Which of the following mosquito-borne diseases continue to occur in Illinois?

The correct answer highlights that the diseases which continue to occur in Illinois include East Equine Encephalitis, Western Equine Encephalitis, and St. Louis Encephalitis. These diseases are actively monitored and known to have been present in the state due to the climate and habitat conditions favorable for the mosquitoes that transmit them.

Eastern Equine Encephalitis and Western Equine Encephalitis are significant because they can cause serious illness and are known to be present in the regions of Illinois, particularly in rural areas. St. Louis Encephalitis is another virus that has been historically reported in Illinois and can lead to severe neurological manifestations.

The other options list diseases that, while notable, do not consistently occur in Illinois. For instance, while West Nile Virus is indeed a concern in Illinois, Zika Virus and La Crosse Encephalitis are not continuously reported at the same levels. Malaria and Dengue are mostly found in tropical areas and do not have a sustained presence in Illinois. Lastly, Chikungunya, Yellow Fever, and Rift Valley Fever typically occur in other geographic regions and are not endemic to Illinois, further distinguishing the focus of local mosquito-borne diseases.