Zika outbreak: What you need to know

   This infection is suspected of leading to thousands of babies being born with underdeveloped brains.

   Some areas have declared a state of emergency, doctors have described it as "a pandemic in progress" and some are even advising women in affected countries to delay getting pregnant.

   But there is much we do not know in this emerging infection.

What are the symptoms?

Deaths are rare and only one-in-five people infected is thought to develop symptoms.

These include:

• mild fever
• conjunctivitis (red, sore eyes)
• headache
• joint pain
• a rash

A rare nervous system disorder, Guillain-Barre syndrome, that can cause temporary paralysis has been linked to the infection.

There is no vaccine or drug treatment so patients are advised to rest and drink plenty of fluids.

But the biggest concern is the impact it could have on babies developing in the womb and the surge in microcephaly.