Hahaha, that's crazy!
- The rate of a shiny encounter is 1 in 8192.
- The rate of an encounter with a Pokemon with Pokerus is 3 in 65,536.
It would be a .0000457763672% x 0.000122070312% chance so if my calculations are correct:
The chance of an encounter with a shiny Pokemon with Pokerus would be a:
0.00000000558793543% chance. Or 1/178956971.