Task List/pkrs lv3
The pay-off from chasing Pokérus is well worth the effort, isn't it? Remember to click as many of the host's Pokémon as you can for the best chance of being the next host!
Click the "Pokérus" button in the top right corner under the bonus counters (on the mobile site, click the arrow in the bottom right corner, then click the "Pokérus" button under the bonus counters) to go to the host's page.
For more information on Pokérus, check the Wiki.