While the virus causes mild symptoms in adults, it has been linked to birth defects in babies born to Zika-infected women. We wish we knew more, we wish we could do more”. Mayo Clinic infectious diseases specialist Dr. Pritish Tosh says, “It is important to remember the primary mode of transmission is from an infected mosquito in an endemic area.” All travelers are advised to use insect repellent and take other steps to avoid mosquito bites.