Achildren’s hospital in a major american city reported a dramatic increase in the number of rheumatic fever cases. doctors were alerted to start monitoring sore throats more carefully. why do you suppose the prevention method was recommended?

As the main illness before you have a fever will normally be sore throat ( if you are heaty ) and flu ( if you caught a cold ) .
Hence the Doctors need to start monitoring the sore throats more carefully to prevent the increase of rheumatic fever cases .
Hope this helps !! :)