Actually in many countries they are...
Not well known is that now all our International Airports have "quarantine" cells. The exact number in each airport is a secret but if more are needed, they have them offsite as well. At the time, I worked for a major International airline and got to see them. We went through the entire bio-war routine.
Anyway, here's an old CDC directive for International airports... it talks about Zika and Dengue. The present directive is now classified.
Upon arrival, travelers undergo visual assessment, and infrared cameras are used to detect abnormal temperatures. If needed, an ear thermometer is used to recheck travelers' temperatures, and a quick in-person assessment is provided. Officials may also investigate travel and health history, symptoms, exposure, and other relevant factors. If the traveler fits the definition of a suspected case of imported dengue or Zika, a blood sample will be collected. Blood samples undergo the dengue NS1 antigen rapid test at international airports, and remaining blood and urine samples are sent to the CDC's laboratory for further active monitoring for flaviviruses.