Oh this one's easy.
First you will need a map, a US map.
Then you will need to locate Pennsylvania on it.
Then you just look up how many illegals from the 2017 Migrant Caravan finally arrived and crossed over the Mexican Border into Pennsylvania.
Then you find out how many of those were the measle cases on account of people who didn't allow their children to be vaccinated at school at the urging of RFK and the other medical experts with their bigly PhDs from Trump University.
You squeeze those numbers through a Lotka-Volterra Equation, and bingo, you got your number.