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Christos Mousoulis is a medical doctor specialising in Public Health. He is currently an Academic Clinical Fellow doing his health protection placement at Public Health England – West Midlands East team. His main interest is in Academic Public Health and in Clinical Trials in particular.
Bharat Sibal is a Lead Consultant in Communicable Disease Control working for Public Health England, Health Protection Team based in Birmingham. He has worked for WHO in Nepal and India and has wide interests in control of infectious diseases internationally.
Over the last few months a lot of media attention has being put on Zika virus and various national guidance has been produced. As Public Health England (PHE) Health Protection Team we have received a number of queries from GPs and other primary care colleagues regarding Zika virus testing and the role of diagnostics in primary care. PHE has produced various guidance on Zika virus and a specific one has been produced for primary care.1 We also read the article published in BJGP2 with interest and based on current guidance from PHE we believe that the following should be helpful to resolve queries from our primary care colleagues. Please note that these recommendations are being updated periodically to reflect up-to-date evidence which is available at: https://www.gov.uk/guidance/zika-virus.3
What is the test for Zika?
A blood test can confirm or exclude the presence of Zika virus in symptomatic patients only. Main symptoms are fever, headache, rash, joint pain and muscle pain. A clotted ‘red top’ (plain) or ‘yellow top’ (serum separator) blood, EDTA ‘purple top’ blood and a small volume of urine without preservative should be sent to the local microbiology/virology laboratory.1 The attending clinician should complete a standard, local laboratory form along with PHE – Rare and Imported Pathogens Laboratory request form (RIPL) available at: https://www.gov.uk/government/publications/rare-and-imported-pathogens-testing-form-to-submit-sample.1 The blood test is then sent to be processed by the RIPL. Travel history and clinical details should also be included on the form. The blood test is a PCR test, i.e. it tests for the presence of DNA of the virus in symptomatic patients only. It can only detect Zika virus during a seven day period following the onset of symptoms. It is not an antibody test, so it cannot confirm or exclude prior infection. RIPL is in the process of developing a prototype antibody test for Zika, but this is not yet widely available.
Who should be tested?
A pregnant woman with a history of travel to a Zika area during pregnancy, who reports clinical illness that raises the suspicion of Zika virus disease, during or within 2 weeks of travel, should be tested for Zika virus infection.4
All other pregnant women who have travelled to a Zika area during pregnancy should have a blood test done which will be stored.4 Please do not forget that all pregnant women who have travelled should also have a baseline ultrasound scan. Non-pregnant individuals who present with active symptoms suggestive of Zika infection should have the blood test as well. However, non-pregnant patients who were diagnosed elsewhere and who have recovered from their infection do not require further investigation and can be reassured that Zika infection is short-lived and self-resolving.5
What if the result is positive?
If a pregnant woman has a positive test she should be referred to the local specialist Fetal Medicine Unit.4 If there is evidence of a problem with a baby (e.g. found on ultrasound scan) from a woman who has or who may have been diagnosed with Zika, the RIPL can test amniotic fluid for the virus. This will only be the case if the patient and the clinical team accept the risk of amniocentesis and the option of therapeutic termination of the pregnancy for a positive result.4 If someone has been diagnosed with the virus, this does not necessarily mean that the virus has affected the baby. They will be cared for and monitored throughout the pregnancy by the Fetal Medicine Unit and their midwife.
1 Public Health England. Zika virus infection: guidance for primary care (4th February 2016) URL: https://www.gov.uk/government/publications/zika-virus-infection-guidance-for-primary-care [23rd March 2016]
2 Burke RM, Pandya P, Nastouli E, Gothard P. Zika virus infection during pregnancy: what, where and why? Br J Gen Pract 2016; 66 (644): 122-123
3 Public Health England. Health protection – guidance. Zika virus (17th March 2016) URL: https://www.gov.uk/guidance/zika-virus [23rd March 2016]
4 Royal College of Obstetricians and Gynaecologists. Interim clinical guidelines on Zika virus infection and pregnancy (29th January 2016) URL: https://www.rcog.org.uk/en/news/interim-clinical-guidelines-on-zika-virus-infection-and-pregnancy/ [23rd March 2016]
5 National Travel Health Network and Centre (NaTHNaC). Travel Health Pro (17th March 2016). URL: http://travelhealthpro.org.uk/diseases/zikavirus/ [23rd March 2016]