Does Dire Rat Filth Fever work like the DMG says it should?

[Phoenix8008]

Probably asked before, but I'm just running into this and wanted to ask.

In the DMG under Diseases, it says after someone is exposed to a disease via a monster attack they make a save at the end of the encounter to see if they are infected with it. (DMG 49)

In the MM (219) the Dire Rat entry says that if the Bite attack hits, the target contracts Filth Fever. My personal definition of contracting a disease would mean they are infected with it, but what is supposed to happen via the rules? Couldn't they just use the same terminology and say that the Bite attack either exposes the person to or infects them with Filth Fever? So are they automatically infected and suffer the initial effect right away, or do they still get to make a save at the end of the encounter before possibly suffering the initial effect if they fail the save?

Your help is appreciated.

 

[Dalzig]

All diseases work the same. You get a Saving Throw at the end of the encounter to throw off the disease. To work otherwise would be slightly overpowered (in terms of diseases).

The wording might seem inconsistent... but try to point out where it IS consistent throughout all 3 books.

 

[James McMurray]

It's in the Index of the MM:

Disease [Keyword]: Some monsters, such as slaads and
lycanthropes, inflict disease on creatures they hit. A creature
that contracts a disease makes a saving throw at the end of
the encounter. If the saving throw succeeds, the creature
shakes off the disease and suffers no ill effects. If the saving
throw fails, the creature is infected and suffers the initial
effect of the disease.