Active Zika virus has been detected in saliva and urine, Brazilian scientists say.
The finding does not mean the virus can be readily transmitted through these bodily fluids.
Meanwhile, the US has advised men to abstain from sex or use condoms after visiting affected countries, if their partner is pregnant.
The US Centers for Disease Control believes a recent case of Zika was spread through sex.
While Zika is normally mild, the infection has been linked to thousands of suspected birth defects.
The updated advice says avoiding mosquitoes remains the best way to prevent infection, but advises men returning from affected countries to “correctly use condoms during sex or abstain from sexual activity for the duration of the pregnancy”.
In another development the governor of Puerto Rico has declared a public health emergency over Zika. The US territory has 22 confirmed cases.
