Approximately how many children nationally have chronic illnesses that
require long-term treatment and care (like asthma, sickle cell,
epilepsy). I don't want disease-specific information rather global
information.

You sort of contridicted yourself: global usually means the whole
world (about one billion chronic)
 If you ment nationally, you need to say which nation.

Thanks for your question. To clarify, I want to know the approximate
number of children with chronic illnesses in the U.S. Is that clearer?