Zika Virus

Zika virus is spread to people primarily through the bite of an infected mosquito, but can also be transmitted through sexual interaction or from mother to child. Zika virus infection during pregnancy can cause birth defects. The mosquitoes that can become infected with and spread Zika virus live in many parts of the world, including parts of the United States.


  • In August 2018, the Centers for Disease Control and Prevention (CDC) updated its recommendation for men with possible Zika exposure to avoid conception and unprotected sex for at least three months after the beginning of illness or after last possible exposure (if no illness developed). The previous recommendation was for men with possible Zika exposure to avoid conception and unprotected sex for at least six months. See the full guidance.
  • A new study from the CDC found that about one in seven babies born to mothers with possible Zika infection during pregnancy, who were at least one year old, had one or more health problems possibly caused by Zika. Some of these problems were not apparent at birth and were identified as the babies grew older.
  • Aedes albopictus, one species of mosquito that is capable of transmitting Zika, has been found in Wisconsin as of 2017. There is no evidence of Zika-infected mosquitoes or local transmission of Zika in Wisconsin. Wisconsin residents at risk for Zika virus infection are people who have traveled or had sexual contact with someone who traveled to locations with a risk of Zika.
Travel-Related Zika Virus, as of November 6, 2019
  2019 2018 2017 2016
Confirmed cases 0 0 9 63
Probable cases* 0 0 0 0
Undetermined flavivirus, confirmed 2 2 1 1
Total testing completed 53 113 948 1062

* Probable cases have presumptive positive laboratory results without confirmatory CDC testing.

Wisconsin case numbers are updated monthly




Last Revised: June 10, 2020