Zika virus is primarily transmitted to people through mosquito bites. Only specific mosquitoes can spread Zika virus. One of those mosquitoes can be found in Indiana from about mid-summer through early fall.
Another transmission route is from a pregnant woman to her fetus. When a woman is infected during pregnancy, there is an increased risk for microcephaly and other severe fetal brain defects. A pregnant woman may also pass Zika virus to her newborn during delivery. There has not been any evidence that Zika virus can be transmitted through breast milk.
Zika virus can also be spread from one partner to another through sexual activity. It can spread a few days before symptoms develop, and has been found to be present in semen for several months. CDC recommendations for protecting sexual partners can be found here: http://www.cdc.gov/zika/transmission/sexual-transmission.html
Blood transfusions may also transmit Zika virus from one person to another. To date, this has not been reported in the US blood supply.
Once a person’s infection has subsided, it is believed that a recovered person will be protected from future infections.