Zika virus, originally found in Africa, was discovered in Brazil in early 2015. Since then, it has
spread rapidly throughout South and Central America, Mexico, the Caribbean, Puerto Rico,
and limited local transmission in Florida by late 2016.
The virus amplifies in humans which is then transmitted to other humans by mosquitoes. Only 1 in 5 people who are infected with the virus will show symptoms and most will recover within a week. While the effect of the virus in adults is usually mild, the greater concern is its potential effect on the development of babies in infected pregnant women, particularly during the first trimester. There is also evidence that the virus can be transmitted through sexual contact. To date, the only cases in Illinois have been in individuals who have travelled to areas with active virus transmission. Local transmission is unlikely.
There are two species of mosquitoes implicated in the spread of the Zika virus. Aedes aegypti is the primary carrier of the virus, found in warm climates but rarely in Illinois. Aedes albopictus is a secondary carrier, with a range that extends into central Illinois. Neither of these species are well established in the District, though on occasion, Aedes albopictus has been found.
Aedes albopictus develops in discarded tires, buckets, and other artificial containers. Populations can be sustained locally during summertime if introduced via human activity, and if eggs are laid in places where the temperature does not get low enough to kill them, the population may emerge again the following year.
These are very aggressive and active during the day. Although they have yet to adapt to the cold Chicagoland winter, we continue to monitor the mosquito population for both species in the event that they do become introduced.
More information can be found on the Centers for Disease Control (CDC) web site here and on the Illinois Department of Public Health (IDPH): here.