It should not be surprising that a pokemon which itself is frequently called an "epidemic" and "infestation" should also be one of the leading vectors of disease in the pokemon world. Zubat are not only fearsome in appearance, with their lack of eyes, purple wings, and fangs, but also extremely dangerous to an unprepared pokemon.

A Zubat's mouth is open frequently for the purposes of echolocation, but this is quite unsanitary and leaves it easy prey for airborne viruses: rare is even the cold which a Zubat does not catch. Although it is far from the only pokemon to learn techniques such as leech life and bite, its sharp fangs pierce the skin deeper and are shaped in a way which allows for the easy transmission of viruses. Finally, its poison-type immune system keeps it alive to carry diseases which would kill an ordinary pokemon.

Thankfully for humans, it is pokemon who suffer the brunt of Zubat bites, although woe betide those who venture into a cave without a pokeball. Typically Zubat infections can be cured at a pokemon center, but occasionally they run across incurable mutant diseases, most of which kill fast and spread faster.

To add insult to injury, Zubat are believed to be one of the few pokemon which can not spread the Pokerus, a strange pathogen which increases a pokemon's abilities and is prized by trainers worldwide.