A man who traveled to South America has developed the third case of Zika virus in Illinois. The Illinois Department of Public Health previously reported two pregnant women tested positive for the mosquito-borne virus after traveling in Honduras and Haiti. The department announced the third Illinois case on its website Thursday. Most people exposed to the virus suffer only mild symptoms, but the risk is far greater for pregnant women because of a possible link to a birth defect. Federal health officials have posted Zika travel notices about countries in Central and South America and in the Caribbean. Also: Cape Verde, off the coast of western Africa, and Samoa in the South Pacific.