.
If Zika virus is suspected, it is important to test and diagnose an infection, even once symptoms begin to clear. Blood and urine tests can detect the presence of the Zika virus, irrespective of the transmission mode (mosquito bite, sexual transmission or other).
Analysis will look at the genetic code of the virus (during an active infection). Tests are not effective once the body has completely cleared the infection.
If a woman is pregnant, a doctor will likely recommend testing between 2 and 12 weeks following possible virus exposure. A doctor may also recommend an ultrasound scan during a woman’s pregnancy to detect any abnormalities of the brain, and specifically microcephaly. Ultrasounds may be recommended every 3 or 4 weeks thereafter to monitor the baby. A doctor may also suggest an amniocentesis test which involves extracting a sample of amniotic fluid (the clear, yellow-ish fluid surrounding a developing foetus during pregnancy, contained in the amniotic sac) using a needle which is inserted into a pregnant woman’s uterus.