Local Transmission

Limited local confirmed transmission is defined as a single, locally acquired case, or cases clustered in a single household or nearby houses. Local transmission of the virus from a person infected while traveling is possible during the summer. A person who becomes infected, while traveling outside Illinois, and then returns to Illinois while the virus is still circulating in their blood, could be bitten by Aedes aeqypti or Aedes albopictus mosquito. That mosquito could then bite a second person and transmit the virus.

In the emergency preparedness and response chart, this would be phases two and three.

Should limited local confirmed transmission occur in Illinois, IDPH will consider requesting assistance from CDC, including the support of the CDC’s Emergency Response Team (CERT). IDPH will conduct weekly, or more frequent, Zika Virus Incident Management meetings and consider activation of the IDPH Incident Management Team (IMT).  If widespread transmission were to occur, IDPH would request this additional support.

With permission from the Florida Department of Health, IDPH has adopted Florida’s local Zika transmission plan, in the event of a local Zika outbreak.  This plan includes guidance for conducting local Zika investigations and community surveys for households, clinics and businesses within a 150 yard radius of the properties of interest.  

Also in the unlikely event of local transmission, IDPH will set up disease surveillance centers around the state and will begin conducting mosquito laboratory testing.

Human Disease Surveillance

If an individual tests positive for Zika virus and did not travel to an area with Zika virus, and has not had unprotected sexual contact with someone who traveled to an area with Zika virus, CDCS would ask about exposures to mosquitoes within Illinois or the U.S. (as well as receipt of blood transfusions/organs). During the summer months in Illinois, IDPH is asking all individuals who have laboratory confirmed Zika virus to wear insect repellant and reduce their outdoor exposure to minimize the possibility of mosquitoes acquiring the virus. CDCS would then provide this information to IDPH environmental health staff and emergency response coordinators to work with the local health department to visit the locations where the individual had exposure to mosquitoes. Staff would check for Aedes aegypti and Aedes albopictus and perform any necessary mosquito control measures. CDCS would monitor for other illnesses/suspected Zika virus cases in that area.

Mosquito Control

Because Aedes aegypti have rarely been detected in Illinois, efforts will focus on the habitat of Aedes albopictus mosquitoes in coordination with LHDs, MADs, and other municipal mosquito control programs. IDPH environmental health staff and emergency response coordinators will work with LHD environmental health staff and emergency response coordinators.

If the traveler infected with Zika virus does not spend time outdoors while the virus is still circulating in their blood, it is very unlikely local mosquitoes will be infected. Therefore, environmental health staff response will be limited to the inspection of local residence properties for water-filled containers and distribution of door hangers recommending the use of insect repellent.