Curing the Zika Virus

Aedes aegypti mosquito. Image credit: Sanofi Pasteur via Flickr (CC BY 2.0 license)

In 2014, fewer than 150 Brazilian babies were born with microcephaly, a rare congenital condition which results in an abnormally small head. Since October 2015, however, more than 4700 cases have been reported in the country 1. While other causes are being investigated, Brazilian authorities have found increasing evidence that the unprecedented rise in this rare birth defect is linked to the recent outbreak of the Zika virus in the area. The virus has now spread across the Americas and the Caribbean to over 20 different countries and has been declared “a public health emergency of international concern” by the World Health organisation2.

The mosquito-borne Zika virus was first identified in humans in Uganda and Tanzania in 1952 and has since been recorded in tropical regions across the world. The virus presents only mild symptoms, such as joint pain, skin rashes and headaches, with 80% of those infected in Brazil’s recent outbreak developing no significant symptoms at all3. Although the entire population is equally at risk of infection, the virus is most dangerous for pregnant women and their unborn children.

Microcephaly is often fatal and can leave infants with lasting brain damage. With no way of knowing if the virus has affected fetal development until late into the pregnancy, pregnant women are being advised to avoid exposure to the mosquitos which carry the virus. Even women of child bearing age have been encouraged to postpone planned pregnancies4. However, a vaccine is urgently needed. In theory, a cure could be developed quickly: vaccines for similar diseases in the same class as the Zika virus already exist. The real problem, however, is not in development but in testing. Pregnant women are the group most in need of a vaccine – yet they are usually excluded from experimental trials. Testing the vaccine could therefore become a “practical and ethical nightmare”5.

While some experts believe it could take up to a decade to be approved,6 work is already underway to fast-track a vaccine at the US National Institute of Allergy and Infectious Diseases. The institute’s director, Dr Anthony Fauci believes a drug could be released as early as 2017 on an “accelerated emergency basis”. This would initially involve testing on non-pregnant women before testing on pregnant volunteers began. Fauci believes that “the highly charged nature and clear demand for a vaccine” will be reason enough for big pharmaceutical companies to get on board7.

For now, prevention is the only cure – but scientists must act quickly to protect the next generation of Brazilian children.

Edited by Sarah Spence



  1. Zika Outbreak: What you need to know, BBC News Online,
  2. World Health Organisation declares Zika virus public health emergency, The Guardian,
  3. For the WHO’s fact sheet on the Zika virus, visit
  4. Q&A: Zika and Pregnancy, Pan American Health Organisation (Regional Office of the WHO)
  5. Race is on to develop Zika vaccine but tests on pregnant women raise concern, The Guardian,
  6. Zika virus: US scientists say vaccine ’10 years away’, BBC News Online,
  7. Race is on to develop Zika vaccine but tests on pregnant women raise concern, The Guardian,

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