Unlike other status ailments, Pokérus
cannot be healed at a Pokémon Center
or with any status ailment healing
item, and can only be obtained by the
Pokémon in question once. When a
Pokémon has the Pokérus, it gains
double the effort values from battling
(i.e., fighting a Magikarp will give
two Speed EVs, rather than one).
Effort points gained from vitamins are
not doubled. The infected Pokémon can
infect other Pokémon with the virus
for a period of about two days.
However, the Pokérus timer can be
delayed by several methods including
placing the infected Pokémon in a PC
There is a 3 in 65,536 (about 1/3 of the chance to encounter a Shiny Pokémon) of enountering it on a wild or newly hatched pokemon.