A young Havana woman is the first known person to have contracted the Zika virus in Cuba, authorities said.

The woman, 21, has been hospitalized though she so far does not have symptoms, the health ministry said.

So far, five people have been diagnosed with the virus in Cuba. The other patients contracted Zika in Venezuela.

The mosquito-borne Zika virus usually causes mild symptoms in adults, with a low fever, headaches and joint pain.

Its quick spread has caused alarm due to an observed association with microcephaly, a severe deformation of the brains of infants, and Guillain-Barre, a rare condition in which the body’s immune system attacks a part of the nervous system that controls muscle strength.

There is currently no vaccine for the Zika virus, and affected countries are focusing on wiping out mosquito populations in an effort to curb its spread.

Brazil has been hardest hit by the Zika outbreak, with some 1.5 million people infected and 745 confirmed cases of microcephaly in children born to women infected with the virus while pregnant.