Most Pokemon fans know by now that the series holds a lot of secrets; it's always been the creators' intent to have monsters that can't be captured or mysteries that leave fans guessing. Just like how shiny Pokemon are a coveted easter egg in the series since Generation II, there's a secret virus in the Pokemon world introduced in the Johto games, and it's a virus that many players want to get: Pokerus.

RELATED: Pokemon: Everything You Need To Know About Natures

It does sound quite odd: Why would anyone want to get infected with a virus? What does it even do, and how do my Pokemon catch it? Rest assured, all these questions and more will be answered, and you'll come out the other side of this guide a certified Pokerus expert.

What Is Pokerus?

Pokerus Graphic Elm Pokemon
Pokerus Graphic Elm Pokemon

The few Generation II players that initially discovered Pokerus must have been quite surprised after healing up at the Pokemon Center. Nurse Joy is perplexed, having never encountered such a phenomenon before, so the only way to learn more is by talking to the reliable Professor Elm.

Elm explains that Pokerus is a virus that infects only Pokemon and multiplies quite fast, but there are no negative side effects to contracting it. Seems like a strange easter egg to put into a game if it doesn't do anything, right? Furthermore, the odds for contracting Pokerus after a wild encounter are 3 in 65,536, or approximately 0.000046%. That's much rarer than what the rate for finding/hatching a shiny was in Gen II, which was 0.012%.

So if this virus has no negative effects and is so rare that most players will never encounter shiny Pokemon in any game they play, what makes Pokerus desirable? Well, what Elm doesn't tell players is that Pokerus is actually a mutualistic virus, which means it benefits both the virus and the host that it resides in. These benefits are what make players scramble to infect all their Pokemon with Pokerus.

What Does Pokerus Do?

pokerus older generation pokemon photo
pokerus older generation pokemon photo

The effect of Pokerus is actually quite hard to spot unless you know what to look for. This is because it impacts another often invisible element of the Pokemon games, which is EVs, or Effort Values. You can learn all about Effort Values here, but essentially EVs are gained whenever your Pokemon wins in battle, and they increase whatever stats they earned the EVs in.

If your Pokemon earns the maximum amount of Speed EVs, they will likely be faster than a similar Pokemon without any Speed EVs. Players who EV train their Pokemon often choose which stat(s) they want to increase and meticulously defeat only Pokemon that yield those specific EVs.

This can be a tiring process, but that's where Pokerus comes in. A Pokemon with Pokerus will gain double the EVs from battling Pokemon, making the process much faster and easier. Ideally, every Pokemon would benefit from having Pokerus.

How Do I Tell If My Pokemon Has Pokerus?

pokemon sword shield drakloak pokerus
pokemon sword shield drakloak pokerus

If you happen to have a Pokemon infected with Pokerus, the Nurse Joy at any Pokemon Center will inform you upon your first time healing that Pokemon since infection. Otherwise, a Pokerus status can be seen on a Pokemon's summary page. Though the indicator icon has changed somewhat over the years, you can usually identify it by its purple/magenta color. In earlier games, the status was abbreviated to PKRS, but more modern games spell out Pokerus fully.

How Long Does Pokerus Last?

pokerus infected cured pokemon
pokerus infected cured pokemon

Pokerus is interesting in that it only progresses when the Pokemon is in the player's party. When a Pokemon is in the PC, it is essentially in a frozen state and will keep its infected status. This is great for players who want to have a Pokemon they can always use to infect other Pokemon for EV training.

The virus only progresses when a Pokemon is in the party at the start of a new day. This can mean either the stroke of midnight or loading the save file into a new day when the game was saved during a previous day. When in the party, a Pokemon's Pokerus will usually last for about one to four days before being cured by itself. However, the Pokemon will still gain double the EVs in battle; it just won't be able to spread the virus. A cured Pokemon will have a unique "cured" icon in the place where it once had the Pokerus infection status on its summary page.

How Do I Get Pokerus?

pokemon sword shield trade screen
pokemon sword shield trade screen

There's really only one way of obtaining Pokerus, and that's through exposure to another Pokemon who has it. As you already know, though, the 3 in 65,536 odds of encountering it after a wild Pokemon battle aren't really in your favor. Luckily, there are plenty of generous people out there that want to share their good fortune with the rest of the community.

RELATED: Piers' Obstagoon In Sword & Shield Is The Only Gym Leader Pokemon To Have EVs Invested In It

A Subreddit called GiveMeTheVirus is full of Pokemon players that request and offer to trade Pokemon that have Pokerus in order to spread the virus to players who want the EV benefits. Players can request help with any games that still have Wifi connection, such as 3DS and Nintendo Switch Pokemon games. Sadly, DS Wifi support was discontinued back in May of 2014.

Once a Pokemon with Pokerus is in the party, it can spread the virus to the Pokemon adjacent to them but no further, which means it'll take some re-ordering of the party to spread to everyone. Sometimes it takes several battles in order for infection to occur between party members, but pretty soon you'll have a full team ready to gain EVs twice as fast.

Next: Pokemon: Everything You Need To Know About IVs