Doctors around the world are looking for ways to help thousands of people in South and Central America and the Caribbean who have been affected by a disease called Zika.
What is the Zika virus?
The Zika virus is a disease which is spread by a type of mosquito found in some hot countries.
The current outbreak was first noticed in Brazil in May 2015, and spread very quickly across South and Central America.
Zika is very unlikely to affect the UK because the mosquitoes that carry the disease live in tropical countries and would find the UK too cold.
Most people who catch Zika aren't affected very badly and one in five don't even realise they have the disease.
Other people might feel unwell, as if they have flu, but it doesn't usually last more than a week.
But it is much more serious for women who are pregnant.
Scientists say they think it may affect how a baby grows before it's born.
How is it spread?
Zika is spread by Aedes mosquitoes which live in hot countries.
When a mosquito bites someone infected with Zika, they start to carry the disease, and then they can pass it on to the next person they bite.
The World Health Organisation has said that the Zika virus is a global public health emergency.
That means that the disease is seen as a serious global threat, like the Ebola virus in West Africa was in 2014 and 2015.
They are worried that it is spreading very fast, and across a big area, so they want people around the world to put more money into helping find a treatment to stop the virus.
How can people protect themselves?
There is no treatment for Zika yet, but people can try to make themselves less likely to be bitten.
Health officials have said that people in affected areas should:
- use insect repellents
- wear long-sleeved clothes to cover their skin
- keep windows and doors closed to keep mosquitoes out
They have also said that pregnant women should stay away from areas that have the disease, if they can.
How can it be stopped?
Doctors around the world are trying to find ways to help solve the problem.
As well as looking for treatments and a vaccine to help people, they think that killing the mosquitoes which spread the disease could help.
Some countries are sending people out in to affected areas with special spray which kills mosquitoes.