This is the first time the mosquito-borne disease has been directly linked to causing deaths
Three people have died in Colombia after contracting the Zika virus, which is spreading across South America and has emerged in Europe and the US.
It is believed to be the first time health officials have directly blamed the mosquito-borne disease for causing fatalities.
Brazil, where the virus is most prevalent, said Zika had been detected in urine and saliva, and officials there and in the US warned even kissing could potentially spread the disease.
Scientists pointed out there was no proof the virus could be transmitted through the fluids, but said people should take precautions, especially expectant mothers.
Brazil's president Dilma Rousseff has urged pregnant women not to kiss strangers as carnival season gets under way.
The victims in Colombia died of complications after being infected with Zika and then developing a rare neurological disorder called Guillain-Barre syndrome.
The condition sees the immune system attack the nervous system, causing weakness and sometimes paralysis or even death, but most Guillain-Barre patients recover.
Cases of the disorder have increased along with the spread of Zika, which is being blamed for causing brain defects in thousands of babies.
Many have been born with microcephaly, or abnormally small heads and brains, and the UN has urged increased access to abortion because of fears of severe birth defects.
Director of Colombia's national health institute Martha Lucia Ospina said: "Other cases (of deaths linked to Zika) are going to emerge.
"The world is realising that Zika can be deadly. The mortality rate is not very high, but it can be deadly."
The World Health Organisation has declared an international emergency and warned Zika could infect up to four million people in the Americas and spread worldwide.
This week, it was announced a pregnant woman in Spain who had travelled to Colombia has the virus - in what is thought to be the first such case in Europe.
Colombia is one of around 30 countries and territories which have been affected so far, with the hardest hit nation being Brazil.
Puerto Rico has become the latest country to declare a public health emergency.
The disease was previously thought to have been passed only by the Aedes mosquito, and not from human-to-human.
But this week came the news in Dallas that a patient had caught the virus after having sexual contact with someone who had returned from Venezuela, where Zika is circulating.
US health officials have issued guidelines to prevent the sexual transmission of the virus, telling men who have been to outbreak areas to use condoms during sex with pregnant women.