Zika virus is primarily transmitted to humans through bites from Aedes mosquitos, which often live around buildings in urban areas and are usually active during daylight hours (peak biting activity occurs in early mornings and late afternoons).
Spread of the virus can also occur through blood transfusion and by people with Zika to their partners. Therefore, it's recommended to avoid sexual contact with people who might be suffering from an active Zika infection.
Zika virus usually remains in the blood of an infected person for a few days but it can be found longer in some people. That is why it is important to avoid mosquito bites within the first week of illness, as this will reduce the risk of you transmitting the virus to mosquitoes, which can then bite and infect more people.