Zika diagnosis

Zika virus, a disease that usually occurs in tropical environments and is spread to humans primarily via mosquito bites, shows symptoms in about 1 in every 5 people who become infected. The symptoms are mild and can be initially confused with viruses from the same family such as dengue fever until the patient has undergone further diagnosis from healthcare professionals. The symptoms can include a fever, joint pain, conjunctivitis, muscle pain and a rash.

The effects of the disease are not yet fully understood. Although the infection can result in mild symptoms, the infection may lead to serious impacts in pregnant women. In a recent outbreak of Zika infection in Brazil, there have been increased cases reported of microcephaly, a condition which cases head and brain defects in babies.

The virus is also thought to cause Guillain-Barré syndrome, a disease that affects the nervous system, in some people. This can lead to paralysis and eventual death in some people.

There are currently no specific treatments or vaccinations for Zika infections. However, patients who suspect they have the disease should visit a doctor. The doctor may conduct the following tests.

The reverse transcription-polymerase chain reaction

This reverse transcription-polymerase chain reaction (RT-PCR) test is carried out to look for viral RNA in the fluids of a person suspected of having the Zika virus. The Zika virus can be in a person’s urine for up to ten days after symptoms of the disease show.

Alongside this an immunoglobulin (Ig) M ELISA and plaque reduction test are used to identify Zika antibodies. When the test results are reviewed they should also be examined for possible confusion with antibodies from other similar diseases such as dengue as mosquitoes can spread these as well.

When it comes to the testing of new born babies, a sample is taken from the umbilical cord within two days of birth to see if Zika virus is present. This can be tested using the RT-PCR method. Additional tests can be carried out on cerebrospinal fluid and placenta.
 

When a pregnant mother has been diagnosed with the Zika virus, further tests can be carried out to observe the development of her baby in the womb. Microcephaly, a condition which causes birth defects such as an underdeveloped brain and smaller head size in a baby has been linked to the Zika virus.

Ultrasound is commonly used to monitor the development of an unborn child. The technology uses sound waves to produce a scan of a child in the womb. The test can be used at regular intervals under medical supervision.

The technology can detect a smaller head size from the time the foetus is about 20 weeks old. This is not always an indication that a child has microcephaly as some babies grow more quickly after this. Ultrasound can however provide some indication.

MRI

In conjunction with ultrasound, magnetic resonance imaging (MRI) can provide some indication of defects in the brain structure of a developing foetus. This technology uses powerful magnetic fields to produce an image of the brain.

Amniocentesis test

With this test, healthcare professionals are looking for any potential abnormalities. It can be conducted between weeks 15 and 20. A sample of the amniotic fluid from the amniotic sac surrounding the baby is taken for testing. However, healthcare professionals need to be take specific care in carrying out this test as there is a risk of miscarriage due to the mother’s age, her health and any inherited conditions.

References

• Centers for Disease Control and Prevention: http://www.cdc.gov/zika/hc-providers/diagnostic.html
• World Health Organization on diagnosis: http://www.who.int/mediacentre/factsheets/zika/en/
• European Center for Disease Prevention and Control: http://ecdc.europa.eu/en/healthtopics/zika_virus_infection/factsheet-health-professionals/Pages/factsheet_health_professionals.aspx
• UK government health protection guidance: https://www.gov.uk/guidance/zika-virus#diagnosis
• NHS Choices on amniocentesis: http://www.nhs.uk/Conditions/amniocentesis/Pages/Introduction.aspx